JPH1154831A - Semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element, which efficiently dissipates heat generated at the time of its operation and, as the result, its life is prolonged. SOLUTION: An n-type GaN layer 103 which is used as a first conductivity type semiconductor layer, an n-type AlGaN clad layer 104, an InGaN active layer 105 which is a luminous layer, a p-type AlGaN clad layer 106 which is used as a second conductivity type semiconductor layer, and a p-type GaN layer 107, are formed on a substrate 101. Thereafter, a striped region having the first conductivity type semiconductor layer, the second conductivity type semiconductor layer and the luminous layer is formed. Here, by forming the width of a layer wider, which is formed with the luminous layer, than a width of 50 μm, the diffusion of heat generated at the time of the operation of a semiconductor light-receiving element takes place efficiently, and the life of the semiconductor light-emitting element is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor light emitting device.

[0002]

2. Description of the Related Art A conventional semiconductor laser in which a gallium nitride-based compound semiconductor is formed on a sapphire substrate is described, for example, in Japanese Patent Application Laid-Open No. 7-176826. Therefore, the above-described conventional semiconductor light emitting device will be described below with reference to the drawings. FIGS. 6 (a) and 6 (b) show Japanese Unexamined Patent Publication No. 7-17682.
6A and 6B are a cross-sectional view and a top view illustrating a structure of a semiconductor light-emitting element described in Japanese Patent Application Publication No. 6-2006.

[0006] The conventional semiconductor light emitting device shown in FIG. 6 is formed by the following procedure. First, sapphire (000
1) A GaN buffer layer 602, an n-type GaN layer 603, and an n-type AlGaN
Cladding layer 604, InGaN active layer 60 as a light emitting layer
5, p-type AlGaN cladding layer 606, p-type GaN layer 6
07 are epitaxially grown. next,
N-type and p-type electrodes are formed on the n-type GaN layer 603 and the p-type GaN layer 607, respectively. At this time, since the sapphire substrate 601 is insulative, the p-type and n-type electrodes need to be taken from the side of the grown semiconductor layer. Therefore, as shown in FIG. 6A, the right and left ends are etched until the n-type GaN layer 603 is exposed, while leaving the center of the semiconductor crystal in a stripe shape using an appropriate mask material. Gallium nitride-based compound semiconductors are chemically extremely stable substances, so they are hardly wet-etched,
The n-type GaN layer 603 is exposed by dry etching. Note that the width of the remaining stripe is 50 μm or less.

[0004] Finally, a p-type electrode 608 is formed on the p-type GaN layer 607 by exposing two n-type electrodes exposed by dry etching.
An n-type electrode 609 is respectively deposited on the type GaN layer 603 by vacuum deposition.

[0005]

However, in the above-mentioned conventional semiconductor light emitting device, the following problems occur because the stripe width at the center of the device is 50 μm or less.

[0006] That is the problem of heat dissipation. When a semiconductor light emitting device (semiconductor laser) is operated, heat is generated. The amount of heat generated is the n-type AlG having the highest resistance.
aN cladding layer 604 to InGaN active layer 605, p
The pn junction up to the AlGaN cladding layer is the largest. Here, in the above-described conventional semiconductor light emitting device,
Since the stripe width is as narrow as 50 μm or less, sufficient heat radiation during operation cannot be performed. As a result,
As shown in FIG. 7, when the light output is fixed at 3 mW, the current value of the element gradually increases with time (the threshold value increases), and finally the element deteriorates in about 40 hours. It will not work at all.

SUMMARY OF THE INVENTION In view of the above problems, it is a primary object of the present invention to provide a semiconductor light emitting device which efficiently dissipates heat generated during operation and, as a result, has a longer life.

