JP4864014B2 - Manufacturing method of surface emitting semiconductor laser device - Google Patents

Description

The present invention relates to the production how the surface-emitting type semiconductor laser element.

  In recent years, the amount of information handled as seen in the explosive spread of the Internet has increased dramatically, and is expected to accelerate further in the future. For this reason, optical fiber is introduced not only in trunk lines but also in subscriber lines such as homes and offices and transmission lines close to users such as LAN (Local Area Network), as well as between each equipment and within the equipment. Large-capacity information transmission technology is extremely important.

  In order to increase the capacity of the optical network and the optical wiring without being concerned about the distance at low cost, the transmission loss of the silica fiber as the light source is small and the matching is good in the 1.3 μm band and the 1.55 μm band. A surface emitting semiconductor laser element (VCSEL: Vertical Cavity Surface Emitting Laser) is very promising. Surface-emitting semiconductor laser devices are suitable for low cost, low power consumption, miniaturization, and two-dimensional integration compared to edge-emitting lasers. The 0.85 μm band that can actually be formed on a GaAs substrate is already a high-speed LAN. It has been put into practical use with a certain 1 Gbit / s Ethernet (registered trademark).

  In the 1.3 μm band, the material system on the InP substrate is common, and the edge emitting laser has a track record. However, this conventional long-wavelength semiconductor laser has a major drawback that the operating current increases three times as the environmental temperature is changed from room temperature to 80 ° C. In addition, since there is no material suitable for a reflecting mirror in a surface-emitting type semiconductor laser element, it is difficult to achieve high performance, and a practical level of characteristics has not been obtained.

  For this reason, the current highest performance is obtained by the structure in which the active layer on the InP substrate and the AlGaAs / GaAs reflecting mirror on the GaAs substrate are bonded together directly (see Non-Patent Document 1).

  However, this method is unavoidable in terms of mass productivity because of the inevitable increase in cost. Therefore, recently, a material system capable of forming a 1.3 μm band on a GaAs substrate has attracted attention, and (Ga) InAs quantum dots, GaAsSb and GaInNAs (see, for example, Patent Document 1) have been studied. GaInNAs, which is a new material, has attracted attention as a material that can make the temperature dependence of laser characteristics extremely small.

  Since the band gap of the GaInNAs semiconductor laser on the GaAs substrate is reduced by adding nitrogen, a long wavelength band such as a 1.3 μm band can be formed on the GaAs substrate. When the In composition is 10%, the nitrogen composition is about 3% and a 1.3 μm band can be formed. However, there is a problem that the threshold current density rapidly increases as the nitrogen composition increases. FIG. 9 is a graph showing the nitrogen composition dependency of the threshold current density. The horizontal axis represents the nitrogen composition ratio (%), and the vertical axis represents the threshold current density. The reason why the threshold current density rapidly increases as the nitrogen composition increases is that the crystallinity of the GaInNAs layer deteriorates as the nitrogen composition increases.

  For this reason, the issue is how to grow GaInNAs with high quality. As such GaInNAs crystal growth methods, MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy) have been tried.

  The MOCVD method does not require a high vacuum like the MBE method. In the MBE method, the material supply is controlled by changing the cell temperature, whereas the MOCVD method only needs to control the material gas flow rate. Since the speed can be increased and the throughput can be easily increased, the growth method is extremely suitable for mass production. The MOCVD method is used in all production of 0.85 μm band surface emitting semiconductor laser devices that are actually put into practical use (in most cases).

Recently, many reports of semiconductor lasers using this new GaInNAs-based material have been reported. However, most of these cases were based on the MBE method. Very recently, surface emitting semiconductor laser elements have also been reported. In 1998, Hitachi (1.18μm) made the first report (Non-Patent Document 2). In 2000, Stanford (1.215μm), Sandia + Cielo (1.294μm), Tokyo Tech + Ricoh (1.262μm), Infineon ( 1.285 μm).
V. Jayaraman, JC Geske, MH MacDougal FH Peters, TD Lowes, and TT Char, Electron.Lett., 34, (14), pp. 1405-1406, 1998. JP-A-6-37355 MC Larson, M. Kondow, T. Kitatani, K. Nakahara, K. Tamura, H. Inoue, and K. Uomi, IEEE Photonics Technol. Lett., 10, pp. 188-190, 1998.

  However, this new GaInNAs surface emitting semiconductor laser device has only one report of MOCVD method suitable for mass production, and all others have been grown by MBE method and have sufficient characteristics. It is not a thing. In particular, those grown by the MBE method have a very high resistance of the p-side multilayer reflector, so a method that does not use the p-side multilayer reflector as a current path is used, but eventually the operating voltage increases. It had problems such as. A manufacturing method and manufacturing apparatus for a novel GaInNAs-based surface-emitting type semiconductor laser device that has solved such a problem has not yet been established.

The present invention improves the manufacturing technology of the surface-emitting semiconductor laser device, it is an object to provide a manufacturing how the GaInNAs surface light emitting semiconductor laser element of the practical level with high quality.

In order to achieve the above object, an invention according to claim 1 includes an active region including at least one active layer for generating laser light on a semiconductor substrate, and an upper portion of the active layer for obtaining laser light. And a method of manufacturing a surface-emitting type semiconductor laser device having a resonator structure including a reflecting mirror provided in a lower part, wherein the active layer contains Ga, In, N, As as main components, At least the lower reflecting mirror includes a semiconductor distributed Bragg reflecting mirror whose refractive index changes periodically and reflects incident light by light wave interference, and the active layer is grown in a MOCVD growth chamber, and the lower reflecting mirror is separated from the lower reflecting mirror. The MOCVD growth chamber or the MBE growth chamber is used, and a regrowth interface that is an interface between the growths is used as a semiconductor distributed Bragg reflector portion .

According to a second aspect of the present invention, an active region including at least one active layer for generating laser light and an upper portion and a lower portion of the active layer for obtaining laser light are provided on a semiconductor substrate. A method of manufacturing a surface-emitting type semiconductor laser device having a resonator structure including a reflecting mirror, wherein the active layer contains Ga, In, N, As as a main component and at least one of the reflecting mirrors reflects The mirror includes a semiconductor distributed Bragg reflector that periodically changes the refractive index and reflects incident light by light wave interference, and the active layer and the reflector are grown in separate MOCVD growth chambers , respectively. The regrowth interface which is the interface of the semiconductor is a semiconductor distributed Bragg reflector part .
According to a third aspect of the present invention, in the method for manufacturing a surface-emitting type semiconductor laser device according to the second aspect, the reflecting mirror is a first MOCVD growth chamber composed of a vertical reaction tube, and the active layer is a lateral reaction. It is characterized by growing in a second MOCVD growth chamber consisting of tubes.
According to a fourth aspect of the present invention, in the method for manufacturing a surface-emitting type semiconductor laser device according to the third aspect, each of the first MOCVD growth chamber and the second MOCVD growth chamber contains a nitrogen source. The first gas line and the second gas line containing the Al raw material are connected, and the first gas line and the second gas line each have a valve, and the valve is opened and closed. The nitrogen raw material and the Al raw material do not meet in the first gas line or the second gas line.

According to a fifth aspect of the present invention, in the method for manufacturing a surface emitting semiconductor laser device according to any one of the first to fourth aspects, the growth chamber for growing the active layer grows a material containing Al. It is a growth room that does not.

According to a sixth aspect of the present invention, in the method for manufacturing a surface emitting semiconductor laser device according to any one of the first to fourth aspects, the growth chamber for growing the active layer grows a material containing Al. A growth chamber that may be formed, and after growing an Al-containing material and before growing an active layer, Al raw material, Al reactant, Al compound, or Al remaining in the growth chamber It is characterized by providing a step of removing the.

According to a seventh aspect of the present invention, in the method for manufacturing a surface-emitting type semiconductor laser device according to any one of the first to sixth aspects, before the active layer is grown in the growth chamber in which the active layer is grown. It is characterized by growing a Ga _x In _1-x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1) layer.

The invention according to claim 8 is the method for manufacturing a surface-emitting type semiconductor laser device according to any one of claims 1 to 7, wherein a plurality of crystal growth chambers are connected by a vacuum transfer path or the like. The crystal growth is carried out by transporting the substrate to be grown without being exposed to the atmosphere.

