JPH11168257A - Semiconductor light emitting device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a III-V compound semiconductor light emitting device which is lessened both in threshold current and in operating current and capable of controlling a lateral mode. SOLUTION: A semiconductor light emitting device is formed of nitride III-V compound semiconductor, wherein a stripe-shaped second conductivity-type contact layer 10 is provided onto a second conductivity clad layer 8, and current constriction layers 11 and 12 of nitride R-V compound semiconductor which are, at least, partly electrically insulated are provided to each side of the contact layer 10 for the formation of a current constriction structure. The current constriction structure is formed through a certain manner where an etching stop layer 9 and the current constriction layers 11 and 12 are grown on the clad layer 8, the current constriction layers 11 and 12 are selectively etched by the use of the etching stop layer 9 to form a stripe-shaped opening, and the contact layer 10 is selectively grown and filled into the opening.

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 of manufacturing the same, and more particularly, to a nitride III-V.
The present invention relates to a semiconductor light emitting device using a group III compound semiconductor and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a semiconductor light emitting device capable of emitting blue or green light having a wavelength of about 380 to 550 nm, a nitride III-V compound semiconductor represented by gallium nitride (GaN) is formed on a sapphire substrate, a SiC substrate, or the like. A semiconductor laser or a light-emitting diode having a laser structure or a light-emitting diode structure formed by growing a semiconductor laser has attracted attention.

FIG. 6 shows a conventional GaN-based semiconductor laser. As shown in FIG. 6, in this GaN-based semiconductor laser, a GaN buffer layer 102, an n-type GaN contact layer 103, and an n-type A
lGaN cladding layer 104, n-type GaN optical waveguide layer 10
5. Active layer 106 composed of Ga _1-x In _x N well layer / Ga _1-y In _y N barrier layer, p-type GaN optical waveguide layer 107, p
An AlGaN cladding layer 108 and a p-type GaN contact layer 109 are sequentially stacked. Here, n-type Ga
Upper layer of N contact layer 103, n-type AlGaN cladding layer 104, n-type GaN optical waveguide layer 105, active layer 10
6. The p-type GaN optical waveguide layer 107, the p-type AlGaN cladding layer 108, and the p-type GaN contact layer 109 have a stripe shape extending in one direction. And p-type G
The p-side electrode 110 is in ohmic contact with the aN contact layer 109, and the n-side electrode 1 is in contact with the n-type GaN contact layer 103 in a portion other than the stripe portion.
11 is in ohmic contact.

[0004] The conventional GaN-based semiconductor laser configured as described above is manufactured as follows. That is,
First, a GaN buffer layer 1 is formed on a sapphire substrate 101 at a low temperature by metal organic chemical vapor deposition (MOCVD).
Grow 02. Subsequently, on the GaN buffer layer 102, an n-type GaN contact layer 103 and an n-type Al
GaN cladding layer 104, n-type GaN optical waveguide layer 105,
Active layer 106, p-type GaN optical waveguide layer 107, p-type AlG
aN cladding layer 108 and p-type GaN contact layer 1
09 is sequentially epitaxially grown. Next, p-type Ga
After a resist pattern (not shown) having a predetermined stripe shape extending in one direction is formed on the N-contact layer 109 by lithography, the resist pattern is used as a mask by a reactive ion etching (RIE) method.
A groove is formed by performing anisotropic etching to a depth halfway in the thickness direction of the n-type GaN contact layer 103.

Next, after removing the resist pattern, a p-side electrode 110 is formed on the p-type GaN contact layer 109.
And an n-side electrode 111 is formed on the n-type GaN contact layer 103.

Thereafter, the sapphire substrate 101 on which the laser structure has been formed as described above is cleaved in a bar shape along a direction perpendicular to the direction in which the stripe portion extends, or by dry etching. Form resonator end faces. Further, the bar is separated into chips by dicing or scribing. Thus, the intended GaN-based semiconductor laser is manufactured.

[0007]

Incidentally, a semiconductor laser often employs a stripe-shaped current path portion, that is, a so-called internal stripe structure, in order to reduce the operating current and control the transverse mode. In this case, a current confinement layer (current stop layer) is provided on both sides of the internal stripe portion to limit the current path. A structure having a gain guiding function of forming a portion where the carrier density is large, that is, a portion where the gain distribution sharply increases, by concentrating the current in the oscillation region of the active layer by forming such a current confinement layer. It is said.