[0008]

In order to achieve the above object, a semiconductor light emitting device of the present invention comprises a semiconductor light emitting device having at least a first conductive type semiconductor layer and a first conductive type semiconductor layer on a substrate. A semiconductor layer of the second conductivity type formed, and a light emitting layer formed between the semiconductor layer of the first conductivity type and the second semiconductor layer, the width of the layer on which the light emitting layer is formed is The configuration is larger than 50 μm. According to this configuration, heat generated near the active layer can be efficiently diffused.

The semiconductor light emitting device of the present invention further comprises a semiconductor layer of at least a first conductivity type on a substrate, a semiconductor layer of a second conductivity type formed on the semiconductor layer of the first conductivity type, and A stripe-shaped region having a light-emitting layer formed between the first conductivity type semiconductor layer and the second semiconductor layer, a first electrode formed on the first conductivity type semiconductor layer, And a second electrode formed on the second conductivity type semiconductor layer, and the first electrode is formed in a direction parallel to and perpendicular to the stripe-shaped region. According to this configuration, the resistance of the electrode can be reduced,
As a result, heat generated during operation of the element can be efficiently diffused.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor light emitting device according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view of a semiconductor light emitting device according to Embodiment 1 of the present invention in a manufacturing process ((a)).
To (d)) and a top view ((e)).
Hereinafter, a semiconductor light emitting device and a method for manufacturing the same according to the first embodiment of the present invention will be described with reference to FIG.
Here, a description will be given of a semiconductor laser in which a gallium nitride-based compound semiconductor is formed on a sapphire substrate as an example.

As shown in FIG. 1, first, sapphire (0
001) on the surface substrate 101 by MOVPE method or the like.
N buffer layer 102, n as a first conductivity type semiconductor layer
-Type GaN layer 103 and n-type AlGaN cladding layer 10
4. The InGaN active layer 105, which is a light emitting layer, is sequentially epitaxially grown. Next, SiO _{2 is formed} on the light emitting layer 105.
After depositing the film 110 by a plasma CVD method or the like, the light emitting layer 105 and the SiO ₂ film 110 are deposited using an appropriate mask.
The region other than the width of 20 μm at the center of the pattern is removed by etching (FIG. 1A).

Next, the insulating layer 111 made of ZnO is regrown to the same thickness as the light emitting layer 105 by MOVPE. At this time, the insulating layer 111 regrows only in a region where the n-type AlGaN cladding layer 104 is exposed.
(B)). After that, the central portion of the SiO ₂ film 110 is removed, and the respective semiconductor layers of the p-type AlGaN cladding layer 106 and the p-type GaN layer 107 as the second conductivity type semiconductor layer are again epitaxially grown by MOVPE or the like. As described above, a buried structure of the light emitting layer (active layer) 105 can be formed (FIG. 1C).

Next, a stripe-shaped region having a width of 150 μm including the buried light-emitting layer 105 is covered with a suitable mask, and the left and right ends thereof are subjected to dry etching until the n-type GaN layer 103 is exposed. Is formed. Note that the thickness of the remaining n-type GaN layer 103 is desirably 1 μm or more in order to reduce resistance. After removing the mask, a p-type electrode 108 is formed on the p-type GaN layer 107 and n-type electrodes are formed on the two exposed n-type GaN layers 103.
When the mold electrodes 109 are respectively deposited by vacuum deposition, a semiconductor laser is completed (FIG. 1D). Thereby, the layer on which the active layer is formed is 50 μm or more (specifically, 15 μm or more).
0 μm).

FIG. 2 shows, as characteristics of the semiconductor laser formed as described above, changes in the current value when the optical output is fixed at 3 mW. According to the present embodiment, since the width of the stripe-shaped region at the center is as large as 150 μm, the surface area of the stripe is large, and mainly occurs at the pn junction of n-type AlGaN layer 104 to p-type AlGaN layer 106. Joule heat can be efficiently dissipated. Therefore, a rise in temperature can be suppressed and an increase in the current value can be suppressed to a minimum, and the life of the element can be extended to about 1000 hours. If the width of the stripe is large, the area of the electrode formed thereon (the p-type electrode 108 formed on the p-type GaN layer 107 in this embodiment) can be increased, so The generated heat can also be efficiently dissipated. Further, in the present embodiment, the width of the layer on which the active layer is formed is set to 150 μm. However, an effect can be obtained if it is formed so as to exceed 50 μm.

