JP2003063896A - Method for growing semiconductor film, device used for the same, device for purifying nitrogen raw material, semiconductor laser and optical communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor film growth method, a nitrogen source refining apparatus, and a semiconductor film growth apparatus capable of producing a group III-V compound semiconductor film containing nitrogen (N) containing few impurities and having good crystal quality. And a semiconductor laser and an optical communication system. SOLUTION: Metal Al or an alloy containing metal Al is arranged in a refining chamber of a refining device 5, and in the refining device 5, a nitrogen raw material (a nitrogen raw material composed of a nitrogen compound) supplied to the refining chamber is replaced It is purified by contacting with metal Al or an alloy containing metal Al (to remove impurities) and supplied to the reaction chamber 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor film growth method, a nitrogen source refining apparatus, a semiconductor film growth apparatus, a semiconductor laser, and an optical communication system.

[0002]

2. Description of the Related Art III-V group compound semiconductors containing nitrogen (N) have band gap energies that can be controlled from the ultraviolet region to the infrared region, and most of them show direct transition type optical transitions. The progress is remarkable.

Nitrogen (N) -containing III attracting the most attention III
The material system of the group V compound semiconductor is GaN-based material and GaN.
It is an As-based material. The elements and manufacturing methods of these materials will be described below.

First, the GaN-based material will be described. Ga
Blue LEDs and blue LDs having an N-based material in the light emitting layer have been vigorously researched and developed since the realization of high-brightness blue light emitting LEDs, and room temperature continuous oscillation LDs have been realized. Along with this, application to a blue light source in a full-color display, a writing light source for a high-definition laser printer, a light source for next-generation high-density optical recording, etc. is being actively studied. In the future, LDs of GaN-based materials with higher performance and longer life will be required, so it is considered necessary to improve the crystal quality of the constituent films of the device.

Many of these GaN-based material elements have M
It is produced by the OCVD method. Here, as the group III raw material, a group III organic metal or hydride is used. Also,
As the nitrogen raw material, NH ₃ gas is used because most of them are inexpensive. Since NH ₃ gas has a high decomposition temperature, it requires a high substrate temperature. Therefore, desorption of constituent atoms from the grown film is likely to occur, the crystal quality deteriorates, and it becomes difficult to obtain a high-performance element. Therefore, for example, Japanese Patent Laid-Open No. 7-
No. 2,309,53 and JP-A No. 9-251957 disclose an example in which hydrazine, which decomposes at a lower temperature, is used as a nitrogen raw material.

Next, the GaNAs-based material will be described.
For the current optical fiber communication, the dispersion and loss in the silica optical fiber are small 1.3 μm, 1. A semiconductor laser having a long wavelength band of 55 μm is used. In the future, optical fiber will be used for each terminal (Fiber To The Ho
It is expected that optical information transmission technology will become more and more important as optical information transmission will be introduced between devices and within devices as well (me (FTTH)). In order to realize these, one of the most important issues is to reduce the cost of optical communication modules by "order of magnitude". They have a long-wavelength band with low power consumption and good temperature characteristics that do not require a cooling system. There is a strong demand for semiconductor lasers.

GaInPA on an InP substrate which is a III-V group semiconductor having a bandgap corresponding to this wavelength
s-based materials currently dominate the market. However, the InP-based material has a small conduction band discontinuity between the cladding layer (spacer layer) and the light emitting layer, and the confinement of injected electrons in the light emitting layer deteriorates as the temperature rises.

As a material capable of solving this problem, Japanese Patent Laid-Open No. 6-
No. 37355 proposes a GaInNAs-based material on a GaAs substrate. GaInNAs is nitrogen (N)
And a group III-V mixed crystal semiconductor containing other group V elements.
GaInNAs has a larger lattice constant than GaAs.
By adding N to InAs, the lattice constant can be lattice-matched to GaAs, the bandgap energy is further reduced, and light emission in the 1.3 μm and 1.5 μm bands is possible. The document “Jpn. J. Ap.
pl. Phys. Vol. 35 (1996) pp
． 1273-1275 ", the band lineup has been calculated by Kondo et al. GaInNAs is G
Since it is an aAs lattice matching system, the band discontinuity of the conduction band becomes large by using AlGaAs or the like for the cladding layer.
Therefore, it is expected that a high characteristic temperature semiconductor laser can be realized.

In this GaInNAs material, it is difficult to mix N into the growth film. For this reason, the MBE method (for example, JP-A-6-334168) or the MOCVD method (for example, JP-A-6-37355) in which N ₂ gas or a nitrogen compound is activated by plasma and introduced is used.

Further, in the MOCVD method which is a crystal growth method excellent in mass productivity, a method using dimethylhydrazine (DMHy) which is a nitrogen compound which is easily decomposed by heat and activated is disclosed in JP-A-7-154023 and JP-A-9-283857.
No. 3, which has been demonstrated experimentally that N is miscible.

However, MOCVD using this DMHy
It is difficult to stably obtain an element having good light emission characteristics by the method. When the element constituent film contains Al, it often exhibits particularly low light emission characteristics. Therefore, a light emitting element made of a GaInNAs material has not yet been put on the market. It is considered that this is because the crystal quality of the device constituent film is not sufficient and many non-radiative recombination centers are present.

As mentioned above, III-V containing nitrogen (N)
An element using a group compound semiconductor material system is a MOCVD method.
In many cases, as a nitrogen source,
NH ₃And hydrazines are used. From now on, the element configuration
Improving the crystal quality of the film is an important issue.

It is known that the nitrogen raw materials as described above have a property that it is difficult to remove water and alcohol, and that they cannot be sufficiently removed even by distillation purification.

It is feared that the impurities contained in these nitrogen raw materials deteriorate the crystal quality of the constituent film of the element using the material system of the III-V group compound semiconductor containing nitrogen (N).

[0015]

SUMMARY OF THE INVENTION The present invention is directed to a method for growing a semiconductor film, a nitrogen source refining apparatus, and a method for growing a nitrogen source capable of producing a III-V group compound semiconductor film containing nitrogen (N) having few impurities and good crystal quality. An object is to provide a semiconductor film growth apparatus, a semiconductor laser, and an optical communication system.

[0016]

In order to achieve the above object, the invention according to claim 1 is to transport a nitrogen raw material consisting of a nitrogen compound to a reaction chamber after contacting it with metal Al or an alloy containing metal Al. Then, a III-V group compound semiconductor film containing nitrogen (N) is grown.

The invention according to claim 2 is the method for growing a semiconductor film according to claim 1, wherein the nitrogen compound is
It is characterized by containing at least hydrazines.

The invention according to claim 3 is the method for growing a semiconductor film according to claim 1 or 2, wherein the metal A is used.
1 or an alloy containing metallic Al is in a liquid phase, and the metallic Al
Alternatively, a nitrogen source gas composed of a nitrogen compound is bubbled through an alloy containing metal Al and then passed through, and then transported to a reaction chamber to grow a III-V group compound semiconductor film containing nitrogen (N). .

The invention according to claim 4 is the method for growing a semiconductor film according to claim 1 or 2, wherein the metal A
The alloy containing 1 or metallic Al is a solid phase, and is characterized by being in the form of particles, fine particles, films, or porosity.

According to a fifth aspect of the present invention, in the method for growing a semiconductor film according to any one of the first to fourth aspects, the III-V compound semiconductor film containing nitrogen (N) is GaN. It is characterized by being a material.

The invention according to claim 6 is the method for growing a semiconductor film according to any one of claims 1 to 4, wherein the III-V compound semiconductor film containing nitrogen (N) is GaInNAs. It is characterized by being a material.

Further, the invention according to claim 7 is characterized in that a nitrogen raw material consisting of a nitrogen compound is brought into contact with metal Al or an alloy containing metal Al to purify the nitrogen raw material. It is a device.

The invention according to claim 8 is the nitrogen (N)
Reaction chamber for growing a III-V compound semiconductor film containing: a group III source for supplying a group III source to the reaction chamber; and a group V source for supplying a group V source to the reaction chamber 8. A nitrogen raw material purifying apparatus comprising: a nitrogen raw material source; and a nitrogen raw material purifying apparatus for removing impurities from a nitrogen raw material composed of a nitrogen compound from the nitrogen raw material source and supplying the nitrogen raw material to the reaction chamber. The apparatus for growing a semiconductor film is characterized in that the nitrogen raw material refining apparatus of 1.

The invention according to claim 9 is produced by using the method for growing a semiconductor film according to claim 5, and Ga is formed in the active layer.
The semiconductor laser is characterized by containing an N-based material.

The invention according to claim 10 is the same as claim 6
The active layer is formed by using the semiconductor film growth method described above.
The semiconductor laser is characterized by containing an aInNAs-based material.

The invention described in claim 11 is the same as claim 1.
0. In the semiconductor laser described in 0, the semiconductor laser is A
_{l x Ga (1-x)} As / Al y Ga (1-y) As (0 ≦ y <x ≦
1) A surface emitting semiconductor laser including at least one semiconductor multilayer film reflecting mirror.

The invention according to claim 12 is the same as claim 1
An optical communication system characterized in that the semiconductor laser according to claim 0 or claim 11 is used as a light source.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The inventor of the present application examined the influence of the impurities contained in the nitrogen raw material as described above by an experiment using an edge emitting laser structure including a GaNAs-based material film as an active layer.