The current confinement layer is usually formed by selectively forming a high-resistance region in the semiconductor layer by ion implantation of protons, boron, or the like, or by forming a current blocking region by a pn junction. I have.

However, in a GaN-based semiconductor laser, it is difficult to form a current confinement layer by these methods. For this reason, the conventional GaN-based semiconductor laser cannot take a current confinement structure, and must have a structure as shown in FIG. 6. There was a problem that the current was high.

Accordingly, an object of the present invention is to provide a semiconductor light emitting device using a nitride III-V compound semiconductor, capable of reducing the operating current and controlling the lateral mode, and a method of manufacturing the same. Is to do.

[0011]

According to a first aspect of the present invention, there is provided a semiconductor light emitting device using a nitride III-V compound semiconductor, wherein the first light emitting device has a first conductivity type. A second cladding layer of a second conductivity type on the active layer; a second cladding layer of the second conductivity type on the active layer;
And a current confinement layer provided on both sides of the contact layer, and at least a part of the current confinement layer is substantially insulative. Characterized by comprising a nitride III-V compound semiconductor.

The second invention of the present invention relates to a nitride-based III
In a method of manufacturing a semiconductor light emitting device using a group V compound semiconductor, a first cladding layer of a first conductivity type, an active layer, a second cladding layer of a second conductivity type, an etching stop layer, and at least one The part is electrically insulative I
A step of sequentially growing a current confinement layer made of a II-V compound semiconductor, a step of forming a stripe-shaped opening by selectively etching the current confinement layer using an etching stop layer, and a step of nitriding inside the opening. System III
Embedding a second conductivity type contact layer made of a group V compound semiconductor.

[0013] In this invention, typically, the lower portion of the current blocking layer is electrically substantially insulating (or high resistance) nitride-based III-V group compound semiconductor, for example, Al _u Ga
_1-uN (where 0.5 ≦ u ≦ 1), and the other portions are made of GaN.

In the present invention, typically, the first cladding layer and the second cladding layer are made of Al _v Ga _{1 -vN.}
(Where 0 <v ≦ 1), and the contact layer is Ga
N.

In the present invention, the etching stop layer made of a nitride III-V compound semiconductor provided on the first clad layer is typically made of GaN.

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 and B and at least N, and optionally further contains As. Or a group V element containing P. Specific examples of the nitride III-V compound semiconductor include GaN, AlGaN, G
aInN, AlGaInN and the like.

According to the first aspect of the present invention configured as described above, the current confinement structure in which the current confinement layers are provided on both sides of the stripe-shaped contact layer is provided. Partially composed of an electrically insulating nitride-based III-V compound semiconductor having a high current blocking effect, a significant reduction in reactive current as compared with a conventional semiconductor light emitting device having no current confinement structure Can be achieved.

According to the second aspect of the present invention configured as described above, at least a part of the nitride-based III-V compound semiconductor is electrically insulative, using the etching stop layer. After forming a stripe-shaped opening by etching the current confinement layer, a current confinement layer was provided on both sides of the stripe-shaped contact layer by burying the contact layer inside the opening. The current confinement structure can be reliably formed at a desired position with good reproducibility.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment 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 GaN according to an embodiment of the present invention.
1 shows a system semiconductor laser. As shown in FIG.
In a system-based semiconductor laser, for example, on a c-plane sapphire substrate 1, a GaN buffer layer 2, an n-type GaN contact layer 3, an n-type AlGaN cladding layer 4, an n-type GaN optical waveguide layer 5, Ga _1-x In _x N Active layer 6 consisting of well layer / Ga _1-y In _y N barrier layer (for example, x = 0.15, y = 0.02), p-type GaN optical waveguide layer 7, p-type AlGaN cladding layer 8, and p-type GaN etching stop layers 9 are sequentially stacked. On the p-type GaN etching stop layer 9, a stripe-shaped p-type GaN contact layer 10 extending in one direction is laminated. The width (stripe width) of the p-type GaN contact layer 10 is, for example, 10 μm.
It is about. On the p-type GaN etching stop layer 9 on both sides of the p-type GaN contact layer 10, an AlN current confinement layer 11 and an n-type GaN current confinement layer 12 are sequentially laminated.