According to the present invention, it is possible to realize a manufacturing how the GaInNAs surface light emitting semiconductor laser element of the practical level with high quality.

More particularly, according to the manufacturing method of the surface emitting semiconductor laser device 請 Motomeko 1, is grown an active layer by an MOCVD growth chamber, growing a lower reflecting mirror on another MOCVD growth chamber or MBE growth chamber As a result, it is possible to grow a multilayer structure of a GaInNAs surface-emitting type semiconductor laser device of good quality by the MOCVD method advantageous for mass production. In particular, according to the method for manufacturing a surface-emitting type semiconductor laser device according to claim 1, the regrowth interface that is an interface between each growth is a semiconductor distributed Bragg reflector portion, thereby improving the device performance by the regrowth interface. The influence can be eliminated.

According to the method for manufacturing a surface-emitting type semiconductor laser device according to claims 2 to 4 , the active layer and the reflecting mirror are grown in separate MOCVD growth chambers, respectively, so that the MOCVD method is advantageous for mass production. A multilayer structure of a GaInNAs surface emitting semiconductor laser element of good quality can be crystal-grown. In particular, according to the method for manufacturing a surface emitting semiconductor laser device according to claim 2, by using a regrowth interface as a semiconductor distributed Bragg reflector portion as an interface between each growth, the device performance by the regrowth interface is improved. The influence can be eliminated.

Moreover, according to the manufacturing method of the surface emitting semiconductor laser device according to claim 5, in the manufacturing method of the surface emitting semiconductor laser device according to any one of claims 1 to 4 , the growth for growing the active layer is performed. Since the chamber is a growth chamber that does not grow Al-containing material, no Al source, Al reactant, Al compound, or Al remains in the growth chamber in which the active layer is grown. Therefore, it is possible to reliably prevent oxygen from being taken into the active layer containing nitrogen together with Al, and to obtain a surface-emitting type semiconductor laser device with high emission efficiency and low threshold current.

According to the method for manufacturing a surface-emitting type semiconductor laser device according to claim 6, in the method for manufacturing a surface-emitting type semiconductor laser device according to any one of claims 1 to 4 , the growth for growing an active layer is performed. The chamber is a growth chamber in which an Al-containing material may be grown. After growing the Al-containing material and before growing the active layer, the Al raw material remaining in the growth chamber or Al A step of removing a reactant, an Al compound, or Al is provided, and a growth chamber for growing an active layer containing nitrogen. Before the growth, an Al raw material remaining in the growth chamber in advance or Al Since the reactant, Al compound, or Al has been removed, no Al source, Al reactant, Al compound, or Al remains in the growth chamber in which the active layer is grown. Nitrogen Inclusive can reliably prevent the oxygen is taken in conjunction with Al in the active layer, high emission efficiency, it is possible to obtain a low surface emitting semiconductor laser device with threshold current.

According to the method for manufacturing the surface emitting semiconductor laser device of claim 7, in the step of growing the active layer, Ga _x In _1-x P _y As _1-y (0 < By growing the x ≦ 1, 0 <y ≦ 1) layer, the influence of the regrowth interface on the device performance can be eliminated.

According to the method of manufacturing the surface emitting semiconductor laser device according to claim 8 , the plurality of crystal growth chambers are connected by a vacuum transfer path or the like, and the substrate to be grown is transferred to the crystal without being exposed to the atmosphere. By making it grow, formation of an oxide film or the like at the regrowth interface that occurs when exposed to the atmosphere can be suppressed, and a good multilayer structure can be grown.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  (1) A method of manufacturing a surface-emitting type semiconductor laser device according to the first aspect is to obtain an active region including at least one active layer (23) for generating laser light on a semiconductor substrate and laser light. Has a resonator structure including reflectors (21, 25) provided on the upper and lower portions of the active layer (23), and reflectors (21, 25) provided on the upper and lower portions of the active layer (23). ) Is a p-side semiconductor reflecting mirror, the active layer (23) contains Ga, In, N, As as main components, and at least the p-side semiconductor of the reflecting mirrors. The reflector includes a semiconductor distributed Bragg reflector that periodically changes the refractive index and reflects incident light by light wave interference, and the active layer (23) is grown by the MBE method, and at least the p-side of the reflector Semiconductor reflector is MOCVD It is characterized by being grown.

  First, two growth methods, MOCVD method and MBE method, will be described with reference to FIGS. The MOCVD method (Metal Organic Chemical Vapor Deposition) is a vapor phase growth method that uses at least a part of an organic metal raw material to grow crystals by thermal decomposition of the raw material gas and surface reaction with the substrate to be grown. is there.

  FIG. 1 is a schematic view of an MOCVD apparatus. As shown in the figure, the MOCVD apparatus includes a source gas supply unit A to which source gas is supplied, a heating means (not shown) for heating the growth substrate, a heating unit (heating body) B, a reaction This is a configuration having an exhaust part C (exhaust pump or the like) for exhausting the exhausted gas. Usually, the substrate is introduced from the substrate loading / unloading port 11 so that air does not enter the growth chamber (reaction chamber) 12 and is transferred to the growth chamber (reaction chamber) 12 after being evacuated by the exhaust part C.

As the pressure in the growth chamber 12, a reduced pressure of about 50 Torr to 100 Torr is often used. As the raw material, an organic metal such as Ga: TMG (trimethylgallium), TEG (triethylgallium), Al: TMA (trimethylaluminum), or In: TMI (trimethylindium) is used as a group III raw material. In addition, the Group V material, AsH ₃ (arsine), TBA (tertiary butyl arsine), PH ₃ (phosphine), TBP (tertiary butyl arsine) hydride gas and an organic compound such as is generally used.

Hydrogen gas (H ₂ ) is normally used as the carrier gas, and is usually supplied after removing impurities through a hydrogen purifier. An organic compound such as DMHy (dimethylhydrazine) or MMHy (monomethylhydrazine) can be used as a raw material for nitrogen. The raw material is not limited to this. Liquid or solid raw materials such as organic metals and organic nitrogen compounds are supplied by bubbling through a carrier gas in a bubbler 14. The hydride is supplied in a gas cylinder 15. FIG. 1 shows an example in which there are two types of bubblers 14 (liquid and solid raw material bubblers # 1, # 2) and gas cylinders 15 (gas cylinders # 1, # 2).

  The path of the source gas is switched by the valve 16, and necessary materials and compositions are grown by controlling the supply amount with an MFC (mass flow controller) or the like. In general, dummy lines (see dummy lines # 1 and # 2 in the figure) are provided so that the gas flow is not disturbed as much as possible. The growth thickness is controlled by the supply time of the source gas. As a result, the necessary structure can be grown, so the throughput is good and the method is suitable for mass production.

  Next, the MBE method will be described. MBE (Molecular Beam Epitaxy) is a type of vacuum deposition method, in which source molecules and atoms released from a source cell reach a heated substrate in a high-vacuum chamber and adsorb to the crystal lattice. It is a method of growing by being embedded.

The MBE method has various names due to differences in raw material supply methods. Solid source (SS) -MBE using a solid source, organometallic (MO) -MBE using an organic metal as a group III material, gas source (GS) -MBE using a hydride as a group V material, an organic metal and a hydride There is CBE (Chemical Beam Epitaxy) used. Generally, a radical cell is used as a raw material for nitrogen, and N ₂ is decomposed and activated.

  FIG. 2 is a schematic diagram of the MBE apparatus. FIG. 2 shows an example in which two types of solid sources (in the figure, raw material molecular beam cell 1, raw material molecular beam cell 2) and nitrogen raw material (in the figure, nitrogen radical cell) are used. In particular, since solid source MBE does not contain carbon and hydrogen as raw materials, it can be grown with a low impurity concentration. Since the vacuum is high in principle, the raw material supply cannot be increased. Increasing it has the disadvantage of placing a burden on the exhaust system. Although a high vacuum exhaust system exhaust pump is required, the throughput is poor because the exhaust system is burdened and easily broken to remove residual raw materials in the MBE chamber.

