JPH10326940A - Semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily manufactured semiconductor light-emitting element of a III group nitride material group with superior controllability of etching depth. SOLUTION: On a sapphire substrate 101, a GaN buffer layer 102, an (n)-type GaN contact layer 103, an (n)-type Al0.15 Ga0.85 N clad layer 104, an In0.05 Ga0.95 N active layer 105, a (p)-type In0.07 Ga0.6 Al0.33 N etching stop layer 106, a (p)-type Al0.15 Ga0.85 N clad layer 107 and a (p)-type GaN contact layer 108 are successively laminated. Also, a (p) side electrode 109 is formed on the (p)-type GaN contact layer 108 and an (n) side electrode 110 is formed on the (n)-type GaN contact layer 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a group III nitride semiconductor light emitting device.

[0002]

2. Description of the Related Art Conventionally, a group III nitride compound semiconductor laser device as disclosed in Japanese Patent Application Laid-Open No. 8-125275 has been known.

FIG. 7 is a block diagram of a conventional group III nitride compound semiconductor laser device disclosed in Japanese Patent Application Laid-Open No. 8-125275. Referring to FIG. 7, n-type α-SiC
On the a surface of the substrate 1, n-type Ga is
An N layer 2, an n-type AlGaN cladding layer 3, an InGaN active layer 4, a p-type AlGaN cladding layer 5, and a p-type GaN layer 6 are sequentially stacked.

On both sides of the p-type GaN layer 6 except for the center of the surface, a striped insulating layer 7 made of SiO ₂ or SiN is formed for current confinement.
And an Au electrode 8 is formed over the surface of the p-type GaN layer 6. The lower surface of the α-SiC substrate 1 is Ni
An electrode 9 is formed. In the structure shown in FIG. 7, the current is confined to a stripe-shaped region by the insulating layer 7 formed on the surface of the p-type GaN layer 6, and the semiconductor laser device is a gain guided semiconductor laser device.

As described above, the group III nitride semiconductor laser device shown in FIG. 7 is of a gain waveguide type. However, the threshold current is further reduced, and the transverse mode is stabilized up to a high optical output. In order to operate, it is necessary to use a refractive index guided type.

FIG. 8 is a cross-sectional view of a group III nitride compound semiconductor laser device disclosed in Japanese Patent Application Laid-Open No. 8-97468. Referring to FIG. 8, on the sapphire substrate 10,
Low-temperature buffer layer 11, high-temperature buffer layer 12, made of n-type GaN, lower cladding layer 1 made of n-type AlGaN
3, an active layer 14 made of non-doped or n-type or p-type InGaN, a p-type upper cladding layer 15 having the same composition as the lower cladding layer 13, a p-type GaN layer 19 and p-type InGa
The contact layers 16 composed of the N layers 20 are sequentially laminated.

Then, the p-side electrode 1 is formed on the contact layer 16.
7 is formed, and the n-side electrode 1 is formed on the high-temperature buffer layer 12 exposed by etching a part of the stacked semiconductor layers.
8 are formed. Further, a part of the contact layer 16 and a part of the p-type cladding layer 15 are etched to form a mesa shape in accordance with the p-side electrode 17.

As described above, in the structure shown in FIG. 8, since the ridge waveguide is formed by the mesa shape formed by etching up to the active layer 14, not only the current but also the light is distributed in the horizontal direction. This is a confined refractive index guided semiconductor laser device.

However, in the group III nitride-based semiconductor laser device shown in FIG. 8, the ridge waveguide is formed such that the contact layer 16 and the p-type cladding layer 15 extend from the surface of the device.
Is formed by stopping the etching above the InGaN active layer 14, and if the etching depth varies, the effective refractive index of the ridge waveguide changes and the threshold current of the laser and the distance The element characteristics such as a field image change. Therefore, it is necessary to precisely control the etching depth.

FIG. 9 is a view showing an example of a typical refractive index guided semiconductor laser based on an AlGaAs material disclosed in Japanese Patent Application Laid-Open No. Hei 8-97503. Referring to FIG. 9, on an n-type GaAs substrate 21, an n-type AlGaAs lower cladding layer 22, a non-doped or n-type or p-type AlGaAs active layer 23, a p-type AlGaAs first upper cladding layer 24, an n-type GaAs current Restriction layer 25, p-type Al
A GaAs second upper cladding layer 26 and a p-type GaAs contact layer 27 are sequentially stacked. And p-type Ga
A p-side electrode 28 and an n-side electrode 29 are formed on the upper surface of the As contact layer 27 and the lower surface of the n-type GaAs substrate 21, respectively. In this structure, the current limiting layer 25 made of n-type GaAs limits the injection current to a stripe-shaped region having a width w, and at the same time, absorbs light generated in the active layer to provide a difference in refractive index between inside and outside of the stripe. it can. Therefore, the light is confined in the region of the width w and can be guided stably.

[0011]

The structure of a semiconductor laser as shown in FIG. 9 is a structure widely used in an AlGaAs material system. In the AlGaAs material system,
Since it is relatively easy to selectively etch GaAs and AlGaAs by chemical etching, the n-type GaAs current limiting layer 25 is selected as a stripe of width w up to the surface of the p-type AlGaAs first upper cladding layer 24. Etching to form a stripe structure.

