JP2002111131A - Semiconductor light emitting device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a semiconductor light emitting device using a nitride based III-V compound semiconductor to be reduced in power consumption and improved in service life and reliability. SOLUTION: An N-type clad layer 4 is grown into a shape like a chevron on a substrate 1 of sapphire or the like, and a plurality of nitride based III-V compound semiconductor layers including an active layer 6 are grown thereon into a shape like a chevron for the formation of a light emitting device structure. At this point, the conditions of growth are so controlled as to make the apex angles of the chevrons of the layers conform to it that the higher they are located, the larger they become.

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 and a method for manufacturing the same, for example, a nitride-based light emitting device.
It is suitable for application to a semiconductor laser using a group V compound semiconductor.

[0002]

2. Description of the Related Art In recent years, as a semiconductor laser capable of emitting light from a blue region to an ultraviolet region, which is necessary for increasing the density of an optical disk, a nitride III-based laser such as AlGaInN has been used.
Research and development of semiconductor lasers using group V compound semiconductors have been actively conducted.

However, the current nitride III-V
Since a semiconductor laser using a group III compound semiconductor has a high oscillation voltage and a high threshold current and a high power consumption, it is desired to reduce the oscillation voltage and the threshold current to reduce the power consumption. Here, the reason why the oscillation voltage is high is that the activation rate of the p-type impurity doped into the p-type layer is low and the resistivity is high.

Although current constriction is effective in reducing the threshold current, the current constriction reduces the contact area between the p-type layer and the p-side electrode, so that the contact resistance increases and the oscillation voltage increases. I will. If the substantial threshold current density can be reduced while maintaining a sufficiently large contact area between the p-type layer and the p-side electrode, the threshold current can be reduced and the oscillation voltage can be reduced. In addition, power consumption is reduced by that amount, so that the amount of heat generated is reduced, which can contribute to a longer life of the semiconductor laser.

[0005]

However, until now, no effective measure has been proposed to reduce the substantial threshold current density while keeping the contact area between the p-type layer and the p-side electrode sufficiently large. Therefore, it has been difficult to reduce power consumption.

Accordingly, an object of the present invention is to reduce the power consumption of a semiconductor light emitting device using a nitride III-V compound semiconductor. Another problem to be solved by the present invention is a nitride III-
It is an object of the present invention to extend the life and improve the reliability of a semiconductor light emitting device using a group V compound semiconductor.

[0007]

According to a first aspect of the present invention, there is provided a light emitting device comprising a light emitting device structure including an active layer and a pair of cladding layers sandwiching the active layer. In a semiconductor light emitting device in which a group III-V compound semiconductor layer is laminated on a substrate, at least one nitride group III-V compound semiconductor layer between the substrate and the active layer is formed in a mountain shape. It is characterized by the following.

[0008] Here, "crest" means that the cross section has a sharp peak, and a trapezoid having a flat top is excluded (the same applies hereinafter). "Yamagata" can be paraphrased as "gabled".

At least one layer between the substrate and the active layer
Of the nitride-based III-V compound semiconductor layer of
Can be any layer, but most typically the substrate
The cladding layer between the and the active layer is formed in a mountain shape.
Then, the nitride III of the upper layer of the mountain-shaped cladding layer
The -V group compound semiconductor layer is also formed in a mountain shape. This place
The angles of the vertices of these layers are identical to each other, or
The larger the upper layer. Where the angles of the vertices of these layers
Controls the growth conditions of these layers, such as pressure, temperature,
It can be performed by controlling the growth rate or the like. This Yamagata
Is, for example, a nitride-based III-
A convex stripe portion formed in the group V compound semiconductor layer,
Nitride III-V compound semiconductor formed on substrate
Stripes formed on the substrate or
Formed on nitride-based III-V compound semiconductor layer
Nitride II in striped openings of long masks
A triangular prism is formed on the IV compound semiconductor layer.
The width of the stripe is determined as necessary,
Is 1 to 5 μm, typically 2 to 4 μm. Yamagata Formation
Nitride III-V Compound Semiconductor Layer Underlying Forming Layer
As, for example, Al _xGa_1-xN (however, 0 ≦ x <
1) Layers can be used. Stripes are typical
Extends in the <11-20> or <1-100> direction.
To be located. The chevron layer is typically n-type clad
Layer. Typically, the top nitride-based III-V group
The compound semiconductor layer is a contact layer, especially a p-type contact layer
And an electrode, particularly a p-side electrode, is formed thereon. Ma
Of the nitride-based III-V group of the upper layer of the angled cladding layer
When the angle of the apex of the compound semiconductor layer is larger in the upper layer,
Between the active layer and the electrode formed on the uppermost contact layer
The distance between them depends on the location.
Is also shorter.

According to a second aspect of the present invention, a plurality of nitride III-V compound semiconductor layers forming a light emitting device structure including an active layer and a pair of cladding layers sandwiching the active layer are laminated on a substrate. A method for manufacturing a semiconductor light-emitting device, wherein at least one nitride III-V compound semiconductor layer between a substrate and an active layer is formed in a mountain shape, wherein an underlying nitride III-V compound is formed on a substrate. Growing a compound semiconductor layer and forming a convex stripe on the upper surface thereof;
Growing a nitride-based III-V compound semiconductor layer on the stripe portion in a chevron shape.

