JPS63288072A - Semiconductor light-emitting device - Google Patents

Abstract

PURPOSE:To obtain a device displaying long-lived stable characteristics as a blue emission source by forming a buffer layer consisting of GaAs and InAs between a GaAs substrate and a ZnSe epitaxial thin-film. CONSTITUTION:An N-type GaAs epitaxial film 2 is shaped onto an N-type GaAs substrate 3. A mixed crystal epitaxial film 3 consisting of InAs and GaAs and having N-type conductivity is used as a buffer layer relaxing the lattice mismatch of 0.27% existing in GaAs and ZnSe. The lattic constant of N-type In0.025Ga0.975As coincides with that of ZnSe. 4 represents an N-type ZnSe epitaxial film, 5 an insulating film composed of SiO, etc., 6 an ohmic contact shaped to the GaAs substrate 1 and 7 an electrode made up of gold, etc. The ohmic contact 6 and the electrode 7 are connected respectively at the negative pole and positive pole of the electrode and DC voltage is applied, thus acquiring blue emission having an emission peak in 460-480nm.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor light emitting device used as a display indicator or a light source in an information processing system using light. More specifically, the present invention relates to the structure of a semiconductor light emitting device that emits blue light.

[Conventional technology]

Semiconductor light-emitting devices that emit blue light are expected to be put to practical use as (1'N components of full-color displays using light-emitting diodes) and as light sources in high-density optical information processing systems.

Regarding the structure of a semiconductor light emitting device that emits blue light, a cross-sectional schematic diagram of a conventionally proposed structure is shown in Fig. 5.
The figure shows a ZnSe epitaxial film.
5 to 10 μm thick on an-uGaAs substrate 35 showing an on-ductor) type LED.
An 11 degree n-type ZnSe epitaxial film 36 is formed. 37 is % S iOx , S isN,
, AI, 0. , R1n made of high resistance Zn5e, etc. 38 is an electrode made of gold, ITO, In*O8, etc., and 39 is an ohmic contact formed on an n-type GaAs substrate. When the 1'u pole 38 is connected to the ■ pole of the DC power supply and the ohmic contact 39 is connected to the e pole, and a forward bias is applied, the insulation 11237 and n-IJ1ZnS
Blue light emission is obtained from near the interface of ez Pitaxy Ar Le B 36. (For example, published patent publication 1985-0
4470. 1988-80883, 1982-21383,
(See 1988, 188889, etc.) [Problems to be solved by the invention] The prior art described in n; f has the following problems. The substrate material is GaAs and the epitaxial film is Zn5e.
There is a lattice mismatch of 0.27% at room temperature. For this reason, many misfit dislocations occur near the substrate interface of the epitaxial film. When current is injected into the Zn5e layer, which is a light-emitting layer, through the interface between the epitaxial film and the substrate, the region near the substrate interface where misfit dislocations occur is a region of high electrical resistance, which increases heat generation due to current flow, and reduces the semiconductor light emission. This may shorten the life of the device. In addition, the presence of misfit dislocations accelerates the phenomenon in which Ga, As, and the like diffuse from the substrate as impurities into the ZnSe epitaxial layer due to substrate heating during crystal growth and heat generation due to energization when using a semiconductor light-emitting HW. Ru. Impurities diffused into the light-emitting layer form non-luminescent recombination centers and luminescent centers that serve as the origin of undesirable light emission, which causes deterioration of the characteristics of the light-emitting device and changes in the characteristics over time.

SUMMARY OF THE INVENTION The present invention aims to solve the above problems and provides a semiconductor light emitting device with a long life and stable characteristics.

[Means for solving problems]

The semiconductor light emitting device of the present invention is a semiconductor light emitting device in which a Zn5c epitaxial thin film formed on a GaAs substrate is pierced by at least −Ω or more.
During nSe epitaxial in, G2LAs and 1nA
It is characterized by having one layer of buff consisting of s.