On the other hand, in a group III nitride material, etching is hardly performed by chemical etching, and InGaN and Ga are different from those in an AlGaAs material.
It is difficult to selectively etch N and AlGaN, respectively. Therefore, the structure as shown in FIG.
In the case of using a group I nitride material, the current confinement layer must be dry-etched while controlling the etching depth precisely, which makes production difficult.

An object of the present invention is to provide a group III nitride material-based semiconductor light emitting device (semiconductor laser device) which has good controllability of etching depth and is easy to manufacture.

The present invention has good controllability of etching depth, is easy to manufacture, and has a ridge waveguide structure.
It is an object of the present invention to provide a semiconductor light emitting device (semiconductor laser device) based on a group III nitride material.

Further, the present invention provides a ridge waveguide type group III nitride material-based semiconductor light emitting device (semiconductor laser device) which has good controllability of etching depth, is easy to manufacture, and has a reduced operating voltage. It is intended to provide.

Another object of the present invention is to provide a group III nitride material-based semiconductor light emitting device (semiconductor laser device) of a refractive index guide type which has good controllability of etching depth and is easy to manufacture. I have.

Further, the present invention provides a semiconductor light emitting device (semiconductor laser) of a group III nitride material based on a refractive index guide, which has good controllability of etching depth, is easy to manufacture, and has a reduced operating voltage. Element).

Further, according to the present invention, the controllability of the etching depth is good, the manufacturing is easy, and the operating voltage is reduced.
It is an object of the present invention to provide a semiconductor light emitting device (semiconductor laser device) of a group III nitride material based on a refractive index guide having an active layer containing.

[0019]

In order to achieve the above object, according to the first aspect of the present invention, a structure in which an active layer is sandwiched between an n-type cladding layer and a p-type cladding layer is laminated on a substrate.
In the group III nitride semiconductor light emitting device, an etching stop layer made of a group III nitride material containing In and having a larger band gap than the active layer is laminated near the active layer, and the etching stop layer In to the surface of
Is characterized in that a stripe structure is formed by etching a layer made of a group III nitride material containing no.

Further, according to the invention of claim 2, the invention is characterized in that:
At least a first conductivity type cladding layer, an active layer, a second conductivity type etching stop layer, a second conductivity type cladding layer, a second
The structure including the conductive type contact layer is laminated, and the second
The conductive type etching stop layer is made of a material having a larger band gap than the active layer in a group III nitride material containing In,
Further, the layer above the etching stop layer is made of a group III nitride material containing no In, and the second conductivity type contact layer and the second conductivity type cladding layer are separated from the element surface by the second conductivity type etching stop. It is characterized in that the ridge waveguide is formed by being etched almost vertically to the surface of the layer.

According to a third aspect of the present invention, there is provided:
At least a first conductivity type cladding layer, an active layer, a second conductivity type etching stop layer, a second conductivity type cladding layer, a second
The structure including the conductive type contact layer is laminated, and the second
The conductive type etching stop layer is made of a material having a larger band gap than the active layer in a group III nitride material containing In,
Further, the layer above the etching stop layer is made of a group III nitride material containing no In, and the second conductivity type contact layer and the second conductivity type cladding layer are separated from the element surface by the second conductivity type etching stop. It is characterized in that a ridge waveguide is formed by etching in an inverted mesa shape up to the surface of the layer.

Further, the invention according to claim 4 is characterized in that:
At least a first conductivity type cladding layer, an active layer, a second conductivity type etching stop layer, a second conductivity type cladding layer, a second
The structure including the conductive type contact layer is laminated, and the second
The conductive type etching stop layer is made of a material having a larger band gap than the active layer in a group III nitride material containing In,
Further, the layer above the etching stop layer is made of a group III nitride material containing no In, and the second conductivity type contact layer and the second conductivity type cladding layer are separated from the element surface by the second conductivity type etching stop. A stripe structure is formed by etching to the surface of the layer, and a second conductivity type contact layer and a second conductivity type cladding layer are formed on both sides of the stripe structure in parallel with the stripe structure from the element surface to form a second conductivity type etching stop layer. It is characterized in that a diffraction grating is formed by etching periodically up to the surface.

Further, according to the invention described in claim 5, the substrate is provided with:
A structure including at least a first conductive type clad layer, an active layer, a second conductive type etching stop layer, a first conductive type or semi-insulating current confinement layer, a second conductive type clad layer, and a second conductive type contact layer. The second conductivity type etching stop layer is formed of a group III nitride material containing In and having a larger band gap than the active layer, and the current confinement layer is made of an active layer containing no In. The current constriction layer is etched to the surface of the second conductivity type etching stop layer to form a stripe groove.

According to a sixth aspect of the present invention, in the semiconductor light emitting device according to the fifth aspect, the active layer contains In.
The current confinement layer of a first conductivity type or semi-insulating current confinement layer containing As or P without containing In
It is characterized by being made of a group I nitride material.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. The semiconductor laser device of the present invention basically has a structure in which an active layer is sandwiched between an n-type cladding layer and a p-type cladding layer, and is a group III nitride material-based semiconductor laser device laminated on a substrate. An etching stop layer made of a group III nitride material containing In and having a larger band gap than the active layer is stacked near the active layer, and does not contain In up to the surface of the etching stop layer. A stripe structure is formed by etching a layer made of a group III nitride material.