  Here, it has been found that the MBE method is easier to improve the quality of GaInNAs than the MOCVD method. GaInNAs is a material with extremely strong immiscibility, and requires non-equilibrium growth such as low-temperature growth. In the MOCVD method, a compound gas is used for each raw material, and the substrate to be grown is heated and grown by utilizing the thermal decomposition of the raw material gas and the substrate surface reaction. Therefore, growth at the decomposition temperature or higher is necessary. Actually, the MBE method can grow at a low temperature of about 100 ° C. as compared with the MOCVD method. In addition, the raw material in the MOCVD method includes carbon (C) and hydrogen (H), and it is considered that impurities are incorporated into the film as impurities and the crystallinity is easily lowered.

  On the other hand, a surface emitting semiconductor laser element is configured by sandwiching an active region including at least one active layer that generates laser light between semiconductor multilayer reflectors. Whereas the thickness of the crystal growth layer of the edge-emitting laser is about 3 μm, for example, a 1.3 μm wavelength band-emitting semiconductor laser element requires a thickness exceeding 10 μm.

  The thickness of the active region is usually very small compared to the whole (10% or less), and most of them are layers constituting the multilayer mirror. The semiconductor multilayer mirror is formed by alternately laminating a low refractive index layer and a high refractive index layer (for example, 20 to 40) with a thickness (1/4) of the oscillation wavelength in each medium (λ / 4 thickness). Pair) is formed.

  In a surface emitting semiconductor laser device on a GaAs substrate, an AlGaAs-based material is used, and an Al composition is changed to form a low refractive index layer (Al composition large) and a high refractive index layer (Al composition small). In practice, however, the resistance is increased particularly on the p side due to the hetero-barrier of each layer. Therefore, an interlayer having an Al composition between the low refractive index layer and the high refractive index layer is inserted to reflect the multilayer film. The resistance of the mirror is reduced.

  As described above, the surface emitting semiconductor laser element has to grow semiconductor layers having different compositions as many as 100 layers, and in addition, between the low refractive index layer and the high refractive index layer of the multilayer reflector. It is an element that needs to control the amount of raw material supply instantaneously, such as providing a layer. However, in the MBE method, the supply amount is controlled by changing the temperature of the raw material cell, and the composition cannot be controlled flexibly. Therefore, it is difficult to reduce the resistance of the semiconductor multilayer mirror grown by the MBE method, and the operating voltage is high.

  In addition, since the MBE method requires a high vacuum, the raw material supply amount cannot be increased, the growth rate is about 1 μm / h, and growth for changing the raw material supply amount to grow a thickness of 10 μm. Even if there is no interruption time, it takes at least 10 hours.

  On the other hand, the MOCVD method only needs to control the raw material gas flow rate, can control the composition instantaneously, does not require a high vacuum like the MBE method, and can easily increase the growth rate to 3 μm / h or more, for example. Since the throughput can be increased, it has been found that this is a growth method extremely suitable for mass production, and that it is easier to grow the semiconductor multilayer mirror by the MOCVD method.

  Therefore, in the present invention, the lower semiconductor multilayer mirror is grown by the MOCVD method in the first first step, the active region including the GaInNAs active layer is grown by the MBE method in the second step, and the upper multilayer reflector is grown in the third step. The film reflector was grown by the MOCVD method. As a result, a low-resistance multilayer mirror can be easily formed, and a high-quality GaInNAs active layer can be easily formed.

In addition, since the growth by the MBE method is very small (about 1 μm or less), the burden on the apparatus is small and the failure is difficult, and the time required for the growth can be shortened as compared with the conventional method of growing all by the MBE method. effective. However, the n-side (n-side semiconductor) multilayer reflector is special in that the carrier concentration is increased to a high concentration of about 1 × 10 ¹⁸ cm ⁻³ even by alternately laminating low refractive index layers and high refractive index layers. Since it is easy to reduce the resistance without doing anything, only the multilayer reflector on the p side (p side semiconductor) may be grown by the MOCVD method. According to this, the growth process can be simplified.

  (2) A method for manufacturing a surface-emitting type semiconductor laser device according to the second aspect includes an active region including at least one active layer (23) for generating laser light on a semiconductor substrate (20), and laser light. In the surface emitting semiconductor laser device having a resonator structure including the reflecting mirrors (21, 25) provided on the upper and lower portions of the active layer, the active layer (23) includes Ga, In, N, As is a main component, at least the lower reflecting mirror of the reflecting mirrors includes a semiconductor distributed Bragg reflecting mirror whose refractive index changes periodically and reflects incident light by light wave interference, and the active layer (23) is formed by MOCVD. Growing is performed in a growth chamber, and at least the lower reflecting mirror (21) of the reflecting mirrors (21, 25) is grown in another MOCVD growth chamber or MBE growth chamber.

  The inventor of the present application stated that one of the reasons why high quality of GaInNAs is easier in the MBE method than in the MOCVD method is that the reaction between the nitrogen source and the Al source is very strong in the MOCVD method. It has been found that the following problems may occur when forming a structure including a layer containing nitrogen and a layer containing nitrogen.

  First, its high reactivity. FIG. 3 shows a molar ratio [DMHy] / ([PH3] of DMHy, which is a nitrogen source, with respect to a group V source when AlGaInNP and GaInNP having an Al composition of 20% are grown (shown here are experimental results of a p-based material). + [DMHy]) and the amount of nitrogen uptake, with the horizontal axis representing the molar ratio [DMHy] / ([PH3] + [DMHy]) and the vertical axis representing the amount of nitrogen uptake. Yes. Here, AlGaInNP was grown at 700 ° C. (experiment points are indicated by white circles), and GaInNP was grown at 650 ° C. (experiment points are indicated by black circles).

In general, the amount of nitrogen uptake is higher when the growth temperature is lower and higher when [DMHy] / ([PH3] + [DMHy]) is larger. The experimental results shown in FIG. According to the study, even though the growth temperature is high and [DMHy] / ([PH3] + [DMHy]) is negligible, the AlGaInNP containing Al (see white circles) captures overwhelmingly nitrogen. It turns out that it is easy to be rare. Further, organic nitrogen compounds such as DMHy, which are nitrogen raw materials, are difficult to exclude water during the purification process, and contain a certain amount of water (H ₂ O). Al is very reactive and reacts particularly well with water.

  The GaInNAs surface emitting semiconductor laser element is a structure including a multilayer reflector made of an AlGaAs-based material containing Al and an active layer made of GaInNAs containing nitrogen. When a lower multilayer mirror including a layer containing Al is grown, if an Al source remains in the reaction tube, it reacts with the nitrogen source when growing the active layer, and the active layer contains Al or oxygen (O) is incorporated into the material, affecting the quality, or reacting with the nitrogen raw material in advance, reducing the amount of nitrogen incorporated into the growth layer, and causing extremely serious problems. In particular, the incorporation of oxygen creates deep impurity levels in the active layer and adversely affects the optical characteristics. That is, the luminous efficiency is lowered and the threshold current is increased in the case of a laser.

  Specific experimental results are shown below.

  FIG. 10 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 produced by the MOCVD apparatus of the inventors of the present application. FIG. 11 is a diagram showing a sample structure of the semiconductor light emitting device. Referring to FIG. 11, the sample structure is such that a lower cladding layer 202, an intermediate layer 203, an active layer 204 containing nitrogen, an intermediate layer 203, and an upper cladding layer 205 are sequentially stacked on a GaAs substrate 201. . In FIG. 10, symbol A is a room temperature photoluminescence spectrum from an active layer 204 of a sample in which a double quantum well structure is formed on an AlGaAs cladding layer 202 with a GaAs intermediate layer 203 interposed therebetween, and symbol B is a GaInP cladding layer 202. It is a room temperature photoluminescence spectrum from an active layer 204 of a sample in which a double quantum well structure is continuously formed with a GaAs intermediate layer 203 interposed therebetween.

  As shown in FIG. 10, the photoluminescence intensity of sample A is reduced to half or less than that of sample B. Therefore, if an active layer containing nitrogen such as GaInNAs is continuously formed on a semiconductor layer containing Al as a constituent element using a single MOCVD apparatus, the light emission intensity of the active layer will deteriorate. There was a problem. Therefore, the threshold current density of the GaInNAs laser formed on the AlGaAs cladding layer is more than twice as high as that formed on the GaInP cladding layer.

  The inventor of the present application further examined the cause elucidation. FIG. 12 shows, as an example of the semiconductor light emitting device shown in FIG. 11, one device in which the cladding layers 202 and 205 are made of AlGaAs, the intermediate layer 203 is made of GaAs, and the active layer 204 is made of 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 this epitaxial growth apparatus (MOCVD apparatus). The measurement was performed by SIMS. The measurement conditions are shown in the following table (Table 1).

