JPH05299693A - Edge face light emission type semiconductor device - Google Patents

Abstract

PURPOSE:To restrain laser oscillation by FP mode without enlarging a light emitting diode device even when a high current is injected and when a device is operated at a low temperature. CONSTITUTION:This light emitting diode device 21 is a light emitting diode device of DH structure wherein an active layer 25 is held between p-type and n-type clad layers 24, 26 and the active layer 25 is composed of an active region 29 and an absorption region 30. An n-type GaAs buffer layer 31, an n-type substrate 22 and an n-type electrode 35 are formed below the n-type clad layer 26. A p-type GaAs contact layer 23, an SiN insulating layer 32, a p-type electrode 33 and a metallic material 34 are formed on the p-type clad layer 24. A part of the insulating layer 32 is etched to a stripe shape and forms an electrode contact part 36. Alloying treatment is performed for a part of an upper side of the absorption region 30 in contact with the metallic material 34 and the part is a roughened strong photo-absorption surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an edge emitting type light emitting diode device suitable for use as a light source for optical communication.

[0002]

2. Description of the Related Art Generally, when high-power incoherent light is to be extracted from an edge-emitting light-emitting diode device, it is important to suppress laser oscillation in the Fabry-Perot (FP) mode. As a method of suppressing this laser oscillation, various methods for lowering the light feedback layer to the active region, such as an end face AR coat, formation of a non-excitation region (absorption region), end face oblique etching, and end face embedding, are performed. Came.

An example of a conventional edge emitting type light emitting diode device in which the non-excitation region is formed will be described with reference to FIG. FIG. 1A is a top view of a conventional light emitting diode device 1, and FIG. 1B is a sectional view taken along line AA. In the light emitting diode device 1 shown in the figure, an n-type clad layer 3, an active layer 4, a p-type clad layer 5, a p-type contact layer 6 and an insulating layer 7 are sequentially laminated on an n-type substrate 2 to form an insulating layer 7. A part is etched in a stripe shape to form an electrode contact portion 8, and then a p-type ohmic electrode 9 is formed thereon and an n-type ohmic electrode 10 is formed on the surface of the n-type substrate 2. Then, at the electrode contact portion 8, p
Since the p-type ohmic electrode 9 and the p-type contact layer 6 are electrically connected to each other, a current flows through this portion, and the active layer 4 directly below the active layer 4 becomes the active region 11 for emitting light, and the active layers in the other parts. 4 is the absorption region 12.

In the light emitting diode device 1 having such a structure, the light emitted in the active region 11 of the active layer 4 is output from the end face 13 to the outside and also to the absorption region 12 side. Then, the light incident on the absorption region 12 is
As it goes through this part, it is attenuated and the end face 14
Most of the light is absorbed before reaching. As a result, laser oscillation in the FP mode can be suppressed and stable incoherent light can be output.

[0005]

However, the light emitting diode device 1 described above has a structure in which the light in the absorption region 12 is absorbed when a high current is injected to obtain a large output light or when it is operated at a low temperature. The amount of light that exceeds the amount of absorption is incident, or the amount of absorption decreases, and the light that has entered the absorption region 12 side is not completely attenuated, and some light reaches the end face 14 and is reflected there. There is a problem in that the laser returns to the active region 11 again to cause laser oscillation in the FP mode. Then, in order to increase the light absorption amount, it is necessary to make the absorption region 12 sufficiently long, which causes a problem that the light emitting diode device 1 becomes considerably large.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a light emitting diode device which can prevent laser oscillation in the FP mode even when a high current is passed with a size substantially the same as the conventional one.

[0007]

As means for achieving the above object, the upper and lower sides of an active layer are sandwiched by p-type and n-type cladding layers having a band gap energy larger than that of the active layer and a small refractive index. In the edge-emitting type semiconductor device having the double hetero structure described above, the active layer includes an active region and an absorption region, and at least a part of the upper surface of the absorption region is a rough surface. The semiconductor device or the upper and lower sides of the active layer are sandwiched by p-type and n-type clad layers having a band gap energy larger than that of the active layer and a smaller refractive index, and the active layer and the p-type and n-type clads. An edge-emitting surface of a double hetero structure having an optical guide layer having a bandgap energy larger than that of the active layer and smaller than that of the cladding layer in at least one of the layers. -Type semiconductor device, wherein the active layer comprises an active region and an absorption region, and at least a part of the upper surface of the light guide layer in contact with the absorption region is a rough surface. It is intended to provide a device.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A light emitting diode device which is an embodiment of an edge emitting semiconductor device of the present invention will be described with reference to the drawings. Figure 1
(A) is a light emitting diode device 2 according to an embodiment of the present invention.
1 is a top view of FIG. 1, and FIG. 1B is a sectional view taken along line BB thereof. In the light emitting diode device 21 shown in the figure, the undoped AlGaAs active layer 25 is formed of p-type and n-type Al _0.7 Ga.
A light emitting diode device having a double hetero (DH) structure sandwiched by _0.3 As clad layers 24 and 26.
On one end side, current confinement is performed in a stripe shape to serve as the active region 29, and on the other end side, it serves as the absorption region 30 without current injection. An n-type GaAs buffer layer 31, an n-type substrate 22, and an n-type electrode 35 are formed on the lower side of the n-type clad layer 26 in FIG. A p-type GaAs contact layer 23, a SiN insulating layer 32, a p-type electrode 33 and a metal material 34 are formed, and a part of the insulating layer 32 is etched into a stripe shape as shown in FIG. A portion 36 is formed, and in this electrode contact portion 36, the p-type contact layer 23 and the p-type electrode 33 are formed.
And are in direct contact with each other, and a current that has undergone current confinement is flowing. Further, a part of the upper surface of the absorption region 30 of the active layer 25 is
It is in contact with the metal material 34 and is subjected to an alloying treatment, and that portion is a roughened and strong light absorption surface.

