JP2000114594A - Semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a structure for long wavelength and enable a light emitting device of low operational voltage by providing a structure wherein a compound containing a specific element in semiconductor is used for a superlattice well or a barrier layer. SOLUTION: Since sapphire, for example, is used for a board, a lamination structure formed thereon has a compound containing P or As of hexagonal system in a semiconductor lattice well or a barrier. Furthermore, an InGaN/ InGaP quantum well layer which becomes a light emitting layer also has a hexagonal system structure. Since a hexagonal system InGaAlNAsP thin film is a compound of direct transition type in a thin region, highly effective light emission or laser oscillation is realized. Furthermore, since P is incorporated, emission of light with a long wavelength is possible and emission of green light which has been extremely difficult in the InGaAlN system alone, or light emission and laser oscillation at still longer wavelengths are possible. Furthermore, enough refractive index distribution is possible and mode control is also possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device that emits light by current injection, and more particularly to a light emitting device using an InGaAlN-based material.

[0002]

2. Description of the Related Art A next-generation high-density recording apparatus represented by a DVD requires a blue light source, and has been actively studied in recent years. In particular, the InGaAlN system represented by GaN is promising as a light source including ultraviolet light, and is attracting attention. However, in this material system, the wavelength is increased by including a large amount of In, but it is difficult to grow a crystal in a region including a large amount of In, and the waveguide mode becomes unstable. Therefore, it is difficult to perform the mode control that is originally required. Therefore, there is a disadvantage that the operating voltage is increased.

[0003]

SUMMARY OF THE INVENTION As described above, the conventional
The GaN-based material does not essentially increase the In composition. Therefore, it is difficult to increase the wavelength. Even if a structure having a layer containing a large amount of In is employed, the operating voltage tends to be higher than that of a conventional device. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a structure having a longer wavelength and to provide a light emitting device having a low operating voltage.

[0004]

The gist of the present invention is to provide a semiconductor light emitting device having a structure using a compound containing hexagonal P or As for a well or a barrier of a semiconductor superlattice. It is to be.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, InGa
In a semiconductor light emitting device having an AlN 2 layer, a structure having a structure using a compound containing hexagonal P or As for a barrier layer or a well of a semiconductor superlattice is important.

As described above, the conventional GaN-based semiconductor light emitting device cannot sufficiently increase the wavelength. This has been a problem that mode control cannot be sufficiently performed because a sufficient refractive index difference cannot be obtained, and that an operating voltage is high. Therefore, the present invention solves the problem by having a structure using a compound containing hexagonal P or As for the well or barrier of the semiconductor superlattice as in the present invention, and the present invention solves the problem, which will be described below.

First, the laminated structure of the present invention will be described. A structure having a compound containing hexagonal P or As in a well or barrier of a semiconductor superlattice will be described. Hexagonal InGaAlNA
Our experiments show that sP is a direct transition compound in thin regions. Therefore, by using this structure, as shown in FIG. 1, light can be emitted in a wider range, the refractive index distribution can be made sufficient, and mode control becomes possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a diagram showing a schematic structure of a semiconductor laser according to one embodiment of the present invention.

In the figure, 11 is a sapphire substrate, 12 is an n-type GaN contact layer, 13 is an n-type AlGaN cladding layer,
14 is a GaN guide layer, 15 is an InGaN guide layer, 16 is
This is a quantum well layer made of InGaN / InGaP. 17 is p-type In
GaN guide layer, 18 is a GaN guide layer, 19 is a GaN current diffusion preventing layer, 20 is a p-type AlGaN cladding layer, 21 is a p-type Ga
The N contact layer 22 and 23 are n and p side electrodes, respectively.

In forming the element structure, a photoresist was used, patterning was performed, and then a step and a surface shape were formed by dry etching.

In this embodiment, since sapphire is used for the substrate, the laminated structure grown thereon becomes hexagonal, and the InGaN / InGaP quantum well layer serving as the light emitting layer also has a hexagonal structure. As described above, since the hexagonal InGaAlNAsP thin film is a compound of direct transition, highly efficient light emission and laser oscillation can be realized. Further, since P is included, it is possible to increase the wavelength, and it is possible to emit light and oscillate at a green wavelength or a longer wavelength, which was extremely difficult with the InGaAlN system alone.