According to the present embodiment, FIG.
The light loss can be reduced as compared with the conventional semiconductor light emitting device shown in FIG.

In the conventional semiconductor light emitting device shown in FIG. 6, the stripe end face at the center of the device is, as described above,
Since it is formed by dry etching, the flatness is poor and light is scattered at the end face. Here, for example, in FIG. 6, when the stripe width is reduced to about the size of the horizontal spread of the light emitting spots in the light emitting layer 605 (about 10 μm), light loss occurs at the end face of the stripe. As shown in FIG. 8, the threshold current increases, and the slope efficiency after oscillation decreases.

On the other hand, according to the present embodiment, since the periphery of the light emitting layer 105 is surrounded by the insulating layer 111, light can be confined, and as a result, light loss can be suppressed to a minimum. . Note that FIG. 3 shows current-light output characteristics of the semiconductor light emitting device in the present embodiment. As is clear from FIG. 3, light loss due to light scattering on the dry etching end face which occurs when the stripe width is reduced to about 10 μm is eliminated, and in fact, the threshold current is reduced, and the oscillation after oscillation is reduced. The slope efficiency also increases. In addition, since the light emitting layer 105 has a buried structure, the current can be narrowed to increase the current density, and the light output can be increased.

Embodiment 2 FIG. 4 shows a sectional view (FIG. 4A) and a top view (FIG. 4B) of a semiconductor light emitting device according to Embodiment 2 of the present invention. Hereinafter, the semiconductor light emitting device according to the second embodiment of the present invention will be described with reference to FIG. Here, as in the first embodiment, a description will be given by taking a semiconductor laser in which a gallium nitride-based compound semiconductor is formed on a sapphire substrate as an example.

This embodiment is different from the first embodiment in that the light emitting layer (active layer) 405 is not surrounded by the insulating layer, and the stripe portion including the light emitting layer has a ridge structure. That is.

Hereinafter, a description will be given of a manufacturing process of the semiconductor light emitting device in the present embodiment shown in FIG.

First, a sapphire (0001) plane substrate 401
A GaN buffer layer 40 is formed thereon by MOVPE or the like.
2. n-type GaN layer 403 as first conductivity type semiconductor layer
And the n-type AlGaN cladding layer 404 and the light emitting layer I
nGaN active layer 405, p as second conductivity type semiconductor layer
-Type AlGaN cladding layer 406 and p-type GaN layer 407
Are epitaxially grown. Next, after depositing a p-type electrode 408 on the p-type GaN layer 407, a region having a width of 20 μm at the center is masked with a photoresist or the like, and p-type AlG is formed by ion milling as shown in FIG.
Etching is performed in a ridge stripe shape until the aN layer 406 is exposed. After removing the mask, width 1 including the ridge
The region of 50 μm is masked with a SiO ₂ film or the like, and the rectangular regions at the left and right ends thereof are dry-etched until the n-type GaN layer 403 is exposed. After removing the dry etching mask, two n-type electrodes 409 are formed on the n-type GaN layer 403 by vacuum evaporation to complete a semiconductor light emitting device. As a result, a semiconductor laser in which the layer on which the active layer is formed is 50 μm or more (specifically, 150 μm) can be obtained.

Also in the semiconductor light emitting device of the present embodiment, the width of the stripe region including the light emitting layer 405 is 1
Since the width of the stripe region at the center is as large as 150 μm, as in the first embodiment,
The surface area of the stripe portion is increased, and mainly n-type Al
Joule heat generated at the pn junction between the GaN layer 404 and the p-type AlGaN layer 406 can be efficiently radiated. In the present embodiment, the width of the layer on which the active layer is formed is set to 150 μm, but an effect can be obtained if the active layer is formed so as to exceed 50 μm.