FIG. 1 is a diagram showing a room temperature photoluminescence spectrum from an active layer having a GaInNAs / GaAs double quantum well structure composed of a GaInNAs quantum well layer and a GaAs barrier layer, which was manufactured by the MOCVD apparatus of the present inventor. is there. FIG. 2 is a diagram showing a sample structure of a semiconductor light emitting device. Referring to FIG. 2, the sample structure is G
A lower clad layer 202, an intermediate layer 203, an active layer 204 containing nitrogen, an intermediate layer 203, and an upper clad layer 205 are sequentially laminated on an aAs substrate 201.
In FIG. 1, reference numeral A is an AlGaAs cladding layer 202.
2 is a room temperature photoluminescence spectrum from an active layer 204 of a sample in which a double quantum well structure is formed by sandwiching a GaAs intermediate layer 203 on the upper side, and a symbol B indicates a 2 by sandwiching a GaAs intermediate layer 203 on a GaInP clad layer 202. It is a room temperature photoluminescence spectrum from the active layer 204 of the sample which formed the quantum well structure continuously.

The introduced gas was Ga (CH ₃ ) ₃ (TMG: trimethylgallium), Al (CH ₃ ) ₃ : (TMA: trimethylaluminum), In (CH ₃ ) with H ₂ gas as a carrier gas. ₃ (TMI: trimethylindium) organometallic, AsH ₃ (arsine), P: P
It is a hydride of H ₃ (phosphine) and a nitrogen compound of DMHy (dimethylhydrazine). DMHy
(Dimethylhydrazine) used was purified by a semiconductor material manufacturer.

As shown in FIG. 1, the photoluminescence intensity of sample A is lower than half that of sample B. Therefore, using one MOCVD device, AlGaA
GaI is formed on the semiconductor layer containing Al such as s as a constituent element.
When an active layer containing nitrogen such as nNAs is continuously formed,
There was a problem that the emission intensity of the active layer deteriorates. Therefore, G formed on the AlGaAs cladding layer
The threshold current density of the aInNAs-based laser is twice or more higher than that when it is formed on the GaInP cladding layer.

The inventor of the present application further examined the elucidation of this cause. FIG. 3 shows an example of the semiconductor light emitting device shown in FIG. 2 in which the cladding layers 202 and 205 are made of AlGaA.
s, the intermediate layer 203 is GaAs, and the active layer 204 is a GaInNAs / GaAs double quantum well structure.
It is a figure which shows the depth direction distribution of nitrogen (N) density | concentration and oxygen (O) density | concentration when it forms using the (device). SI is measured
Performed by MS. The following table (Table 1) shows the measurement conditions.

[0034]

[Table 1]

In FIG. 3, GaInNAs / GaAs
Two nitrogen (N) peaks are seen in the active layer 204 corresponding to the double quantum well structure. Then, in the active layer 204, a peak of oxygen (O) is detected. However, the oxygen concentration in the intermediate layer 203 that does not contain N and Al is about one digit lower than the oxygen concentration in the active layer 204.

On the other hand, the cladding layers 202 and 205 are made of GaI.
nP, the intermediate layer 203 is GaAs, and the active layer 204 is
When the depth direction distribution of the oxygen (O) concentration was measured with respect to the element having the GaInNAs / GaAs double quantum well structure as described above, the oxygen (O) concentration in the active layer 204 was at the background level.

That is, the nitrogen compound raw material and the organometallic Al
The substrate 2 is formed by using the raw material and using an epitaxial growth apparatus.
When the semiconductor light emitting device in which the semiconductor layer containing Al is provided between 01 and the active layer 204 containing nitrogen is continuously crystal-grown, oxygen is taken into the active layer 204 containing nitrogen. It became clear by the experiment. Oxygen taken into the active layer 204 forms a non-radiative recombination level, which reduces the luminous efficiency of the active layer 204.
It has been newly found that the oxygen taken into the active layer 204 is a cause of lowering the light emission efficiency in the semiconductor light emitting element in which the semiconductor layer containing Al is provided between the substrate 201 and the active layer 204 containing nitrogen. . The origin of this oxygen is considered to be a substance containing oxygen remaining in the apparatus or a substance containing oxygen contained as an impurity in the nitrogen compound raw material.

Next, the cause of oxygen uptake was examined. FIG. 4 is a diagram showing the Al concentration distribution in the depth direction of the same sample as FIG. The measurement was performed by SIMS.
The following table (Table 2) shows the measurement conditions.

[0039]

[Table 2]

From FIG. 4, Al is detected in the active layer 204 which originally does not contain Al raw material. However, a semiconductor layer containing Al (cladding layers 202 and 205)
In the intermediate layer (GaAs layer) 203 adjacent to
The l concentration is about one digit lower than that of the active layer. This indicates that Al in the active layer 204 was not diffused, replaced, and mixed in from the semiconductor layer (cladding layers 202 and 205) containing Al.

On the other hand, when an active layer containing nitrogen was grown on a semiconductor layer containing no Al such as GaInP, Al was not detected in the active layer.

Therefore, Al detected in the active layer 204
Is an Al raw material, an Al reactant, an Al compound, or Al that remains in the growth chamber or the gas supply line, and is combined with impurities (moisture, alcohol) in hydrazine and taken into the active layer 204. It is believed that That is, when a semiconductor light emitting device in which a semiconductor layer containing Al is provided between the substrate 201 and the active layer 204 containing nitrogen is continuously crystal-grown using hydrazine and an organic metal Al raw material, the active layer 204 containing nitrogen is obtained. Naturally in A
It was newly found that l was taken in.

Comparing the depth distribution of nitrogen (N) concentration and oxygen (O) concentration in the same device shown in FIG. 3, two oxygen peak profiles in the double quantum well active layer show that It does not correspond to the peak profile, but corresponds to the Al concentration profile of FIG. From this, it was found that the oxygen impurities in the GaInNAs well layer were not incorporated together with the nitrogen source, but rather were combined with Al incorporated in the well layer and incorporated together. That is, when the Al raw material remaining in the growth chamber, the Al reaction product, the Al compound, or Al comes into contact with the nitrogen compound raw material, Al and impurities (water, alcohol) contained in hydrazine are combined with each other. For the first time, it was clarified by experiments conducted by the inventors of the present application that Al and oxygen are taken into the active layer 204, and the oxygen taken into the active layer 204 reduces the luminous efficiency of the active layer 204.

Incidentally, JP-A-7-230953 and JP-A-9-251957 disclose purification methods of hydrazine.

That is, JP-A-7-230953 discloses that the water content of hydrazine is 100 ppm by weight or less.
A vapor phase growth method for a group IV compound semiconductor is shown,
Commercially available hydrazine was dehydrated with calcium carbide, then distilled in a nitrogen atmosphere, and InGaA was formed by the MOVPE method.
An example of growing an IN film is shown.

Further, Japanese Patent Application Laid-Open No. 9-251957 discloses a method for producing an InGaAlN film by MOCVD using hydrazine and ammonia as nitrogen sources. Commercially available hydrazine is dehydrated with calcium carbide and then in a nitrogen atmosphere. An example in which the InGaAlN film is grown by the MOVPE method after being distilled at.

However, III-V containing nitrogen (N)
In order to improve the crystal quality of a constituent film of an element using a material system of a group compound semiconductor, it is purified by a conventional method as disclosed in JP-A-7-230953 and JP-A-9-251957. However, the removal of water and alcohol is not sufficient.
Therefore, it was further found that it is necessary to remove water and alcohol from the nitrogen raw material.

The present invention intends to sufficiently remove impurities from a nitrogen source to produce a III-V group compound semiconductor film containing nitrogen (N) with few impurities and good crystal quality.

FIG. 5 is a diagram showing a configuration example of a semiconductor film growth apparatus according to the present invention. Referring to FIG. 5, this semiconductor film growth apparatus includes a reaction chamber 1 for growing a III-V compound semiconductor film containing nitrogen (N) on a substrate, and a reaction chamber 1.
Group III source 2 for supplying Group III source and reaction chamber 1
To remove the impurities from the group V source material 3 for supplying the group V source, the nitrogen source (N source) 4, and the nitrogen (N) source composed of the nitrogen compound from the N source 4 (nitrogen (N)
It has a purifying device (nitrogen raw material purifying device) 5 for purifying the raw material and supplying it to the reaction chamber 1, and a gas exhaust unit 6.

An example of such a growth apparatus is MOC.
VD (metalorganic chemical vapor deposition) equipment,
A MONBE (metal organic molecular beam epitaxy) apparatus, a CBE (chemical beam epitaxy) apparatus, etc. are mentioned. That is, MOCVD, MOMBE, CBE, or the like can be used as the growth method in the reaction chamber 1.

Further, in FIG. 5, B, Al, Ga, In, and Tl can be used as the group III element (group III raw material), and N is included as the group V element (group V raw material). P, As, Sb and Bi can be used. Also,
As the nitrogen raw material (N raw material) of the nitrogen compound, in addition to NH ₃ and hydrazine, amines composed of NH ₂ R, NHR ₂ , and NR ₃ (R is an alkyl group or an aryl group) can be used. However, the nitrogen compound preferably contains at least hydrazines.

That is, NH ₃ and amines have high decomposition temperatures, and 900 to generate a sufficient concentration of active species.
It is necessary under the temperature condition of about ℃. Therefore, the constituent elements are likely to escape from the growth film. In the case of a growth film containing In or N, the loss of these atoms becomes particularly noticeable.
On the other hand, the decomposition temperature of hydrazines is low, 500 ° C.
A sufficient concentration of active species can be generated in the vicinity, and it becomes easy to obtain a good quality growth film.