〔Example〕

Hereinafter, the present invention will be explained in more detail according to Examples.

(Example 1) FIG. 1 is a schematic cross-sectional view of an example of a semiconductor light emitting device according to the present invention.

On the n-UGaAs substrate 1, the thickness is 5000λ~1u.
An n-type GaAs epitaxial film 2 having a temperature of 11 degrees is formed. 3 is made of InAs and GaAs and has a thickness of 5~
A mixed crystal epitaxial film with n-HIC conductivity of 10 μm and 0°27% of tGaAs and Zn5e.
This is a single layer of buffer 1 that alleviates the lattice mismatch. N-type Ink, 025GaO, 075As has a lattice constant of Zn
It matches that of 5e. As a buffer notification, uniform composition (7) n-type 1n0.025GaO, 075As
Alternatively, InA may be formed continuously from the GaAs film 2.
Ink, 025GaO by increasing the composition of s.

A mixed crystal epitaxial layer including a composition distribution up to 075ΔS may also be used. In both cases, the same effect can be obtained when the buff 1 is used as a single layer. 4 is I'7-n of about 5 to 10 μm
- type ZnSe epitaxial layer, 5 has a thickness of 300~20
About 00 people S i O * s S is N = ,
A l *Os, insulating film such as high resistance Zn5e, 6
1 is an ohmic contact formed on a GaAs substrate 1, and 7 is an electrode made of gold, ITO, or the like. When the ohmic contacts 6 and electrodes 7 are connected to the e and -poles of a power source, and a DC voltage is applied, a constant current drive is performed for the light-emitting device that emits blue light with an emission peak in the range of 460 to 480 nm. As a result, no changes in emission intensity or emission spectrum over time were observed, and extremely stable emission characteristics were obtained. A detailed reliability evaluation of the light emitting device conducted under the same conditions showed that the lifespan was 5 to 6 times longer than that of conventional light emitting devices.

[Embodiment 2] FIG. 2 is a schematic cross-sectional view showing an embodiment of a semiconductor light emitting device according to the present invention.

Similarly to [Example 1], an n-! GaA that fosters J1C conductivity
A buffer layer 10 of a mixed crystal epitaxial film made of S and InAs is formed. The thickness is about 1 to 10 μm. As the buffer y-H, n-type Ink with a uniform composition is used.
, 025Ga0°975As or NG
Ink by continuously increasing the InAs composition from Comparison 9.

A mixed crystal epitaxial layer including a composition distribution such as 025GaO and 975As may be used. Both can provide the same effect as a buffer layer.

11 is an n-type Zn5e epitaxial film with a thickness of 5 to 10 μm, and 12 is a P-type 2nSe epitaxial film with a thickness of 5 to 10 μm. 13.14 are GaAs substrates 8 and i
' - This is an ohmic contact to the ZnSe epitaxial trace 12 . When connecting 13.14 to the O and ■ poles of the power supply and applying DC voltage, 460 to 48
Blue light emission having an emission peak at 0 nm is obtained. With respect to changes in the properties of the luminescent bag over time, life span, etc., similar results were obtained as in Example 1, confirming that the buffer was even more effective.

[Embodiment 3] FIG. 3 is a schematic cross-sectional view showing an embodiment of a semiconductor light emitting device according to the present invention.

