JPH08330632A - Light-emitting semiconductor device - Google Patents

Abstract

PURPOSE: To obtain a light-emitting semiconductor device in which light radiated to the side face or the rear side of a light-emitting region is absorbed by a substrate by a method wherein a silicon single-crystal substrate or a germanium polycrystal substrate is used as the substrate on which an indium gallium arsenide film is to be grown. CONSTITUTION: When a silicon single-crystal substrate is used as a substrate 1, its absorption coefficient with reference to a wavelength of 1050nm (1.180eV) or lower is 20cm<-1> . When a germanium polycrystal substrate is used, its absorption coefficieht with reference to a wavelength of 1050nm (1.180eV) is 10<3> cm<-1> or higher. As a result, when a light-emitting element which uses indium gallium arsenide [Inx Ga1-x As] (where 0<x<=0.1) as light-emitting layers 2, 3 is formed on the silicon single-crystal substrate or the germanium polycrystal substrate 1, light which is radiated to the side face or the rear side of a light-emitting region can be absorbed by the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device,
In particular, the present invention relates to a semiconductor light emitting device having a light emitting element formed on a silicon substrate or a germanium substrate and used in an electrophotographic process.

[0002]

2. Description of the Related Art Conventionally, a semiconductor light emitting device has a structure in which gallium arsenide phosphorus (GaAs) is formed on a single crystal substrate made of gallium arsenide.
_y P _1-y ) and aluminum gallium arsenide (Al _Z Ga)
_1-Z As) and the like, and a gallium arsenide-phosphorus or aluminum gallium arsenide layer exhibiting another conductivity type is formed on the compound semiconductor layer to form a light emitting layer. A light emitting region is formed by forming a PN junction by partially diffusing impurities exhibiting another conductivity type, and containing a compound semiconductor layer exhibiting another conductivity type or containing impurities of another conductivity type. It had a structure in which an electrode was formed on the region and an electrode was formed on the back surface side of the gallium arsenide single crystal substrate.

[0003]

However, in this conventional semiconductor light emitting device, gallium arsenide used as a substrate for forming a light emitting layer and a light emitting region has a bandgap energy (Eg) of 1.424 eV (at room temperature). (870 nm)
Therefore, the emission spectrum of an infrared LED using indium gallium arsenide as a light emitting layer or a light emitting region is 870.
It becomes transparent to infrared rays of nm or more. In particular, as shown in FIG. 4, the absorption coefficient (α) of gallium arsenide is 10 cm ⁻¹ for wavelengths of 910 nm or more (1.362 eV or less).
And I = I ₀ exp (−αt) (α: GaAs
Absorption coefficient [cm ^-1 ], t: distance from light emitting source [c
m], I: light intensity at a distance t [cm] from the light emitting source, and I ₀ : light intensity at the light emitting source), from a relational expression of 500 μm from the light source (PN junction) (of the gallium arsenide substrate). 60% or more of the light is transmitted also on the back surface). The light thus transmitted is reflected by the back surface of the gallium arsenide single crystal substrate, and 36% or more of the light appears again on the surface even if absorption up to the surface of the gallium arsenide single crystal substrate is taken into consideration, and light is emitted. There was a problem that the isolation of the area was deteriorated and light leakage from the edge of the gallium arsenide single crystal substrate was induced, and when used in the electrophotographic process, bleeding occurred and the printing quality was significantly deteriorated. .

Further, the composition of phosphorus or aluminum in gallium arsenide phosphorus and aluminum gallium arsenide is increased to obtain 870 nm (1.42) which is the emission wavelength of gallium arsenide.
When the wavelength is shorter than 4 eV), there is a problem that the transition probability of electrons due to indirect transition increases and the light emission efficiency decreases, and it cannot be used in a high-speed or high-density electrophotographic process.