According to a third aspect of the present invention, a plurality of nitride III-V compound semiconductor layers forming a light emitting device structure including an active layer and a pair of cladding layers sandwiching the active layer are laminated on a substrate. A method of manufacturing a semiconductor light emitting device, wherein at least one nitride III-V compound semiconductor layer between a substrate and an active layer is formed in a mountain shape, wherein the nitride III-V compound is formed on the substrate. The method includes a step of forming a stripe portion made of a semiconductor and a step of growing a nitride-based III-V compound semiconductor layer on the stripe portion in a mountain shape.

According to a fourth aspect of the present invention, a plurality of nitride III-V compound semiconductor layers forming a light emitting device structure including an active layer and a pair of cladding layers sandwiching the active layer are laminated on a substrate. A method for manufacturing a semiconductor light-emitting device, wherein at least one nitride III-V compound semiconductor layer between a substrate and an active layer is formed in a mountain shape, wherein an underlying nitride III-V compound is formed on a substrate. A step of growing a compound semiconductor layer, a step of forming a growth mask having a stripe-shaped opening on the underlying nitride III-V compound semiconductor layer, and a step of forming a stripe by selective growth using the growth mask. Nitride III-V in opening
Growing a nitride-based III-V compound semiconductor layer in a chevron on the group III compound semiconductor layer.

In the second, third and fourth aspects of the present invention, typically, a plurality of stripe portions or stripe-shaped openings are formed in parallel with each other. The width of the stripe portion is determined as necessary, but is generally 1 to
5 μm, typically 2-4 μm. The interval between the stripe portions or the stripe-shaped openings is also determined as necessary, but is typically 2 to 500 μm. If the interval is sufficiently large, the chevron layers formed in the stripe portion or the stripe-shaped opening are formed separately from each other, but if the interval is sufficiently small, the mountain-shaped layer is formed in the stripe portion or the stripe-shaped opening. The chevron layers are formed continuously with one another. The stripe portion is generally formed to extend from one end of the substrate to the other end. For example, the stripe portion may be divided into lengths corresponding to individual element sizes. In this case, a length corresponding to the resonator length, for example, 0.1 to 1 mm may be used. In the latter case, the chevron layer formed in the striped portion or the striped opening is also formed to have the same length as the striped portion or the striped opening. As the underlying nitride III-V compound semiconductor layer forming the chevron layer, for example, Al _x Ga ₁ -xN (where 0 ≦ x <1)
Layers can be used. The stripe portion typically extends in the <11-20> direction or the <1-100> direction.

In the present invention, the nitride III-V compound semiconductor contains at least one group III element selected from the group consisting of Ga, Al, In, B and Tl and at least N, and in some cases. Further, it is made of a group V element containing As or P. This nitride III-
Specific examples of group V compound semiconductors include GaN, AlG
aN, AlN, GaInN, AlGaInN, InN and the like. Examples of the substrate include a sapphire substrate, particularly a c-plane sapphire substrate, a SiC substrate,
Nitride III such as substrate, spinel substrate, GaN substrate
A -V compound semiconductor substrate or the like can be used. The semiconductor light emitting device is typically a semiconductor laser, but may be a light emitting diode.

According to the present invention having the above-described structure, at least one nitride III-V compound semiconductor layer between the substrate and the active layer is formed in a mountain shape, so that at least one active layer is formed. Nitride based I containing layer
The II-V compound semiconductor layer also has a mountain shape. When the nitride III-V compound semiconductor layer forming the light emitting device structure has a mountain shape, an electric field generated when a voltage is applied between the p-side electrode and the n-side electrode during device operation is high. Tends to concentrate near the apex, so that current flows intensively there. In particular, when the angle of the peak of the mountain increases toward the upper layer, the nitride III-V compound semiconductor layer forming the light emitting device structure has the smallest thickness at the peak of the mountain, and the thickness increases as the distance from the peak increases. Is smaller, the path passing near the peak of the mountain has the lowest resistance, and current flows intensively on this path. Due to these effects, the current density increases as approaching the peak of the mountain, and the current density flowing in the active layer increases. That is, the current confinement effect can be obtained without forming the conventional current confinement structure. Therefore, the substantial threshold current density can be reduced while keeping the contact area between the contact layer, particularly the p-type layer, and the electrode formed on the contact layer, particularly the p-side electrode, sufficiently large.

Further, when a peak of a nitride III-V compound semiconductor layer that grows in a mountain shape is formed in a stripe portion or a stripe-shaped opening, dislocations are difficult to propagate above the peak. Therefore, the nitride III of the upper layer
-The dislocation density of the group V compound semiconductor layer is reduced.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same or corresponding portions are denoted by the same reference numerals.