An n-'MGaAs epitaxial film 16 having a thickness of approximately 5,000 to 1 μm is formed on an n-WGaAs substrate 15. 17 is GaAs with n-type 4 conductivity
This is a buffer layer of an A-grade epitaxial film made of and InAs. The thickness was about 1 to 10 μm. Buff 1
One layer is n-type Ink of uniform composition, 025GaO
, 975As, or by continuously increasing the composition of 1 nAs from the GaAs film 16, Ink, 025G
A mixed crystal epitaxial layer including a composition distribution such as aO and 975As may also be used, and both can provide the same effect as a single buffed layer. 18 is thickness 50-500
About a person's n-! ! This is a strained superlattice layer formed by alternately laminating about 10 to 100 GaAsz bitaxial films I9 and n-MI InAs epitaxial films 20 having a thickness of about 50 to 500λ. Inside the strained superlattice layer 18, the lattice constant in the crystal growth plane is Ink, 025GaO,9
In agreement with that of 75As, the crystal lattices of GaAs and InAs form a laminated structure while maintaining a mutually distorted V-shaped structure. Because the bonding state of the elements that make up the crystal changes due to the strain in the crystal lattice, a strained superlattice A! ! 1B
The generation of internal dislocations and lattice defects is suppressed. moreover,
The propagation of dislocations existing in the buffer layer 17 is also stopped in the strained superlattice layer 18 and does not extend into the film laminated on top of the strained superlattice layer. , the lattice constant in the crystal growth plane is Zn5e
It is possible to form a single layer of buffed fiber that matches the above and has extremely few dislocations and defects. 21 is an n-type Zn5e epitaxial film with a thickness of approximately 5 to 10 μm, and 22 is a thickness of 300 μm.
~510m for about 2000 people, S11 Na Ale
Os, high resistance insulating film such as Zn5e, 23 is GaAs
E & ohmic contact formed on plate 15, 24 is gold,
The electrode is made of ITO or the like. Ohmic contact 2
3 and the electrode 24 are respectively connected to the O pole and the ■ pole of the rrL source, and a DC voltage is applied, blue light emission with an emission peak at 460 to 480 nm is obtained. With regard to changes over time in characteristics of light emission ka, lifetime, etc., results similar to those in Example 1.2 were obtained, confirming the effects of the single buffer layer and the strained superlattice layer.

(Embodiment 4) FIG. 4 is a schematic cross-sectional view showing an embodiment of a semiconductor light emitting device according to the present invention.

Thickness 5000λ~1μ on n-IJ1GaAs substrate 25
An n-type GaAsz pitaxial IQ 26 of MRI degree is formed. 27 is GaA having n-type conductivity
This is a bubble 7'y-1ia made of crystalline epitaxial structure consisting of S and 1nAs. The thickness was 1 to 10 μm and 11 degrees.

As the Babufa single layer, n-Ulna, 02 with a uniform composition is used.
5Ga0.075As may be formed, or the composition of 1n8S may be continuously increased from the GaAs film 26 to form Ink.
, 025GaO, 975As may be used as a mixed crystal epitaxial layer containing a uniform composition distribution, both of which are buff 7.
The same effect can be obtained with a single-layer tosswork. 28 is thickness 5
A strained film formed by alternately laminating about 10 to 100 layers of an n-type GnAsZ epitaxial layer 29 with a thickness of 0 to 500 degrees and an n-type 1nAs epitaxial film 230 with a thickness of about 50 to 500 degrees. It is a superlattice layer. Distorted superlattice A! i2
Similarly to [Embodiment 3], 411it of No. 8 is intended to suppress the generation of dislocations and lattice defects and to stop the propagation of dislocations. 31 is an n-type Z with a thickness of 5 to 10 μm f1 degree
n5e epitaxial grain, 32 is 5-10 umri thick
This is a p-type Zn5c epitaxial film. 33.3
4 is an ohmic contact with respect to the GaAs substrate 25 and the p-2nSe epitaxial film 32. 33.34
When connected to the e and -pole of a power source and applying a DC voltage, blue light emission having an emission peak at 460 to 480 nm is obtained. Regarding the changes over time in the characteristics of the light emitting device, the life span, etc., the same results as in Examples 1 to 3 were obtained, and the effects of the single layer of Buff 1 and the strained superlattice layer were confirmed.

In manufacturing the semiconductor light emitting device according to the present invention, various epitaxial growth methods such as molecular beam epitaxy (MnE method), metal organic vapor phase pyrolysis method (MOCVD method), CVD method, and hot wall epitaxy method (II WE method) are used. The law can be used.