Here, hydrazines mean hydrazine,
Monomethylhydrazine, dimethylhydrazine, butylhydrazine, hydrazobenzene, etc., and NR ₂ NR ₂
(R is hydrogen, or an alkyl group or an aryl group).

Further, in the semiconductor growth apparatus of FIG. 5, metal Al or an alloy containing metal Al is arranged in the refining chamber of the refining apparatus 5, and in the refining apparatus 5, the nitrogen raw material ( Nitrogen raw material consisting of nitrogen compound)
Alternatively, it is supplied to the reaction chamber 1 by bringing it into contact with an alloy containing metallic Al for purification (removing impurities). Here, the transportation of the nitrogen source gas may be by carrier gas or by vapor pressure of the nitrogen source gas.

Examples of the alloy containing metal Al include Al-In, Al-Ga, Al-In-Ga and the like. These can change the melting point from around room temperature to about the melting point of Al (660 ° C.) depending on the composition. For example, the weight ratio of GaInAl is 100: 10 :.
Those of 1.8 are liquid at room temperature.

In the semiconductor film growth apparatus configured as shown in FIG. 5, metal Al or an alloy containing metal Al is placed in advance in the refining chamber of the refining apparatus 5. Thereafter, the nitrogen raw material (nitrogen raw material gas) consisting of a nitrogen compound is introduced into the purification chamber of the purification device 5 by using H ₂ , He, Ar, N ₂ or the like as a carrier gas or by the vapor pressure of the nitrogen raw material itself. Then, it is brought into contact with metal Al or an alloy containing metal Al for purification (after removing impurities), and then transported to the reaction chamber 1.

At the same time, the reaction chamber 1 contains nitrogen (N) II
By introducing vapors of organometallic compounds, hydrides, and simple substances of the constituent elements of the IV compound semiconductor film, a III-V compound semiconductor film containing nitrogen (N) can be obtained on the substrate.

In the refining device 5, since the metal Al has a large oxide formation energy and is negative, when the nitrogen source gas composed of a nitrogen compound comes into contact with the water,
It can easily react with alcohol to increase the purity of the nitrogen raw material.

As described above, in the present invention, the nitrogen raw material composed of the nitrogen compound is brought into contact with the metal Al or the alloy containing the metal Al, and then transported to the reaction chamber 1 to contain nitrogen (N) -containing III.
Since the group V compound semiconductor film is grown and the nitrogen source is brought into contact with the metal Al, it is possible to remove water and alcohol from the nitrogen source gas, and the nitrogen source of the nitrogen compound from which the water and alcohol have been removed. A gas (fully purified nitrogen raw material) can be supplied to the reaction chamber 1, and a III-V group compound semiconductor film containing nitrogen (N) with few impurities and good crystal quality can be obtained.

When the nitrogen compound contains at least hydrazines, the amount of impurities is smaller,
A III-V group compound semiconductor film containing nitrogen (N) with better crystal quality can be obtained. That is, when hydrazines having high reactivity and easily obtaining an epitaxially grown film of good crystal quality are used as the nitrogen raw material, the hydrazines from which water and alcohol have been removed by the above-described purification method of the present invention are placed in the reaction chamber 1. Since it can be supplied, it contains less impurities and contains nitrogen (N) with better crystal quality.
A Group V compound semiconductor film is obtained.

In the above semiconductor film growth method of the present invention, when the metal Al or the alloy containing the metal Al is in a liquid phase, the nitrogen containing the nitrogen compound in the metal Al or the alloy containing the metal Al is used. After bubbling and passing the source gas, the source gas can be transported to the reaction chamber 1 to grow a III-V group compound semiconductor film containing nitrogen (N).

In FIG. 6, when the metal Al or the alloy containing the metal Al is in the liquid phase, the metal Al or the metal Al is used.
A configuration example of a refining device 5 is shown in which a nitrogen source gas made of a nitrogen compound is bubbled through an alloy containing Al (in the molten Al or the molten Al alloy) and then passed to the reaction chamber 1.

When the metal Al or the alloy containing the metal Al is a liquid, the nitrogen source gas bubbling and passing through the liquid of the metal Al or the alloy containing the metal Al, the gas-liquid contact area is It is possible to obtain a III-V group compound semiconductor film containing nitrogen (N), which has a large size, can efficiently remove water and alcohol in the nitrogen source gas, has less impurities, and has good crystal quality.

In the semiconductor film growth method of the present invention described above, a solid phase alloy may be used as the metal Al or the alloy containing the metal Al.

When the metal Al or the alloy containing the metal Al is a solid phase (solid), the metal Al or the alloy containing the metal Al is in the form of particles, fine particles, a film or a porous material so that the contact area becomes large. Is preferred.

FIG. 7 shows an example of a refining apparatus using solid Al or solid Al alloy pellets or fine particles. Further, FIG. 8 shows another example of a refining apparatus using solid Al or solid Al alloy pellets or fine particles.

The particulate metal Al or the alloy containing the metal Al is the metal Al or the metal A melted in an inert gas.
It can be prepared by dropping an alloy containing 1 into a cooled metal plate or a cooled inert liquid such as fluorinated oil or silicone oil. In addition, fine particle metal Al or metal Al
The alloy containing can be produced by evaporating the metal Al or the alloy containing metal Al in an inert gas. Further, the film-shaped metal Al or the alloy containing the metal Al can be manufactured by a vapor deposition method or a sputtering method. In addition, the metal A can be deposited by a vapor deposition method or a sputtering method while rotating glass or ceramic particles.
It is also possible to prepare a film of an alloy containing 1 or metal Al. In this case, the glass or ceramic may be porous.

Even when the metal Al or the alloy containing the metal Al is in the solid phase, if it is in the form of particles, fine particles, film or porous, the nitrogen source gas and the metal Al or the alloy containing the metal Al is used. Since a large contact area with nitrogen can be obtained and water and alcohol in the nitrogen source gas can be efficiently removed, it is possible to obtain a III-V group compound semiconductor film containing nitrogen (N) with less impurities and good crystal quality.

In the structure shown in FIG. 5, the reaction chamber 1 may be provided with heating means for heating the substrate, reaction exciting means such as plasma generating means and electron beam generating means for exciting the reaction of the raw materials. good. When the raw material is a liquid, it is preferable to introduce it into the reaction chamber 1 by bubbling with an inert gas as a carrier gas. When the raw material is solid, it can be heated to evaporate and sublime in the direction of the substrate, or the sublimed raw material can be transported to the reaction chamber 1 by a carrier gas. Further, when performing film growth under reduced pressure or vacuum, a vacuum pump is connected to the gas exhaust unit 6.

FIGS. 9 and 10 show an example of a structure in which the nitrogen raw material is supplied by bubbling when the nitrogen raw material source is a liquid.

In the configuration example of FIG. 9, a first bubbler 11 containing a nitrogen raw material is provided, a purifying device 5 is provided between the first bubbler 11 and the reaction chamber 1, and H ₂ gas or the like is used as a carrier. As a gas, a nitrogen source gas is transported to the reaction chamber 1.

Further, in the configuration example of FIG. 10, the second bubbler 22 and the refining device 5 are provided upstream of the first bubbler 21 so that the nitrogen raw material (N raw material) in the second bubbler 22 is temporarily provided.
After being stored in the first bubbler 21 while purifying an appropriate amount thereof, the nitrogen source purified by bubbling the first bubbler 21 is transported to the reaction chamber 1.

In the configuration examples of FIGS. 9 and 10, the presence or absence of the mass flow controller, the valve, the pressure gauge, etc., and the location of the arrangement are not limited. Further, in order to prevent the oxide produced in the purifier 5 from becoming dust and transported to the reaction chamber 1, it is desirable to provide a dust filter in the pipe between the purifier 5 and the reaction chamber 1.

As described above, according to the present invention, it is possible to provide a III-V compound semiconductor film containing nitrogen (N) with few impurities and good crystal quality. And II containing nitrogen (N)
The range of the element including the IV compound semiconductor film as the constituent film is not limited to the light emitting element, the light receiving element, and the solar cell, and the FET,
It also includes electronic devices such as bipolar transistors.

In the present invention, III-containing nitrogen (N)
The group V compound semiconductor film may be a GaN-based material.

Here, as the GaN-based material, GaN,
GaInN, AlGaInN, AlGaN, GaPN,
GaInPN, AlGaInPN, AlGaPN, BG
aN, BGaInN, BAlGaInN, BAlGa
N, GaNSb, GaInNSb, AlGaInNS
b, AlGaNSb and the like.

This GaN-based material has bandgap energy in the ultraviolet to visible region. In particular, GaN, Ga
InN, AlGaInN, AlGaN are α-Al
Epitaxial growth is possible not only on a single crystal film of ₂ O ₃ , β-SiC, h-ZnO, etc., but also on a selectively grown GaN film.

A manufacturing example in this case is as follows. That is, a GaInNAs-based material film can be formed by reacting a hydride of Ga, In, Al, B, P, an organometallic compound, or a halide with the nitrogen raw material that has passed through the above-mentioned purification device 5.