The light emitting diode device 21 having such a configuration
The light emitting state of will be described with reference to FIG. When a current is applied by applying a bias between the p-type electrode 33 and the n-type electrode 35, carriers are injected into the active layer 25 just below the electrode contact portion 36 to become the active region 29, and the carriers are recombined. As a result, light having a wavelength corresponding to the band gap energy of the semiconductor material (GaAs) of the active layer 25 is emitted. The light emitting diode device 21 has the active layer 25 with p
Since the DH structure is sandwiched between the n-type and n-type clad layers 24 and 26, the light emitted from the active region 29 is guided in the active layer 25 and is output to the outside from the end face 37. It is also output to the absorption region 30 side.

At this time, the active layer 2 in the absorption region 30
Since the upper surface of 5 which is in contact with the metal material 34 is alloyed with this metal material 34 to be a rough surface, the light emitted in the active region 29 and guided in the active layer 25 is absorbed in the absorption region 30. While being absorbed by the semiconductor material, it is incident on this rough surface and is attenuated while undergoing strong losses such as scattering and absorption. At this time, if the distance to the end face 38 is shortened, the light may reach the end face 38 without being completely absorbed while passing through the absorption region 30, but the light reflected by the end face 38 is absorbed again. Even while passing through the region 30, it is attenuated by receiving the same strong loss, so that even if the length of the absorption region 30 is made shorter than before, it can be completely attenuated before reaching the active region 29. The end face 37 can be prevented from acting as a Fabry-Perot (FP) mode resonance surface. As a result, even when injecting high current or operating at low temperature,
It is possible to suppress laser oscillation in the FP mode while keeping the light emitting diode device small, and to output stable incoherent light.

Next, a method of manufacturing the light emitting diode device 21 shown in FIGS. 1A and 1B will be described with reference to FIGS. First, as shown in FIG.
0.6 μm n-type G formed on the substrate 22 by MOCVD
aAs buffer layer 31, 1 μm n-type Al _0.7 Ga _0.3
As clad layer 26, 0.2 μm undoped GaAs
An active layer 25, a 1 μm p-type Al _0.7 Ga _0.3 As clad layer 24, and a 0.1 μm p-type GaAs contact layer 23 are sequentially laminated to form an inorganic oxide SiN (or S).
The p-type contact layer 23 is chemically etched using a phosphoric acid-based etching solution with the insulating layer 32 of iO ₂ ) as a mask, and the p-type clad layer 24 is selectively etched with hydrochloric acid to partially remove the active layer 25. Exposed, same figure (B)
A step as shown in FIG. Subsequently, as shown in FIG. 6C, the insulating layer 32 immediately above the active region 29 is removed in a stripe shape by a normal photolithography method,
The p-type contact layer 23 in that portion is exposed again to form an electrode contact portion 36 (see FIG. 1A).

Next, as shown in FIG. 3D, the p-type electrode 33 including the electrode contact portion 36 immediately above the active region 29 is vapor-deposited by the photolithography method and the lift-off method. A metal material 34 electrically separated from 33 is deposited on the absorption region 30. At this time, a part of the metal material 34 is directly deposited on the upper surface of the active layer 25 in the absorption region 30. Then, as shown in FIG. 7E, the n-type substrate 22 is polished and etched to have a total thickness of 100 μm, and the n-type electrode 35 is deposited on the surface of the n-type substrate 22. After that, annealing treatment (heat treatment) is performed, and each electrode 33, 34, 35 and each electrode 3
The crystal layers in contact with 3, 34 and 35 are alloyed. Then, by this alloying, the p-type and n-type electrodes 33, 35 are formed.
Becomes an ohmic electrode, and current can be injected into the active region 29. The upper surface of the active layer 25 in the absorption region 30 contacting the metal material 34 is roughened by alloying and passes through the absorption region 30. The scattered light is lost by scattering and absorption, and can be attenuated in a short distance.

