WO2008056530A1

WO2008056530A1 - Semiconductor laser and process for manufacture thereof

Info

Publication number: WO2008056530A1
Application number: PCT/JP2007/070516
Authority: WO
Inventors: Kazuo Aoki; Takekazu Ujiie
Original assignee: Koha Co., Ltd.
Priority date: 2006-11-06
Filing date: 2007-10-22
Publication date: 2008-05-15
Also published as: JP2008117966A

Abstract

Disclosed is a semiconductor laser equipped with an accurate laser resonator formed by a simple manufacture process. Also disclosed is a process for manufacturing the semiconductor laser. An epitaxial layer (11) is provided on a substrate (10,50) comprising a β-Ga2O3-type single crystal. The epitaxial layer (11) can be formed by growing (0001)face (A5) of a GaN-type compound having a wurtzite structure on a face (A3,B3) defined in a given substrate orientation. The semiconductor laser has a laser resonator which is formed by utilizing (1-100)face (A4,B4) (which is a cleavage plane of the epitaxial layer (11)) as the edge face of the resonance surface.

Description

Specification

Semiconductor laser and manufacturing method thereof

Technical field

[0001] The present invention relates to a semiconductor laser and a method of manufacturing the same, and in particular, using a β-GaO substrate.

The present invention relates to a semiconductor laser and a manufacturing method thereof. Background art

[0002] Shortening of the wavelength of a semiconductor laser is highly expected in order to enable high-density optical recording and high-speed and large-capacity optical communication over a long distance. In addition, in the fields of optical sensing and laser processing and displays, semiconductor lasers are expected to have shorter wavelengths.

[0003] As a conventional semiconductor laser, a plurality of layers made of a nitride semiconductor are formed on a sapphire substrate, and the other portion is removed by etching while leaving the laser resonator portion, thereby making the resonator a mesa type. There is a semiconductor laser formed. For example, Patent Document 1 discloses such a conventional semiconductor laser.

In this configuration, a semiconductor laser is formed by reactive ion beam etching using C1 gas.

2

Therefore, etching with a high etching rate is possible, and the mirror surface accuracy of the end face of the laser resonator can be improved.

Patent Document 1: Japanese Patent Laid-Open No. 11 145566

Disclosure of the invention

Problems to be solved by the invention

[0005] However, according to the semiconductor laser of Patent Document 1, the force of forming a plurality of layers made of a nitride semiconductor on a sapphire substrate Since the sapphire substrate has almost no cleavage, Is difficult to form. Therefore, it is necessary to form a laser resonator by etching, and it is difficult to form an accurate laser resonator by a simple manufacturing process.

Accordingly, an object of the present invention is to provide a semiconductor laser having a structure in which a laser resonator with high accuracy is formed by cleavage without using etching or the like, and a method for manufacturing the same. Means for solving the problem

[0007] [1] In order to achieve the above object, the present invention provides a substrate comprising a 13-GaO-based single crystal,

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An epitaxy layer formed by growing a (0001) plane of a GaN-based compound having a wurtzite structure on a plane defined by a predetermined plane orientation of the substrate, and a cleavage plane of the epitaxy layer ( 1. The present invention provides a semiconductor laser having a laser resonator formed with a 1100) plane as an end face of a resonant surface.

[2] The semiconductor laser according to [1], wherein the surface defined by a predetermined plane orientation of the substrate is a (100) plane of the substrate.

[3] The semiconductor laser according to [1], wherein the surface defined by the predetermined plane orientation of the substrate is a surface perpendicular to the (001) surface of the substrate. Also good.

[0010] [4] In order to achieve the above object, the present invention provides a group comprising a 13-GaO single crystal.

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A step of preparing a plate, and an epitaxial step of forming an epitaxial layer by growing a (0001) plane of a GaN-based compound having a wurtzite structure on a surface defined by a predetermined plane orientation of the substrate. And a resonator forming step of cleaving the (1100) plane of the epitaxial layer to form a laser resonator.

[5] The method of manufacturing a semiconductor laser as described in [4] above, wherein the plane defined by the predetermined plane orientation of the substrate is the (100) plane of the substrate. Good.

[6] The method of manufacturing a semiconductor laser as described in [4] above, wherein the plane defined by the predetermined plane orientation of the substrate is a plane perpendicular to the (001) plane of the substrate. It may be. The invention's effect

[0013] According to the present invention, it is possible to provide a semiconductor laser in which an accurate laser resonator is formed by a simple manufacturing process and a manufacturing method thereof.

Brief Description of Drawings

FIG. 1 is a schematic perspective view of a semiconductor laser according to a first embodiment of the present invention. FIG. 2 shows the crystal orientation and the / 3 Ga O-based single crystal. It is a figure which shows a crystal plane.