FIG. 11 shows a GaN-based material in the MOCVD apparatus.
Equipment for growing epitaxial growth film
An example is shown. The configuration example of FIG. 11 includes GaN and GaI.
Epitaxial growth of nN, AlGaInN, AlGaN
It has a structure in which long films can be stacked. That is, FIG.
In the configuration example of, in the reaction chamber 1 in which the pressure can be reduced by a vacuum pump
A heatable susceptor is installed on the₂Gas to carrier gas
As Ga (CH₃) ₃(TMG: Trimethylgaliu
), Al (CH₃)₃: (TMA: trimethylaluminium
Um), In (CH₃)₃(TMI: Trimethylindiu
Metal) and AsH₃(Arsine), PH
₃Supply hydride such as (phosphine) to the reaction chamber 1.
A line is provided. Furthermore, SiH_Four(Silane) and
Zn (CH₃)₂(DMZn: dimethyl zinc) line
Is provided. These are n-type and p-type, respectively.
It is a raw material gas line for ping. Furthermore, NH₃Of gas
A cylinder 31 is provided between the cylinder 31 and the reaction chamber 1.
In addition, the above-mentioned refining device 5 is provided.

By using the apparatus having the structure as shown in FIG. 11, it is possible to supply the nitrogen source gas from which water and alcohol have been removed to the reaction chamber 1, so that there are few impurities and the crystal quality is good.
A system material film (GaN-based compound semiconductor film) can be obtained.

The range of the element including the GaN compound semiconductor film as the constituent film is not limited to the light emitting element, the light receiving element, and the solar cell, and includes electronic devices such as FET and bipolar transistor.

In the present invention, nitrogen (N) is included.
The III-V group compound semiconductor film can be made of a GaInNAs-based material.

Here, as the GaInNAs-based material,
GaNAs, GaInNAs, GaInAsSb, Ga
InNP, GaNP, GaNAsSb, GaInNAs
Sb, InNAs, InNPAs, etc. are mentioned.

As described above, the light-emitting element using the GaInNAs-based material for the active layer has excellent temperature characteristics and, in addition, the emission wavelength is 1.1 μm or more in the long wavelength band, and therefore has good compatibility with the silica-based fiber. Therefore, it is considered to be a key device in optical communication systems, computers, chips, optical interconnections in chips, and optical computing.

For the GaInNAs-based material, the composition is adjusted so that G
It can be lattice-matched with aAs and can be epitaxially grown on a GaAs substrate.

An example of fabrication in this case is as follows. That is, a GaInNAs-based material film can be formed by reacting a hydride of Ga, In, As, Sb, P, an organometallic compound, or a halide with the nitrogen raw material that has passed through the refining device 5.

In FIG. 12, GaInN is formed by MOCVD equipment.
An example of a device configuration for growing an epitaxial growth film of an As-based material is shown. The configuration example of FIG. 12 is GaA.
A supply line of Al raw material and P raw material is also provided so that 1As, AlAs, and GaInP epitaxial growth films can also be stacked. In the configuration example of FIG. 12, a susceptor that can be heated is provided in the reaction chamber 1 that can be decompressed by a vacuum pump, and H ₂ gas is used as a carrier gas for TMG and TM.
A, TMI organometallic, AsH ₃ (arsine), PH ₃
A line for supplying a hydride of (phosphine) to the reaction chamber 1 is provided. Furthermore, SeH ₂ (hydrogenated selenium) and Zn (CH _{3) 2:} is provided with a line of (DMZn dimethyl zinc). These are n-type and p-type source gas lines for doping, respectively. Further, a first bubbler 41 containing a nitrogen source is provided, and the first bubbler 4
1 and the reaction chamber 1 are provided with a nitrogen source refining apparatus 5 of the present invention, and the nitrogen source gas is transported to the reaction chamber 1 using H ₂ gas as a carrier gas.

By using the apparatus having the structure shown in FIG. 12, the nitrogen source gas from which water and alcohol have been removed can be supplied to the reaction chamber 1, so that there are few impurities and the GaI has good crystal quality.
nNAs-based material film (GaInNAs-based compound semiconductor film)
Can be obtained.

The range of elements including a GaInNAs compound semiconductor film as a constituent film is a light emitting element, a light receiving element,
Not only solar cells but also electronic devices such as FETs and bipolar transistors are included.

Specifically, a semiconductor laser can be manufactured as an element using the semiconductor film growth method and semiconductor film growth apparatus of the present invention as described above.

That is, as an example of a semiconductor laser, a III-V compound semiconductor film containing nitrogen (N) can be formed of a GaN-based material, and a semiconductor laser including an active layer of a GaN-based material can be formed.

Such a semiconductor laser is, for example, Ga
N, GaInN, AlGaInN, AlGaN, GaP
N, GaInPN, AlGaInPN, AlGaPN,
BGaN, BGaInN, BAlGaInN, BAlG
aN, GaNSb, GaInNSb, AlGaInNS
b, a semiconductor laser including a growth film made of AlGaNSb or the like in an active layer.

As an example of the element structure of the semiconductor laser, an edge emitting type and a surface emitting type can be cited. In the case of the edge emitting semiconductor laser, depending on the type of the active layer, a single heterojunction type, a double heterojunction type, a separate confinement heterojunction (S
CH) type, multiple quantum well structure (MQW) type,
In addition, depending on the form of the resonator, Fabry-Perot (FP)
Type, distributed feedback (DFB) type, distributed Bragg reflector (DB
R) type.

The surface-emitting type semiconductor laser has a structure in which a laser resonator is formed in a direction perpendicular to the substrate and light is emitted perpendicularly to the substrate. In the surface-emitting type semiconductor laser, a semiconductor multilayer film reflecting mirror, a dielectric multilayer film reflecting mirror, or a metal reflecting mirror having a high reflectance is provided on the surface of the substrate, and an active layer is provided between these reflecting mirrors. And a spacer layer is provided between the two reflecting mirrors. Furthermore, in the surface emitting semiconductor laser,
In many cases, a current constriction structure that narrows the current path in the region near the active layer is included in order to reduce the threshold current, to cause single-mode oscillation, and to prevent non-radiative recombination on the side wall.

The surface-emitting type semiconductor laser is capable of two-dimensional parallel integration and has a relatively narrow output light divergence angle (around 10 degrees), which facilitates coupling with an optical fiber. The feature is that the device can be easily inspected. Therefore, it is considered to be an element particularly suitable for forming a parallel transmission type optical transmission module (optical interconnection device). The current application of the optical interconnection device is parallel connection between cabinets of computers and boards and short-distance optical fiber communication.
A large-scale computer network can be cited as an application expected in the future.

FIG. 13 shows a configuration example of an edge emitting semiconductor laser in the case of an SCH type laser device having an InGaN film as an active layer. With reference to FIG. 13, this edge-emitting type semiconductor laser includes α-Al ₂ O ₃ and β-Si.
A buffer GaN layer 302 and a base n-GaN are formed on a substrate 301 of a single crystal of C, h-ZnO or a selectively grown GaN film.
Layer 303, n-AlGaN cladding layer 304, n-Ga
N guide layer 305, InGaN active layer 306, p-Ga
N guide layer 307, p-AlGaN cladding layer 308,
A p-GaN contact layer 309 is sequentially stacked to form a p-
A p-electrode 310 is formed on the GaN contact layer 309, an n-electrode 311 is formed on the underlying n-GaN layer 303, and a resonator parallel to the film surface is formed by dry etching or the like.

The edge-emitting type semiconductor laser shown in FIG.
Holes and electrons are injected into the clad layer 308 and the n-clad layer 304, respectively, and the active layer 306 emits light.

FIG. 14 shows a quantum well structure (Q with InGaN film as a well layer and AlGaN as a barrier layer).
W) A structural example of a surface emitting semiconductor laser having an active layer is shown. Referring to FIG. 14, this surface-emitting type semiconductor laser includes an AlN buffer layer 402 and a GaN buffer on a substrate 401 of a single crystal of α-Al ₂ O ₃ , β-SiC, h-ZnO or a selectively grown GaN film. Layer 403, AlN / GaN
A semiconductor multilayer film reflecting mirror (lower semiconductor distributed Bragg reflecting mirror) 404 consisting of 20 pairs or more, an n-GaN contact layer 405, an n-GaN spacer layer 406, InGaN / A.
lGaN quantum well (QW) active layer 407, p-GaN spacer layer 408, p-GaN contact layer 409, Al
A semiconductor multilayer film reflecting mirror (upper semiconductor distributed Bragg reflecting mirror) 410 made up of about 20 pairs of N / GaN is sequentially provided. Further, in the configuration example of FIG. 14, the active layer 40
7, an insulating region is formed by a method such as implantation of protons and oxygen ions to form the current constriction portion 411.
Is provided. Then, the p-electrode 412 is formed on the p-contact layer 409, and the n-contact layer 405 is formed.
An n-electrode 413 is formed on the upper surface of the n-electrode 413, and the n-electrode 413 is formed as a surface emitting type having a resonator structure perpendicular to the film surface.

In the surface-emitting type semiconductor laser of FIG. 14, a p-semiconductor multilayer film reflecting mirror 410 and an n-semiconductor multilayer film reflecting mirror 404.
Holes and electrons are respectively injected into the active layer 407, and the active layer 407 emits light.