  In FIG. 12, two nitrogen (N) peaks are seen in the active layer 204 corresponding to the GaInNAs / GaAs double quantum well structure. In the active layer 204, an oxygen (O) peak is detected. However, the oxygen concentration in the intermediate layer 203 not containing N and Al is about one digit lower than the oxygen concentration in the active layer 204.

  On the other hand, when the depth direction distribution of oxygen (O) concentration is measured for an element in which the cladding layers 202 and 205 are made of GaInP, the intermediate layer 203 is made of GaAs, and the active layer 204 is made of a GaInNAs / GaAs double quantum well structure. The oxygen (O) concentration in the active layer 204 was at the background level.

  That is, when a semiconductor light emitting device in which a semiconductor layer containing Al is provided between a substrate 201 and an active layer 204 containing nitrogen is continuously grown by an epitaxial growth apparatus using a nitrogen compound raw material and an organometallic Al raw material, It has become clear from experiments by the inventors of the present application that oxygen is taken into the active layer 204 containing nitrogen. Oxygen incorporated into the active layer 204 forms a non-radiative recombination level, which reduces the light emission 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 device in which the semiconductor layer containing Al is provided between the substrate 201 and the active layer 204 containing nitrogen. . The origin of 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. 13 is a diagram showing a depth direction distribution of Al concentration of the same sample as FIG. The measurement was performed by SIMS. The measurement conditions are shown in the following table (Table 2).

  From FIG. 13, Al is detected in the active layer 204 which is not originally introduced with the Al raw material. However, in the intermediate layer (GaAs layer) 203 adjacent to the Al-containing semiconductor layer (cladding layers 202 and 205), the Al concentration is about one digit lower than that of the active layer. This indicates that Al in the active layer 204 is not mixed by diffusion and substitution from a semiconductor layer containing Al (clad layers 202 and 205).

  On the other hand, when an active layer containing nitrogen was grown on a semiconductor layer not containing Al, such as GaInP, Al was not detected in the active layer.

  Therefore, the Al detected in the active layer 204 is the Al raw material remaining in the growth chamber or the gas supply line, or the Al reactant, Al compound, or Al is contained in the nitrogen compound raw material or the nitrogen compound raw material. It is incorporated into the active layer 204 by combining with impurities (water, alcohol, etc.). That is, using a nitrogen compound raw material and an organometallic Al raw material, a semiconductor light-emitting element in which a semiconductor layer containing Al is provided between a substrate 201 and an active layer 204 containing nitrogen is continuously crystallized by a single epitaxial growth apparatus. It has been newly found that, when grown, Al is naturally taken into the active layer 204 containing nitrogen.

  Compared with the depth distribution of the nitrogen (N) concentration and the oxygen (O) concentration in the same element shown in FIG. 12, the two oxygen peak profiles in the double quantum well active layer are: It does not correspond, and corresponds to the Al concentration profile of FIG. From this, it was found that the oxygen impurities in the GaInNAs well layer were taken together with Al taken in the well layer rather than taken together with the nitrogen source. That is, when the Al raw material, Al reactant, Al compound, or Al remaining in the growth chamber comes into contact with the nitrogen compound raw material, the moisture contained in the Al and nitrogen compound raw material or in the gas line or reaction chamber Residual substances containing oxygen such as moisture are combined, and Al and oxygen are taken into the active layer 204. It has become clear for the first time through experiments by the inventors of the present application that oxygen taken into the active layer 204 reduces the luminous efficiency of the active layer 204.

  Therefore, in order to improve this, there is no Al raw material, Al reactant, Al compound, or Al at least in a place where the nitrogen compound raw material or impurities contained in the nitrogen compound raw material are in contact with the growth chamber. It has been found that it is preferable to grow an active layer containing nitrogen in the state.

  As this method, it is preferable to grow an active layer containing nitrogen by growing the semiconductor layer containing Al and then moving the substrate to another reaction chamber. That is, it is preferable to grow an active layer containing nitrogen after growing a semiconductor layer containing Al in another growth chamber such as another MOCVD growth chamber or MBE growth chamber. According to this method, when a nitrogen compound raw material is supplied to the growth chamber to grow an active layer containing nitrogen, the Al raw material remaining in the reaction chamber, the Al reactant, the Al compound, or Al and The concentration of Al and oxygen impurities taken into the active layer can be reduced by the reaction between the nitrogen compound raw material or the impurities contained in the nitrogen compound raw material and the substance containing oxygen remaining in the apparatus.

For example, the continuous oscillation at room temperature became possible by reducing the Al concentration in the active layer containing nitrogen to 1 × 10 ¹⁹ cm ⁻³ or less. Furthermore, by reducing the Al concentration in the active layer containing nitrogen to 2 × 10 ¹⁸ cm ⁻³ or less, light emission characteristics equivalent to those formed on a semiconductor layer not containing Al were obtained.

  In the following table (Table 3), a broad stripe laser using AlGaAs as a cladding layer (a layer containing Al) and a GaInNAs double quantum well structure (a layer containing nitrogen) as an active layer was prototyped and the threshold current density was evaluated. Results are shown.

In a structure in which an active layer containing nitrogen is continuously formed on a semiconductor layer containing Al as a constituent element, 2 × 10 ¹⁹ cm ⁻³ or more of Al and 1 × 10 ¹⁸ cm ⁻³ or more of oxygen are contained in the active layer. Was taken in, and the threshold current density was as high as 10 kA / cm ² or more. However, by reducing the Al concentration in the active layer to 1 × 10 ¹⁹ cm ⁻³ or less, the oxygen concentration in the active layer is reduced to 1 × 10 ¹⁸ cm ⁻³ or less, and the threshold current density is 2 to ³ kA / cm. ^{At 2} the broad stripe laser oscillated. If the threshold current density of the broad stripe laser is an active layer quality of several kA / cm ² or less, continuous oscillation at room temperature is possible. Therefore, by suppressing the Al concentration in the active layer containing nitrogen to 1 × 10 ¹⁹ cm ⁻³ or less, it is possible to provide a semiconductor laser capable of continuous oscillation at room temperature.

  Semiconductor light emission in which a semiconductor layer containing Al is provided between a substrate and an active layer containing nitrogen when the crystal growth method does not use an organometallic Al raw material and a nitrogen compound raw material, as in a normal MBE method There is no particular report on a significant decrease in luminous efficiency in the device.

  The MBE method grows crystals under ultra-low pressure (in a high vacuum), whereas the MOCVD method usually has a pressure of several tens of Torr to atmospheric pressure, and the pressure in the reaction chamber is higher than the MBE method. This is presumably because the material and carrier gas supplied are in contact with and react with each other in the gas line and reaction chamber. Therefore, in the case of a growth method in which the pressure in the reaction chamber or gas line is high, such as the MOCVD method, after growing the semiconductor layer containing Al, the active layer containing nitrogen is not grown in the same reaction chamber. It is preferable to grow the substrate by moving it to the reaction chamber.

  As described above, it has been found that the present invention is effective in the case of an active layer containing nitrogen, such as GaNAs, GaPN, GaNPAs, GaInNAs, GaInNP, GaNASSb, GaInNAsSb.

  As a result, a multilayer structure of a GaInNAs surface-emitting type semiconductor laser device of good quality can be crystal-grown by the MOCVD method advantageous for mass production.

  (3) A method for manufacturing a surface-emitting type semiconductor laser device according to a third aspect includes an active region including at least one active layer (23) for generating laser light on a semiconductor substrate (20), and laser light. In the surface emitting semiconductor laser device having a resonator structure including the reflecting mirrors (21, 25) provided on the upper and lower portions of the active layer, the active layer (23) includes Ga, In, N, As as a main component, at least one of the reflecting mirrors includes a semiconductor distributed Bragg reflector that periodically changes the refractive index and reflects incident light by light wave interference, and includes the active layer (23). The reflecting mirrors 21 and 25 (both are semiconductor multilayer mirrors) are grown in separate MOCVD growth chambers.

