JP4617546B2 - Array-type broad stripe semiconductor laser and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an array-type broad stripe semiconductor laser in which each layer is formed using unevenness previously formed on a substrate and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, semiconductor lasers having an output of several tens of watts or more have been developed as light sources used for laser display, laser processing, harmonic generation, and the like. In particular, an array type broad stripe laser having a configuration in which a plurality of light emitting portions are arranged is expected as a light source capable of emitting high-power light.
[0003]
FIG. 10 is a schematic diagram for explaining a conventional array type semiconductor laser. In this array type semiconductor laser, an n-type cladding layer 51, an active layer 52, a p-type cladding layer 53, and a p-type contact layer 54 are sequentially formed over a plurality of light emitting regions, and a p-type contact layer 54 other than the light emitting region is formed. The current suppression layer 55 is formed by performing ion implantation. As a result, a current is injected into a portion other than the current suppression layer 55, and laser light is emitted from a plurality of light emitting regions corresponding thereto.
[0004]
[Problems to be solved by the invention]
However, in such an array type semiconductor laser, since the active layers constituting each light emitting region are connected, defects (such as defects due to deterioration) generated in any light emitting region are activated along the <100> direction. It grows in the layer plane and transitions to the adjacent light emitting region. This is because defects easily pass through the inactive region in the active layer, which should be non-injection of current, and photoexcitation due to current diffusion in the active layer and light output of the adjacent active layer is a growth energy. Presumed to be the source. As a result, there arises a problem that the deterioration of each light emitting region is accelerated and the reliability is lowered.
[0005]
Thus, as shown in FIG. 11, an array type semiconductor laser is considered in which etching reaching the active layer from the position of the current suppressing layer is formed, and the active layer 52 in each light emitting region is separated. Thereby, defects generated in any one of the light emitting regions do not reach the adjacent light emitting region through the active layer 52.
[0006]
However, in such a structure, although defect transfer can be suppressed, there is a problem that the interface of the active layer 52 (a portion where the end is exposed) is generated by etching, and defect transfer occurs from this point as a new starting point.
[0007]
[Means for Solving the Problems]
The present invention has been made to solve such problems. That is, the array-type broad stripe semiconductor laser of the present invention, Rutotomoni convex area and the convex area and a concave area is formed adjacent are provided a plurality at a constant pitch, the width of the first convex area is 10μm~100μm The same structure as the functional layer in the conductive type substrate, the functional layer formed in the convex region of the substrate in the order of the first conductive type cladding layer, the active layer, and the second conductive type cladding layer, and the concave region of the substrate The buried layer formed to fill the concave region, the first contact layer of the second conductivity type formed on the functional layer and the buried layer, and the first contact layer formed on the buried layer And a current block layer of the first conductivity type formed so as to be in contact with at least the entire end portion of the active layer.
[0008]
In the present invention, since the functional layer is formed on the convex region and the current blocking layer is in contact with the end portion of the active layer in the functional layer, the generation and transfer of defects can be suppressed. become able to.
[0009]
Further, the method of manufacturing the array type broad stripe semiconductor laser of the present invention, a plurality of Rutotomoni convex area at a predetermined pitch to form adjacent the convex area and a concave area on a first conductive type substrate, the protruding area A step of setting the width to 10 μm to 100 μm, a first conductive type cladding layer, an active layer, and a second conductive type cladding layer are sequentially laminated on the substrate, and a functional layer is formed on the convex region and a buried layer is formed in the concave region simultaneously. A step of forming, a step of forming a first contact layer of the second conductivity type on the functional layer and the buried layer, a current blocking layer of the first conductivity type on the first contact layer, and A step of bringing the current blocking layer into contact with at least the entire end portion of the active layer on the first contact layer formed on the first contact layer; and forming a second contact layer of the second conductivity type on the current blocking layer. Process, And a step of removing a layer formed above the first contact layer on the convex region.
[0010]
In the present invention, the functional layer is formed in the convex region, and at the same time, the buried layer is formed in the concave region, and the end portion of the active layer of the functional layer can be surrounded by the current blocking layer formed thereafter. As a result, each layer can be formed continuously in the crystal growth furnace so as to surround the end portion of the active layer, and the generation and transfer of defects can be suppressed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating the semiconductor laser according to the present embodiment. That is, the semiconductor laser 1 includes an n-type substrate 10 in which a convex region 10a and a concave region 10b are formed adjacent to each other, and an n-type clad layer 21, an active layer 22, p in the convex region 10a of the substrate 10. The functional layer 20 formed in the order of the mold cladding layer 23, the buried layer 30 formed so as to fill the concave region 10 b in the concave region 10 b of the substrate 1 with the same configuration as the functional layer 20, and the buried layer 30 and the functional layer 20 An n-type first contact layer 11 formed thereon, and an n-type current blocking layer 12 formed on and in contact with at least the entire end portion of the active layer 22 on the first contact layer 11 on the buried layer 30; A p-type second contact layer 13 formed on the current blocking layer 12.