As described above, the III-V group compound semiconductor film containing nitrogen (N) is made of a GaN-based material, and Ga is formed in the active layer.
When a semiconductor laser including an N-based material is formed, a nitrogen raw material made of a nitrogen compound is brought into contact with metal Al or an alloy containing metal Al to purify the nitrogen raw material, and the purified nitrogen raw material is used to obtain a good crystal. A semiconductor laser component film having high quality can be obtained. In particular, the crystal quality of the active layer containing the GaN-based material is improved. Further, since the active layer contains a GaN-based material, it is possible to obtain an oscillation wavelength in the visible-ultraviolet region, which is expected to be widely applied. Therefore, a long-lived semiconductor laser having an oscillation wavelength in the visible-ultraviolet region, which has a low threshold current, high luminous efficiency, and high reliability, can be obtained.

As another example of the semiconductor laser, a III-V group compound semiconductor film containing nitrogen (N) may be formed of a GaN-based material, and a semiconductor laser including an GaInNAs-based material in its active layer may be formed. .

Such a semiconductor laser is, for example, Ga
NAs, GaInNAs, GaInAsSb, GaIn
NP, GaNP, GaNAsSb, GaInNAsS
It is a semiconductor laser including a growth film made of b, InNAs, InNPAs or the like in an active layer.

FIG. 15 shows an example of the structure of an edge emitting semiconductor laser in the case of a SCH type laser device using a GaInNAs film as an active layer. Referring to FIG.
This edge emitting semiconductor laser is composed of a GaAs single crystal substrate 5
01, n-AlGaAs or n-GaInP n-clad layer 502, GaAs or GaInP guide layer 50
3, GaInNAs active layer 504, GaAs or GaIn
P guide layer 505, p-AlGaAs or p-GaIn
P p-cladding layers 506 are sequentially stacked, and p-electrodes (striped electrodes) 5 are formed on the p-cladding layers 506.
07 is formed, and on the back surface of the substrate 501, an n-electrode (lower electrode film) 508 is formed. Then, a cavity parallel to the film surface is formed by cleavage to form an edge emitting semiconductor laser.

In this edge emitting semiconductor laser, holes and electrons are injected into the p-cladding layer 506 and the n-cladding layer 502, respectively, and the active layer 504 emits light.

Further, FIG. 16 shows a quantum well structure (Q with a GaInNAs film as a well layer and GaAs as a barrier layer).
W) A structural example of a surface emitting semiconductor laser having an active layer is shown. Referring to FIG. 16, this surface-emitting type semiconductor laser has an n-GaIn single crystal substrate 601 and an n-GaIn substrate.
N-semiconductor multilayer film reflecting mirror 602, n-GaAs, n-GaIn composed of 25 pairs or more such as P / n-GaAs
Spacer layer 603 such as P, n-AlGaAs, GaI
nNAs / GaAs quantum well (QW) active layer 604, p
-GaAs, p-GaInP, p-AlGaAs or other spacer layer 605, p-GaInP / p-GaAs or other 20-pair or more p-semiconductor multilayer mirror 60
6, p-contact layer 607 is sequentially laminated.
Here, the active layer 604 is composed of a GaInAs quantum well active layer 604a and a GaAs barrier layer 604b. Further, in the example of FIG. 16, the AlAs film is oxidized in the vicinity of the active layer 604 to form an insulating Al _x O _y film, and the insulating region is formed in the vicinity of the active layer 604 by implantation of protons or oxygen ions. And a current constriction portion 608 is provided. A p-side electrode 609 is formed on the p-contact layer 607, and the substrate 6
An n-side electrode 610 is formed on the back surface of 01 to form a surface emitting semiconductor laser having a resonator structure perpendicular to the film surface.

In the surface emitting semiconductor laser having such a structure, holes and electrons are injected into the p-semiconductor multilayer film reflecting mirror 606 and the n-semiconductor multilayer film reflecting mirror 602, respectively, and the active layer 604 emits light.

As described above, when the III-V group compound semiconductor film containing nitrogen (N) is made of a GaInNAs-based material and the active layer is made of a semiconductor laser containing a GaInNAs-based material, a nitrogen source made of a nitrogen compound is used. Is contacted with metal Al or an alloy containing metal Al to purify the nitrogen raw material,
By using the purified nitrogen raw material, a semiconductor laser having a constituent film having good crystal quality can be obtained. In particular, GaI
The crystal quality of the active layer containing the nNAs-based material is significantly improved. Further, this semiconductor laser has GaInN in the active layer.
Since it contains an As-based material, it emits light in the infrared region, which is highly compatible with optical fibers. Further, since the carriers are well confined, the change in the light emitting characteristics is small with respect to the change in temperature. Therefore, it is possible to obtain an infrared optical semiconductor laser having a low threshold current, high luminous efficiency, good temperature characteristics, high reliability, a long lifetime, and an oscillation wavelength that is suitable for optical communication.

The III-V group compound semiconductor film containing nitrogen (N) is a GaInNAs-based material, and Ga is used as the active layer.
In the semiconductor laser InNAs based material is included, the semiconductor laser _{Al x Ga (1-x)} As / Al y Ga
_(1-y) As (0 ≦ y <x ≦ 1) A surface emitting semiconductor laser including at least one semiconductor multilayer film reflecting mirror can be formed.

As the reflecting mirror of the surface emitting semiconductor laser,
A semiconductor distributed Bragg reflector in which a low refractive index layer and a high refractive index layer are alternately laminated is widely used because it can be formed together with an active layer region with good controllability and carriers for driving a laser can also flow. The material of the semiconductor distributed Bragg reflector is a material that does not absorb the light generated from the active layer (generally a material having a wider bandgap than the active layer),
A material that is lattice-matched to the substrate is used to prevent lattice relaxation. Here, the reflectance of the reflecting mirror needs to be extremely high at 99% or more, and the reflectance is increased by increasing the number of laminated layers. However, as the number of stacked layers increases, it becomes difficult to manufacture a surface-emitting type semiconductor laser. Therefore, it is preferable that the difference in refractive index between the low refractive index layer and the high refractive index layer is large. AlGaAs-based materials are AlAs and GaAs
Is a terminating material, the lattice constant is almost the same as that of GaAs which is a substrate, the difference in refractive index is large depending on the composition, and a high reflectance can be obtained with a small number of laminated layers.
(Ga) As / GaAs, or more broadly, Al _x Ga
Is preferably used as the _{(1-x) As / Al} y Ga (1-y) As (0 ≦ y <x ≦ 1) semiconductor multilayer reflecting mirror of the surface-emitting type semiconductor laser.

However, conventionally, Al (Ga) As / GaA
When the s-semiconductor multilayer film was used as a reflecting mirror of a surface-emitting type semiconductor laser, sufficient luminous efficiency was not obtained. this is,
As verified by the above-described experiment, the material containing Al is chemically very active, and it is easy to form crystal defects due to Al, and the active layer containing GaInNAs-based material is grown in the reaction chamber during the growth. This is because the remaining Al raw material or Al raw material reaction product reacts with water and alcohol in hydrazine and takes them into the crystal, which becomes a crystal defect and non-radiative recombination is introduced, which lowers the luminous efficiency. is there.

Therefore, in JP-A-08-340146 and JP-A-07-307525, Ga containing no Al is disclosed.
Proposals have been made to construct a semiconductor distributed Bragg reflector from InP and GaAs. However, GaIn
The difference in the refractive index between P and GaAs is about half the difference in the refractive index between AlAs and GaAs, and the number of laminated reflecting mirrors increases significantly, making fabrication difficult and reducing the yield. However, there is a problem that the element resistance increases, it takes time to manufacture, the total thickness of the surface emitting laser increases, and the electrical wiring becomes difficult.

On the other hand, in the present invention, the nitrogen raw material composed of the nitrogen compound is brought into contact with the metal Al or the alloy containing the metal Al, and then transported to the reaction chamber to contain III-containing nitrogen (N).
Since a group V compound semiconductor film is grown, Al _x Ga _(1-x)
Be used as a _{As / Al y Ga (1-} y) As (0 ≦ y <x ≦ 1) semiconductor multilayer film of a surface-emitting type semiconductor laser reflector,
Fabrication of surface-emitting type semiconductor laser with good quality active layer with few defects while having a semiconductor multilayer film that can reduce the incorporation of oxygen element into the active layer and obtain high reflectance with a small number of layers. Will be possible. Therefore, it is possible to obtain a surface-emitting type semiconductor laser having a high yield, a low-cost process, a simple structure, a low device resistance, a low threshold current, a high luminous efficiency, a high reliability, and a good temperature characteristic. .

Further, in the present invention, III containing nitrogen (N) is used.
It is possible to configure an optical communication system in which the group V compound semiconductor film is composed of a GaInNAs-based material and a semiconductor laser (surface-emitting semiconductor laser) containing an GaInNAs-based material in the active layer is used as a light source.

FIG. 17 is a diagram showing an example of a parallel transmission type optical communication system (optical transmission system) using the above-described semiconductor laser (surface-emitting type semiconductor laser) of the present invention. In the optical transmission system shown in FIG. 17, signals from the surface emitting semiconductor laser can be transmitted simultaneously using a plurality of fibers.

FIG. 18 is a diagram showing an example of a multi-wavelength transmission type optical communication system (optical transmission system) using the above-described surface emitting semiconductor laser of the present invention. In the optical transmission system of FIG. 18, optical signals from a plurality of light emitting elements (GaInNAs surface emitting lasers) having different oscillation wavelengths are respectively introduced into an optical multiplexer (combiner) via an optical fiber, and a plurality of optical signals having different wavelengths are introduced. The optical signal of is combined by the optical multiplexer,
It is introduced into one optical fiber and transmitted. The transmitted optical signal is an optical demultiplexer (demultiplexer) that is connected to the destination device.
To be separated into a plurality of optical signals having different original wavelengths and reach a plurality of light receiving elements via respective fibers.

