JP2000183399A - GaN compound semiconductor light emitting device - Google Patents

Abstract

(57) [Problem] To provide a GaN-based compound semiconductor light-emitting device including a high-quality active layer with low bandgap energy and capable of obtaining stable light emission with high luminous efficiency. As An active layer _{15 In 1-x Ga x N} 1-yz As
_y P _z [where 0 ≦ x, y, z <1], a semiconductor layer is formed, and Al is formed as cladding layers 14 and 16 sandwiching the active layer.
_{a In b Ga 1-ab N} 1-cd As c P d [ where, 0 ≦ a, b, c , d
≦ 1]. By changing the composition of each semiconductor layer, a GaN-based compound semiconductor light emitting device whose emission wavelength can be set in a wide range from the ultraviolet region to the infrared region is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GaN-based compound semiconductor light-emitting device capable of obtaining stable light emission with high luminous efficiency.

[0002]

2. Related Background Art Recently, light emitting diodes (LEDs) using GaN-based compound semiconductors have been actively developed. This type of GaN-based light-emitting diode (light-emitting element) is generally formed on a semi-insulating sapphire substrate using a metal-organic chemical vapor deposition (MOCVD) method or a gas source molecular beam epitaxy (MEB) method. This is realized by epitaxially growing a layer and an active layer.

For example, when using the MOCVD method, as shown in FIG. 2, on a sapphire substrate 1, ammonia [NH ₃ ] as a nitrogen source and trimethylaluminum [ TMA]
The AlN buffer layer 2 is grown using
A doped n-GaN layer 3 is grown. This n-GaN layer 3
Is formed by, for example, using trimethyl gallium [TMG], ammonia [NH ₃ ], and silane as raw materials and performing epitaxial growth in a temperature environment of 1050 ° C.

[0004] Thereafter, trimethylaluminum [TMA] and silane are further added to the raw material to grow an n-AlGaN cladding layer 4 on the n-GaN layer 3, on which non-doped InGaN is formed as an active layer 5. Let it grow. The non-doped InGaN active layer 5 is formed in a 750 ° C. atmosphere using trimethylindium [TMI], trimethylgallium [TMG], and ammonia [NH ₃ ] as raw materials. Thereafter, a p-AlGaN cladding layer 6 is grown on the InGaN active layer 5, and a p-GaN cap layer 7 is further grown thereon. By the way, the above p-
The AlGaN cladding layer 6 is grown using biscyclopentadienyl magnesium as a dopant.

After forming an epitaxially grown film having a multilayer structure in which the active layer 5 is sandwiched between the clad layers 4 and 6 as described above, an SiO ₂ film or the like is deposited on the surface thereof by using a plasma CVD apparatus. The SiO ₂ film is etched by a photoresist and a chemical etching or the like, and is patterned. Thereafter, a metal such as Au / Ni is deposited as a p-electrode and a metal such as Ti / Al is deposited as an n-electrode to form a light-emitting element (LE) made of a GaN-based compound semiconductor.
D) is manufactured.

[0006]

However, in a light emitting device manufactured as described above and having InGaN grown as the active layer 5, the In component in the active layer 5 is reduced by the high temperature applied during the crystal growth. There is a problem that it is difficult to obtain a high quality InGaN active layer 5 because the active layer 5 is easily separated. Moreover, as the band gap energy of the active layer 5 increases with the elimination of the In component, there arises a problem that the light emission efficiency is reduced and light emission becomes difficult.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a high-quality active layer in which the band gap energy is suppressed to a low level. An object of the present invention is to provide a GaN-based compound semiconductor light-emitting device that can be obtained. Another object of the present invention is to provide a GaN-based compound semiconductor light-emitting device in which the emission wavelength region (center emission wavelength) can be set widely from ultraviolet to infrared by changing the band gap energy of the active layer. I do.