The semiconductor laser according to the present embodiment rises at 2.5 V, and the rising voltage is reduced by 0.5 V or more as compared with the prior art. In addition, vertical and horizontal modes. Both horizontal and horizontal modes are narrower than before. The laser light was green at a wavelength of 550 nm. Also, although the substrate uses sapphire,
For example, AlGaN / GaN grown by MOVPE after growing a part by chloride VPE
A substrate may be used.

Next, the embodiment shown in FIG. 3 will be described. In the figure, 21 is a sapphire substrate, 22 is an n-type GaN contact layer,
23 is an n-type AlGaN cladding layer, 24 is a GaN guide layer, 2
5 is an InGaN / InGaAs quantum well layer, 26 is a p-type AlGaN compensation layer, 27 is a GaN guide layer, 28 is an AlGaN current diffusion prevention layer, 29 is a p-type AlGaN cladding layer, 230 is a p-type GaN contact layer, 231 and 232 Are n and p electrodes, respectively.

The crystal growth uses MOVPE. However, the layer containing As uses the MBE method. Patterning was performed using a resist, and an island structure was formed by dry etching. The threshold value of the laser having this structure is 1 kA.
/ Cm2 and the threshold voltage was 2.04V. The oscillation wavelength was 630 nm and the color was red.

In the third embodiment, the effect of compensating the lattice constants of the P layer and the As layer is used. In the figure, 31 is a sapphire substrate, 32 is an n-type GaN contact layer, and 33 is an n-type AlGaN
Cladding layer, 34 is a GaN guide layer, 35 is InGaN / Ga
As / InGaN / InGaP quantum well compensation layer, 36 is a p-type AlGaN compensation layer, 330 is a p-type GaNP / GaN contact layer, 331, 3
Reference numeral 32 denotes n and p electrodes, respectively. MOVP for crystal growth
E was used, and MBE was used for the superlattice structure. The element shape was formed by patterning using a resist. The laser of this structure had a threshold value of 1 kA / cm2 and a threshold voltage of 2V. The oscillation wavelength was 630 nm. Also, by changing the composition and structure of the active layer, oscillation was possible in a wide range from 400 nm to 1600 nm.

The present invention is not limited to the embodiment described above. For example, in the embodiment, the material system is In
Although a GaNAsP system was used, it can be changed as appropriate. In addition, a plurality of elements can be integrated on the same substrate. In addition, various modifications can be made without departing from the scope of the present invention.

[0017]

As described above in detail, according to the present invention, it is possible to provide a light emitting diode or a laser diode device capable of realizing a wide range of oscillation wavelengths, which could not be obtained conventionally, with the same material.

[Brief description of the drawings]

FIG. 1 is a diagram showing a comparison of a wavelength range between a conventional material and a material of the present invention.

FIG. 2 is a diagram showing a gallium nitride-based compound semiconductor laser according to a first embodiment of the present invention.

FIG. 3 is a diagram showing a gallium nitride-based compound semiconductor laser according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a gallium nitride-based compound semiconductor laser according to a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 sapphire substrate 12 n-type GaN contact layer 13 n-type AlGaN cladding layer 14 GaN guide layer 15 InGaN guide layer 16 InGaN / InGaP 17 p-type InGaN guide layer 18 GaN guide layer 19 GaN current diffusion prevention layer 20 p-type AlGaN cladding layer 21 p-type GaN contact layer 22 n-side electrode 23 p-side electrode

Claims (3)

[Claims] 1. A laminated film having a plurality of layers which are basically formed of a group III nitride and are laminated so as to form a pn junction, and are joined to the laminated film so as to supply a current to the pn junction. A gallium nitride-based compound semiconductor device, characterized in that the semiconductor layer sandwiching the light emitting layer and the n-side and p-side electrodes has a structure in which a quantum well contains a compound containing hexagonal P. 2. A laminated film having a plurality of layers which are basically formed of a group III nitride and are laminated so as to form a pn junction, and are joined to the laminated film so as to supply a current to the pn junction. A gallium nitride-based compound semiconductor device, characterized in that the semiconductor layer sandwiching the light emitting layer with the n-side and p-side electrodes has a structure in which a quantum well contains a compound containing hexagonal As. 3. A laminated film having a plurality of layers which are basically formed of a group III nitride and are laminated so as to form a pn junction, and are joined to the laminated film so as to supply a current to the pn junction. A gallium nitride-based compound semiconductor device, characterized in that the semiconductor layer sandwiching the light emitting layer with the n-side and p-side electrodes has a structure in which a quantum well contains a compound containing hexagonal As and P.