As described above, in the present invention, Al _x Ga is used.
_{(1-x) As / Al} y Ga (1-y) As (0 ≦ y <x ≦ 1) be a semiconductor multilayer film as a reflecting mirror of the surface-emitting type semiconductor laser, the incorporation into the active layer of the oxygen element Al _x, which can obtain high reflectance with a small number of layers, because
_{Ga (1-x) As /} Al y Ga (1-y) As (0 ≦ y <x ≦
1) It becomes possible to fabricate a surface-emitting type semiconductor laser having an active layer containing a GaInNAs-based material with good quality and few defects while having a semiconductor multilayer film. Therefore, a high yield, low cost process, simple structure, low element resistance, low threshold current, high emission efficiency, high reliability, and surface emitting laser with good temperature characteristics can be mounted in an optical communication system. Therefore, a highly reliable and high-performance optical communication system can be obtained with a simple structure that does not require a cooling device.

[0117]

EXAMPLES Examples of the present invention will be described below.

Example 1 In Example 1, the semiconductor film growth apparatus (MOCVD of the present invention was used.
Device), an epitaxial growth film of a GaN-based material was grown on the selectively grown GaN substrate, and a semiconductor laser was produced. The MOCVD apparatus used has the structure shown in FIG.

That is, the MOCVD used in Example 1
The apparatus is provided with a susceptor that can be heated in the reaction chamber 1 that can be decompressed by a vacuum pump, and a line that supplies TMG, TMA, and TMI to the reaction chamber 1 using H ₂ gas as a carrier gas. Further, lines for supplying SiH ₄ (silane) and Zn (CH ₃ ) ₂ (DMZn: dimethylzinc) to the reaction chamber 1 are provided. These are n-type and p-type source gas lines for doping, respectively. is there. Furthermore, a line for supplying NH ₃ gas is provided,
In the middle of this line, a nitrogen material refining device 5 in which AlGaIn alloy particles are filled in a cylinder is provided.
Here, the particles of the AlGaIn alloy were produced as follows. That is, after melting an AlGaIn alloy in a BN crucible in an N ₂ gas atmosphere, the fluorinated oil (AUSIMONT SP manufactured by Fomblin YL manufactured by cooling) was cooled.
-VAC 14/6) and drop it into A with a diameter of 1-5 mm
Particles of 1GaIn alloy were obtained and filled in the above cylinder in N ₂ gas atmosphere. In such a configuration,
The nitrogen source gas is transported to the reaction chamber 1 through the refining device 5 using H ₂ gas as a carrier gas.

In Example 1, a semiconductor laser as shown in FIG. 19 was produced by using the MOCVD apparatus shown in FIG.
That is, on the c-plane sapphire single crystal substrate 701, an amorphous buffer GaN having a thickness of 200 Å at a substrate temperature of 550 ° C.
Layer 702 was grown. Subsequently, a base GaN layer 703 having a thickness of 2 μm was grown at a substrate temperature of 1050 ° C. Next, the sample was taken out of the MOCVD growth chamber into the atmosphere, and C
VD method by growing the SiO ₂ film 704 thickness of 0.1 [mu] m, making the SiO ₂ film 704 is processed by photolithography and wet etching, striped window of 4μm width (mask pattern) with a period of 11μm width To do. The sample was placed in the MOCVD growth chamber again and the substrate temperature was set to 1
Selective growth n-GaN on this mask pattern at 050 ° C.
The film 705 is grown. In this case, the buffer GaN layer 7
The GaN film grown from No. 02 grows laterally on the mask pattern, has a large area and has few defects, and is a good quality single crystal film 705.
was gotten. In addition, such a growth film is a selective growth film or an ELOG substrate (Epitaxially Laterally Overgrown Ga).
N Substrate). Then, n-GaN contact layer 706, n-AlGaN cladding layer 707, n-
GaN guide layer 708, In _0.02 Ga _0.98 N / In _0.15
Ga _0.85 N triple MQW active layer 709, p-GaN guide layer 710, p-AlGaN cladding layer 711, p-
The GaN contact layer 712 was epitaxially grown.

Next, a laser element processing process is performed,
A ridge stripe as shown in FIG.
A p-type electrode 713 is formed on the GaN contact layer 712, and an n-type electrode 714 is formed on the n-GaN contact layer 706.
Forming a semiconductor laser (broad stripe laser)
Was produced.

The threshold current of this semiconductor laser device (broad stripe laser) was 50 mA in CW at room temperature. As a comparative example, in the MOCVD apparatus used, in the broad stripe laser having the same structure produced without using the nitrogen source refining apparatus 5, the threshold current was 80 mA in CW at room temperature.

As can be seen from the above, according to the present invention,
By passing the nitrogen source (NH ₃ ) through the nitrogen source refining apparatus 5, NH _{3 from} which water and alcohol have been removed can be supplied to the reaction chamber 1, and a GaN-based material film with few impurities and good crystal quality can be obtained. It became possible to fabricate a ridge stripe laser capable of continuous oscillation at room temperature with a low threshold current.

Example 2 In Example 2, a semiconductor laser was manufactured using the MOCVD apparatus shown in FIG.

That is, the MOCVD used in Example 2
The apparatus has a susceptor that can be heated in the reaction chamber 1 that can be decompressed by a vacuum pump, and uses H ₂ gas as a carrier gas, TMG, TMA, TMI, AsH ₃ , PH ₃ , SeH.
₂ has a line for supplying Zn (CH ₃ ) ₂ to the reaction chamber 1. Bubbler 4 with dimethylhydrazine
1, and a purifying device (hydrazine purifying device) 5 between the bubbler 41 and the reaction chamber 1. Purifier 5
The refining operation in is as follows. In other words, GaInAl (weight ratio 100: 10: 1.8) was used in the refining device 5.
A liquid is put therein, and H ₂ gas is used as a carrier gas for bubbling a vapor of hydrazines therein for purification, and thereafter, it is transported to the reaction chamber 1.

In the second embodiment, the MOCVD shown in FIG.
A semiconductor laser as shown in FIG. 20 was produced using the apparatus. That is, on the n-GaAs substrate 720, n-A
lGaAs lower clad layer 721, GaAs intermediate layer 72
2, GaInNAs / GaAs double quantum well structure active layer 723, GaAs intermediate layer 724, p-AlGa
An As upper clad layer 725 is sequentially laminated, a p-type electrode (stripe electrode) 726 is formed on the p-clad layer 725, and an n-type electrode 727 is formed on the back surface of the substrate 720 to produce a broad stripe laser. did.

Here, the Al concentration in the active layer 723 is 1 ×.
10 ¹⁸ cm ⁻³ or less, and oxygen (O) in the active layer 723
The concentration was 2 × 10 ¹⁷ cm ^-3 or less. Further, the threshold current was 25 mA CW at room temperature.

As a comparative example, in the MOCVD apparatus used, a broad stripe laser of the same structure produced without using the refining apparatus 5 was 2 × 10 ¹⁹ cm in the active layer.
^-3 or more Al and 1 × 10 ¹⁸ cm ^-3 or more oxygen were incorporated, and the threshold current was a significantly high value of 250 mA or more in CW at room temperature.

As can be seen from the above, according to the present invention,
By passing the nitrogen raw material (hydrazine) through the nitrogen raw material purifying apparatus 5, hydrazine from which water and alcohol have been removed can be supplied to the reaction chamber 1, so that G having few impurities and good crystal quality can be obtained.
An aInNAs-based material film was obtained, and it became possible to fabricate a broad stripe laser capable of continuous oscillation at room temperature with a lower threshold current.

Example 3 In Example 3, a surface emitting semiconductor laser device was manufactured using the MOCVD apparatus shown in FIG.

The MOCVD apparatus of FIG. 21 has a susceptor that can be heated in the reaction chamber 1 whose pressure can be reduced by a vacuum pump, and uses H ₂ gas as a carrier gas for TMG, TMA,
It has a line for supplying TMI, AsH ₃ , PH ₃ , SeH ₂ , and Zn (CH ₃ ) ₂ to the reaction chamber 1.

Further, a bubbler 51 containing dimethylhydrazine is provided, and a purifying device (hydrazine purifying device) 5 is provided between the bubbler 51 and the reaction chamber 1. The refining device (refining cylinder) 5 includes a first vacuuming valve 52.
It is connected to the vacuum pump 53 via. Furthermore, the refining device (refining cylinder) 5 has a resistance heating boat,
The metal Al is vapor-deposited on the inner surface of the opposing cylinder.

In the growth apparatus (MOCVD apparatus) having such a structure, before introducing hydrazine into the reaction chamber 1, the purification apparatus (purification cylinder) 5 is shut off from the supply line by the first line valve and the second line valve. , The gate valve is opened, and while vacuuming with the vacuum pump 53, Al is vapor-deposited on the inner surface of the refining device (refining cylinder) 5. next,
The gate valve is closed, the first line valve and the second line valve are opened, and DM gas is used with H ₂ gas as a carrier gas.
The y vapor is brought into contact with the Al vapor deposition surface and then transported to the reaction chamber 1.