In the semiconductor light-emitting device of the present invention, when a current is injected into the semiconductor light-emitting device, the light-emitting recombination occurs in the active layer made of the group III nitride material sandwiched between the n-type cladding layer and the p-type cladding layer, and the blue to blue light is recombined. Light in the ultraviolet region is emitted. The emitted light is amplified by stimulated emission while being guided through the active layer sandwiched between the cladding layers, and resonates between the reflecting mirrors on both end faces of the element to oscillate laser.

The stripe structure formed by etching up to the surface of the etching stop layer laminated near the active layer functions to concentrate the current injected into the active layer only to the width of the stripe. Thereby, the threshold current of the laser can be reduced.

Further, the etching stop layer laminated near the active layer is made of a material having a larger forbidden band width than the active layer. Therefore, the injected carriers do not recombine in the etching stop layer, and the generation of a leak current can be suppressed. Further, light emitted from the active layer is not absorbed by the etching stop layer, so that light absorption loss does not occur.

In dry etching using a chlorine-based gas, since the boiling point of chloride of In is as high as 500 ° C. or more, I
The etching rate of a material containing n tends to be lower than that of a material not containing In. Therefore, by performing etching while controlling the temperature of the sample at a low temperature so that the temperature of the sample to be etched does not increase, the etching rate of the layer containing In can be extremely reduced. In the semiconductor laser device of the present invention, In
Does not contain In up to the surface of the etching stop layer containing
A layer made of a group III nitride material is dry-etched with a chlorine-based gas to form a stripe structure. Therefore, the etching depth can be strictly defined by the position and the thickness of the etching stop layer.

FIG. 1 is a view showing one configuration example of a semiconductor light emitting device (semiconductor laser device) according to the present invention. Referring to FIG. 1, this semiconductor laser device includes a sapphire substrate
1, a GaN buffer layer 102, an n-type GaN contact layer 103, an n-type Al _0.15 Ga _0.85 N clad layer 10
4, In _0.05 Ga _0.95 N active layer 105, p-type In _0.07 G
a _0.6 Al _0.33 N etching stop layer 106, p-type A
A l _0.15 Ga _0.85 N cladding layer 107 and a p-type GaN contact layer 108 are sequentially laminated. Reference numeral 109 denotes a p-side electrode formed on the p-type GaN contact layer 108, and 110 denotes an n-side electrode formed on the n-type GaN contact layer 103.

FIG. 2 is a diagram showing an example of a manufacturing process of the semiconductor laser device of FIG. In this manufacturing process example, first, a GaN buffer layer 102 having a layer thickness of about 0.02 μm, an n-type GaN contact layer 103 having a layer thickness of about 3 μm, and an n-type Al _0.15 Ga layer having a layer thickness of about 0.8 μm are formed on a sapphire substrate 101.
_0.85 N cladding layer 104, In thickness of about 0.05 μm
_0.05 Ga _0.95 N active layer 105, p of about 0.1 μm thickness
Type In _0.07 Ga _0.6 Al _0.33 N etching stop layer 1
06, a p-type Al _0.15 Ga _0.85 N cladding layer 107 having a layer thickness of about 0.8 μm and a p-type GaN contact layer 108 having a layer thickness of about 0.2 μm are sequentially epitaxially grown by MOCVD (FIG. 2A).

Next, the p-type GaN contact layer 108 and p-type Al _0.15 are removed except for a stripe region having a width of about 5 μm.
The Ga _0.85 N cladding layer 107 is dry-etched almost vertically by using the ECR-RIBE method (FIG. 2B). As a result, a ridge waveguide for confining horizontal current and light is formed. At this time, the p-type GaN contact layer 108 containing no In and the p-type Al _0.15 Ga _0.85 N cladding layer 107 are controlled by using a chlorine-based gas as an etching gas and controlling the substrate temperature to be around room temperature. Etched, but p-type In _0.07 containing In
When reaching the surface of the Ga _0.6 Al _0.33 N etching stop layer 106, the etching is almost stopped. This is because the boiling point of the chlorine compound of In is as high as 500 ° C. or higher.

Next, in order to form an n-side electrode, a p-type In _0.07 Ga _0.6 Al _0.33 N etching stop layer 10 is formed.
6 from the surface to the middle of the n-type GaN contact layer 103
Dry etching is performed by CR-RIBE method (FIG. 2).
(c)). At this time, a chlorine-based gas is used as an etching gas, and control is performed so that the substrate temperature becomes 200 ° C. or higher.
Thereby, the In _0.07 Ga _0.6 Al _0.33 N etching stop layer 106 containing In and the In _0.05 Ga _0.95 N active layer 105 are also etched.

Thereafter, the p-type Ga on the top of the ridge waveguide is formed.
A p-side electrode 109 is formed on the surface of the N-contact layer 108 by vacuum evaporation, and the n-side electrode 1 is formed on the surface of the n-type GaN contact layer 103 which is etched and exposed in the step of FIG.
10 are each formed by vacuum evaporation. Finally, the substrate is separated into chips to form a resonator (FIG. 2D).