Since aluminum is active for oxygen, if an aluminum gallium arsenide film is used for the light emitting layer or the light emitting region, oxygen is prevented from remaining in the crystal growth apparatus.
There is a problem in that degassing needs to be performed sufficiently, degassing by heating and vacuum exhaust of the crystal growth apparatus takes a long time, and manufacturing cost becomes high.

Further, gallium arsenide phosphide has a large difference in lattice constant from gallium arsenide, and when gallium arsenide phosphide is grown on a single crystal substrate made of gallium arsenide, it has a thickness of 10 μm.
There is a problem in that a buffer layer of a certain degree is required, and the manufacturing cost of a single crystal thin film made of gallium arsenide phosphide increases.

Further, since the single crystal substrate made of gallium arsenide is used as the substrate for forming the light emitting element, the semiconductor light emitting device becomes very expensive, and there are problems such as cracks and chips in the manufacturing process of the semiconductor light emitting device. There is a problem in that it easily occurs and the production yield is significantly reduced.

[0008]

SUMMARY OF THE INVENTION The semiconductor light emitting device according to the present invention has been invented in view of the above problems of the prior art.
It is an object of the present invention to eliminate a decrease in luminous efficiency and a deterioration in printing quality that occur due to the relationship between the light emitting layer and the material of the substrate.

Another object of the present invention is to prevent the semiconductor light emitting device from becoming expensive, cracking, and cracking in terms of material and manufacturing process.

[0010]

[Means for Solving the Problems] To achieve the above object
In the semiconductor light emitting device according to the present invention,
The emission spectrum is on a single crystal substrate made of rumanium.
One conductivity type having a wavelength range of 890 nm to 1050 nm
Indium gallium arsenide (In_xGa _1-xAs
(0 <x ≦ 0.1)) layer and other conductive types
Magallium arsenide (In_xGa_1-xAs (0 <x ≦ 0.
1)) layers provided by laminating the layers and exhibiting one conductivity type
Indium gallium arsenide layer and other conductivity type indium oxide
Forming an island of a arsenic layer, the surface of the silicon substrate is
Indium-Galliu that exhibits other conductivity types with the front side or back side
An electrode is formed on the mu-arsenic layer, and
The emission spectrum is 890 nm to 1050 nm in the muarsenic layer.
Indium with other conductivity types having a wavelength range of nm
Gallium arsenide (In_xGa_1-xAs (0 <x ≦ 0.
1)) The area is provided and the front surface side or the back surface of the silicon substrate is provided.
Side and on other indium gallium arsenide regions exhibiting other conductivity types
An electrode is formed on.

[0011]

Function As described above, indium gallium arsenide (In
_When a silicon single crystal substrate or a germanium single crystal substrate is used as a substrate for growing the _x Ga _1-x As (0 <x ≦ 0.1)) film, the emission spectrum wavelength from the indium gallium arsenide single crystal thin film is , 870 nm to 1050
nm, the absorption coefficient of the silicon single crystal is 20 cm ⁻¹ or more and the absorption coefficient of the germanium single crystal is 10 ³ cm ⁻¹ or more in this wavelength range, and the separation of each light emitting region in the light emitting device is Sufficient and high print quality can be obtained in the electrophotographic process.

Further, since the indium gallium arsenide film is not easily affected by the residual oxygen in the growth apparatus even during its growth, it does not require time for heating and evacuation for degassing before film formation, and has high mass productivity. Since the characteristics are stable and the semiconductor is a direct transition type semiconductor in the entire composition region, it has high emission intensity and can be used as a high-speed and high-density electrophotographic semiconductor light-emitting device.

Furthermore, when a silicon single crystal substrate or a germanium single crystal substrate is used, an inexpensive semiconductor light emitting device can be manufactured as compared with the case where a gallium arsenide single crystal substrate is used, and cracks or cracks are generated in the semiconductor light emitting device manufacturing process. It can be manufactured with a high yield without causing problems such as cracking.