[0008]

GaN-based compound semiconductor light-emitting device according to the present invention in order to achieve the above object, according to an aspect of _{the, In 1-x Ga x N} 1-yz As y P z [ However, as an active layer, 0 ≤
x, y, z <1]. More preferably, as the cladding layer sandwiching the active layer as described in claim 2, the In _1-x Ga _{x
N 1-yz As y P z} [ where, 0 ≦ x, y, z <1] a large Al _a band gap energy than the _{In b Ga 1-ab N 1} -cd
As _c P _d [where, 0 ≦ a, b, c , d ≦ 1] is characterized by forming a semiconductor layer made of.

That is, according to the present invention, In _{1-x
Ga x N 1-yz As y} P z be to the growth, if InGaN
Even in the case where the In component in the AsP active layer is released and the content of In becomes extremely small, the band gap energy of the active layer is reduced by As or P of the V group, and furthermore, non-emission is performed. The occurrence of defects due to nitrogen loss, which is one of the causes of
The present invention provides a GaN-based compound semiconductor light emitting device having a high-quality active layer capable of realizing stable light emission with high luminous efficiency.

Furthermore the present _{invention, In 1-x Ga x N} 1-yz As y
By changing the composition of the active layer composed of P _z , the band gap energy can be changed over a wide range, for example, from 3.5 eV to 1 eV or less, so that the emission wavelength region (center emission wavelength) can be set over a wide range. And a GaN-based compound semiconductor light-emitting device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A GaN-based compound semiconductor light-emitting device according to an embodiment of the present invention will be described below with reference to the drawings according to the manufacturing procedure. The GaN-based compound semiconductor light emitting device according to this embodiment uses a gas source molecular beam epitaxial growth (GSMB) using an ultra-high vacuum device.
The method is realized by epitaxially growing a semiconductor multilayer film including an active layer and a cladding layer on the substrate 11 by sapphire, SiC, silicon or the like by the method E) as shown in FIG.

Specifically, first, dimethylhydrazine (5 ×
Using 10 ⁻⁵ Torr and Ga (5 × 10 ⁻⁷ Torr), a GaN buffer layer 12 having a thickness of 5 nm is grown on the substrate 11 at a growth temperature of 640 ° C. Next, 850 g of Ga (5 × 10 ⁻⁷ Torr) and ammonia [NH ₃ ] (5 × 10 ⁻⁶ Torr) are formed on the GaN buffer layer 12.
An n-type GaN layer 13 is grown at 2 ° C. to a thickness of 2 μm.

After performing the above pretreatment, the n-type Ga
As the cladding layer 14 of n-type on the N layer 13 Al _a In _b Ga
_1-ab a _{N 1-cd As c P d} , and specifically Al _0.16 In _0.01 Ga
_A crystal of _0.83 N _0.99 As _0.01 is grown to a thickness of 100 nm.
However, in this case, the composition d of P is zero [= 0]. The growth of the n-type cladding layer 14 is performed by adding Al (2
× 10 ⁻⁷ Torr), In (1 × 10 ⁻⁷ Torr), Ga (6 × 1 Torr)
0 ^-7 Torr), arsine (6 × 10 ^-7 Torr), ammonia [NH ₃ ] (5 × 10 ^-6 Torr), and Si (5 × 10 ^-9 Torr)
Torr).

[0014] Then the _{In 1-x Ga x N 1} -yz As y P z, non-doped _{In 0.1 Ga 0.9 N 0.98 As 0.01} P 0.01 and specifically as an active layer 15 on the n-type cladding layer 14, the growth A crystal is grown to a thickness of 50 nm at a temperature of 780 ° C. The crystal growth of the active layer 15 is performed by using ammonia [N
H ₃ ] (5 × 10 ⁻⁵ Torr), Ga (7 × 10 ⁻⁷ Torr), I
n (1 × 10 ⁻⁷ Torr), arsine (6 × 10 ⁻⁷ Torr),
This is performed using phosphine (5 × 10 ⁻⁷ Torr).