FIG. 1 shows a G according to a first embodiment of the present invention.
1 shows an aN-based semiconductor laser. This GaN-based semiconductor laser has a SCH (Separate Confinement Heterostructure).
It has a structure.

As shown in FIG. 1, the GaN semiconductor laser according to the first embodiment has a thickness of, for example, 4 mm.
An undoped G is placed on a 00 μm c-plane sapphire substrate 1.
An n-type GaN layer 3 is stacked via an aN buffer layer 2. On the upper surface of the n-type GaN layer 3, <11-2
A stripe portion 3a extending in the <0> direction and having a rectangular cross-sectional shape is provided. The n-type AlGaN is formed on the stripe portion 3a and the n-type GaN layer 3 on both sides thereof.
The clad layer 4 is laminated. Here, the n-type AlGaN cladding layer 4 on the stripe portion 3a has a mountain shape with a triangular cross section, and is formed in a triangular prism shape extending in the <11-20> direction. This triangular prism-shaped n-type AlG
Both slopes of the aN cladding layer 4 are, for example, 6
Make an angle of 1.8-62 °.

On the n-type AlGaN cladding layer 4, an n-type G
aN optical waveguide layer 5, for example, Ga _1-x In _x N / Ga _1-y I
An active layer 6 having an n _y N multiple quantum well structure, a p-type AlGaN cap layer 7, a p-type GaN optical waveguide layer 8, a p-type AlGaN cladding layer 9, and a p-type GaN contact layer 10 are sequentially laminated. The n-type GaN optical waveguide layer 5, the active layer 6, the p-type AlGaN cap layer 7, the p-type GaN optical waveguide layer 8, the p-type AlGaN cladding layer 9, and the p-type GaN contact layer 10 all have a stripe portion 3a. The upper n-type AlGaN cladding layer 4 has an apex having a vertex above the vertex of the clad layer 4. In this case, these n
The vertices (vertical angles) of the p-type GaN optical waveguide layer 5, the active layer 6, the p-type AlGaN cap layer 7, the p-type GaN optical waveguide layer 8, the p-type AlGaN cladding layer 9, and the p-type GaN contact layer 10 are upper layers. The layers are therefore progressively thinner towards their vertices, the thinnest at the vertices.

The GaN buffer layer 2 has a thickness of, for example, 40 n.
m. The n-type GaN layer 3 other than the stripe portion 3a has a thickness of, for example, 5.0 μm, and is doped with, for example, silicon (Si) as an n-type impurity, for example, at about 2 × 10 ¹⁸ cm ⁻³ . The width of the stripe portion 3a formed on the n-type GaN layer 3 is, for example, 3 μm, and the height is, for example, 1 μm.
m. The n-type AlGaN cladding layer 4 has a thickness of, for example, 1.5 μm, an Al composition of, for example, 0.08, and is doped with, for example, Si as an n-type impurity. n-type GaN
The optical waveguide layer 5 has a thickness of, for example, 0.1 μm, and is doped with, for example, Si as an n-type impurity. Ga _1-x In
_{x N / Ga 1-y In} y N multiquantum well structure active layer 6
For example, a Ga _1-x In _x N layer serving as a barrier layer has a thickness of 0.007 μm, an In composition x is 0.02, Si is doped as an n-type impurity, and a Ga _1-y well layer is used. I
The n _y N layer has a thickness of 0.0035 μm, and the In composition y has a thickness of 0.3 μm.
10 is undoped, and the number of wells is 3.

The p-type AlGaN cap layer 7 has a thickness of, for example, 0.02 μm and an Al composition of, for example, 0.15.
For example, magnesium (Mg) is doped as the type impurity. This p-type AlGaN cap layer 7 is made of p-type G
aN optical waveguide layer 8, p-type AlGaN cladding layer 9, and p
From the active layer 6 during the growth of
Are prevented from being diffused and deteriorated, and from overflowing of carriers from the active layer 6. The p-type GaN optical waveguide layer 8 has a thickness of, for example, 0.1
μm, for example, Mg is doped as a p-type impurity. The p-type AlGaN cladding layer 9 is composed of upper and lower layers having different Al compositions from each other.
The upper layer has a thickness of, for example, 0.4 μm and the Al composition is, for example, 0.06, and the upper layer has, for example, 0.06, and both are doped with, for example, Mg as a p-type impurity.
The p-type GaN contact layer 10 has a thickness of, for example, 0.1 μm.
And Mg is doped as a p-type impurity.

A p-side electrode 11 is provided on the p-type GaN contact layer 10. This p-side electrode 11 is, for example, P
Pd / Pt / in which a d film, a Pt film, and an Au film are sequentially laminated
It has an Au structure, and the Pd film, Pt film and Au film have a thickness of, for example, 10 nm, 100 nm and 3 nm, respectively.
00 nm. Here, instead of the Pd film, for example, Ni
A membrane may be used. On the other hand, an n-side electrode 12 is provided on a portion of the n-type GaN layer 3 adjacent to the mesa portion forming the laser resonator. This n-side electrode 12 is made of, for example, a Ti film,
It has a Ti / Pt / Au structure in which a Pt film and an Au film are sequentially laminated, and these Ti, Pt, and Au films are, for example, 10 nm, 50 nm, and 100 nm, respectively.