  For example, if both the lower and upper reflectors are semiconductor multilayer reflectors, they are grown in the first MOCVD growth chamber and the active layer is grown in the second growth chamber. If only the lower reflector is a semiconductor multilayer reflector, this is grown in the first MOCVD growth chamber and the active layer is grown in the second growth chamber. Further, when only the upper reflecting mirror is a semiconductor multilayer film reflecting mirror, it can be considered that this is grown in the first MOCVD growth chamber and the active layer is grown in the second growth chamber.

  Thus, in the above manufacturing method, the multilayer film reflecting mirror made of a material system containing Al and the active layer made of a material system containing nitrogen are grown in separate growth chambers. It is possible to prevent growth of Al-containing material in the reaction chamber for growing the active layer made of the system, and oxygen related to the reaction with Al is taken into the active layer made of the material system containing nitrogen. Can be prevented. That is, oxygen uptake creates a deep impurity level in the active layer and adversely affects the optical characteristics (that is, the emission efficiency is lowered and the threshold current is increased in the case of a laser), but in the present invention, nitrogen is contained. As a result, it is possible to prevent oxygen related to the reaction with Al from being taken into the active layer made of a material system, so that a good quality GaInNAs surface emission can be obtained by the MOCVD method advantageous for mass production. The multilayer structure of the type semiconductor laser device can be crystal-grown.

  (4) The fourth aspect of the method for manufacturing a surface emitting semiconductor laser element is the method for manufacturing the surface emitting semiconductor laser element of the second or third aspect, wherein the growth chamber for growing the active layer contains Al. It is characterized by a growth chamber that does not grow materials.

  In the fourth aspect of the surface emitting semiconductor laser device manufacturing method, no Al source, Al reactant, Al compound, or Al remains in the growth chamber in which the active layer is grown. It is possible to reliably prevent oxygen from being taken into the active layer containing nitrogen together with Al, and to obtain a surface-emitting type semiconductor laser device with high emission efficiency and low threshold current.

  (5) The method for manufacturing the surface-emitting type semiconductor laser device according to the fifth aspect is the method for manufacturing the surface-emitting type semiconductor laser device according to the second or third mode, wherein the growth chamber for growing the active layer contains Al. It is a growth chamber that may grow a material, and after growing an Al-containing material and before growing an active layer, Al raw material remaining in the growth chamber, or an Al reactant, or Al It is characterized by providing a step of removing a compound or Al.

  In the fifth aspect of the surface emitting semiconductor laser device manufacturing method, in the growth chamber in which the active layer containing nitrogen is grown, before the growth, the Al raw material remaining in the growth chamber in advance, the Al reactant, or Since the Al compound or Al has been removed, no Al source, Al reactant, Al compound, or Al remains in the growth chamber for growing the active layer, and nitrogen is removed. It is possible to reliably prevent oxygen from being taken into the active layer contained together with Al, and to obtain a surface emitting semiconductor laser element with high emission efficiency and low threshold current.

  The step of removing the Al raw material, the Al reactant, the Al compound, or Al is, for example, evacuating a gas line or a growth chamber, supplying a carrier gas (for example, hydrogen gas), or supplying a carrier gas (for example, hydrogen). It is preferable to heat the heating body in the growth chamber while supplying the gas), but this is not restrictive. When heating a heating body, it is preferable to carry out at a temperature higher than the growth temperature. These steps are preferably performed before the substrate to be grown is introduced into the growth chamber.

(6) A method for manufacturing a surface-emitting type semiconductor laser device according to a sixth aspect is the method for manufacturing a surface-emitting type semiconductor laser device according to the first, second, third, fourth, or fifth mode. In the growing chamber, a Ga _x In _1-x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1) layer is grown before the active layer is grown.

If the regrowth interface is in the active region into which carriers are injected, non-radiative recombination may occur due to oxidation or the like, which may reduce the luminous efficiency. However, the active layer is grown after the growth chamber moves as in the fourth embodiment When _{Ga x in 1-x P y} As 1-y (0 <x ≦ 1,0 <y ≦ 1) layer is grown _{before, Ga x in 1-x P} y As 1-y (0 <x ≦ 1 , 0 <y ≦ 1), it is possible to form an active region with a material having a narrow gap (for example, GaAs). Can do. Note that the Ga _x In _1-x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1) layer does not contain Al and has a wider gap than the region where carriers are mainly injected. Any other group III-V elements such as BN, Sb, etc. may be included.

  (7) The manufacturing method of the surface-emitting type semiconductor laser device according to the seventh aspect is the same as the manufacturing method of the surface-emitting type semiconductor laser device according to the first, second, third, fourth, or fifth mode. The regrowth interface which is the interface of the semiconductor is a semiconductor distributed Bragg reflector part.

  If the regrowth interface is in the active region into which carriers are injected, non-radiative recombination may occur due to oxidation or the like, which may reduce the luminous efficiency. However, if the regrowth interface is provided in the reflector portion as in the fifth embodiment, Since the low refractive index layer having a wide gap exists between the growth interface and the active region, the above-mentioned fear is eliminated, and the influence of the regrowth interface on the device performance can be eliminated.

  (8) The manufacturing method of the surface-emitting type semiconductor laser device according to the eighth aspect is the same as the manufacturing method of the surface-emitting semiconductor laser device according to the first, second, third, fourth, or fifth mode. The chambers are connected by a vacuum transfer path or the like, and the growth substrate is transferred and crystal growth is performed without being exposed to the atmosphere.

  According to the configuration of the eighth embodiment, since it is not exposed to the atmosphere, the formation of an oxide film or the like at the regrowth interface that occurs when exposed to the atmosphere can be suppressed, and a good multilayer structure can be grown.

  (9) The crystal growth apparatus of the ninth aspect is characterized in that the MBE growth chamber and the MOCVD growth chamber are connected by a vacuum transfer path or the like that can transfer the growth target substrate without being exposed to the atmosphere.

  According to the configuration of the ninth embodiment, since it is not exposed to the atmosphere, the formation of an oxide film or the like at the regrowth interface that occurs when exposed to the atmosphere can be suppressed, and the advantages of the MBE method and the MOCVD method are utilized. The ideal multilayer film structure can be crystal-grown.

  (10) In the crystal growth apparatus of the tenth aspect, the first MOCVD growth chamber and the second MOCVD growth chamber are connected by a vacuum transfer path or the like that can transfer the growth target substrate without being exposed to the atmosphere. It is characterized by.

  According to the configuration of the tenth embodiment, since it is not exposed to the atmosphere, it is possible to suppress the formation of an oxide film or the like at the regrowth interface that occurs when exposed to the atmosphere, and to bring incompatible source gases together However, it is possible to ideally grow a multilayer film structure including a growth layer using them separately. In addition, each of the growth chambers can be formed in a growth chamber in a form adapted to a separate layer, such as a vertical growth chamber, a combination of a horizontal growth chamber and a growth chamber, and the multilayer structure can be grown more optimally.

  (11) The surface-emitting type semiconductor laser device according to the eleventh aspect is formed using the manufacturing method according to any one of the first to eighth aspects, or the crystal growth apparatus according to the ninth or tenth aspect. It is characterized by that.

  That is, by adding N to GaInAs, which has a larger lattice constant than GaAs, GaInNAs can be lattice-matched to GaAs, and its band gap is reduced, and light emission in the 1.3 μm and 1.55 μm bands is achieved. Is possible. Since it is a GaAs substrate lattice matching system, wide gap AlGaAs or GaInP can be used for the cladding layer.

  In addition, the addition of N reduces the band gap as described above, lowers the energy levels of both the conduction band and the valence band, and extremely increases the band discontinuity of the conduction band at the heterojunction. Temperature dependence can be made extremely small.

  Furthermore, the surface emitting semiconductor laser device is advantageous for parallel transmission by small size, low power consumption and two-dimensional integration. Although it is difficult to obtain performance that can be put to practical use in the conventional GaInPAs / InP system, the surface emitting semiconductor laser element is a 0.85 μm band surface emitting semiconductor laser element using a GaAs substrate according to a GaInNAs material. Al (Ga) As / (Al) GaAs-based semiconductor multilayer distributed Bragg reflectors and the current narrowing structure by selective oxidation of AlAs can be applied, so that practical application can be expected.