In such a ridge waveguide type semiconductor laser device, it is important to control the distance from the active layer to the bottom of the ridge stripe. This is because the effective refractive index difference inside and outside the ridge waveguide changes depending on this distance. When the distance from the active layer to the bottom of the ridge stripe varies, the distribution of light in the horizontal and horizontal directions changes, and characteristics such as the far-field pattern and threshold current of the laser vary.

In the semiconductor laser device shown in FIGS.
An In _0.07 Ga _0.6 Al _0.33 N etching stop layer 106 containing GaN is laminated on the In _0.05 Ga _0.95 As active layer 105, and dry etching is stopped at the surface of the In _0.07 Ga _0.6 Al _0.33 N etching stop layer 105 to perform etching. The depth d1 is controlled. Therefore, the active layer 1
05 from the bottom of the ridge stripe (p-type Al _0.15 Ga _0.85
The distance to the bottom surface of the N cladding layer 107 is In _0.07 G
Since the thickness can be set by the layer thickness of the a _0.6 Al _0.33 N etching stop layer 106, the element can be manufactured with good controllability.

On the other hand, in the dry etching step shown in FIG. 2C, the etching stop layer 106 is also etched, and the function of the etching stop layer 106 is not used. In this case, in order to obtain the n-side electrode, the etching bottom only needs to be in the n-type GaN contact layer 103 having a layer thickness of about 3 μm, so that strict control of the etching depth is not required.

In the configuration example of FIG. 1, In _0.07 G
The forbidden band width of the a _0.6 Al _0.33 N etching stop layer 106 is larger than the forbidden band width of the In _0.05 Ga _0.95 As active layer 105. Therefore, the etching stop layer 1
Even if 06 is formed adjacent to the active layer 105, carriers do not recombine in the etching stop layer 106, so that generation of a leak current can be suppressed. In addition, In _0.07 Ga _0.6 A
l _0.33 N etching stop layer 106 is In _0.05 Ga
_Since it is a transparent medium that does not absorb the light emitted by the _0.95 As active layer 105, no light absorption loss occurs. Also, as for the refractive index, the In _0.07 Ga _0.6 Al _0.33 N etching stop layer 106 is smaller than the In _0.05 Ga _0.95 As active layer 105, and thus acts to confine light in the active layer 105.

From the above, the etching stop layer 1
The material used for 06 must be a group III nitride containing In and having a larger forbidden band width than the active layer 105. For example, if the material of the active layer 105 is GaN, the etching stop layer 106 is made of In _0.18 Al _0.82 N lattice-matched with GaN or a mixed crystal of In _0.18 Al _0.82 N and GaN. The material of the active layer 105 is InG.
In the case of aN, InGaN having less In content than the active layer 105 can be used as the etching stop layer 106 in addition to the above materials.

As described above, the group III nitride semiconductor laser device shown in FIG. 1 has at least the first conductivity type cladding layer 104, the active layer 105, the second conductivity type etching stop layer 106, Second conductivity type cladding layer 1
07, a structure including the second conductivity type contact layer 108 is laminated, and the second conductivity type etching stop layer 106 is formed.
Is a group III nitride material containing In and made of a material having a larger band gap than the active layer 105, and a layer above the etching stop layer 106 is made of a group III nitride material containing no In. The ridge waveguide is formed by etching the second conductivity type contact layer 108 and the second conductivity type cladding layer 107 almost vertically from the element surface to the surface of the second conductivity type etching stop layer 106. .

In the group III nitride semiconductor laser device shown in FIG. 1, the active layer 1 is made of a group III nitride material containing In.
A second conductivity type etching stop layer 106 made of a material having a larger forbidden band width than that of the active layer 105 is provided on the active layer 105. The mold contact layer 108 and the second conductivity type cladding layer 107 are etched substantially perpendicularly to the surface of the second conductivity type etching stop layer 106 to form a ridge waveguide, and dry on the surface of the etching stop layer 106 containing In. Since the etching can be stopped, the etching depth of the ridge waveguide can be strictly controlled. Since the current is confined in the ridge waveguide region, the threshold current is reduced. In addition, since the light emitted from the active layer 105 is guided through the ridge waveguide, it operates as a refractive index guided semiconductor laser in which the horizontal and transverse modes are stable.

FIG. 3 is a view showing another configuration example of the semiconductor light emitting device (semiconductor laser device) according to the present invention. The semiconductor laser device shown in FIG. 3 has the same layer configuration as that of the semiconductor laser device shown in FIG. 1 except that the ridge waveguide has an inverted mesa shape. Is different. The inverted mesa ridge waveguide is ECR-
In the step of forming the ridge waveguide by dry etching by the RIBE method, the ridge waveguide is formed by irradiating the substrate 101 obliquely with an ion beam and performing dry etching at an angle of about 45 degrees. In this case, since the side surfaces of the ridge waveguide are dry-etched obliquely at different angles, it is necessary to perform dry etching twice. And, like the semiconductor laser device shown in FIG.
In _0.07 Ga _0.6 Al _0.33 N etching stop layer 10
Since the dry etching can be stopped on the surface of No. 6, it is easy to control the etching depth.