[0014]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an embodiment of a semiconductor light emitting device according to the present invention, in which 1 is a single crystal substrate made of silicon (Si) or germanium (Ge), and 2 is an indium gallium arsenide layer exhibiting one conductivity type. Reference numeral 3 is an indium gallium arsenide layer exhibiting another conductivity type.

A single crystal substrate 1 made of silicon or germanium and an indium gallium arsenide layer 2 having one conductivity type.
The semiconductor impurity of, for example, selenium (Se) or silicon (Si) is added to the semiconductor to have one conductivity type.
In addition, the indium gallium arsenide layer 3 having another conductivity type
An impurity for semiconductor such as zinc (Zn) is added to. In addition, the indium gallium arsenide layer 2 having one conductivity type and the indium gallium arsenide layer 3 having another conductivity type.
Are liquid phase epitaxy (LPE), chloride vapor phase epitaxy (V
PE), metalorganic chemical vapor deposition (MOCVD), molecular beam vapor phase epitaxy (MBE), and the like, and each light emitting element is formed into an island shape by etching or the like.

A protective film 4 made of a silicon nitride film or a silicon oxide film is provided on the indium gallium arsenide layer 3 having another conductivity type, and a through hole is formed on the protective film 4. , Through this hole, gold (Au),
Silver (Ag), Aluminum (Al), Nickel (N
i), an electrode 5 made of chromium (Cr) or the like is provided, and gold (Au), silver (Ag), aluminum (Al), nickel (Ni) is also provided on the back surface side of the single crystal substrate 1 made of silicon or germanium. ), Chromium (Cr), and the like.

The indium gallium arsenide (In _x Ga _1-x As (0 <x ≦ 0.1)) forming the light emitting layers 2 and 3 is
The wavelength range of the LED emission spectrum is 890 nm (1.3
It is from 92 eV) to 1050 nm (1.180 eV). Further, as shown in FIG. 2, when a silicon single crystal is used as the substrate 1, its absorption coefficient (α) is 20 cm ⁻¹ or more for a wavelength of 1050 nm (1.180 eV) or less, and a germanium single crystal is used. In case of 1050
The absorption coefficient (α) is 10 ³ cm ⁻¹ or more for wavelengths of nm (1.180 eV) or less. Note that FIG. 2 is a diagram showing an absorption coefficient for light energy in a semiconductor substance.

Therefore, the wavelength region is 890 nm (1.39
2 eV) to 1050 nm (1.180 eV) indium gallium arsenide (In _x Ga _1-x As (0 <x ≦
When a light emitting device having 0.1)) as the light emitting layers 2 and 3 is formed on the silicon single crystal substrate or the germanium single crystal substrate 1, the light emitted to the side or the back surface of the light emitting region is absorbed by the substrate 1. . Therefore, the blurring of printing in the electrophotographic process due to diffused reflection light on the back surface side of the semiconductor substrate 1 and leakage light emission from the end of the semiconductor substrate 1 which has been a problem when conventionally formed on a gallium arsenide single crystal substrate is eliminated. be able to.

FIG. 3 is a diagram showing another embodiment of the semiconductor light emitting device according to the present invention. In this embodiment, a semiconductor impurity such as selenium (Se) or silicon (Si) is formed on a silicon single crystal substrate or a germanium single crystal substrate 11 having one conductivity type by adding a semiconductor impurity such as antimony (Sb). Indium gallium arsenide (In _x Ga _1-x As (0
<X ≦ 0.1)) layer 12 is formed, and in the indium gallium arsenide layer 12 having one conductivity type, for example, zinc (Z
n) and other regions 13 exhibiting a conductivity type are formed, and gold (Au), silver (Ag), aluminum (A) is formed on the regions 13 exhibiting other conductivity types and on the rear surface side of the single crystal substrate 11.
l), nickel (Ni), chromium (Cr), etc. are provided in the electrodes 15, 16. When forming the region 13 exhibiting one conductivity type, silicon nitride (SiN
_x ) and the like through the diffusion mask 14.