[0015] Thereafter, Al _a as p-type conductivity clad layer 16 on the active layer _{15 In b Ga 1 -ab N 1} -cd As c P d
Specifically, Al _0.16 In _0.01 Ga _0.83 N _0.99 As _0.01 is grown to a thickness of 100 nm. This p-type cladding layer 1
The growth of Al 6 (1 × 10 ⁻⁷ Torr), In
(1 × 10 ⁻⁷ Torr), Ga (6 × 10 ⁻⁷ Torr), arsine (6 × 10 ⁻⁷ Torr), ammonia [NH ₃ ] (5 × 1
0 ^-6 Torr) and magnesium (1 × 10 ^-8 Torr).

Next, a p-type GaN layer is grown as a cap layer 17 on this p-type cladding layer 16 so as to have a thickness of 100 nm. The p-GaN cap layer 17 is made of ammonia [NH ₃ ] (5 × 10 ⁻⁶ Torr), Ga (5 × 10 ⁻⁷ Torr).
r) and magnesium (1 × 10 ⁻⁸ Torr) as a raw material. Thereafter, an SiO ₂ film or the like is deposited on the surface thereof using a plasma CVD apparatus, and the SiO ₂ film is patterned by a photoresist and chemical etching, and the epitaxial growth film is selectively etched using the mask as a mask. The n-type GaN layer 13 is partially exposed. Thereafter, Au / Ni is formed on the surface of the p-type GaN cap layer 17 as a p-electrode.
And a metal such as Ti / Al is formed as an n-electrode on the surface of the n-type GaN layer 13 by vapor deposition.
Thus, a light emitting device (LED) made of a GaN-based compound semiconductor having an emission wavelength in the ultraviolet region is manufactured.

[0017] In this manner is produced, GaN growing the _{In 0.1 Ga 0.9 N 0.98 As 0.01} P 0.0 1 as an active layer 15
When a voltage was applied to the light-emitting element made of a system compound semiconductor and the light-emitting characteristics were examined, a remarkably strong light-emitting peak was observed near a band edge of 430 nm at an applied voltage of 4 V, and no other light-emitting peaks were observed. That is, a light emitting element capable of emitting ultraviolet light with high luminance was realized.

On the other hand, as another embodiment, the Al
Instead of the n-type conductive cladding layer 14 made of _0.16 In _0.01 Ga _0.83 N _0.99 As _0.01 , Al _0.1 Ga _0.9 N in which each composition b, c, and d of In, As, and P is zero [0] is used. An n-type clad layer 14 was formed. This Al _0.1 Ga
The formation of the n-type cladding layer 14 of _0.9 N is performed by using Al (1 × 10 ⁻⁷ Torr) and Ga (7 × 10 ⁻⁷ Torr) as raw materials.
r), ammonia [NH ₃ ] (5 × 10 ⁻⁶ Torr), and Si (5 × 10 ⁻⁹ Torr).

Next, an active layer 15 is formed on the cladding layer 14.
As _{In 1-x Ga x N 1} -yz As y P z, in particular Ga, non-doped In that the composition x of P, y and respectively zero [0]
The N _{0. 9} As _0.01, grown crystal at a growth temperature of 780 ° C. to 50nm thick. The crystal growth of the active layer 15 is performed by using ammonia [NH ₃ ] (5 × 10 ⁻⁵ Torr) and Ga (7
× 10 ⁻⁷ Torr), In (1 × 10 ⁻⁷ Torr), arsine (6 × 10 ⁻⁷ Torr), phosphine (5 × 10 ⁻⁷ Torr)
This is performed using

On this active layer 15, Al _0.1 Ga _0.9 N is formed as a p-type cladding layer 16 by Al (1 × 10 ⁻⁷ Torr).
r), Ga (7 × 10 ⁻⁷ Torr), ammonia [NH ₃ ]
(5 × 10 ⁻⁵ Torr), and magnesium (1 × 10 ⁻⁸ Torr)
Torr) is formed to a thickness of 100 nm, and Ga (5 × 10 ⁻⁷ Torr) and ammonia [N
H ₃ ] (5 × 10 ⁻⁶ Torr), and magnesium (1 ×
A cap layer 17 made of p-type GaN is formed to a thickness of 100 nm using 10 ^-8 Torr as a raw material.