In the structure in which the ridge waveguide has an inverted mesa shape as shown in FIG. 3, the lower width w ₂ of the ridge waveguide is set to, for example, 3 μm.
Even when the width is made as small as possible, the upper width w ₁ of the ridge waveguide can be made as large as about 6 μm. Therefore, the current can be confined to the narrow stripe region of the active layer 105, and at the same time, the contact area between the p-side electrode 109 and the p-type GaN contact layer 108 can be widened to suppress an increase in contact resistance. The threshold current and operating voltage of the device can be reduced.

In other words, the group III nitride semiconductor laser device shown in FIG.
Conductive type cladding layer 104, active layer 105, second conductive type etching stop layer 106, second conductive type cladding layer 10
7, a structure including the second conductivity type contact layer 108 is laminated, and the second conductivity type etching stop layer 106 is
The In-containing group III nitride material is made of a material having a larger band gap than the active layer 105, and the layer above the etching stop layer 106 is made of a group III nitride material containing no In. The second conductive type contact layer 108 and the second conductive type clad layer 107 are
A ridge waveguide is formed by etching the surface of the conductive type etching stop layer 106 into an inverted mesa shape.

That is, in the III-nitride material semiconductor laser device shown in FIG. 3, the second conductivity type etching stop layer 106 made of a III-nitride material containing In and having a larger forbidden band width than the active layer 105 is used. Is provided on the active layer 105, and the second conductivity type contact layer 10 made of a group III nitride material containing no In from the element surface is provided.
The ridge waveguide is formed by etching the cladding layer 107 of the second conductivity type and the second conductivity type up to the surface of the etching stop layer of the second conductivity type in an inverted mesa shape.

Therefore, like the semiconductor laser device of FIG. 1, the structure of the refractive index waveguide type semiconductor laser having the ridge waveguide is adopted. In the semiconductor laser device of FIG. 3, the ridge waveguide has an inverted mesa shape. By making the ridge waveguide an inverted mesa shape, the current constriction width is reduced,
In addition, the contact area between the upper electrode 109 and the second conductivity type contact layer 108 can be increased. That is, the contact resistance with the electrode can be reduced, and the operating voltage of the element can be reduced. In particular, in a group III nitride material, it is difficult to increase the carrier concentration of the p-type semiconductor layer, and the contact resistance between the p-side electrode and the p-type semiconductor layer increases. Therefore, when the upper electrode is the p-side electrode, an inverted mesa shape that can reduce the contact resistance with the electrode is effective.

FIG. 4 is a diagram showing another configuration example of the semiconductor light emitting device (semiconductor laser device) according to the present invention. The semiconductor laser device shown in FIG.
The semiconductor laser device shown in FIG. 3 is the same as the semiconductor laser device shown in FIG. 3, but in the semiconductor laser device shown in FIG. 4, In _0.07 Ga _{0.6 is placed on} both sides of the ridge waveguide (stripe structure) in parallel with the ridge waveguide (stripe structure). The diffraction grating 401 is formed by periodic etching up to the surface of the Al _0.33 N etching stop layer 106.

Here, more specifically, the diffraction grating 401 is formed by dry etching by an ECR-RIBE method using a chlorine-based gas, and contains In _0.07 Ga _0.6 A containing In.
The dry etching stops on the surface of the l _0.33 N etching stop layer 106. Therefore, the etching depth of the diffraction grating 401 can be formed with good controllability.

In the configuration shown in FIG. 4, light leaked to the outside of the stripe regions (ridge waveguides) 107 and 108 into which current is injected is reflected by the diffraction grating 401. Is surely guided. This allows
The semiconductor laser device of FIG. 4 operates as a stable refractive index guided semiconductor laser.

In other words, the group III nitride semiconductor laser device shown in FIG. 4 has at least a first conductivity type cladding layer 104, an active layer 105, a second conductivity type etching stop layer 106, a second conductivity type Conductive cladding layer 10
7, a structure including the second conductivity type contact layer 108 is laminated, and the second conductivity type etching stop layer 106
The n-containing group III nitride material is made of a material having a larger bandgap than the active layer 105, and the layer above the etching stop layer 106 is made of a group III nitride material containing no In. , Stripe structure (ridge structure) 10
The second conductive type contact layer 107 and the second conductive type cladding layer 108 are periodically etched from the element surface to the surface of the second conductive type etching stop layer 106 on both sides of the layers 7 and 108 in parallel with the stripe structures 107 and 108. By having the diffraction grating 401 formed,
It can be operated as a refractive index guided laser.

In this case, the etching stop layer 1
Numeral 06 is made of a material containing In, and since the dry etching can be stopped on the surface of the etching stop layer 106, the etching depth of the diffraction grating 401 can be strictly controlled.

FIG. 5 is a diagram showing another configuration example of the semiconductor light emitting device (semiconductor laser device) according to the present invention. The semiconductor laser device shown in FIG.
Buffer layer 102, n-type GaN contact layer 103, n
Type Al _0.15 Ga _0.85 N cladding layer 104, In _0.05 Ga
_0.95 N active layer 105, p-type In _0.07 Ga _0.6 Al _0.33 N
An etching stop layer 106 is formed, and p-type In _0.07
On the Ga _0.6 Al _0.33 N etching stop layer 106, except for a stripe region into which current is injected, n-type Ga
An N _0.9 P _0.1 current confinement layer 501 is formed. Further, the n-type GaN _0.9 P _0.1 current confinement layer 501 and the p-type I
n _0.07 Ga _0.6 Al _0.33 N etching stop layer 106
A p-type Al _0.15 Ga _0.85 N cladding layer 107, p
Type GaN contact layers 108 are sequentially stacked.
A p-side electrode 109 is formed on the p-type GaN contact layer 108, and an n-side electrode 110 is formed on the n-type GaN contact layer 103.