[0020]

As described above, according to the semiconductor light emitting device of the present invention, the emission spectrum is 890 nm to 1050 n on the single crystal substrate made of silicon or germanium.
Indium gallium arsenide (In _x Ga _1-x As (0 <x ≦ 0.1)) layer exhibiting one conductivity type having a wavelength region of m and indium gallium arsenide exhibiting another conductivity type (In _x
Ga _1-x As (0 <x ≦ 0.1)) layers are laminated and provided.
The indium gallium arsenide layer having one conductivity type and the indium gallium arsenide layer having another conductivity type are formed in an island shape, and the front surface or the back surface side of the silicon substrate and the indium gallium arsenide layer having another conductivity type are formed. Electrodes, or indium gallium arsenide (In _x Ga _{1 -x} As) having another conductivity type in the indium gallium arsenide layer.
Indium gallium arsenide single crystal thin film is formed by providing a (0 <x ≦ 0.1) region and forming an electrode on the front surface side or the back surface side of the silicon substrate and on the indium gallium arsenide region having another conductivity type. The emission spectrum wavelength from is 870 nm to 1050 nm, but the absorption coefficient of the silicon crystal substrate is 20 cm ^-1 or more in this wavelength region, and the separation of each light emitting region in the light emitting device is sufficient. It does not cause bleeding when used for printing.

Indium gallium arsenide (In _x G
Since a _1-x As (0 <x ≦ 0.1)) single crystal thin film is not easily affected by residual oxygen even during its growth, heating and evacuation for degassing before film formation does not require time. In addition to high mass productivity and stability of characteristics, since it is a direct transition type semiconductor in the entire composition region, it can be used as a high-speed and high-density electrophotographic semiconductor light emitting device with high emission intensity.

Further, as compared with the case of using a gallium arsenide single crystal substrate, a semiconductor light emitting device which is less expensive can be manufactured, and in the manufacturing process of the semiconductor light emitting device, there is no problem due to cracking or chipping, and the manufacturing is performed with high yield it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a semiconductor light emitting device according to claim 1 of the present invention.

FIG. 2 is a diagram showing an absorption coefficient for light energy in a semiconductor material.

FIG. 3 is a sectional view showing an embodiment of the semiconductor light emitting device according to claim 2 of the present invention.

FIG. 4 is a diagram showing an absorption coefficient for light energy in gallium arsenide containing an n-type semiconductor impurity.

[Explanation of symbols]

1 ... Silicon or germanium single crystal substrate, 2
... Indium gallium arsenide layer having one conductivity type, 3
... Indium gallium arsenide layer exhibiting other conductivity type,
5, 6 ... Electrodes

Claims (2)

[Claims] 1. An emission spectrum of 890 nm to 1050 n on a single crystal substrate made of silicon or germanium.
Indium gallium arsenide (In _x Ga _1-x As (0 <x ≦ 0.1)) layer exhibiting one conductivity type having a wavelength region of m and indium gallium arsenide exhibiting another conductivity type (In _x
Ga _1-x As (0 <x ≦ 0.1)) layers are laminated and provided.
The indium gallium arsenide layer having one conductivity type and the indium gallium arsenide layer having another conductivity type are formed in an island shape, and the front surface or the back surface side of the silicon substrate and the indium gallium arsenide layer having another conductivity type are formed. A semiconductor light emitting device, characterized in that an electrode is formed on the semiconductor light emitting device. 2. The emission spectrum is 890 nm to 1050 n on a single crystal substrate made of silicon or germanium.
An indium gallium arsenide (In _x Ga _1-x As (0 <x ≦ 0.1)) layer having one conductivity type having a wavelength region of m is provided, and an emission spectrum is 890 nm to 1050 nm in the indium gallium arsenide layer. Indium gallium arsenide (In _x G
a _1-x As (0 <x ≦ 0.1)) region is provided, and an electrode is formed on a front surface side or a back surface side of the silicon substrate and an indium gallium arsenide region having another conductivity type. Semiconductor light emitting device.