Next, a method of manufacturing the GaN-based semiconductor laser according to the first embodiment configured as described above will be described.

In order to manufacture this GaN-based semiconductor laser, first, as shown in FIG. 2, on a c-plane sapphire substrate 1 whose surface has been previously cleaned by thermal cleaning or the like, a temperature of about 490.degree. After growing the undoped GaN buffer layer 2 at a pressure of, for example, 1.6 atm (1216 Torr), the substrate temperature is raised to a predetermined growth temperature, for example, 1050 ° C., and then, for example, 1.6 atm (1216 T) by MOCVD.
orr) pressure on the GaN buffer layer 2
Layer 3 is grown epitaxially. Note that FIG. 2 is different from FIG. 1 in scale, and in particular, the horizontal scale is significantly reduced from that in FIG.

Next, after the c-plane sapphire substrate 1 on which the n-type GaN layer 3 has been epitaxially grown is taken out from the MOCVD apparatus, the upper part of the n-type GaN layer 3 is patterned by etching to extend in the <11-20> direction. The stripe portions 3a having a width of, for example, 3 μm are formed at an interval of, for example, 300 μm in the <1-100> direction. This etching is performed to a depth of, for example, 1 μm. The patterning of the upper portion of the n-type GaN layer 3 can be specifically performed, for example, in the following procedure. That is, after forming an SiO ₂ film (not shown) having a thickness of, for example, 0.4 μm on the entire surface of the n-type GaN layer 3 by, for example, a CVD method, a vacuum evaporation method, a sputtering method, or the like, lithography is performed on the SiO ₂ film. A resist pattern (not shown) having a predetermined shape is formed by using the resist pattern as a mask, for example, wet etching using a hydrofluoric acid-based etchant, or etching gas containing fluorine such as CF ₄ or CHF _3. The one-dimensional array of the pattern made of the SiO ₂ film is formed by etching the SiO ₂ film by the used reactive ion etching (RIE) method. Next, this S
For example, RIE is performed by using a pattern composed of an iO ₂ film as a mask.
The upper portion of the n-type GaN layer 3 is etched by a wet etching method or a wet etching method. When the RIE method is used for the etching, the etching gas for the RIE is, for example, C
Using a fluorine-based gas or a chlorine-based gas such as F _4. Thereafter, the SiO ₂ film is removed by etching.

Next, as described above, the stripe portion 3a
Is formed on the n-type GaN layer 3 on which
For example at a temperature of 990 ° C. and for example 1.0 atm (760
At a pressure of Torr), the n-type AlGaN cladding layer 4 is epitaxially grown. Under this growth condition, the n-type AlGaN cladding layer 4 grows in a triangular prism shape on the stripe portion 3a of the n-type GaN layer 3, and grows almost flat in a portion outside the stripe portion 3a. This is shown in FIG. 3 on the same scale as FIG.

Next, as shown in FIG. 1, n-type AlGaN cladding layer 4 grown in a mountain shape as described above
MOCVD of the p-type GaN optical waveguide layer 5, the active layer 6, the p-type AlGaN cap layer 7, the p-type GaN optical waveguide layer 8, the p-type AlGaN cladding layer 9, and the p-type GaN contact layer 10
The epitaxial growth is performed sequentially by the method. The n-type GaN optical waveguide layer 5, the active layer 6, the p-type AlGaN cap layer 7, the p-type GaN optical waveguide layer 8, the p-type AlGaN cladding layer 9, and the p-type GaN contact layer 10 are formed at the top of the stripe portion 3a. It grows into a chevron with a peak at the top.

Here, the growth temperature of these layers is n-type G
The aN optical waveguide layer 5 is, for example, 990 ° C., the active layer 6 and the p-type AlGaN cap layer 7 are, for example, 780 ° C., p-type GaN.
The optical waveguide layer 8 is, for example, 860 ° C., and the p-type AlGaN cladding layer 9 and the p-type GaN contact layer 10 are, for example, 990 ° C.
° C. The growth pressure of these layers is n-type GaN
The optical waveguide layer 5, the active layer 6, and the p-type AlGaN cap layer 7 have a pressure of 1.0 atm (760 Torr), the p-type GaN optical waveguide layer 8 has a pressure of 0.66 atm (500 Torr), and p-type AlGa.
The N cladding layer 9 and the p-type GaN contact layer 10 are set at 0.26 atm (200 Torr). Here, since the growth pressure is lower in the upper layer and the growth temperature is higher in the upper layer, the material molecules are more likely to migrate on the growth surface in the upper layer, and therefore the angle of the peak of the chevron increases in the upper layer.