FIG. 6 is a diagram showing an example of a manufacturing process of the semiconductor laser device of FIG. In this manufacturing process example, first, a GaN buffer layer 102 having a layer thickness of about 0.02 μm, an n-type GaN contact layer 103 having a layer thickness of about 3 μm, and an n-type Al _0.15 Ga layer having a layer thickness of about 0.8 μm are formed on a sapphire substrate 101.
_0.85 N cladding layer 104, In thickness of about 0.05 μm
_0.05 Ga _0.95 N active layer 105, p of about 0.1 μm thickness
Type In _0.07 Ga _0.6 Al _0.33 N etching stop layer 1
06, an n-type GaN _0.9 P _0.1 current confinement layer 501 having a layer thickness of about 0.2 μm is sequentially epitaxially grown by MOCVD (FIG. 6A).

Next, the n-type GaN _0.9 P _0.1 current confinement layer 50
6 is dry-etched using the ECR-RIBE method to form a stripe region 601 having a width of 5 μm (FIG. 6).
(b)). At this time, the n-type GaN _0.9 P _0.1 current confinement layer 501 not containing In is etched by using a chlorine-based gas as an etching gas and controlling the substrate temperature to be around room temperature. Including p-type In _0.07
When the surface reaches the surface of the Ga _0.6 Al _0.33 N etching stop layer 106, the etching is almost stopped.

Next, the n-type GaN _0.9 P _0.1 current confinement layer 50
1 and p-type In _0.07 Ga _0.6 Al _0.33 N etching stop layer 10 exposed on the surface of stripe region 601
6, p-type Al _0.15 Ga _0.85 N having a layer thickness of about 0.8 μm
A cladding layer 107 and a p-type GaN contact layer 108 having a thickness of about 0.2 μm are epitaxially grown by MOCVD (FIG. 6C).

Then, in order to form the n-side electrode, p
Dry etching is performed by ECR-RIBE from the surface of the n-type GaN contact layer 103 to the middle of the n-type GaN contact layer 103 (FIG. 6D). At this time, a chlorine-based gas is used as an etching gas, and control is performed so that the substrate temperature becomes 200 ° C. or higher. Thereby, In _0.07 containing In
The Ga _0.6 Al _0.33 N etching stop layer 106 and the In _0.05 Ga _0.95 N active layer 105 are also etched.

After that, the p-type GaN contact layer 108
A p-side electrode 109 is formed on the surface by vacuum evaporation.
An n-side electrode 110 is formed by vacuum evaporation on the surface of the n-type GaN contact layer 103 which has been etched and exposed in the step (d). Finally, the substrate is separated into chips to form a resonator (FIG. 6E).

In the semiconductor laser device of FIG. 5, the n-type GaN _0.9 P _0.1 current confinement layer 501 has a p-type In _0.07 Ga
_{The surface of the 0.6} Al _0.33 N etching stop layer 106 is etched in a stripe shape, and the stripe region has a pn structure and a current flows, but the outside of the stripe region has a pnpn structure. Blocked. As a result, carriers can be confined in the active layer 105 below the stripe region, and the threshold current of the device can be reduced.

In the semiconductor laser device shown in FIG. 5, the p-type In _0.07 Ga _0.6 Al _0.33 N etching stop layer 10 is used.
Numeral 6 is made of a group III nitride-based material containing In.
Since the aN _0.9 P _0.1 current confinement layer 501 is made of a material that does not contain In, the GaN _0.9 P _0.1 current confinement layer 501 can be selectively etched by dry etching using a chlorine gas. Therefore, n-type Ga
The N _0.9 P _0.1 current confinement layer 501 may be left unetched or may be excessively etched, resulting in an etching bottom of In _0.05 Ga.
It does not reach the _0.95 N active layer 105, and the device is easy to manufacture.

As the current confinement layer 501, In _0.05
Since GaN _0.9 P _0.1 , which is a material having a smaller forbidden band width and containing no In than the Ga _0.95 N active layer 105, is used, the GaN _0.9 P _0.1 current confinement layer 501 has In _0.05 G
a _{0.95 The} light emitted by the N active layer 105 is absorbed. Therefore, light loss is large outside the stripe region,
An effective refractive index difference occurs inside and outside the stripe, and light is guided through the stripe region. Thereby, it operates as a stable refractive index guided semiconductor laser.

The semiconductor laser device of FIG. 5 has a current confinement layer inside the device, so that the p-side electrode 109 is different from the semiconductor laser device having the structure shown in FIGS.
Contact area with the p-type GaN contact layer 108 can be increased. Therefore, the contact resistance with the p-side electrode can be reduced, and the operating voltage of the element can be further reduced.