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[Fig. 3] Fig. 3 shows the hexagonal crystal G on the (100) plane of the substrate 10 made of / 3-GaO single crystal.

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a-axis, b-axis, and c, respectively, when the (0001) plane of aN compound is epitaxially grown It shows the relationship of the axes.

4] FIG. 4 is a schematic perspective view of a semiconductor laser according to the second embodiment of the present invention.

[0015] 10, 50 substrate

1 1 Epitakishanore layer

12 Active region

13 Resonance ¾ ^ 耑 HP

21 GaN buffer layer

22 n— GaN layer

23 n— InGaN layer

24 n—AlGaN layer

25 n— GaN layer

26 InGaN MQW

27 p— AlGaN layer

28 p— GaN layer

29 p— AlGaN layer

30 p— GaN layer

31

32 p it pole

(001) plane of A1 and B1 substrates

(010) surface of A2 and B2 boards

(100) side of A3, B3 board

A4, B4 Epoxy layer 1 1 (1-

A5 Epitakishanore layer 11 (0001)

a axis angle

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] (First embodiment) FIG. 1 is a schematic perspective view of a semiconductor laser according to the first embodiment of the present invention. The semiconductor laser 1 includes a substrate 10 made of a / 3-GaO single crystal exhibiting n-type conductivity, and a substrate 10.

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An epitaxial layer 11 formed by growing a (0001) plane of a GaN-based compound with a wurtzite structure on the plate 10, and a resonator end face 13 which is a cleavage plane of the epitaxial layer 11 at both ends of the active region 12 And a laser resonator formed.

FIG. 2 is a diagram showing the crystal orientation and crystal plane of a β-Ga 2 O single crystal. The crystal orientation is

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, & Axis <100> (al), 1 ^ axis <010> (bl), c axis <001> (cl), a axis and c axis are 103.7

The axis angle α is °. The substrate 10 of the semiconductor laser according to the first embodiment of the present invention has the above crystal orientation and crystal plane, and exhibits η-type conductivity.

[0018] It should be noted that the / 3—GaO single crystal force, the substrate 10 is made of / 3—GaO single crystal as described above.

2 3 2 3

It may be composed of an oxide composed mainly of Ga to which one or more selected from the group consisting of Cu, Ag, Zn, Cd, Al, In, Si, Ge and Sn are added. . By adding these elements, the lattice constant or the band gap energy can be controlled. For example, by adding A1 and In elements, (Ga Al In) O (just χ y (1 -xy) 2 3 and 0≤x≤l, 0≤y≤l, 0≤x + y≤ A substrate 10 represented by l) can be obtained.

[0019] Figure 3 shows the hexagonal G on the (100) plane (A3) of the substrate 10 that also has a / 3-GaO single crystal force.

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The b-axis (bl) and c-axis (cl) of the substrate 10 and the a-axis (a2) and b of the hexagonal GaN compound when the (0001) plane (A5) of the aN compound is epitaxially grown This shows the relationship of the axis (b2). β-GaO single crystal (001) plane (A1) and GaN compound (1-100) plane (A4

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) And force coincide with each other on the (100) plane (A3) of the substrate 10, so that the cleavage direction of the substrate 10 and the epitaxial layer 11 of the GaN-based compound is the same direction.

As shown in FIG. 1, the semiconductor laser 1 includes a substrate 10 made of a β-Ga 2 O-based single crystal (10

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On the (0) plane (A3), GaN buffer layer 21, n—GaN layer 22, n—InGaN layer 23, n-AlGaN layer 24, n—GaN layer 25, InGaN MQW (multiple quantum well) layer 26, p— The AlGaN layer 27, the p—GaN layer 28, the p—AlGaN layer 29, and the p—GaN layer 30 are formed as the epitaxial layer 11. Further, an n-electrode 31 is formed on the surface of the substrate 10 where the epitaxial layer 11 is not formed, and a p-electrode 32 is formed on the opposite surface. Note that the epitaxial layer 11 is configured to include all or a part of each of the above layers. [0021] In the above, mainly, the GaN buffer layer 21 is a buffer layer for relaxing lattice mismatch with the substrate 10, the n-GaN layer 22 is a contact layer, the n- InGaN layer 23 is a cladding layer, and n-A1G aN layer 24 is an underlayer, n—GaN layer 25 is a guide layer, InGaN MQW layer 26 is a light emitting layer, p—AlGaN layer 27 is a cap layer, p—GaN layer 28 is a guide layer, and p—AlGaN layer 29 is a cladding layer. The p-GaN layer 30 functions as a contact layer.

As shown in FIG. 1, the p-electrode 32 is a stripe-type electrode, and the range of the active region 12 is set by defining the range of current confinement by the stripe width.