Here, the upper part of the n-type GaN contact layer 3, the n-type AlGaN cladding layer 4, the n-type GaN optical waveguide layer 5, the active layer 6, the p-type GaN optical waveguide layer 7, the p-type AlGaN
Clad layer 8, p-type GaN etching stop layer 9, A
The 1N current confinement layer 11 and the n-type GaN current confinement layer 12 have a stripe shape extending in a direction parallel to the direction in which the p-type GaN contact layer 10 extends, and have a width of p-type Ga.
The width is larger than the width of the N contact layer 10.

As an example of the thickness of each nitride III-V compound semiconductor layer, the GaN buffer layer 2 has a thickness of 50 nm.
The n-type GaN contact layer 3 is 3 μm, the n-type AlGaN cladding layer 4 is 0.5 μm, and the n-type GaN optical waveguide layer 5 is 0.3 μm.
1 μm, p-type GaN optical waveguide layer 7 is 0.1 μm, p-type Al
The GaN cladding layer 8 is 0.5 μm, the p-type GaN etching stop layer 9 is 0.1 μm, the AlN current confinement layer 11 is 20 nm, and the n-type GaN current confinement layer 12 is 0.5 μm. Here, the AlN current confinement layer 11 has a thickness of 20 nm.
Even if it is thin, it has a sufficiently high current interruption effect.

The surface of the n-type GaN current confinement layer 12 is made of SiN
It is covered with the _x film 13. The p-side electrode 14 is in ohmic contact with the p-type GaN contact layer 10 and the n-type Ga
The n-side electrode 15 is in ohmic contact with the N-contact layer 3. As the p-side electrode 14, for example, a Ni / Au film is used, and as the n-side electrode 15, for example, a Ti / Au film is used.

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

That is, first, as shown in FIG. 2, on a c-plane sapphire substrate 1 by MOCVD, for example.
For example, the GaN buffer layer 2 is grown at a low temperature of about 550 ° C. Subsequently, on this GaN buffer layer 2, n
-Type GaN contact layer 3, n-type AlGaN cladding layer 4, n-type GaN optical waveguide layer 5, active layer 6, p-type GaN optical waveguide layer 7, p-type AlGaN cladding layer 8, p-type GaN etching stop layer 9, AlN current The constriction layer 11 and the n-type GaN current confinement layer 12 are sequentially grown epitaxially. Here, the n-type AlGaN cladding layer 4 and the n-type GaN
Optical waveguide layer 5, p-type GaN optical waveguide layer 7, p-type AlGaN cladding layer 8, p-type GaN etching stop layer 9, Al
The N current confinement layer 11 and the n-type GaN current confinement layer 12 are epitaxially grown at a temperature of, for example, about 1000 ° C.
The active layer 6 composed of the Ga _1-x In _x N well layer / Ga _1-y In _y N barrier layer is epitaxially grown at a temperature of about 800 ° C., for example.

Next, an SiN _x film 13 is formed on the n-type GaN current confinement layer 12 by, for example, a CVD method. Thereafter, a stripe-shaped resist pattern (not shown) extending in one direction is formed on the SiN _x film 13 by lithography.

Next, a stripe-shaped opening 13a is formed by etching the SiN _x film 13 using this resist pattern as a mask.

Next, after removing the resist pattern, the n-type GaN current confinement layer 12 and the underlying AlN current confinement layer 12 are formed using the SiN _x film 13 as a mask and the p-type GaN etching stop layer 9. 11 is selectively etched. During this etching, the etching is automatically stopped when the p-type GaN etching stop layer 9 is exposed. In this way, as shown in FIG.
Stripe-shaped openings 16 are formed in the 1N current confinement layer 11 and the n-type GaN current confinement layer 12.

Next, as shown in FIG. 4, SiN _x film 13
Is used as a mask to form the opening 16 by MOCVD, for example.
The p-type GaN contact layer 10 is selectively grown and buried in the inside.

Next, a stripe-shaped resist pattern (not shown) extending in one direction is formed on the SiN _x film 13 and the p-type GaN contact layer 10 by lithography, and the resist pattern is used as a mask.
For example, a groove is formed by anisotropic etching to an intermediate depth in the thickness direction of the n-type GaN contact layer 3 by RIE. After that, the resist pattern is removed. Thereby, as shown in FIG. 5, the upper part of the n-type GaN contact layer 3, the n-type AlGaN cladding layer 4,
-Type GaN optical waveguide layer 5, active layer 6, p-type GaN optical waveguide layer 7, p-type AlGaN cladding layer 8, p-type GaN etching stop layer 9, AlN current confinement layer 11, n-type GaN current confinement layer 12, and SiN _x The film 13 is patterned in a stripe shape extending in a direction parallel to the direction in which the p-type GaN contact layer 10 extends.