Further, according to the present embodiment, the light emitting layer 405
Is not surrounded by an insulating layer, but since the p-type electrode is formed in a ridge stripe shape, current is not applied to the light emitting layer 4.
The light output can be increased because the light is injected at a high density into the substrate.

(Embodiment 3) FIG. 5 shows a sectional view (FIG. 5A) and a top view (FIG. 5B) of a semiconductor light emitting device according to Embodiment 3 of the present invention. Hereinafter, the semiconductor light emitting device according to the third embodiment of the present invention will be described with reference to FIG. Here, as in the first embodiment, a description will be given by taking a semiconductor laser in which a gallium nitride-based compound semiconductor is formed on a sapphire substrate as an example.

The present embodiment is different from the above-described first embodiment in the shape of the n-type electrode 509, and the other parts are basically the same as those in the first embodiment, and therefore description thereof is omitted. . The central region left without dry etching has a length of 300 μm and a width of 1 μm as shown in FIG.
It is 50 μm.

In the semiconductor light emitting device of the present embodiment, the n-type electrode 509 is formed so as to surround the stripe portion including the light emitting layer when the device is viewed from above (FIG. 5B). When the light-emitting element operates, current flows in all directions from the central p-type electrode 508 to the peripheral n-type electrode 509, so that the region of the semiconductor crystal in which the current flows can be enlarged. Therefore, the p-type electrode 508 and n
Electric resistance between the mold electrodes 509 can be reduced, and as a result, heat generation during operation of the element (such as Joule heat generated during operation from the element itself) can be suppressed, and the life of the element can be extended.

In the example shown in FIG. 5, the n-type electrode is formed so as to surround the stripe portion. However, it is not necessary to form the n-type electrode so as to surround the stripe portion. As long as the n-type electrode is formed in any direction, the area of the n-type electrode can be increased at least as compared with the semiconductor light-emitting element shown in FIG. 6, and heat generation during operation of the semiconductor light-emitting element can be suppressed. it can.

In this embodiment, since the structure of the stripe portion is the same as that of the first embodiment, the surface area of the stripe portion can be increased and the area of the n-type electrode can be increased. Heat can be dissipated very efficiently.

Although the present invention has been described with the embodiments, the shapes of the exposed n-type GaN and n-type electrode in any of the first to third embodiments are as shown in the drawings. Not limited to this, any shape can be adopted. Further, the p-type and n-type electrodes may be formed by being divided into several regions. Furthermore, although a semiconductor laser using a gallium nitride-based compound semiconductor on a sapphire substrate has been described here as an example, the effect of the present invention is not limited to this, and a light-emitting element other than a semiconductor laser or a gallium nitride-based compound semiconductor may be used. It can be applied to any material.

[0031]

As described above, in the semiconductor laser in which the surface of the semiconductor crystal is dry-etched in a convex shape and both the p-type and n-type electrodes are formed on the side of the epitaxial growth layer, the stripe-shaped region is left without dry etching. By making the width larger than 50 μm, heat can be efficiently radiated at the time of device operation, and as a result, the threshold current of the laser can be reduced and the slope efficiency after oscillation can be increased. Further, the life of the element can be prolonged, and the reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing process of a semiconductor laser according to a first embodiment of the present invention;

FIG. 2 is a diagram showing a change in a current value at a constant optical output of the semiconductor laser according to the first embodiment of the present invention.

FIG. 3 is a diagram showing current-light output characteristics of the semiconductor laser according to the first embodiment of the present invention;

FIG. 4 is a sectional view showing an element structure of a semiconductor laser according to a second embodiment of the present invention;

FIG. 5 is a sectional view showing an element structure of a semiconductor laser according to a third embodiment of the present invention;

FIG. 6 is a sectional view showing an element structure of a conventional semiconductor laser.