[0023] Here, as shown in FIG. 1, the (100) plane (A3) of the substrate 10 also has β-GaO single crystal force.

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In addition, the force of forming the epitaxial layer 11 in parallel The (001) plane (A1) of the substrate 10 forms an axial angle (α) of 10 · 7 ° with the (100) plane (A3). Therefore, the (001) plane (A1), which is the cleavage plane of the substrate 10, and the (1-100) plane (4), which is the cleavage plane of the epitaxial layer 11, correspond to the above axial angle «= 103.7 ° However, there is no particular problem with the cleaving property.

The laser resonator of the semiconductor laser 1 includes (1) of the epitaxial layer 11 including the active region 12.

— The (100) plane () 4), that is, the cleavage plane at both ends of the epitaxial layer 11 is formed as the resonator end face 13.

[0025] Although not shown, the semiconductor laser 1 is provided with wiring for current supply to the η electrode 31 and the ρ electrode 32 by wire bonding or the like, and packaging for mounting is performed. .

[0026] (Effects of the first embodiment)

The first embodiment has the following operational effects.

(1) The (100) face (A3) of the substrate 10 also has β-Ga Ο-based single crystal force.

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1) Since the plane (A5) is grown, the cleavage plane is a plane in almost the same direction. Therefore, a good-quality resonator end face 13 can be easily obtained using cleavage.

(2) Since the substrate 10 made of β-GaO single crystal has conductivity, the electrode is

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Since the vertical structure provided on the side of the partial layer 11 and the substrate 10 on the opposite side can be provided, a semiconductor laser can be manufactured by a simple manufacturing process.

(3) Since the substrate 10 made of β-GaO single crystal has a thermal expansion coefficient very close to that of GaN,

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Uniform epitaxy across the entire substrate 10 that is less affected by substrate warpage during processing Shal layer 1 1 is obtained and the yield is improved.

[0027] From the above, it is possible to achieve accuracy with a simple manufacturing process using cleavage, which is performed in the prior art, for example, without the need to provide a process for removing the sapphire substrate by the laser lift method and attaching it to a Si substrate or the like. The ability to provide a semiconductor laser with a good laser cavity is possible.

[0028] (Second Embodiment)

FIG. 4 is a schematic perspective view of a semiconductor laser according to the second embodiment of the present invention. Unlike the first embodiment, in the second embodiment, the 13-GaO single connection is

On the surface perpendicular to the (001) plane (B 1) of the 2 3 crystal substrate 50, the GaN buffer layer 21, n—GaN layer 22, n—InGaN layer 23, n—AlGaN layer 24, n—GaN layer 25 InGaN MQW layer 26, p—AlGaN layer 27, p—GaN layer 28, p—AlGaN layer 29, and p—GaN layer 30 are formed as the epitaxial layer 11. In addition, the configuration of the n-electrode 31, the p-electrode 32, and the like is the same as that of the first embodiment, and thus description thereof is omitted. In FIG. 4, B2 indicates the (01 0) plane of the substrate 50, and B3 indicates a plane perpendicular to the (001) plane of the substrate 50.

In FIG. 4, the (001) plane (B1) of the substrate 50 forms an angle of 90 ° with the growth plane of the epitaxial layer. Therefore, the (001) plane (B 1) that is the cleavage plane of the substrate 50 and the (1-100) plane (B4) that is the cleavage plane of the epitaxial layer 11 are planes in the same direction! / RU

[0030] (Effects of Second Embodiment)

According to the second embodiment, since the epitaxial layer 11 is formed on the plane (B3) perpendicular to the (001) plane (B1) of the substrate 50, it is the cleavage plane (001) of the substrate 50. The plane (B 1) and the (1-100) plane (B4) which is the cleavage plane of the epitaxial layer 11 coincide with each other, and a rectangular chip can be obtained. As a result, the cleavage of the epitaxial layer 11 is easier and more accurate than in the first embodiment, so that a high-precision laser resonator can be formed by a simple manufacturing process using cleavage. A semiconductor laser can be realized. Other functions and effects are the same as those of the first embodiment.

(Semiconductor laser manufacturing method according to first and second embodiments)

The manufacturing method of the semiconductor laser 1 according to the first embodiment and the second embodiment includes a step of preparing a substrate made of a β-GaO single crystal and a predetermined plane orientation of the substrate. An epitaxial process in which a (0001) plane of a GaN-based compound with a wurtzite structure is grown on the surface to form an epitaxy layer; And a resonator forming step to be formed.

[0032] (Process for Preparing Substrate 10)

A substrate 10 or a substrate 50 made of a β—Ga 2 O-based single crystal is prepared. Board 10 or base

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The plate 50 is manufactured by an EFG (Edge Defined Film Fed Growth) method or an FZ (Floating Zone) method. In this process, the epitaxial layer growth surface of the substrate 10 is a (100) plane (A3), or the epitaxial layer growth surface of the substrate 50 is a plane (B3) perpendicular to the (001) plane (B1). Prepare.