Formation of a single layer of buffer containing a compositional distribution can be carried out by continuously changing the supply amount ratio of raw materials supplied to the GaAs substrate. In addition, the formation of the strained superlattice layer is caused by Ga
Either the raw materials for growing As and InAs are alternately supplied to the GaAs substrates, or the GaAs substrates are alternately inserted into a continuously supplied 2% class 1 flux. It can be carried out by a method. In addition, formation of an epitaxial film, an insulating film, an ohmic electrode, etc. can be easily carried out by a process similar to that used for light emitting diodes, semiconductor lasers, and the like.

〔Effect of the invention〕

As described above, according to the present invention, a ZnSe epitaxial FJ film formed on a GaAs substrate is used as a G
Between the λAs substrate and the ZnSe epitaxial Fj film,
By manufacturing a semiconductor light emitting device having a single layer of buffing made of a As and In-As, a semiconductor light emitting device exhibiting long life and stable characteristics as a blue light emitting light source can be obtained6. We are confident that it will become an extremely important device as a light source for display devices and information processing systems.

[Brief explanation of drawings]

FIG. m1 is a schematic cross-sectional view showing one embodiment of a semiconductor light emitting device according to the present invention. 1...GλAs substrate 2...n-type GaAs epitaxial film 3...buffer y-T! J 4...N-type Zn5e epitaxial film 5...Insulating film 6...Ohmic property: +7 Tact 7...Electrode FIG. Cross-sectional schematic ■δ diagram shown. 8-G a As U; Plate 9...n-type GaAs epitaxial lO...buffer single layer 11...n-type Zn5e epitaxial film 12...
P-type ZnSe epitaxial comparison 13.14 Ohmic contact FIG. 3 is a schematic cross-sectional view showing one embodiment of a semiconductor laser according to the present invention. 15-GaAs substrate 16...n-type GaAs epitaxial film 17...
Buffer y-IWJ 18...Strained superlattice layer 19...N-type GaAs epiximal model 20...
n-WInAs epitaxial comparison 21...n-HI
ZnSe epitaxial film 22...insulating film 23...ohmic contact 24...rr1 pole FIG. 4 is a schematic cross-sectional view showing one embodiment of the semiconductor light-emitting bag 2 according to the present invention. 25- GaAs substrate 26...n-type GaAs epitaxial film 27
...Buffer 1 layer 28...Strained superlattice layer 20...N-type GaAs epitaxial trace 30...
N-type 1nAs epitaxial film 31...n-1j
lZ n S e epitaxial film 32...p-type Z
n5e epitaxial film 33.34...ohmic contact Figure 5 is a conventionally proposed semiconductor light emitting device! aF! Section I of l! Schematic diagram. 35-G a su board 36... Low type Zn5e epitaxial film 37...
Insulating film 38 ... Electrode 39 ... Ohmic contact or more Output 4) "°-"27' stock "': 0 company ... 1° Agent Patent attorney Tsutomu Mogami and 1 other person:) Sheep Doom
l

Claims (1)

[Scope of Claims] 1) In a semiconductor light emitting device having at least one layer of a ZnSe epitaxial thin film formed on a GaAs substrate, a buffer layer made of GaAs and InAs is provided between the GaAs substrate and the ZnSe epitaxial thin film. Characteristic semiconductor light emitting device. 2) The buffer layer made of GaAs and InAs is
2. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device is a mixed crystal epitaxial film of As and InAs, and the lattice constant of the mixed crystal epitaxial film matches that of ZnSe. 3) The buffer layer made of GaAs and InAs is
GaAs having a lattice constant equal to that of Se;
2. The semiconductor light emitting device according to claim 1, comprising a mixed crystal epitaxial film of InAs and a strained superlattice layer of GaAs and InAs formed on the mixed crystal epitaxial film.