Thereafter, an etching process is performed in the same manner as in the previous embodiment, and a p-electrode and an n-electrode are formed by vapor deposition, respectively. Is manufactured.
Manufactured in this manner, the active layer 15 is formed of In _0.1 N
_{When a} voltage was applied to a light emitting device made of a GaN-based compound semiconductor on which _0.9 As _0.1 was grown and its light emitting characteristics were examined,
At an applied voltage of 4 V, a remarkably strong emission peak was observed near the band edge of 860 nm, and no other emission peak was observed. That is, a light emitting element capable of emitting infrared light with high luminance was realized.

In the above-described embodiment, the crystal is grown using the gas source MBE method, but it is also possible to use the metal organic chemical vapor deposition (MOCVD) method. In this case, trimethylgallium, trimethylindium, trimethylaluminum or the like which is an organic metal may be used as the raw material, and ammonia and n
It is sufficient to use silane as the type dopant and biscyclopentadienyl magnesium as the p-type dopant.

[0023] Al _a an In _b forming the cladding layers 14 and 16
_{Ga 1-ab N 1-cd} As c P 0 ≦ a composition of _{d, b, c, d ≦} 1
It is also possible to change the emission wavelength by changing the emission wavelength in the range described above. In this case, the cladding layer 14,
It goes without saying that the composition is selected so that the bandgap energy of 16 is always large. Furthermore it may be used InN _1-z P z and InN _1-yz As _y P _z as the active layer 15.

Further, in the embodiment, the light emitting layer is realized as a double hetero structure composed of the active layer 15 and the cladding layers 14 and 16, but the light emitting layer is formed of InNAs, InNP, InNN.
It is also possible to realize a multiple or single quantum well structure such as AsP. Furthermore different compositions on a single substrate 11 by using a selective growth method _{In 1-x Ga x N 1} -yz As
_{y P z / Al a In b} Ga 1-ab N 1-cd As c P d based growth film was selectively formed in, for example, red, green, and white light to emit light of three primary colors consisting of blue It is also possible to obtain. In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0025]

According to the present invention as described in the _{foregoing, In 1-x Ga x N} 1-yz As y P z as an active layer [where, 0 ≦ x,
Since the semiconductor layer composed of y, z <1] is formed, the band of the active layer is determined by As or P even when the In component is released during the crystal growth process and the content thereof is reduced. The gap energy can be kept small, and the occurrence of defects due to nitrogen elimination can be reduced by the above-mentioned InGaNAs.
Since compensation can be performed by As or P in P, a GaN-based compound semiconductor light emitting device having a high quality active layer capable of realizing stable light emission with high luminous efficiency can be realized.

[0026] Moreover In _1-x Ga _x N change their bandgap energy at a _1-yz As changing the composition of _y P _z comprising the active layer, realizing a GaN-based compound semiconductor light-emitting device having an emission wavelength corresponding to the specification And the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a GaN-based compound semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional general GaN-based compound semiconductor light emitting device.

[Explanation of symbols]

11 substrate 12 GaN buffer layer 13 n-type GaN layer 14 n-type cladding layer of _{(Al a In b Ga 1-} ab N 1-cd As
_c P _d) 15 active layer _{(In 1-x Ga x N} 1-yz As y P z) 16 p -type cladding layer _{(Al a In b Ga 1-} ab N 1-cd As
_c P _d ) 17p-type GaN cap layer

Claims (2)

[Claims] 1. A light emitting device comprising an active layer and a clad layer composed of a GaN-based compound _{semiconductor, In 1-x Ga x N} 1-yz As y P z [ However, as the active layer, 0
GaN-based compound semiconductor light-emitting device, wherein a semiconductor layer comprising ≦ x, y, z <1] is formed. As claimed in claim 2, wherein said cladding layer Al _a In _b Ga _{1-ab
N 1-cd As c P d} [ where, 0 ≦ a, b, c , d ≦ 1] GaN -based compound semiconductor light-emitting device according to claim 1, characterized in that the formation of the semiconductor layer made of.