In other words, the group III nitride semiconductor laser device shown in FIG.
Including a conductive type cladding layer 104, an active layer 105, a second conductive type etching stop layer 106, a first conductive type or semi-insulating current constriction layer 501, a second conductive type cladding layer 107, and a second conductive type contact layer 108. The structure is laminated, the second conductivity type etching stop layer 106 is a group III nitride material containing In and made of a material having a larger bandgap than the active layer, and the current confinement layer 501 is active without containing In. Made of the same or smaller material than the layer
The present invention is characterized in that the current confinement layer 501 is etched to the surface of the etching stop layer of the second conductivity type to form a stripe groove (stripe region).

In the group III nitride semiconductor laser device of FIG. 5, a second conductivity type etching stop layer 106 is formed on an active layer 105, and a first conductivity type or semi-insulating current confinement is formed thereon. A layer 501 is laminated, and a stripe groove (stripe region) between the current confinement layers 501 is formed.
Flows into the active layer 105.

The second conductive type etching stop layer 1
Reference numeral 06 is made of a group III nitride material containing In, and the current confinement layer 501 is made of a group III nitride material containing no In. Therefore, the current confinement layer 501 is selectively etched by dry etching using a chlorine gas. It has become possible. Therefore, the etching depth can be strictly controlled.

The current confinement layer 501 has a smaller band gap than the active layer 105 or is made of the same material, and absorbs light emitted from the active layer 105. Therefore, an effective refractive index is generated inside and outside the stripe region, and light is guided through the stripe region. Thereby, it is possible to operate as a refractive index guided laser.

In the above structure, since the current confinement layer 501 is embedded in the element, the width of the second conductivity type contact layer 108 can be increased without depending on the width of the stripe groove. . Thereby, the upper electrode 109
The contact area between the contact layer and the second conductivity type contact layer 108 can be increased, and the operating voltage of the element can be reduced.

Further, in the group III nitride material based semiconductor laser device of FIG.
The first conductivity type or semi-insulating current confinement layer 105 may be made of a group III nitride material containing As or P without containing In.

That is, in the semiconductor laser device of FIG.
When GaN is used as the material of the active layer 105, GaN, which is the same material as the active layer 105, can be used as the material of the current confinement layer 501. However, the active layer 10
5 is a material containing In such as InGaN, for example, contains In.
aN cannot be used. Therefore, in the group III nitride semiconductor laser device shown in FIG.
01, a group III nitride material containing As or P is used as a material which does not contain In and has the same or smaller band gap than the active layer. For example, GANP, GANA
s, GNAsP or the like is used as the current confinement layer 501. Thus, the current confinement layer 501 can be selectively etched by chlorine-based dry etching, and can be operated as a refractive index guided semiconductor laser.

[0069]

As described above, according to the first aspect of the present invention, the etching stop layer made of a group III nitride material containing In is laminated near the active layer, and the surface of the etching stop layer is formed. A layer made of a group III nitride material containing no In is etched to form a stripe structure. At this time, the temperature of the sample is controlled to a low temperature, and etching is performed by dry etching using a chlorine-based gas. Thereby, the etching can be stopped at the surface of the etching stop layer containing In. Therefore, the controllability of the etching depth is good, and the manufacture of the element is easy.

According to the second aspect of the present invention, the second conductive type contact layer and the second conductive type clad layer made of a group III nitride material containing no In from the element surface are formed of the second conductive type clad layer containing In. Since the ridge waveguide is formed by etching almost vertically to the upper surface of the two-conductivity type etching stop layer, the controllability of the etching depth is good, and the ridge waveguide type semiconductor laser device can be easily manufactured and provided. be able to.

According to the third aspect of the present invention, the second conductive type contact layer and the second conductive type clad layer made of a group III nitride material containing no In from the element surface are formed of the second conductive type clad layer. Since the ridge waveguide is formed by etching the upper surface of the two-conductivity type etching stop layer in an inverted mesa shape, the controllability of the etching depth is good, and the ridge waveguide type semiconductor laser device can be easily manufactured. Can be. Further, by performing the reverse mesa-shaped etching, the contact area between the upper electrode and the second conductivity type contact layer can be increased, and the operating voltage of the element can be reduced.

According to the fourth aspect of the present invention, the second conductivity type contact layer and the second conductivity type cladding layer are formed on both sides of the stripe structure in parallel with the stripe structure from the element surface. Since the diffraction grating is formed by periodically etching the surface, light can be confined in the stripe region, and the device can be operated as a refractive index guided semiconductor laser. Further, in the production of the diffraction grating, the etching can be stopped at the surface of the second conductivity type etching stop layer, and the controllability of the etching depth of the diffraction grating is excellent.

According to the fifth aspect of the present invention, the second
A first conductivity type or semi-insulating current confinement layer having a stripe groove is laminated on the conduction type etching stop layer, and the current confinement layer has a smaller band gap than the active layer or is made of the same material. Therefore, the light emitted by the active layer can be absorbed to operate as a refractive index guided semiconductor laser. Further, the second conductivity type etching stop layer is made of a group III nitride material containing In, and the current confinement layer is made of a group III nitride material containing no In.
The current confinement layer can be selectively etched by chlorine gas-based dry etching, and the depth of the stripe groove can be formed with good controllability. Further, since the area of the second conductivity type contact layer can be increased, the contact resistance with the upper electrode can be reduced, and the operating voltage of the element can be reduced.