[0012]
For the substrate 10, for example, n-type GaAs, AlGaInP, GaN, InGaAs, or InP is used. In the present embodiment, a GaAs substrate 1 having a (100) plane is used. On the surface of the substrate 10, stripes of convex regions 10a and concave regions 10b in the <011> direction are formed by wet etching, for example. The height of the convex region 10a (depth of the concave region 10b) is about 3 μm to 4 μm, and the width of the convex region 10a along the horizontal direction in the drawing is about 10 μm to 100 μm.
[0013]
The n-type cladding layer 21 is made of Al _0.4 Ga _0.2 As and has a thickness of 2 μm. The active layer 22 is made of non-doped Al _0.12 Ga _0.88 As and has a thickness of 0.05 μm. Further, the p-type cladding layer 23 is made of Al _0.4 Ga _0.6 As and is formed with a thickness of 2 μm. The n-type cladding layer 21, the active layer 22, and the p-type cladding layer 23 constitute a functional layer 20 for light emission on the convex region 10a. Further, the thickness of the three layers and the depth of the recessed region 10b are set to be substantially equal, and the recessed region 10b is filled with the embedded layer 30 by forming the three layers.
[0014]
The p-type first contact layer 11 formed on the buried layer 30 is made of GaAs and has a thickness of 0.3 μm or more. The n-type current blocking layer 12 is made of Al _0.5 Ga _0.5 As and is formed with a thickness of 0.5 μm. The illustrated current blocking layer 12 includes a height adjusting dummy layer formed on the first contact layer 11. As a result, the end portion of the active layer 22 of the functional layer 20 formed on the convex region 10 a is surrounded by the n-type current blocking layer 12.
[0015]
A p-type height adjusting layer (not shown) is provided on the n-type current blocking layer 12 as necessary, and the p-type second contact layer 13 is formed thereon. The p-type second contact layer 13 is made of GaAs and has a thickness of 0.5 μm.
[0016]
In the semiconductor laser 1 of this embodiment having such a configuration, electrodes are formed on the first contact layer 11 on the functional layer 20 and the back surface of the substrate 10, and current is injected into the functional layer 20. At this time, in the recessed region 10b, the npnp type thyristor is configured by the n-type cladding layer 21, the p-type cladding layer 23, the n-type current blocking layer 12 and the p-type second contact layer 13, and no current flows. It becomes. Thereby, a laser beam having a wavelength corresponding to the band gap of the active layer 22 of the functional layer 20 is emitted.
[0017]
In particular, in the present embodiment, by setting the width of the convex region 10a to about 10 μm to 100 μm, the broad stripe functional layer 20 can be configured, and a wide laser beam can be emitted. In addition, by providing a plurality of functional layers 20 and emitting laser light from each, high-power laser light can be emitted.
[0018]
In such a semiconductor laser 1, the functional layer 20 and the buried layer 30 can be manufactured in the same process, and the first contact layer 11 and the current blocking layer are continuously formed from the formation of the functional layer 20 and the buried layer 30. Since an upper layer such as 12 can be formed, the end of the active layer 22 is not exposed during the manufacturing process, and the generation of defects at the end of the active layer 22 can be suppressed.
[0019]
Further, in the semiconductor laser 1 of the present embodiment, the functional layer 20 can be formed on each of the plurality of convex regions 10a by forming a plurality of stripes in which the convex regions 10a and the concave regions 10b are adjacent to each other on the substrate 10. The semiconductor laser 1 can be easily configured. At this time, as described above, since the end portion of the active layer 22 is surrounded by the current blocking layer 12, the transfer of defects to the adjacent active layer 22 can be accurately prevented.
[0020]
Next, a method for manufacturing the semiconductor laser 1 according to this embodiment will be described. First, as shown in FIG. 2, using a substrate 10 made of n-type GaAs, a photoresist is applied to the main surface made of the (100) plane, patterned in a stripe shape, and wet etched in the <011> direction. The convex regions 10a and the concave regions 10b are alternately formed.