  To achieve this, it is important to improve the crystal quality of the GaInNAs active layer, to reduce the resistance of the multilayer reflector, and to improve the crystal quality and controllability of the multilayer structure as a surface emitting semiconductor laser device. However, by using one or more of the manufacturing methods according to the first to eighth embodiments of the present invention and the manufacturing apparatuses of the ninth and tenth embodiments, the driving voltage is low and the driving voltage is low. A surface-emitting semiconductor laser element that operates with current and has good temperature characteristics can be easily realized.

  (12) The optical transmission module of the twelfth aspect is characterized by using the surface emitting semiconductor laser element of the eleventh aspect as a light source. By using a surface emitting semiconductor laser element having a low resistance, a low driving voltage, a low threshold current operation, and good temperature characteristics, a low-cost optical transmission module that does not require a cooling element can be realized. it can.

  (13) The optical transceiver module of the thirteenth aspect is characterized by using the surface emitting semiconductor laser element of the eleventh aspect as a light source. By using a surface emitting semiconductor laser element having a low resistance, a low driving voltage, a low threshold current operation, and good temperature characteristics, a low-cost optical transceiver module that does not require a cooling element can be realized. it can.

(14) The optical communication system of the fourteenth aspect is characterized by using the surface emitting semiconductor laser element of the eleventh aspect as a light source. Low-cost optical fiber communication system, optical interconnection system, etc. that do not require a cooling element by using a surface emitting semiconductor laser device with low resistance, low drive voltage, low threshold current operation, and good temperature characteristics as described above An optical communication system can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  A GaInNAs surface-emitting type semiconductor laser device according to Example 1 of the present invention will be described.

FIG. 4 is a diagram showing the structure of the surface-emitting type semiconductor laser device according to Example 1 of the present invention. As shown in FIG. 4, the surface-emitting type semiconductor laser device in Example 1 is formed on an n-GaAs substrate 20 having a surface orientation (100) having a size of 2 inches and ¼ of the oscillation wavelength in each medium. fold in thickness made of _{n-Al x Ga 1-x} as (x = 0.9) and then 35 cycles laminated n-GaAs alternating periodic structure n- semiconductor distributed Bragg reflector (lower semiconductor distributed Bragg reflector : Simply referred to as a lower reflecting mirror) 21 is formed (details are omitted in FIG. 4). _{Ga x In 1-x N y} As 1-y (x, y) of an undoped lower GaAs spacer layer 22,3 layer on the well layer and the multiple quantum well active layer 23 made of GaAs barrier layer 15 nm, an undoped upper GaAs spacer Layer 24 is formed.

A p-semiconductor distributed Bragg reflector (upper semiconductor distributed Bragg reflector: also simply referred to as an upper reflector) 25 is formed thereon. The upper reflecting mirror 25 is a 3λ / 4-thick low refractive index layer (λ / 4-15 nm C-doped p-Al _x Ga _1-x As (x = 0) sandwiching AlAs serving as a selective oxidation layer between AlGaAs. .9), 30 nm C-doped p-AlAs selectively oxidized layer 251, 2λ / 4-15 nm C-doped p-Al _x Ga _1-x As (x = 0.9)) and thickness λ / 4 GaAs (1 cycle), and alternately laminated _{p-Al x Ga 1-x} as (x = 0.9) and p-GaAs of C doped in the fourth of the thickness of the oscillation wavelength in the respective medium The periodic structure is composed of, for example, 25 periods (details are omitted in the figure).

  The uppermost GaAs layer 252 of the upper reflecting mirror 25 also serves as a contact layer that contacts the electrode. The In composition x of the well layer in the active layer 23 was 37%, and the nitrogen composition was 0.5%. The thickness of the well layer was 7 nm. The GaAs substrate 20 had a compressive strain (high strain) of about 2.5%.

  Crystal growth of each layer of the surface-emitting type semiconductor laser device of FIG. 4 in Example 1 is performed by a crystal growth apparatus as shown in FIG. As shown in FIG. 5, in the crystal growth apparatus according to the first embodiment, the MOCVD growth chamber 31 and the MBE growth chamber 32 are coupled through a vacuum transfer path, and a reflecting mirror is grown in the MOCVD growth chamber 31 to obtain GaInNAs. The GaAs substrate 20 was moved in the middle of the GaAs spacer layer so that the active layer was grown in the MBE growth chamber 32. The MOCVD apparatus and the MBE apparatus in the crystal growth apparatus may be separated from each other, and the GaAs substrate 20 may be once taken out into the atmosphere. However, it is preferable that the GaAs substrate 20 is integrated and not exposed to the atmosphere as shown in FIG. Good. This is because the concentration of oxygen taken into the regrowth interface can be reduced.

In this embodiment, GaInNAs growth by MBE was performed using solid source Ga, In, As, and nitrogen obtained by decomposing N ₂ gas in an RF radical cell. In addition, TMG (trimethylgallium), TMI (trimethylindium), AsH ₃ (arsine) was used for AlGaAs growth by the MOCVD apparatus, and H ₂ (hydrogen) was used for the carrier gas. When the strain is large as in the active layer of the device of this example, low temperature growth that is non-equilibrium is preferable. In this example, the GaInNAs layer was grown at 430 ° C.

A mesa having a predetermined size was formed by exposing at least the side surface of the p-AlAs selective oxidation layer 251, and the AlAs that appeared on the side surface was oxidized from the side surface with water vapor to form the Al _x O _y current narrowing layer 26. Then, the etched portion is buried and planarized with polyimide 27 to remove the polyimide on the upper reflecting mirror having the p contact layer 252 and the light emitting portion 28, and the p-side electrode other than the light emitting portion 28 on the p contact layer 252. 29 and the n-side electrode 30 was formed on the back surface of the substrate 20.

  The oscillation wavelength of the manufactured surface emitting semiconductor laser element was about 1.3 μm. Since GaInNAs was used for the active layer, a long wavelength surface emitting semiconductor laser element could be formed on the GaAs substrate. In addition, the threshold current was low because the current was narrowed by selective oxidation of the selective oxidation layer mainly composed of Al and As. According to the current narrowing structure using the current narrowing layer made of the Al oxide film that selectively oxidizes the selective oxidation layer, the current spreading can be suppressed by forming the current narrowing layer close to the active layer, so that it does not touch the atmosphere. Carriers can be confined efficiently in the region.

  Furthermore, the refractive index is reduced by oxidizing to an Al oxide film, and light can be efficiently confined in a minute region in which carriers are confined by the effect of the convex lens, which is extremely efficient and the threshold current is reduced. The In addition, the manufacturing cost can be reduced because the current narrowing structure can be easily formed. As described above, according to the present embodiment, a 1.3 μm band surface emitting semiconductor laser device with low power consumption and low cost can be realized. In order to reduce the number of movements and shorten the manufacturing time, the n-side multilayer reflector 21 and the active layer 23 are grown in the MBE growth chamber, and only the p-side multilayer reflector 25 is grown in the MOCVD growth chamber. You can also.

  A GaInNAs surface-emitting type semiconductor laser device according to Example 2 of the present invention will be described. The structure of the GaInNAs surface-emitting type semiconductor laser device in Example 2 is as shown in FIG. 4 as in Example 1. The difference from Example 1 is the crystal growth method. The crystal growth in Example 2 was performed by an MOCVD apparatus having two MOCVD growth chambers.

  FIG. 6 is a schematic diagram of an MOCVD apparatus having two MOCVD growth chambers 41 and 42 for crystal growth of a GaInNAs surface emitting semiconductor laser element in the second embodiment.

  In Example 2, the reflecting mirrors using the Al-containing layer (the lower reflecting mirror 21 and the upper reflecting mirror 25 in FIG. 4) are grown in the first MOCVD growth chamber 41, and the GaInNAs using the layer containing nitrogen is used. The active layer (GaInNAs active layer 23 in FIG. 4) was grown in the second MOCVD growth chamber 42. In Example 2, the first MOCVD growth chamber 41 used a vertical reaction tube, and the second MOCVD growth chamber 42 used a horizontal reaction tube. During the growth of the GaAs spacer layer 22, the substrate was moved through the vacuum transfer path 43 and grown.