The above-mentioned GaN-based semiconductor layer growth raw materials include, for example, trimethylgallium ((CH ₃ ) ₃ Ga, TMG) as a group III element Ga source,
Trimethylaluminum ((CH ₃ ) ₃ Al, TMA) is used as a source of Al as a group II element, and trimethylindium ((C
H ₃ ) ₃ In, TMI) and ammonia (NH ₃ ) as a raw material of N which is a group V element. As the carrier gas, for example, a mixed gas of hydrogen (H ₂ ) and nitrogen (N ₂ ) is used. As for the dopant, for example, monosilane (SiH ₄ ) is used as the n-type dopant, and bis = methylcyclopentadienyl magnesium ((CH ₃ C ₅ H ₄ ) ₂ Mg) or bis = cyclopentadienyl is used as the p-type dopant. magnesium ((C ₅
H ₅ ) ₂ Mg).

Next, the c-plane on which the GaN-based semiconductor layer was grown
The sapphire substrate 11 is taken out of the MOCVD apparatus. Next
Next, for example, CVD is performed on the entire surface of the p-type GaN contact layer 20.
Method, vacuum evaporation method, sputtering method etc.
0.4 μm SiO_TwoFormed a film (not shown)
Later, this SiO_TwoPredetermined shape by lithography on film
Of a resist pattern (not shown)
Using the pattern as a mask, for example, hydrofluoric acid based etchin
Wet etching using a liquid solution or CF _FourAnd C
HF_ThreeUsing fluorine-containing etching gas such as
SiO by reactive ion etching (RIE)_TwoD membrane
To form a stripe shape having a predetermined width. Next,
Stripe-shaped SiO_TwoUsing the film as a mask,
Etching by IE method until the n-type GaN layer 3 is exposed
By performing the above, as shown in FIG.
Clad layer 4, n-type GaN optical waveguide layer 5, active layer 6, p-type
AlGaN cap layer 7, p-type GaN optical waveguide layer 8, p-type
AlGaN cladding layer 9 and p-type GaN contact layer
10 is patterned into a mesa shape. After this, Etchin
SiO used as a mask_TwoEtch off film
You.

Next, a resist pattern (not shown) having a predetermined shape is formed on the surface of the substrate by lithography, and a Ti film, a Pt film, and an Au film are formed on the entire surface of the substrate by a vacuum deposition method or the like.
After sequentially forming the films, the resist pattern is
It is removed together with the film, the Pt film and the Au film (lift-off). Thereby, as shown in FIG. 1, an n-side electrode 12 is formed on the n-type GaN layer 3 in a portion adjacent to the mesa portion. Next, an alloy process for bringing the n-side electrode 12 into ohmic contact with the n-type GaN layer 3 is performed.

Next, a resist pattern (not shown) having a predetermined shape is formed on the surface of the substrate by lithography, and for example, a Pd film, a Pt film, and an Au film are sequentially formed on the entire surface of the substrate by a vacuum deposition method or the like. Is removed together with the Pd film, Pt film and Au film thereon (lift-off). Thereby, as shown in FIG. 1, the p-side electrode 11 is formed on the p-type GaN contact layer 10. Next, an alloy process for bringing the p-side electrode 11 into ohmic contact is performed.

Next, the c-plane sapphire substrate 1 on which the laser structure is formed as described above is placed on the back surface side, for example, with a thickness of 1 mm.
After lapping to about 00 μm, the c-plane sapphire substrate 1 on which this laser structure is formed is cleaved by <1
The two resonator end faces are formed by processing into a bar shape extending in the <1-20> direction. Next, a dielectric multilayer film is formed on both resonator end faces of the bar, and the end face coating is performed. Thereafter, the bar is chipped by cleavage or the like. As described above, the intended GaN-based semiconductor laser having the SCH structure is manufactured as shown in FIG.

According to the first embodiment, the following various advantages can be obtained. That is, in the first embodiment, the n-type GaN optical waveguide layer 5, the active layer 6, and the p-type
-Type AlGaN cap layer 7, p-type GaN optical waveguide layer 8, p-type
In the AlGaN cladding layer 9 and the p-type GaN contact layer 10, the angle of the peak of the chevron becomes larger toward the top, and their thickness gradually decreases toward the peak of the chevron, and becomes thinnest at the top of the peak. Has become. Therefore, the shortest distance between the p-side electrode 11 and the active layer 6 is a path passing through the peak of the mountain, and therefore, the resistance value between the p-side electrode 11 and the n-side electrode 12 is the lowest on the path passing through the peak of the mountain. That is, the current flowing during operation concentrates on the vicinity. Further, since the electric field generated when a voltage is applied between the p-side electrode 11 and the n-side electrode 12 is concentrated near the peak of the mountain, the current flowing during operation is also close to the path passing through the peak of the mountain. Focus on This is shown in FIG. Therefore, it is possible to easily obtain a current density required for laser oscillation at a low current. That is, the threshold current density can be significantly reduced while the contact area between the p-type GaN contact layer 10 and the p-side electrode 11 is kept sufficiently large without forming a current confinement structure as in the related art. it can.

In this GaN-based semiconductor laser, the n-type GaN optical waveguide layer 5, the n-type AlGaN cladding layer 4, and the p-type GaN optical waveguide 5 have lower refractive indices at the top, bottom, left and right of the active layer 6 near the peak of the chevron. Since the structure is surrounded by the layer 7 and the p-type AlGaN clad layer 6, the light confinement efficiency is increased, thereby further reducing the threshold current density.