The present invention can also be applied to an edge emitting semiconductor device having a light guide layer. In the light emitting diode device 41 shown in FIG. 4, an optical guide layer 42 having a larger bandgap energy than the active layer 25 and a smaller bandgap energy than the p-type cladding layer 24 is provided on the active layer 25. The other configurations are the same as those of the light emitting diode device 21 described above. Then, in this light emitting diode device 41, the upper surface portion of the light guide layer 42 on the absorption region 30 of the active layer 25 is roughened by alloying with the metal material 34.

The light emitting diode device 41 having such a structure.
In, the light emitted from the active region 29 of the active layer 25 is guided inside the active layer 25 and the light guide layer 42, and is output to the outside from the end face 37, and at the same time, the absorption region 30 of the active layer 25 and above it. The light is also output into the light guide layer 42.
Then, at this time, the light guide layer 42 on the absorption region 30
Since the upper surface in contact with the metal material 34 is alloyed with the metal material 34 and becomes a rough surface, it emits light in the active region 29 and is guided in the absorption region 30 and the light guide layer 42 thereabove. The light is absorbed by the semiconductor material of the absorption region 30 and the light guide layer 42, is incident on the rough surface, and is attenuated while undergoing a strong loss such as scattering and absorption. At this time, if the distance to the end face 38 is shortened, the light may reach the end face 38 without being completely absorbed.
While the light reflected at is again attenuated by receiving the same strong loss while passing through the absorption region 30 and the light guide layer 42 thereabove, the length of the absorption region 30 is made shorter than in the conventional case. However, it can be completely attenuated before reaching the active region 29, and the end face 37 can be prevented from functioning as a resonance plane of the FP mode. As a result, even when a high current is injected or when the device is operated at a low temperature, it is possible to suppress laser oscillation in the FP mode while keeping the light emitting diode device small, and to output stable incoherent light. ..

Further, in each of the above-mentioned embodiments, the gain waveguide type light emitting device using the electrode stripe structure which is easy to manufacture has been described. Type light emitting device,
In addition to GaAs / AlGaAs, semiconductor materials are In
Other semiconductor materials such as GaAsP type and InGaAlP type may be used. As the crystal growth method for the semiconductor material, other crystal growth methods such as the MBE method may be used in addition to the MOCVD method used in the above-described embodiment.

[0016]

In the edge emitting semiconductor device of the present invention, at least a part of the upper surface of the absorption region of the active layer or the light guide layer in contact with the absorption region is a rough surface, and therefore, in the active region of the active layer. The light emitted and incident on the absorption region is absorbed by the semiconductor material forming the absorption region, and when it is incident on this rough surface, it undergoes strong losses such as scattering and absorption and is attenuated. Even if the absorption region is shorter than that of the edge-emitting type semiconductor device, the light can be completely attenuated and the light can be prevented from returning to the active region. As a result, even when a high current is injected to obtain a high output or when the device is operated at a low temperature, it is possible to suppress the laser oscillation in the FP mode without increasing the size of the light emitting diode device, and it is stable. There is an effect that the high output incoherent light can be output.

[Brief description of drawings]

1A and 1B are a top view and a cross-sectional view showing an embodiment of an edge emitting semiconductor device of the present invention.

FIG. 2 is a sectional view for explaining a light emitting state of the present invention.

3A to 3E are process diagrams showing a manufacturing method according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of the edge emitting semiconductor device of the present invention.

5A and 5B are a top view and a cross-sectional view showing a conventional example.

[Explanation of symbols]

1,21,41 Light emitting diode device (edge emitting semiconductor device) 2,22 n type substrate 3,26 n type cladding layer 4,25 active layer 5,24 p type cladding layer 6,23 p type contact layer 7,32 Insulating layer 8,36 Electrode contact portion 9,33 p-type electrode (p-type ohmic electrode) 10,35 n-type electrode (n-type ohmic electrode) 11,29 Active region 12,30 Light absorbing region 13,14,37,38 End face 31 n-type buffer layer 34 metallic material 42 optical guide layer

Claims (2)

[Claims] 1. An edge emitting semiconductor device having a double hetero structure in which upper and lower sides of an active layer are sandwiched by p-type and n-type cladding layers having a band gap energy larger than that of the active layer and a refractive index smaller than that of the active layer. An edge emitting semiconductor device, wherein the active layer comprises an active region and an absorption region, and at least a part of the upper surface of the absorption region is a rough surface. 2. The active layer and the p-type and n-type claddings are sandwiched by p-type and n-type cladding layers having a bandgap energy larger than that of the active layer and a smaller refractive index than the active layer. In an edge emitting semiconductor device having a double hetero structure, which comprises an optical guide layer having a bandgap energy larger than that of the active layer and smaller than that of the cladding layer in at least one of the layers, the active layer is active. An edge emitting semiconductor device, comprising an area and an absorption area, wherein at least a part of the upper surface of the light guide layer in contact with the absorption area is a rough surface.