TMG (trimethylgallium), TMI (trimethylindium), AsH ₃ (arsine) were used as raw materials for the GaInNAs active layer 23 by MOCVD, and DMHy (dimethylhydrazine) was used as a raw material for nitrogen. H ₂ was used as a carrier gas. DMHy is suitable for low-temperature growth at 600 ° C. or lower because it decomposes at low temperatures, and is a preferable raw material for growing a quantum well layer having a large strain required for low-temperature growth. When the strain is large as in the active layer 23 of the GaInNAs surface-emitting type semiconductor laser device of Example 2, low temperature growth that is non-equilibrium is preferable. In Example 2, the GaInNAs layer 23 was grown at 540 ° C. Nitrogen and Al materials were not allowed to meet in the gas line. Specifically, the ON / OFF valve shown in FIG. 6 is not opened or closed.

  The vertical reaction tube used in the first MOCVD growth chamber 41 has excellent uniformity and is suitable for the growth of a multilayer mirror. In addition, the horizontal reaction tube used in the second MOCVD growth chamber 42 has a feature that a laminar flow is easily generated. Further, since there are upstream and downstream, the raw material gas can be decomposed in advance, which is advantageous for low temperature growth and suitable for the growth of GaInNAs. It is not limited to the combination of the vertical reaction tube and the horizontal reaction tube as shown in FIG. 6, but has a plurality of growth chambers such as a combination of vertical reaction tubes having different forms, for example, a growth suitable for each growth layer. There is an advantage that it can be made into a chamber shape and various multilayer film structures can be easily optimized and grown.

  In Example 2, all of the MOCVD apparatus was used and they were coupled by the vacuum transfer path 43, so that a GaInNAs surface-emitting type semiconductor laser device could be manufactured with good throughput without adverse effects of the regrowth interface.

  In addition, although the regrowth interface is in the middle of the GaAs spacer layer, it is not limited to this (the same applies to Example 1). If the active region into which carriers are injected is used as a regrowth interface, non-radiative recombination may occur due to oxidation or the like, which may reduce luminous efficiency. For example, the high-refractive index layer and the low-refractive index layer constituting the reflecting mirror may be grown by one pair 2nd growth (step of growing the active region).

In this case, it is preferable to use a layer that does not contain Al as the regrowth interface (if the layer containing Al is used as the regrowth interface, the negative effect of oxidation may be a problem even if vacuum transfer is performed), so a high refractive index. The layer may be GaAs, the low refractive index layer may be Al (Ga) As, and the GaAs layer may be a regrowth interface. In particular, in the MOCVD method, a problem may occur when an Al-containing layer is grown in a reaction chamber for growing GaInNAs (particularly, when an Al-containing layer is grown between a substrate and an active layer containing nitrogen). Therefore, it is preferable to use a material that does not contain Al, such as Ga _x In _1-x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1), for the low refractive index layer.

An example of this is shown in FIG. In FIG. 14, a Ga _x In _1-x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1) layer is formed before the GaInNAs active layer is grown in the step of growing the active region (2nd growth). Growing. The Ga _x In _1-x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1) layer is one of the low-refractive index layers constituting the lower reflecting mirror. . The upper reflecting mirror has the same configuration as that shown in FIG. 4, and only the low refractive index layer of the lower reflecting mirror is Ga _x In _1-x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1). ing. Low-refractive-index layer portion (3λ / 4-thickness low-refractive-index layer in which AlAs to be a selective oxidation layer is sandwiched between AlGaAs) constituting the upper reflector in the step of growing the active region (2nd growth) is an AlGaAs-based material However, since there is sufficient time until the next active layer growth including nitrogen, mixing of the Al and oxygen into the active layer can be prevented by cleaning the apparatus during that time by vacuuming or the like. In addition, since this cleaning is usually performed, the manufacturing process is not particularly increased. As a cleaning method, it is efficient to heat the heating body in the growth chamber while supplying hydrogen gas as a carrier gas. When heating a heating body, it is preferable to carry out at a temperature higher than the growth temperature. Desirably, the growth chamber for growing the active layer is a growth chamber that does not grow a material containing Al, that is, does not supply an Al raw material. This is because it is possible to reliably prevent oxygen from being taken into the active layer containing nitrogen together with Al.

  FIG. 7 is a diagram illustrating a third embodiment of the present invention, and is a schematic diagram of an optical transmission module in which a surface-emitting type semiconductor laser device according to the first embodiment and an optical fiber are combined. In the third embodiment, the laser light 53 from the 1.3 μm band GaInNAs surface emitting semiconductor laser element 51 is input to the silica-based optical fiber 52 and transmitted. It is possible to increase the transmission speed by arranging a plurality of surface emitting semiconductor laser elements having different oscillation wavelengths in an array in one or two dimensions and performing wavelength multiplexing transmission. It is also possible to increase the transmission speed by arranging the surface-emitting type semiconductor laser elements in a one-dimensional or two-dimensional array and combining them with optical fiber bundles composed of a plurality of optical fibers 52 corresponding thereto.

  Furthermore, when the surface emitting semiconductor laser device according to the present invention is used in an optical communication system, a low-cost and highly reliable optical transmission module can be realized, and a low-cost and high-reliability optical communication system using the same can be realized. . In addition, since the surface emitting semiconductor laser element using GaInNAs has a good temperature characteristic and a low threshold value, a system that generates less heat and can be used without cooling to a high temperature can be realized.

  FIG. 8 is a diagram showing a fourth embodiment of the present invention, and is a schematic diagram of an optical transceiver module in which the surface emitting semiconductor laser element of the second embodiment, a receiving photodiode, and an optical fiber are combined.

  When the surface-emitting type semiconductor laser device according to the present invention is used in an optical communication system, the surface-emitting type semiconductor laser device is low in cost, and therefore, as shown in FIG. A low-cost and high-reliability optical communication system using an optical transmission module in which a GaInNAs surface emitting semiconductor laser element) 61, a receiving photodiode 62, and an optical fiber 63 are combined can be realized. Further, in the case of the surface emitting semiconductor laser device using GaInNAs according to the present invention, the temperature characteristics are good, the operating voltage is low, and the threshold value is low, so there is little heat generation and no cooling to high temperature. A lower cost system can be realized.

  Furthermore, when a fluorine-doped POF (plastic fiber) that has a low loss in a long wavelength band such as 1.3 μm and a surface emitting laser using GaInNAs as an active layer are combined, the cost of the fiber is reduced and the diameter of the fiber is reduced. Since it is large and can be easily coupled with a fiber and the mounting cost can be reduced, a very low-cost module can be realized.

  The optical communication system using the surface emitting semiconductor laser device according to the present invention can be used not only for long-distance communication using an optical fiber, but also for transmission between devices such as a LAN (Local Area Network) and the like, and Can be used for short-distance communication as an optical interconnection such as data transmission between boards, between LSIs in a board, between elements in an LSI, and the like.

  In recent years, the processing performance of LSIs and the like has improved, but the transmission speed of the portion connecting them will become a bottleneck in the future. When the signal connection in the system is changed from the conventional electrical connection to the optical interconnect, for example, the optical transmission module or the optical transmission / reception module according to the present invention is used between the boards of the computer system, between the LSIs in the board, between the elements in the LSI, etc. Connection, an ultra-high-speed computer system becomes possible.

  In addition, when a plurality of computer systems are connected using the optical transmission module or the optical transmission / reception module according to the present invention, an ultra-high speed network system can be constructed. In particular, the surface-emitting type semiconductor laser element is suitable for a parallel transmission type optical communication system because the power consumption can be reduced by orders of magnitude compared to the edge-emitting type laser and the two-dimensional array can be easily formed.

  As described above, according to the GaInNAs-based material, an Al (Ga) As / (Al) GaAs-based semiconductor multilayer distributed Bragg reflector having a proven record in a 0.85 μm band-emitting semiconductor laser device using a GaAs substrate, etc. The current narrowing structure by selective oxidation of AlAs can be applied, and the surface-emitting type semiconductor laser device is manufactured as in Example 1, Example 2, or Example 5 described later, thereby improving the crystal quality of the GaInNAs active layer. Because it can reduce the resistance of the multilayer reflector, and improve the crystal quality and controllability of the multilayer structure as a surface emitting semiconductor laser element, it has a long wavelength band surface such as a high-performance 1.3 μm band with a practical level of performance. Light-emitting semiconductor laser devices can be realized, and when these devices are used, low-cost optical fiber communication systems and optical interconnection systems that do not require cooling elements An optical communication system such as a network can be realized.