Since the threshold current density is greatly reduced as described above, the threshold current can be significantly reduced, and the power consumption can be greatly reduced.

Further, since the amount of heat generated by the reduction in power consumption is also reduced, the life is prolonged. Furthermore, when the n-type AlGaN cladding layer 4 grows in a mountain shape on the stripe portion 3a of the n-type GaN layer 3 and its vertex is formed, it is generated from the interface with the c-plane sapphire substrate 1 and propagates to the upper layer. Since dislocations are unlikely to grow above their vertices (see FIG. 7), the GaN-based semiconductor layer grown thereon, especially the active layer 6, can have a low dislocation density, thus reducing the power consumption described above. Coupled with the decrease in heat generation due to
It is possible to extend the life and improve the reliability of the aN-based semiconductor laser.

Further, in this GaN-based semiconductor laser, a current flows intensively in the active layer 6 near the apex of the chevron, and the substantial width of the active layer 6 is extremely narrow. Has a good shape that is almost circular.

Next, G according to the second embodiment of the present invention will be described.
The aN-based semiconductor laser will be described.

In the GaN semiconductor laser according to the second embodiment, the nitride II
As an undersubstrate used for growing an IV group compound semiconductor layer, one as shown in FIG. 7 is used. That is, as shown in FIG. 7, an n-type GaN layer 3 is grown on a c-plane sapphire substrate 1 with a GaN buffer layer 2 interposed therebetween.
By patterning the N layer 3 by etching, <11-2>
0> The stripe shape extends in the direction. in this case,
The thickness of the n-type GaN layer 3, that is, the height of the stripe portion is, for example, 1 μm, the width of the stripe portion is, for example, 3 μm, and the interval between the stripe portions in the <1-100> direction is, for example, 3 μm.
And The n-type AlGaN cladding layer 4 is grown in a mountain shape on the substrate on which the stripe portion composed of the n-type GaN layer 3 is formed in the same manner as in the first embodiment.
In this case, since the interval between the stripe portions is narrow, this n-type A
The lGaN cladding layer 4 grows continuously in the substrate plane.

On the base substrate thus manufactured,
Similarly to the first embodiment, the n-type GaN optical waveguide layer 5,
Active layer 6, p-type AlGaN cap layer 7, p-type GaN optical waveguide layer 8, p-type AlGaN cladding layer 9, and p-type Ga
The laser structure is formed by sequentially growing the N contact layers 10 in a mountain shape. In this case, one laser structure is formed in each stripe portion, and a laser array in which the laser structures are arranged at a pitch of, for example, 6 μm is formed. Thereafter, in the same manner as in the first embodiment, necessary steps such as formation of the n-side electrode 12 and the p-side electrode 11 are executed to manufacture a target GaN-based semiconductor laser.

According to the second embodiment, the integrated type G in which the laser structures as shown in FIG.
An aN-based semiconductor laser can be realized. This integrated GaN-based semiconductor laser is suitable for, for example, high-power applications.

Next, G according to the third embodiment of the present invention will be described.
The aN-based semiconductor laser will be described.

In the GaN semiconductor laser according to the third embodiment, the nitride II forming the laser structure
As a base substrate used for growing an IV group compound semiconductor layer, a substrate as shown in FIG. 8 is used. That is, as shown in FIG. 8, an n-type GaN layer 3 is grown on a c-plane sapphire substrate 1 via a GaN buffer layer 2. Next, after forming, for example, a SiO ₂ film or a SiN _x film on the n-type GaN layer 3, the film is patterned by etching to have a stripe-shaped opening 13 a extending in the <11-20> direction. A growth mask 13 is formed.

Next, using this growth mask 13, the EL
Using an OG (Epitaxial Lateral Overgrowth) technique, a growth pressure higher than normal pressure is applied to the opening 13 of the growth mask 13.
An n-type AlGaN cladding layer 4 is selectively grown on the n-type GaN layer 3 in a.

On the base substrate thus manufactured,
Similarly to the first embodiment, the n-type GaN optical waveguide layer 5,
Active layer 6, p-type AlGaN cap layer 7, p-type GaN optical waveguide layer 8, p-type AlGaN cladding layer 9, and p-type Ga
The laser structure is formed by sequentially growing the N contact layers 10 in a mountain shape. In this case, one laser structure is formed in each stripe portion. Thereafter, in the same manner as in the first embodiment, necessary steps such as formation of the n-side electrode 12 and the p-side electrode 11 are executed to manufacture a target GaN-based semiconductor laser.

According to the third embodiment, the same advantages as in the first embodiment can be obtained.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments, and various modifications based on the technical concept of the present invention are possible.

For example, the numerical values, structures, substrates, raw materials, processes, and the like described in the first, second, and third embodiments are merely examples, and different numerical values, structures, and the like may be used as necessary. Substrates, raw materials, processes, and the like may be used.