FIG. 7 is a diagram showing a change in current value at a constant light output of a conventional semiconductor laser.

FIG. 8 is a diagram showing current-light output characteristics of a conventional semiconductor laser.

[Explanation of symbols]

101 insulating substrate 102 buffer layer 103 n-type GaN layer 104 n-type AlGaN layer 105 InGaN active layer 106 p-type AlGaN layer 107 p-type GaN layer 108 p-type electrode 109 n-type electrode 110 SiO ₂ film 111 insulating layer 401 insulating substrate 402 buffer layer 403 n-type GaN layer 404 n-type AlGaN layer 405 InGaN active layer 406 p-type AlGaN layer 407 p-type GaN layer 408 p-type electrode 409 n-type electrode 501 insulating substrate 502 buffer layer 503 n-type GaN layer 504 n-type AlGaN layer 505 InGaN active layer 506 p-type AlGaN layer 507 p-type GaN layer 508 p-type electrode 509 n-type electrode 511 insulating layer 601 insulating substrate 602 buffer layer 603 n-type GaN layer 604 n-type AlGaN layer 605 InGaN active layer 06 p-type AlGaN layer 607 p-type GaN layer 608 p-type electrode 609 n-type electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Isao Kidoguchi 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Yuzaburo Ban 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A semiconductor layer of at least a first conductivity type on a substrate, a semiconductor layer of a second conductivity type formed on the semiconductor layer of the first conductivity type, and the first conductivity type. A semiconductor light-emitting element in which a stripe-shaped region having a light-emitting layer formed between the semiconductor layer and the second semiconductor layer is formed, wherein the width of the layer on which the light-emitting layer is formed is 50 μm
A semiconductor light emitting device characterized by being larger than the above. 2. The semiconductor light emitting device according to claim 1, wherein the semiconductor layer of the second conductivity type has a ridge stripe structure. 3. The semiconductor light emitting device according to claim 1, wherein the light emitting layer has a buried structure sandwiched between insulating layers. 4. A semiconductor layer of at least a first conductivity type on a substrate, a semiconductor layer of a second conductivity type formed on the semiconductor layer of the first conductivity type, and the first conductivity type. A stripe-shaped region having a light emitting layer formed between the first semiconductor layer and the second semiconductor layer; a first electrode formed on the first conductivity type semiconductor layer; A second electrode formed on a conductive type semiconductor layer, wherein the first electrode is formed in a direction parallel to and perpendicular to the stripe-shaped region. A semiconductor light emitting device characterized by the above-mentioned. 5. A semiconductor layer of at least a first conductivity type on a substrate, a semiconductor layer of a second conductivity type formed on the semiconductor layer of the first conductivity type, and the first conductivity type. A stripe-shaped region having a light emitting layer formed between the first semiconductor layer and the second semiconductor layer; a first electrode formed on the first conductivity type semiconductor layer; A semiconductor light emitting device having a second electrode formed on a conductive type semiconductor layer, wherein the first electrode is formed so as to surround the stripe-shaped region. Semiconductor light emitting device. 6. A semiconductor layer of at least a first conductivity type on a substrate, a semiconductor layer of a second conductivity type formed on the semiconductor layer of the first conductivity type, and the first conductivity type. A stripe-shaped region having a light emitting layer formed between the first semiconductor layer and the second semiconductor layer; a first electrode formed on the first conductivity type semiconductor layer; A second electrode formed on a conductive type semiconductor layer, wherein the width of the layer on which the light emitting layer is formed is larger than 50 μm and the first electrode Are formed in a direction parallel to and perpendicular to the stripe-shaped region. 7. The semiconductor device according to claim 1, wherein the first conductivity type semiconductor layer and the second conductivity type semiconductor layer are Al _x Ga _y In _z N (0 ≦ x, y, z ≦
1; x + y + z = 1). The semiconductor light emitting device according to claim 1, wherein x + y + z = 1).