[0033] (Epitaxial process)

The epitaxy process can be performed by a known semiconductor process as described below. In the first embodiment, on the (100) plane (A3) of the substrate 10, and in the second embodiment, on the plane (B3) perpendicular to the (001) plane (B1) of the substrate 50, GaN buffer layer 21, n— GaN layer 2 2, n— InGaN layer 23, n—AlGaN layer 24, n— GaN layer 25, InGaN MQW layer 26, p— AlGaN layer 27, p— GaN layer 28, p— AlGaN The layers 29 and the p-GaN layer 30 are epitaxially grown sequentially by MOCVD (Metal Organic Chemical Vapor Deposition) method or the like.

[0034] The InGaN MQW layer 26 is formed of, for example, a semiconductor made of non-doped InGaN to which no impurity is added, and has a multiple quantum well structure (MQW). By adjusting the composition ratio of In and Ga, or by using p-type or n-type conductivity, the emission wavelength can be changed by changing the band gap of the InGaN light-emitting layer.

[0035] (Resonator forming step)

The bare substrate obtained by the epitaxial process is cleaved at the (001) plane (Al, B1) which is the cleavage plane of the substrate 10 or the substrate 50 so as to have a predetermined resonator length. The cleavage plane (001) (Al, B1) is formed as a cavity end face 13 parallel to both ends of the epitaxial layer 11, and constitutes the cavity of the semiconductor laser 1.

[0036] (Other processes)

The direction perpendicular to the cleavage plane (001) (Al, B1) is cut by dicing, etc. A chip is produced. The n-electrode 31 and the p-electrode 32 are wired for supplying current by wire bonding or the like, and packaged for mounting, whereby the semiconductor laser 1 is manufactured.

[0037] (Effects of manufacturing method of semiconductor laser 1)

The method for manufacturing the semiconductor laser 1 has the following operational effects.

(1) (100) plane (A3) of substrate 10 made of β-Ga O single crystal or cleavage plane of substrate 50

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Since the (0001) plane of the GaN compound is grown on the plane (B3) perpendicular to the (001) plane (B1), the cleaved planes are almost the same plane. Therefore, a high-quality resonator end face 13 can be easily obtained using cleavage.

(2) Since the substrate made of β-GaO single crystal has conductivity, the electrode is

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Since the vertical structure provided on the side of the laser layer 11 and the substrate on the opposite side can be provided, the semiconductor laser can be manufactured by a simple manufacturing process.

(3) A substrate made of β-GaO single crystal has a thermal expansion coefficient very close to that of GaN.

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A uniform epitaxial layer 11 can be obtained over the entire substrate, which is less affected by warpage of the substrate during the process, and the yield is improved.

[0038] From the above, for example, accuracy is achieved by a simple manufacturing process using the cleavage that is not necessary for the process of removing the sapphire substrate by the laser lift method and pasting it to the Si substrate or the like, which is performed in the prior art. Providing a method of manufacturing a semiconductor laser with a good laser cavity is a powerful force.

Industrial applicability

[0039] According to the present invention, it is possible to provide a semiconductor laser in which an accurate laser resonator is formed by a simple manufacturing process and a manufacturing method thereof.

Claims

The scope of the claims

[1] A substrate made of β-GaO single crystal;

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An epitaxial layer formed by growing a (0001) plane of a GaN-based compound having a wurtzite structure on a plane defined by a predetermined plane orientation of the substrate;

A laser resonator formed with a (1 100) plane which is a cleavage plane of the epitaxy layer as an end face of the resonance plane;

A semiconductor laser.

2. The semiconductor laser according to claim 1, wherein the surface defined by the predetermined plane orientation of the substrate is a (100) surface of the substrate.

[3] The semiconductor laser according to [1], wherein the plane defined by the predetermined plane orientation of the substrate is a plane perpendicular to the (001) plane of the substrate.

[4] preparing a substrate made of β-GaO single crystal;

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An epitaxial process for forming an epitaxial layer by growing a (0001) plane of a GaN-based compound having a wurtzite structure on a plane defined by a predetermined plane orientation of the substrate; and (1 A resonator forming step of cleaving the (100) plane to form a laser resonator;

A method for manufacturing a semiconductor laser comprising:

5. The method for manufacturing a semiconductor laser according to claim 4, wherein the surface defined by the predetermined plane orientation of the substrate is a (100) surface of the substrate.

6. The method for manufacturing a semiconductor laser according to claim 4, wherein the plane defined by the predetermined plane orientation of the substrate is a plane perpendicular to the (001) plane of the substrate.