In the first, second and third embodiments, the stripe extends in the <11-20> direction of the c-plane sapphire substrate 1, but the stripe extends in the <11-20> direction. 1-100> direction.

In the first embodiment described above,
Although the p-side electrode 11 and the n-side electrode 12 are formed by a lift-off method, the p-side electrode 11 and the n-side electrode 12 may be formed by forming an electrode film and then patterning by etching.

In the first, second and third embodiments, the stripe extends in the <11-20> direction of the c-plane sapphire substrate 1, but the stripe extends in the <11-20> direction. 1-100> direction.

In the first, second and third embodiments, the c-plane sapphire substrate is used as the substrate. However, if necessary, the GaN substrate, the SiC substrate, the S
An i-substrate, a spinel substrate, or the like may be used.

Further, in the first, second and third embodiments described above, the case where the present invention is applied to a GaN-based semiconductor laser having an SCH structure has been described. However, the present invention relates to, for example, a DH (Double Heterostructure). The present invention may be applied to a GaN-based semiconductor laser having a structure.

[0056]

As described above, according to the present invention, at least one nitride III-V compound semiconductor layer between the substrate and the active layer is formed in a mountain shape, Upper nitride containing active layer I
Since the group II-V compound semiconductor layer has a mountain shape, the operating current flows intensively near the path passing through the peak of the mountain, so that the contact area between the contact layer and the electrode formed thereon is sufficiently large. The operating current density can be reduced while maintaining a large value, and the operating current can be reduced. Therefore, power consumption can be reduced. Further, when growing a nitride III-V compound semiconductor layer forming a light emitting device structure, dislocations are hardly formed on the peaks of the chevron, so that the dislocation density of the active layer and the like on the peaks is reduced, and the semiconductor light emission is reduced. The reliability and life of the element can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a GaN-based semiconductor laser according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining the method for manufacturing the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 3 is a sectional view for explaining the method for manufacturing the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view for explaining the method for manufacturing the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 5 is a sectional view showing a path of a current flowing through the laser structure during oscillation in the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view showing the manner in which dislocations propagate during the growth of the nitride-based III-V compound semiconductor layer in the manufacturing process of the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 7 is a sectional view for explaining a GaN-based semiconductor laser according to a second embodiment of the present invention.

FIG. 8 is a sectional view for explaining a GaN-based semiconductor laser according to a third embodiment of the present invention.

[Explanation of symbols]

1 ... c-plane sapphire substrate, 3 ... n-type GaN layer,
4 ... n-type AlGaN cladding layer, 5 ... n-type Ga
N optical waveguide layer, 6 ... active layer, 7 ... p-type AlGaN
Cap layer, 8 ... p-type GaN optical waveguide layer, 9 ... p
-Type AlGaN cladding layer, 10 ... p-type GaN contact layer, 11 ... p-side electrode, 12 ... n-side electrode, 1
3. Growth mask

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) EA28

Claims (41)