In Example 3, the surface emitting type semiconductor laser as shown in FIGS. 22A and 22B was manufactured by using the apparatus shown in FIG. 22 (b) is a partially enlarged view of FIG. 22 (a). The steps of manufacturing the surface-emitting type semiconductor laser of FIGS. 22 (a) and 22 (b) are as follows. That is, n
-On a GaAs (100) substrate 901, n-AlAs /
a lower mirror layer 902 consisting of 28 pairs of n-GaAs,
First GaAs spacer layer 903, three layers of GaInNA
s active layer 904a and two GaAs barrier layers 904b, multiple quantum well active layer 904, second GaAs spacer layer 905, AlAs selective oxidation layer 906, p-AlG.
An upper mirror layer 907 and a p-GaAs contact layer 908 made of 20 pairs of aAs / p-GaAs are formed.

Next, the laminated structure of 30 μm × 30 μm
The semiconductor pillar of the post-shaped laser oscillator in the area
As deep as the depth of reaching the AlAs selective oxide layer 906.
Cl ₂ECR etching with gas. At this time, the semiconductor
The height of the pillar is 6.0 μm.

Next, water vapor was introduced from the end surface of the selectively oxidized AlAs film of the semiconductor pillar to leave a current path of a cross section of about 25 μm ² , and an insulating Al _x O _y film (Al _x O _y current narrowing layer) 9 was formed.
Change to 06b. Next, non-photosensitive polyimide 910
Is applied by spin coating and cured at 350 ° C. so that the height from the etched bottom surface becomes 4.0 μm. Next, a resist is applied, and the polyimide 910 in the area of 28 μm × 28 μm on the upper surface of the semiconductor pillar is removed by lithography and RIE etching using O ₂ gas. Next, the p-side electrode 91 is formed on a region of the upper surface of the semiconductor pillar from which the polyimide has been removed except the light emitting portion and on the polyimide surface.
1 and the wiring portion are formed by electrode film deposition and lift-off method.
Further, an n-side electrode 912 is formed on the back surface of the substrate 901.

In the surface-emitting type semiconductor laser thus manufactured, the Al concentration in the active layer 904 is 1 × 10 ¹⁸ c.
m ⁻³ or less, and the oxygen (O) concentration was 2 × 10 ¹⁷ cm ⁻³ or less. In addition, the threshold current is 0.7 mA CW at room temperature.
Met.

As a comparative example, the surface-emitting type semiconductor laser of the same structure manufactured without using the refining device (refining cylinder) 5 in the MOCVD apparatus used has the active layer 904.
3 × 10 ¹⁹ cm ⁻³ or more of Al and 2 × 10 ¹⁸ cm ⁻³
The above oxygen is taken in, and the threshold current is CW at room temperature.
The value was significantly higher than 4 mA.

As can be seen from the above, according to the present invention,
By passing the nitrogen raw material (hydrazine) through the nitrogen raw material purifying apparatus 5, hydrazine from which water and alcohol have been removed can be supplied to the reaction chamber 1, so that a GaInNAs-based material film with few impurities and good crystal quality can be obtained, and the threshold value lower. It has become possible to fabricate a surface emitting semiconductor laser capable of continuous oscillation at room temperature with an electric current.

[0140]

As described above, according to the first to sixth aspects of the present invention, the nitrogen source made of the nitrogen compound is brought into contact with the metal Al or the alloy containing the metal Al, and then the reaction mixture is introduced into the reaction chamber. It is designed to transport and grow a group III-V compound semiconductor film containing nitrogen (N). By contacting a nitrogen source made of a nitrogen compound with metal Al or an alloy containing metal Al, water and alcohol are removed. Since the nitrogen raw material consisting of the removed nitrogen compound can be supplied to the reaction chamber, III-V containing nitrogen (N) with few impurities and good crystal quality
A group compound semiconductor film can be obtained.

In particular, according to the invention described in claim 2, in the method for growing a semiconductor film according to claim 1, since the nitrogen compound contains at least hydrazines, the nitrogen compound contains less impurities and has a higher crystal quality. Contains good nitrogen (N)
A III-V compound semiconductor film can be obtained. That is, hydrazines, which have a high reactivity and a low decomposition temperature, make it easy to obtain an epitaxially grown film of good crystal quality, are used as a nitrogen raw material, and the hydrazines are purified by the method of claim 1 to remove water and alcohol. The removed hydrazines can be supplied to the reaction chamber, and a group III-V compound semiconductor film containing nitrogen (N) with less impurities and better crystal quality can be obtained.

Further, according to the invention of claim 3, in the method of growing a semiconductor film according to claim 1 or 2,
The metal Al or the alloy containing the metal Al is in a liquid phase, and a nitrogen source gas made of a nitrogen compound is bubbled through the metal Al or the alloy containing the metal Al, and then the gas is transported to a reaction chamber to obtain nitrogen (N). A group III-V compound semiconductor film containing Al is grown.
Since the alloy containing 1 is a liquid and the nitrogen source gas is bubbled through this liquid to pass through it, a large contact area between the gas and liquid can be taken, water and alcohol in the nitrogen source gas can be removed efficiently, and the amount of impurities is reduced High quality nitrogen (N)
It is possible to obtain a III-V compound semiconductor film containing

Further, according to the invention of claim 4, in the method of growing a semiconductor film according to claim 1 or 2,
Since the metal Al or the alloy containing the metal Al is in a solid phase and is in the form of particles, fine particles, film or porous,
A large contact area between the nitrogen source gas and metallic Al or an alloy containing metallic Al enables efficient removal of water and alcohol in the nitrogen source gas, and nitrogen (N) containing less impurities and good crystal quality III- A group V compound semiconductor film can be obtained.

According to the invention of claim 5, in the method for growing a semiconductor film according to any one of claims 1 to 4, the III-V group compound semiconductor film containing nitrogen (N) is , Which is a GaN-based material, can obtain a GaN-based material film with few impurities and good crystal quality.

According to the invention described in claim 6, in the method for growing a semiconductor film according to any one of claims 1 to 4, the III-V group compound semiconductor film containing nitrogen (N) is , A GaInNAs-based material, which has few impurities and has good crystal quality, can be obtained.

According to the seventh aspect of the invention, the nitrogen source made of the nitrogen compound is brought into contact with the metal Al or the alloy containing the metal Al to purify the nitrogen source. (Water and alcohol) can be removed, and the nitrogen raw material can be sufficiently purified.

According to the invention described in claim 8, a reaction chamber for growing a III-V group compound semiconductor film containing nitrogen (N) and a III group for supplying a group III source material to the reaction chamber.
Group source material, group V source source for supplying group V source to the reaction chamber, nitrogen source, and nitrogen supplied to the reaction chamber after removing impurities from the nitrogen source consisting of the nitrogen compound from the nitrogen source A raw material refining apparatus, and the nitrogen raw material refining apparatus according to claim 7 is used as the nitrogen raw material refining apparatus. Therefore, a III-V compound semiconductor containing nitrogen (N) with less impurities and good crystal quality is included. It enables the production of a film.

Further, according to the invention described in claim 9, since it is a semiconductor laser which is manufactured by using the semiconductor film growth method described in claim 5 and the active layer contains a GaN-based material, a good crystal is obtained. A semiconductor laser structure having a quality constituent film can be obtained. In particular, the crystal quality of the active layer containing the GaN-based material is improved. Further, since the active layer contains a GaN-based material, it is possible to obtain an oscillation wavelength in the visible-ultraviolet region, which is expected to be widely applied. Therefore, it is possible to obtain a semiconductor laser having an oscillation wavelength in the visible-ultraviolet region, which has a low threshold current, high luminous efficiency, and high reliability, and has a long life.

According to the tenth aspect of the invention, since the semiconductor laser is manufactured by using the semiconductor film growth method according to the sixth aspect and the GaInNAs-based material is contained in the active layer, a good crystal is obtained. It is possible to obtain a semiconductor laser having a quality constituent film. In particular, the crystal quality of the active layer containing the GaInNAs-based material is significantly improved. further,
Since this semiconductor laser contains a GaInNAs-based material in the active layer, it emits light in the infrared region, which is highly compatible with optical fibers. Further, since the carriers are well confined, the change in the light emission characteristics is small with respect to the change in temperature. Therefore, it is possible to obtain an infrared light semiconductor laser having a low threshold current, high emission efficiency, good temperature characteristics, high reliability, a long life, and an oscillation wavelength that is suitable for optical communication.

[0150] Also, according to the invention of claim 11, wherein, in the semiconductor laser according to claim 10, the semiconductor _{laser, Al x Ga (1-x} ) As / Al y Ga (1-y) As (0 ≤ y
<X ≦ 1) A surface-emitting type semiconductor laser including at least one semiconductor multilayer film reflecting mirror, wherein Al _x Ga _(1-x) As / Al.
_{Even when a y} Ga _(1-y) As (0 ≦ y <x ≦ 1) semiconductor multilayer film is used as a reflecting mirror of a surface-emitting type semiconductor laser, incorporation of oxygen element into the active layer can be reduced, so that the number of layers is small. It becomes possible to fabricate a surface-emitting type semiconductor laser having an active layer of good quality with few defects, while having a semiconductor multilayer film capable of obtaining a high reflectance. Therefore, it is possible to obtain a surface-emitting type semiconductor laser having a high yield, a low cost process, and a simple structure, which has a low element resistance, a low threshold current, a high luminous efficiency, a high reliability, and a good temperature characteristic. .