[0021]
Here, as the wet etching, crystallographic etching is performed with an etching solution in which sulfuric acid-based H ₂ SO ₄ , H ₂ 0 _2, and H ₂ 0 are mixed at a ratio of 3: 1: 1. By this etching, the width of the convex region 10a is 10 μm to 100 μm, the width of the concave region 10b is 200 μm, and the depth is 3 μm to 4 μm.
[0022]
Next, as shown in FIG. 3, the first conductivity type is formed on the (100) surface of the substrate 10 on which the convex regions 10a and the concave regions 10b are formed by metal organic chemical vapor deposition (hereinafter referred to as “MOCVD”). For example, an n-type cladding layer 21 made of, for example, n-type Al _0.4 Ga _0.6 As is formed to a thickness of 2 μm.
[0023]
At this time, on the side wall 21a of the n-type cladding layer 21 formed on the convex region 10a, a (111) B crystal plane formed at an angle of about 55 ° with respect to the main surface of the substrate 10 occurs spontaneously. Since this (111) B crystal plane hardly causes epitaxial growth, the n-type cladding layer 21 is divided and formed on the convex region 10a and in the concave region 10b.
[0024]
Next, as shown in FIG. 4, a non-doped active layer 22 is formed on the n-type cladding layer 21 by, for example, MOCVD. The active layer 22 is formed with a composition of Al _0.12 Ga _0.88 As and a thickness of 0.05 μm, for example.
[0025]
Next, as shown in FIG. 5, an n-type cladding layer 21 made of a second conductivity type, for example, p-type Al _0.4 Ga _0.6 As, is formed on the active layer 22 to a thickness of 2 μm. As a result, the functional layer 20 including the n-type cladding layer 21, the active layer 22, and the p-type cladding layer 23 is formed on the convex region 10a of the substrate 10, and the functional layer 20 is configured in the concave region 10b of the substrate 10 from the same configuration. A buried layer 30 is formed. Note that the recessed layer 10b is substantially filled with the buried layer 30.
[0026]
Next, as shown in FIG. 6, for example, a p-type first contact layer 11 of the second conductivity type is formed on the p-type cladding layer 23. The first contact layer 11 is made of, for example, GaAs and is formed with a thickness of about 0.3 μm.
[0027]
Thereafter, as shown in FIG. 7, for example, an n-type current blocking layer 12 of the first conductivity type is formed on the first contact layer 11. The n-type current blocking layer 12 is made of Al _0.5 Ga _0.5 As and is formed with a thickness of 2.5 μm. As a result, the end portion 22a of the active layer 22 of the functional layer 20 formed on the convex region 10a is surrounded by the n-type current blocking layer 12.
[0028]
Next, as shown in FIG. 8, for example, a p-type second contact layer 13 of the second conductivity type is formed on the current blocking layer 12. Here, in order to match the height of the second contact layer 12 formed on the concave region 10b with the height of the first contact layer 11 formed on the convex region 10a, the current blocking layer 12 and the second contact layer 13 are aligned. A height adjusting layer (for example, Al _0.4 Ga _0.6 As of the second conductivity type) not shown may be provided between the two.
[0029]
Then, as shown in FIG. 9, the current blocking layer 12 and the second contact layer 13 that are formed to protrude on the convex region 10a of the substrate 10 are etched so that the first contact layer 11 on the convex region 10a is exposed. To.
[0030]
Thereafter, a p-side electrode (not shown) is formed on the first contact layer 11, and an n-side electrode (not shown) is formed on the back surface of the substrate 10. Thereafter, the substrate 10 is cleaved to a predetermined size, and the semiconductor laser 1 of this embodiment is completed.
[0031]
In such a manufacturing method of the semiconductor laser 1, each layer can be formed by one operation, that is, one crystal growth by switching the supply gas by a series of MOCVD. That is, each layer can be formed without releasing the atmosphere in the MOCVD chamber.
[0032]
As a result, the end 22a of the active layer 22 can be surrounded by the current blocking layer 12 without being exposed to the atmosphere, and can be separated by the active layer 22 and the current blocking layer in the adjacent functional layer 20. Generation and metastasis can be suppressed.
[0033]
In the present embodiment, the example in which the functional layer 20 is formed on each of the two convex regions 10a has been shown in relation to the drawings. However, the present invention is not limited to this, and each of the functional layers 20 functions on three or more convex regions. A layer may be provided. One functional layer may be formed on one convex region.