[Claims] 1. A semiconductor light emitting device in which a plurality of nitride III-V compound semiconductor layers forming a light emitting device structure including an active layer and a pair of cladding layers sandwiching the active layer are stacked on a substrate, A semiconductor light emitting device, wherein at least one of the nitride-based III-V compound semiconductor layers between a substrate and the active layer is formed in a mountain shape. 2. The semiconductor light emitting device according to claim 1, wherein said cladding layer between said substrate and said active layer is formed in a mountain shape. 3. The nitride-based III-V compound semiconductor layer on the cladding layer between the substrate and the active layer is formed in a mountain shape, and the angles of their vertices are the same. 3. The semiconductor light emitting device according to claim 2, wherein the upper layer is larger. 4. The chevron-shaped cladding layer between the substrate and the active layer is formed on a convex stripe portion formed on an underlying nitride III-V compound semiconductor layer. 3. The semiconductor light emitting device according to claim 2, wherein: 5. The semiconductor light emitting device according to claim 4, wherein said chevron-shaped cladding layer is formed in a triangular prism shape. 6. The semiconductor light emitting device according to claim 4, wherein the width of the stripe portion is 1 to 5 μm. 7. The semiconductor light emitting device according to claim 4, wherein the width of the stripe portion is 2 to 4 μm. 8. The semiconductor light emitting device according to claim 4, wherein the underlying nitride-based III-V compound semiconductor layer is an Al _x Ga ₁ -xN (0 ≦ x <1) layer. element. 9. The semiconductor light emitting device according to claim 2, wherein said clad layer between said substrate and said active layer is an n-type clad layer. 10. The semiconductor light emitting device according to claim 4, wherein said stripe portion extends in a <11-20> direction. 11. The semiconductor light emitting device according to claim 4, wherein said stripe portion extends in a <1-100> direction. 12. The semiconductor light emitting device according to claim 1, wherein the uppermost nitride III-V compound semiconductor layer is a contact layer, and an electrode is formed thereon. 13. The semiconductor light emitting device according to claim 12, wherein said contact layer is a p-type contact layer, and said electrode is a p-side electrode. 14. The semiconductor light emitting device according to claim 12, wherein a distance between said active layer and said electrode differs depending on a place. 15. The semiconductor light emitting device according to claim 12, wherein a distance between said active layer and said electrode is the shortest on a peak of a chevron. 16. A nitride-based III-V compound semiconductor layer forming a light-emitting device structure including an active layer and a pair of cladding layers sandwiching the active layer is laminated on a substrate, wherein the substrate and the active layer A method of manufacturing a semiconductor light-emitting device, wherein at least one of the nitride-based III-V compound semiconductor layers is formed in a mountain shape, wherein an underlying nitride-based III-V compound semiconductor layer is formed on the substrate. Forming a convex stripe portion on the upper surface thereof; and growing a nitride III-V compound semiconductor layer in a mountain shape on the stripe portion. Device manufacturing method. 17. The method according to claim 16, wherein a plurality of the stripe portions are formed in parallel with each other. 18. The method according to claim 16, wherein the width of the stripe portion is 1 to 5 μm. 19. The method according to claim 16, wherein the width of the stripe portion is 2 to 4 μm. 20. An interval between the stripe portions is 2 to 500.
The method for manufacturing a semiconductor light emitting device according to claim 17, wherein the thickness is μm. 21. The method according to claim 16, wherein the stripe portion extends in a <11-20> direction. 22. The method according to claim 16, wherein the stripe portion extends in a <1-100> direction. 23. The semiconductor light emitting device according to claim 16, wherein the underlying nitride III-V compound semiconductor layer is an Al _x Ga ₁ -xN (0 ≦ x <1) layer. Manufacturing method. 24. A plurality of nitride III-V compound semiconductor layers forming a light emitting device structure including an active layer and a pair of cladding layers sandwiching the active layer are laminated on a substrate, wherein the substrate and the active layer A method of manufacturing a semiconductor light-emitting device in which at least one of the nitride-based III-V compound semiconductor layers is formed in a mountain shape, comprising a nitride-based III-V compound semiconductor on the substrate. A method for manufacturing a semiconductor light emitting device, comprising: a step of forming a stripe portion; and a step of growing a nitride-based III-V compound semiconductor layer in a mountain shape on the stripe portion. 25. The method according to claim 24, wherein a plurality of the stripe portions are formed in parallel with each other. 26. The method according to claim 24, wherein the width of the stripe portion is 1 to 5 μm. 27. The method according to claim 24, wherein the width of the stripe portion is 2 to 4 μm. 28. An interval between the stripe portions is 2 to 500.
The method for manufacturing a semiconductor light emitting device according to claim 25, wherein the thickness is μm. 29. The length of the stripe portion is 0.1 to 1
25. The method for manufacturing a semiconductor light emitting device according to claim 24, wherein the thickness is mm. 30. The method according to claim 24, wherein the stripe portion extends in a <11-20> direction. 31. The method according to claim 24, wherein the stripe portion extends in a <1-100> direction. 32. The semiconductor according to claim 24, wherein the nitride III-V compound semiconductor constituting the stripe portion is Al _x Ga ₁ -xN (where 0 ≦ x <1). A method for manufacturing a light-emitting element. 33. A plurality of nitride-based III-V compound semiconductor layers forming a light emitting device structure including an active layer and a pair of clad layers sandwiching the active layer are laminated on a substrate, wherein the substrate and the active layer A method of manufacturing a semiconductor light-emitting device, wherein at least one of the nitride-based III-V compound semiconductor layers is formed in a mountain shape, wherein an underlying nitride-based III-V compound semiconductor layer is formed on the substrate. A step of forming a growth mask having a stripe-shaped opening on the underlying nitride-based III-V compound semiconductor layer; and a step of selectively growing using the growth mask. Base nitride system III in opening
Growing a nitride-based III-V compound semiconductor layer on the group V compound semiconductor layer in a mountain shape. 34. The method according to claim 33, wherein a plurality of the stripe portions are formed in parallel with each other. 35. The width of the stripe-shaped opening is 1 to
The method for manufacturing a semiconductor light emitting device according to claim 33, wherein the thickness is 5 µm. 36. The width of the striped opening is 2 to 36.
The method for manufacturing a semiconductor light emitting device according to claim 33, wherein the thickness is 4 µm. 37. The interval between the stripe-shaped openings is 2
The method for manufacturing a semiconductor light emitting device according to claim 33, wherein the thickness is from 500 to 500 m. 38. The method according to claim 33, wherein the length of the stripe-shaped opening is 0.1 to 1 mm. 39. The stripe-shaped opening has the shape of <11-
The method for manufacturing a semiconductor light emitting device according to claim 33, wherein the semiconductor light emitting device extends in a <20> direction. 40. The stripe-shaped opening portion is <1-1.
The method for manufacturing a semiconductor light emitting device according to claim 33, wherein the semiconductor light emitting device extends in the <00> direction. 41. The semiconductor light emitting device according to claim 33, wherein the underlying nitride-based III-V compound semiconductor layer is an Al _x Ga ₁ -xN (0 ≦ x <1) layer. Manufacturing method.