According to the sixth aspect of the present invention, the second
A first conductivity type or semi-insulating current confinement layer having a stripe groove is laminated on a conduction type etching stop layer, and a group III nitride containing As or P without containing In as a material of the current confinement layer Since the material system is used, I
Even when the active layer is made of a material containing n, the bandgap of the current confinement layer can be made smaller or the same as that of the active layer, and a refractive index guided semiconductor laser can be formed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a semiconductor light emitting device (semiconductor laser device) according to the present invention.

FIG. 2 is a diagram illustrating an example of a manufacturing process of the semiconductor light emitting device (semiconductor laser device) of FIG. 1;

FIG. 3 is a diagram showing another configuration example of the semiconductor light emitting device (semiconductor laser device) according to the present invention.

FIG. 4 is a diagram showing another configuration example of the semiconductor light emitting device (semiconductor laser device) according to the present invention.

FIG. 5 is a diagram showing another configuration example of the semiconductor light emitting device (semiconductor laser device) according to the present invention.

6 is a diagram illustrating an example of a manufacturing process of the semiconductor light emitting device (semiconductor laser device) of FIG. 5;

FIG. 7 is a diagram showing a conventional gain guided semiconductor laser using a group III nitride material.

FIG. 8 is a view showing a conventional refractive index guided semiconductor laser using a group III nitride material.

FIG. 9 is a diagram showing a conventional refractive index guided semiconductor laser using an AlGaAs material system.

[Explanation of symbols]

Reference Signs List 101 sapphire substrate 102 GaN buffer layer 103 n-type GaN contact layer 104 n-type AlGaN cladding layer 105 InGaN active layer 106 p-type InGaAlN etching stop layer 107 p-type AlGaN cladding layer 108 p-type GaN contact layer 109 p-side electrode 110 n-side electrode 401 diffraction grating 501 n-type GaNP current confinement layer 601 stripe region

Claims (6)

[Claims] 1. A group III nitride semiconductor light emitting device having a structure in which an active layer is sandwiched between an n-type cladding layer and a p-type cladding layer is laminated on a substrate. An etching stop layer made of a material having a larger bandgap than the active layer is laminated near the active layer,
No In containing up to the surface of the etching stop layer II
A semiconductor light emitting device, wherein a stripe structure is formed by etching a layer made of a group I nitride material. 2. A structure comprising at least a first conductivity type clad layer, an active layer, a second conductivity type etching stop layer, a second conductivity type clad layer, and a second conductivity type contact layer are laminated on a substrate. The second conductivity type etching stop layer is made of a group III nitride material containing In and having a larger bandgap than the active layer, and a layer above the etching stop layer is a group III nitride material containing no In. A ridge waveguide is formed by etching the second conductive type contact layer and the second conductive type clad layer substantially vertically from the element surface to the surface of the second conductive type etching stop layer from the element surface. A semiconductor light emitting device characterized by the above-mentioned. 3. A structure including at least a first conductive type clad layer, an active layer, a second conductive type etching stop layer, a second conductive type clad layer, and a second conductive type contact layer is laminated on a substrate. The second conductivity type etching stop layer is made of a group III nitride material containing In and having a larger bandgap than the active layer, and a layer above the etching stop layer is a group III nitride material containing no In. The ridge waveguide is formed by etching the second conductive type contact layer and the second conductive type clad layer from the element surface to the surface of the second conductive type etching stop layer in an inverted mesa shape from the element surface. A semiconductor light-emitting device. 4. A structure including at least a first conductive type clad layer, an active layer, a second conductive type etching stop layer, a second conductive type clad layer, and a second conductive type contact layer is laminated on a substrate. The second conductivity type etching stop layer is made of a group III nitride material containing In and having a larger bandgap than the active layer, and a layer above the etching stop layer is made of a group III nitride material containing no In. And a second conductive type contact layer and a second conductive type clad layer are etched from the element surface to the surface of the second conductive type etching stop layer to form a stripe structure, and both sides of the stripe structure are formed. In parallel with the stripe structure, the second conductive type contact layer and the second conductive type clad layer are periodically etched from the element surface to the surface of the second conductive type etching stop layer. A semiconductor light-emitting device, wherein a diffraction grating is formed by forming a diffraction grating. 5. A substrate comprising at least a first conductivity type clad layer, an active layer, a second conductivity type etching stop layer, a first conductivity type or semi-insulating current confinement layer, a second conductivity type clad layer, A structure including a two-conductivity-type contact layer is laminated. The second-conductivity-type etching stop layer is made of a group III nitride material containing In and having a larger forbidden band width than the active layer. Is made of the same material or a material having a smaller forbidden band width than the active layer without containing In,
A semiconductor light emitting device, wherein a current confinement layer is etched to a surface of an etching stop layer of a second conductivity type to form a stripe groove. 6. The semiconductor light emitting device according to claim 5, wherein the active layer is made of a group III nitride material containing In, and the first conductivity type or semi-insulating current confinement layer is made of As without containing In. A semiconductor light-emitting device comprising a group III nitride material containing P.