Next, as shown in FIG. 1, the opening 1 of the SiN _x film 13 is formed by, for example, a vacuum evaporation method or a sputtering method.
On the p-type GaN contact layer 10 in the portion of FIG.
While forming the side electrode 14, the n-side electrode 15 is formed on the n-type GaN contact layer 3 in a portion other than the stripe portion.
To form

Thereafter, the sapphire substrate 1 on which the laser structure is formed as described above is cleaved in a bar shape along a direction perpendicular to the direction in which the stripe portion extends, or is dry-etched. Form resonator end faces. Further, the bar is separated into chips by dicing or scribing. From the above, the target G
An aN-based semiconductor laser is manufactured.

As described above, the Ga according to this embodiment is
According to the N-based semiconductor laser, the p-type Ga
AlN current confinement layers 1 are formed on both sides of N contact layer 10.
An AlN current having a current confinement structure provided with a current confinement layer including an n-type GaN current confinement layer 1 and an n-type GaN current confinement layer 12 thereon, and a lower portion of the current confinement layer having high electrical insulation, in other words, an extremely high resistance. With the constriction layer 11, the reactive current during operation can be significantly reduced, and thereby the threshold current and the operating current can be significantly reduced. Further, by having such a current confinement structure, the transverse mode can be stably controlled.

Further, according to this embodiment, the following advantages can be obtained. That is, according to this embodiment, the SiN _x film 13 is used as a mask, and p
N-type GaN using the n-type GaN etching stop layer 9
After the opening 16 is formed by selectively etching the current confinement layer 12 and the AlN current confinement layer 11 thereunder, the p-type GaN contact layer 10 is formed inside the opening 16.
, The current constriction structure is formed, so that the current confinement structure can be reliably formed at a required position with good reproducibility.

The layer directly under the p-type GaN contact layer 10 is a p-type Ga layer which does not contain Al.
With the N etching stop layer 9, the following advantages can be obtained. That is, if the p-type AlG
If the p-type GaN contact layer 10 is grown directly on the aN clad layer 9, the p-type AlGaN clad layer 9 contains Al and is a layer that easily reacts. When the opening 16 comes into contact with the outside air before the growth of, the surface reacts with oxygen in the outside air to be deteriorated. For this reason, the p-type GaN
When the contact layer 10 is grown, a high-resistance layer is formed at the interface between the p-type GaN contact layer 10 and the p-type AlGaN cladding layer 9, or the interface portion becomes the maximum point or the minimum point of the carrier concentration. . As a result, when energization is actually performed to drive the GaN-based semiconductor laser, device characteristics such as an increase in operation current, an increase in operation voltage, and a decrease in the life of the device are caused. On the other hand, in this embodiment, the layer contacted by the p-type GaN contact layer 10 is made of the same material as the p-type GaN contact layer 10 and is the p-type GaN etching stop layer 9 containing no Al. There is no such problem.

As described above, one embodiment of the present invention has been specifically described. However, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. .

For example, the numerical values, structures, materials, processes, and the like described in the above-described embodiment are merely examples, and different numerical values, structures, materials, and the like may be used as necessary.
A process or the like may be used.

Specifically, in the above-described embodiment, the AlN current confinement layer 11 and the n-type GaN current confinement layer 12 thereon are used as the current confinement layer. Has a high current blocking effect, so that the effect of reducing the reactive current is slightly reduced.
The p-type GaN current confinement layer 12 may be used instead of the p-type GaN current confinement layer 12.

Although the sapphire substrate 1 is used in the above-described embodiment, a GaN substrate, a SiC substrate, a ZC
An nO substrate, a spinel substrate, or the like may be used. When a conductive substrate such as a SiC substrate is used,
An n-side electrode 15 can be formed on the back surface of the substrate.

Further, in the above embodiment, the conductivity type of each nitride-based III-V compound semiconductor layer may be reversed.

In the above embodiment, the case where the present invention is applied to a GaN-based semiconductor laser has been described. However, the present invention can be applied to, for example, a GaN-based light emitting diode.