FIG. 15 is a diagram illustrating a configuration example of the surface-emitting type semiconductor laser device according to the fifth embodiment. An enlarged view near the active region is also shown. The difference from the element of the second embodiment (FIG. 14) is that Ga _x In _1-x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1) layer (second spacer layer) is in the resonator. It is to be. In the fifth embodiment, the thickness of the resonator portion is a thickness for one wavelength. The resonator unit includes an active layer composed of a GaInNAs quantum well layer composed of three layers and a GaAs barrier layer, GaAs as a first spacer layer, Ga _x In _1-x P _y As _1-y (0 <x ≦ 1,0 <Y1) The layer is a second spacer layer. Since the Ga _x In _1-x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1) layer has a larger band gap than the GaAs layer, the active region into which carriers are injected is substantially a GaAs first spacer. Up to the layer, the same effect as the device of Example 2 can be obtained.

Note that the growth interruption interface for moving the growth chamber is provided in the middle of the Ga _x In _1-x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1) layer, but the Ga _x In ₁₋ It is also possible to provide a GaAs layer between the _x P _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1) layer and the Al-containing layer and in the middle of the layer.

Further, as the growth apparatus, an apparatus in which the MOCVD reaction chamber and the MBE reaction chamber are coupled by a vacuum transfer path can be used. In this case, the n-side lower reflecting mirror can be grown in the MBE reaction chamber, and the active layer containing nitrogen and the p-side reflecting mirror can be continuously grown in the MOCVD growth chamber. In this case, since the substrate can be moved between the growth chambers only once, it can be grown in a short time. Even in this case, the incorporation of oxygen in the active layer containing nitrogen by MOCVD growth can be reduced. Moreover, the resistance of the p-side reflecting mirror can be reduced.

It is the schematic of a MOCVD apparatus. It is the schematic of a MBE apparatus. It is a figure which shows the relationship between [DMHy] / ([PH3] + [DMHy]) which is a nitrogen raw material with respect to the V group raw material when growing AlGaInNP and GaInNP with an Al composition of 20% and the amount of nitrogen incorporated. It is a figure which shows the structure of the surface emitting semiconductor laser element which concerns on Example 1 of this invention. It is a conceptual diagram of the crystal growth apparatus which concerns on Example 1 of this invention. It is a schematic diagram of the MOCVD apparatus which has two MOCVD growth chambers concerning Example 2 of this invention. It is a schematic diagram of the optical transmission module which combined the surface emitting semiconductor laser element and fiber based on Example 3 of this invention. It is a schematic diagram of the optical transmission / reception module which combined the surface emitting semiconductor laser element based on Example 4 of this invention, the photodiode for reception, and the optical fiber. It is a figure which shows the nitrogen composition dependence of a threshold current density. It is a figure which shows the room temperature photoluminescence spectrum from the active layer which consists of a GaInNAs / GaAs double quantum well structure which consists of a GaInNAs quantum well layer and GaAs barrier layer which were produced with the MOCVD apparatus of the inventor of this application. It is a figure which shows the sample structure of a semiconductor light-emitting device. As an example of the semiconductor light emitting device shown in FIG. 11, a single epitaxial growth apparatus (MOCVD apparatus) is used in which the cladding layer is made of AlGaAs, the intermediate layer is made of GaAs, and the active layer is made of 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. It is a figure which shows the depth direction distribution of Al concentration of the same sample as FIG. FIG. 6 is a diagram showing a structure of a surface emitting semiconductor laser according to Example 2. FIG. 6 is a view showing a structure of a surface emitting semiconductor laser according to Example 5.

Explanation of symbols

11 Substrate loading / unloading port 12 Growth chamber (reaction chamber)
13 Hydrogen purifier 14 Liquid and solid bubbler 15 Gas cylinder 16 Valve A Raw material gas supply part B Heating part C Exhaust part 20 n-GaAs substrate 21 n-semiconductor distributed Bragg reflector (lower semiconductor distributed Bragg reflector)
22 Lower GaAs spacer layer 23 Multiple quantum well active layer 24 Upper GaAs spacer layer 25 p-semiconductor distributed Bragg reflector (upper semiconductor distributed Bragg reflector)
251 Selectable oxidation layer 252 p-GaAs layer (contact layer)
26 Al _x O _y current narrowing portion 27 polyimide 28 light emitting portion 29 p-side electrode 30 n-side electrode 31 MOCVD growth chamber 32 MBE growth chamber 41 first MOCVD growth chamber 42 second MOCVD growth chamber 43 vacuum transfer path 44 substrate Loading / unloading chamber 45 Gas supply unit 51 1.3 μm band GaInNAs surface emitting semiconductor laser element 52 Silica-based optical fiber 53, 64 Laser light 61 1.3 μm band GaInNAs surface emitting semiconductor laser element 62 Receiver photodiode 63 Optical fiber 201 GaAs Substrate 202 Lower clad layer 203 Intermediate layer 204 Active layer 205 Upper clad layer

Claims (8)

An active region including at least one active layer for generating laser light on a semiconductor substrate, and a resonator structure including reflectors provided above and below the active layer for obtaining laser light. A method of manufacturing a surface-emitting type semiconductor laser device, wherein the active layer contains Ga, In, N, As as main components, and at least a lower reflecting mirror among the reflecting mirrors has a refractive index that periodically changes. Including a semiconductor distributed Bragg reflector that reflects incident light by light wave interference, wherein the active layer is grown in a MOCVD growth chamber, and the lower reflector is grown in another MOCVD growth chamber or MBE growth chamber, between each growth A method of manufacturing a surface-emitting type semiconductor laser device, wherein a regrowth interface which is an interface is a semiconductor distributed Bragg reflector portion . An active region including at least one active layer for generating laser light on a semiconductor substrate, and a resonator structure including reflectors provided above and below the active layer for obtaining laser light. A method of manufacturing a surface-emitting type semiconductor laser device, wherein the active layer contains Ga, In, N, As as main components, and at least one of the reflecting mirrors has a periodically changing refractive index. A semiconductor distributed Bragg reflector that reflects incident light by light wave interference, the active layer and the reflector are grown in separate MOCVD growth chambers, and a regrowth interface that is an interface between each growth is distributed over the semiconductor A method for manufacturing a surface-emitting type semiconductor laser device, characterized by comprising a Bragg reflector portion . 3. The method of manufacturing a surface emitting semiconductor laser device according to claim 2, wherein the reflecting mirror is a first MOCVD growth chamber composed of a vertical reaction tube, and the active layer is a second MOCVD growth chamber composed of a horizontal reaction tube. A method of manufacturing a surface-emitting type semiconductor laser device characterized by growing. 4. The method of manufacturing a surface emitting semiconductor laser device according to claim 3, wherein a first gas line containing a nitrogen source and an Al source are provided in each of the first MOCVD growth chamber and the second MOCVD growth chamber. The first gas line and the second gas line each have a valve, and the nitrogen source and the Al source are opened and closed by opening and closing the valve. A method of manufacturing a surface-emitting type semiconductor laser device, characterized in that it does not meet in the first gas line or the second gas line. 5. The method for manufacturing a surface-emitting type semiconductor laser device according to claim 1, wherein the growth chamber for growing the active layer is a growth chamber that does not grow a material containing Al. Manufacturing method of surface emitting semiconductor laser device. 5. The surface emitting semiconductor laser device manufacturing method according to claim 1, wherein the growth chamber in which the active layer is grown is a growth chamber in which a material containing Al may be grown. A step of removing the Al raw material, Al reactant, Al compound, or Al remaining in the growth chamber after the growth of the material containing the silicon and before the active layer is grown is provided. method for producing be that the surface-emitting type semiconductor laser element and. 7. The method for manufacturing a surface-emitting type semiconductor laser device according to claim 1 , wherein Ga _x In _1-x P _y As _{1 is formed} before growing the active layer in the growth chamber for growing the active layer. _{-y (0 <x ≦ 1,0 <} y ≦ 1) a method for manufacturing a surface-emitting type semiconductor laser element you characterized by growing a layer. 8. The method for manufacturing a surface-emitting type semiconductor laser device according to claim 1, wherein a plurality of crystal growth chambers are connected by a vacuum transfer path or the like, and the substrate to be grown is exposed without being exposed to the atmosphere. method for manufacturing a surface-emitting type semiconductor laser element you characterized by crystal growth transported to.

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