According to the twelfth aspect of the invention, since the semiconductor laser of the tenth or eleventh aspect is an optical communication system that is used as a light source, a simple structure that does not require a cooling device is provided. A highly reliable and high performance optical communication system can be obtained.

[Brief description of drawings]

FIG. 1 is a Ga produced by an MOCVD apparatus of the inventor of the present application.
G composed of InNAs quantum well layer and GaAs barrier layer
It is a figure which shows the room temperature photoluminescence spectrum from the active layer which consists of aInNAs / GaAs double quantum well structure.

FIG. 2 is a diagram showing a sample structure of a semiconductor light emitting device.

3 is an example of the semiconductor light emitting device shown in FIG. 2, in which the clad layer is AlGaAs and the intermediate layer is GaAs,
An element in which the active layer has a GaInNAs / GaAs double quantum well structure is used as one epitaxial growth apparatus (M
It is a figure which shows the depth direction distribution of nitrogen (N) density | concentration and oxygen (O) density when it forms using an OCVD apparatus.

FIG. 4 is a diagram showing a distribution of Al concentration in the depth direction of the same sample as FIG.

FIG. 5 is a diagram showing a configuration example of a semiconductor film growth apparatus according to the present invention.

FIG. 6 shows a case where the metal Al or the alloy containing the metal Al is in a liquid phase, after bubbling a nitrogen source gas consisting of a nitrogen compound through the metal Al or the alloy containing the metal Al and passing the gas into the reaction chamber. It is a figure which shows the structural example of the refining apparatus which does.

FIG. 7 is a diagram showing an example of a refining apparatus using solid Al or solid Al alloy pellets or fine particles.

FIG. 8 is a diagram showing another example of a refining apparatus using solid Al or solid Al alloy pellets or fine particles.

FIG. 9 is a diagram showing a configuration example in which a nitrogen raw material is supplied by bubbling when the nitrogen raw material source is a liquid.

FIG. 10 is a diagram showing a configuration example in which a nitrogen source is supplied by bubbling when the nitrogen source is a liquid.

FIG. 11 is a diagram showing an example of a device configuration in the case of growing an epitaxial growth film of a GaN-based material with a MOCVD device.

FIG. 12 is a diagram showing a device configuration example in the case of growing an epitaxial growth film of a GaInNAs-based material with a MOCVD device.

FIG. 13 is a diagram showing a configuration example of an edge emitting semiconductor laser in the case of an SCH type laser device having an InGaN film as an active layer.

FIG. 14 is a diagram showing a configuration example of a surface-emitting type semiconductor laser having a quantum well structure (QW) active layer in which an InGaN film is a well layer and AlGaN is a barrier layer.

FIG. 15 is a diagram showing a configuration example of an edge-emitting semiconductor laser in the case of a SCH laser device having a GaInNAs film as an active layer.

FIG. 16 is a diagram showing a configuration example of a surface-emitting type semiconductor laser having a quantum well structure (QW) active layer in which a GaInNAs film is a well layer and GaAs is a barrier layer.

FIG. 17 is a diagram showing an example of a parallel transmission type optical communication system (optical transmission system) using the semiconductor laser (surface-emitting type semiconductor laser) of the present invention.

FIG. 18 is a diagram showing an example of a multi-wavelength transmission type optical communication system (optical transmission system) using the surface-emitting type semiconductor laser of the present invention.

19 is a diagram showing a semiconductor laser manufactured using the MOCVD apparatus in FIG.

FIG. 20 is a diagram showing a semiconductor laser manufactured using the MOCVD apparatus in FIG.

FIG. 21 is a diagram showing an example of a MOCVD apparatus.

22 is a diagram showing a surface-emitting type semiconductor laser device of Example 3. FIG.

[Explanation of symbols]

201 GaAs substrate 202 Lower clad layer 203 Intermediate layer 204 Active layer 205 Upper clad layer 1 Reaction chamber 2 Group III source material 3 Group V source material 4 Nitrogen source source 5 Refining device 6 Gas exhaust section 11 First bubbler 21 First Bubbler 22 Second bubbler 31 NH ₃ gas cylinder 41 First bubbler 301 Substrate of selectively grown GaN film 302 Buffer GaN layer 303 Base n-GaN layer 304 n-AlGaN cladding layer 305 n-GaN guide layer 306 InGaN active layer 307 p-GaN guide layer 308 p-AlGaN cladding layer 309 p-GaN contact layer 310 p-electrode 311 n-electrode 401 substrate for selective growth GaN film 402 AlN buffer layer 403 GaN buffer layer 404 semiconductor multilayer film mirror (lower semiconductor Distributed Bragg reflector) 405 n-GaN contact Layer 406 n-GaN spacer layer 407 InGaN / AlGaN quantum wells (Q
W) Active layer 408 p-GaN spacer layer 409 p-GaN contact layer 410 Semiconductor multilayer film reflection mirror (upper semiconductor distributed Bragg reflection mirror) 411 Current constriction portion 412 p-electrode 413 n-electrode 501 GaAs single crystal substrate 502 n- Cladding layer 503 Guide layer 504 GaInNAs active layer 505 Guide layer 506 p-cladding layer 507 p-electrode (striped electrode) 508 n-electrode (lower electrode film) 601 n-GaAs single crystal substrate 602 n-semiconductor multilayer film reflector 603 spacer layer 604 GaInNAs / GaAs quantum well (QW) active layer 605 spacer layer 606 p-semiconductor multilayer film reflecting mirror 607 p-contact layer 608 current constriction portion 609 p-side electrode 610 n-side electrode

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/205 H01L 21/205 5F102 21/338 H01S 5/183 5K002 29/812 5/323 610 H01S 5 / 183 H01L 29/80 B 5/323 610 H04B 9/00 W H04B 10/02 10/28 (72) Inventor Takashi Takahashi 1-3-6 Nakamagome, Ota-ku, Tokyo In-house of Ricoh Company (72) Kaminishi Seisei Nakamamagome 1-3-6, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 4D020 AA08 AA10 BA06 BB01 BB02 CA05 CB01 4G075 AA24 BC04 CA51 CA54 CA57 DA02 FB02 4G077 AA03 BE11 BE15 DB08 EG22 TH04 5F045 A0 AA05 AB09 AB14 AB17 AB18 AB19 AC19 BB16 CA01 CA06 CA09 CA13 DA52 DA63 5F073 AA04 AA45 AA65 AA74 AB17 CA07 CB05 CB07 DA05 EA29 5F102 GB01 GC01 GD01 GJ04 GL04 GM04 HC01 5K002 AA01 BA01 BA13 DA02 FA01

Claims (12)

[Claims] 1. A nitrogen source made of a nitrogen compound is used as a metal Al.
Alternatively, a method for growing a semiconductor film, which comprises contacting with an alloy containing metal Al and then transporting the alloy to a reaction chamber to grow a III-V group compound semiconductor film containing nitrogen (N). 2. The method for growing a semiconductor film according to claim 1, wherein the nitrogen compound contains at least hydrazines. 3. The method for growing a semiconductor film according to claim 1, wherein the metal Al or the alloy containing the metal Al is in a liquid phase, and the metal Al or the alloy containing the metal Al contains nitrogen containing a nitrogen compound. After bubbling the raw material gas and passing it, the raw material gas is transported to a reaction chamber and contains nitrogen (N) III-
A method for growing a semiconductor film, which comprises growing a Group V compound semiconductor film. 4. The method for growing a semiconductor film according to claim 1, wherein the metal Al or an alloy containing metal Al is a solid phase and is in the form of particles, fine particles, a film or a porous material. A method for growing a semiconductor film. 5. The method for growing a semiconductor film according to claim 1, wherein the film contains nitrogen (N) II.
A method for growing a semiconductor film, wherein the IV compound semiconductor film is a GaN-based material. 6. The method of growing a semiconductor film according to claim 1, further comprising II containing nitrogen (N).
The semiconductor film growth method, wherein the IV compound semiconductor film is a GaInNAs-based material. 7. A nitrogen source made of a nitrogen compound is used as a metal Al.
Alternatively, the nitrogen raw material refining apparatus is characterized in that the nitrogen raw material is refined by bringing it into contact with an alloy containing metallic Al. 8. A reaction chamber for growing a group III-V compound semiconductor film containing nitrogen (N), a group III source material for supplying a group III source material to the reaction chamber, and a group V source material for the reaction chamber. A nitrogen source, a nitrogen source, and a nitrogen source refining device for removing impurities from the nitrogen source consisting of a nitrogen compound from the nitrogen source and supplying the nitrogen source to the reaction chamber. A semiconductor film growth apparatus, wherein the nitrogen source purification apparatus according to claim 7 is used as the purification apparatus. 9. A semiconductor laser produced by the method for growing a semiconductor film according to claim 5, wherein the active layer contains a GaN-based material. 10. A semiconductor laser manufactured by the method for growing a semiconductor film according to claim 6, wherein the active layer contains a GaInNAs-based material. 11. The semiconductor laser of claim 10, the semiconductor _{laser, Al x Ga (1-x} ) As / Al y G
a _(1-y) As (0 ≦ y <x ≦ 1) A surface emitting semiconductor laser including at least one semiconductor multilayer film reflecting mirror. 12. An optical communication system, wherein the semiconductor laser according to claim 10 or 11 is used as a light source.