[0042]

As described above, according to the semiconductor light emitting device of the present invention, at least a part of the nitride-based III-V group is at least partially electrically insulated on both sides of the stripe-shaped contact layer. With the current confinement structure provided with the current confinement layer made of a compound semiconductor, the threshold current and the operating current can be reduced, and the lateral mode can be controlled.

Further, according to the method of manufacturing a semiconductor light emitting device of the present invention, at least a part of a nitride-based III-V compound semiconductor that is at least partially electrically insulative is formed on both sides of a stripe-shaped contact layer. A semiconductor light emitting device having a current confinement structure provided with a current confinement layer can be formed with good reproducibility and reliably.

[Brief description of the drawings]

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

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

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

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

FIG. 5 is a cross-sectional view for explaining the method for manufacturing the GaN-based semiconductor laser according to one embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a conventional GaN-based semiconductor laser.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sapphire substrate, 3 ... n-type GaN contact layer, 4 ... n-type AlGaN cladding layer, 5 ... n
-Type GaN optical waveguide layer, 6 ... active layer, 7 ... p-type Ga
N optical waveguide layer, 8... P-type AlGaN cladding layer, 9.
..P-type GaN etching stop layer, 10 ... p-type GaN contact layer, 11 ... AlN current confinement layer, 1
2 ... n-type GaN current confinement layer, 13 ... SiN
_x film, 14 ... p-side electrode, 15 ... n-side electrode, 16
... Opening

Claims (13)

[Claims] 1. A semiconductor light emitting device using a nitride-based III-V compound semiconductor, a first conductive type first clad layer, an active layer on the first clad layer, and an active layer on the active layer. A second cladding layer of a second conductivity type; and a second cladding layer having a stripe shape on the second cladding layer.
A conductive type contact layer; and a current confinement layer provided on both sides of the contact layer. At least a part of the current confinement layer is an electrically substantially insulating nitride III-V compound. A semiconductor light-emitting device comprising a semiconductor. 2. The semiconductor light emitting device according to claim 1, wherein a lower portion of said current confinement layer is made of a nitride III-V compound semiconductor which is substantially electrically insulative. 3. The current confinement layer has a lower portion of Al _u Ga _1-u.
2. The semiconductor light emitting device according to claim 1, wherein N (where 0.5 ≦ u ≦ 1), and the other portion is made of GaN. 4. The first cladding layer and the second cladding layer are formed of Al _v Ga _{1 -vN} (where 0 <v ≦ 1).
2. The semiconductor light emitting device according to claim 1, comprising: 5. The semiconductor light emitting device according to claim 1, wherein said contact layer is made of GaN. 6. A nitride-based II on the second cladding layer.
2. The semiconductor light emitting device according to claim 1, wherein an etching stop layer made of an IV group compound semiconductor is provided, and the contact layer and the current confinement layer are provided on the etching stop layer. 7. The semiconductor light emitting device according to claim 6, wherein said etching stop layer is made of GaN. 8. A method for manufacturing a semiconductor light emitting device using a nitride III-V compound semiconductor, comprising: a first conductive type first cladding layer, an active layer, and a second conductive layer on a substrate.
Sequentially growing a conductive type second cladding layer, an etching stop layer and a current confinement layer at least partly made of a substantially III-V compound semiconductor which is electrically insulative; Forming a stripe-shaped opening by selective etching using a layer; and embedding a second conductivity type contact layer made of a nitride III-V compound semiconductor in the opening. A method for manufacturing a semiconductor light emitting device, comprising: 9. The method for manufacturing a semiconductor light emitting device according to claim 8, wherein a lower portion of said current confinement layer is made of a substantially nitride-based group III-V compound semiconductor that is electrically insulative. 10. The current constriction layer has a lower portion of Al _u Ga.
9. The method for manufacturing a semiconductor light emitting device according to claim 8, wherein _1-u N (where 0.5 ≦ u ≦ 1) is used, and the other portion is made of GaN. 11. The first cladding layer and the second cladding layer.
Cladding layer is Al _v Ga _1-v N (However, 0 <v ≦
9. The method for manufacturing a semiconductor light emitting device according to claim 8, comprising the following: 12. The method according to claim 8, wherein the contact layer is made of GaN. 13. The method according to claim 8, wherein the etching stop layer is made of GaN.