[0034]
Furthermore, in the present embodiment, the first conductivity type has been described as n-type and the second conductivity type as p-type, but the opposite may be possible. That is, although the example using the substrate 10 made of n-type GaAs has been shown, a substrate made of p-type GaAs may be used. Advantages of using this p-type GaAs substrate are that there is less current leakage and that Se dopant is doped later, so that the steepness of Se distribution is improved and the reliability is improved.
[0035]
Further, the substrate 10 may be any material other than GaAs as long as it is a material suitable for an AlGaInP-based, GaN-based, InGaAs-based, or InP-based semiconductor laser.
[0036]
【The invention's effect】
As described above, the present invention has the following effects. That is, even in an array type broad stripe semiconductor laser having a plurality of functional layers, since the active layer of each functional layer is independent, defect transfer does not occur, and reliability can be improved. In addition, since the end portion of the active layer is surrounded by the current blocking layer, generation of defects from here can be suppressed. Moreover, since it can manufacture by one crystal growth, it becomes possible to simplify a manufacturing process.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view illustrating a semiconductor laser according to an embodiment.
FIG. 2 is a schematic cross-sectional view (No. 1) for explaining the method of manufacturing a semiconductor laser according to the embodiment.
FIG. 3 is a schematic cross-sectional view (No. 2) for explaining the method of manufacturing a semiconductor laser according to the embodiment.
FIG. 4 is a schematic cross-sectional view (No. 3) for explaining the method of manufacturing a semiconductor laser according to the embodiment.
FIG. 5 is a schematic cross-sectional view (No. 4) for explaining the method of manufacturing a semiconductor laser according to the embodiment.
FIG. 6 is a schematic cross-sectional view (No. 5) for explaining the method of manufacturing a semiconductor laser according to the embodiment.
FIG. 7 is a schematic cross-sectional view (No. 6) for explaining the method of manufacturing a semiconductor laser according to the embodiment.
FIG. 8 is a schematic cross-sectional view (No. 7) for explaining the method of manufacturing a semiconductor laser according to the embodiment.
FIG. 9 is a schematic cross-sectional view (No. 8) for explaining the method of manufacturing a semiconductor laser according to the embodiment.
FIG. 10 is a schematic cross-sectional view (part 1) illustrating a conventional example.
FIG. 11 is a schematic cross-sectional view (part 2) for explaining a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser, 10 ... Substrate, 10a ... Convex region, 10b ... Concave region, 11 ... 1st contact layer, 12 ... Current block layer, 13 ... 2nd contact layer, 20 ... Functional layer, 21 ... N-type clad layer , 22 ... active layer, 23 ... p-type cladding layer, 30 ... buried layer

Claims (5)

Rutotomoni the convex region and the convex area and a concave area is formed adjacent are provided a plurality at a constant pitch, a substrate of a first conductivity type the width of the convex area is 10 m - 100 m,
A functional layer formed in the order of a first conductivity type cladding layer, an active layer, and a second conductivity type cladding layer on the convex region of the substrate;
In the concave region of the substrate, the buried layer formed to fill the concave region with the same configuration as the functional layer,
A first contact layer of a second conductivity type formed on the functional layer and the buried layer;
At least the active layer array broad stripe semiconductors lasers Ru and a first conductivity type current blocking layer formed so as to be in contact over the end the whole area of on the first contact layer formed on the buried layer. It said current blocking layer is substantially the same position as the first contact layer on the functional layer, that has second contact layer of the second conductivity type is formed
Array-type broad stripe semiconductor laser 請 Motomeko 1 wherein. Height adjustment layer that are disposed between the second contact layer and said current blocking layer
Array-type broad stripe semiconductor laser 請 Motomeko 2 wherein. Wherein the substrate is Ru GaAs-based substrate Der
Array-type broad stripe semiconductor laser 請 Motomeko 1 wherein. A step of the 10μm~100μm plurality, the width of the convex area in Rutotomoni the convex region a constant pitch to form adjacent the convex area and a concave area on a first conductive type substrate,
Laminating a first conductive type cladding layer, an active layer, and a second conductive type cladding layer on the substrate in order, and simultaneously forming a functional layer on the convex region and an embedded layer in the concave region;
Forming a first contact layer of the second conductivity type on the functional layer and the buried layer,
Said current blocking layer of the first conductivity type formed on the first contact layer, in the top of the first contact layer formed on the buried layer, the current blocking layer over the ends entire area of at least the active layer A process of making contact,
Forming a second conductivity type second contact layer on the current blocking layer;
Method for producing an array-type broad stripe semiconductors lasers Ru and a step of removing the layer formed above the first contact layer on the convex region.

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