JP2003051641A - Semiconductor laser and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability in a semiconductor laser by preventing heating at the end faces while operating in a high output. SOLUTION: An n-GaAlAs clad layer 102, n-or i-InGaP lower optical waveguide layer 103, i-InGaAsP lower barrier layer 104, InGaAsP compressive strain quantum well active layer 105, p-InGaAsP or i-InGaAsP upper barrier layer 106, and InGaP cap layer (thickness of about 10 nm) 107 are laminated on an n-GaAs substrate 101. Regions of layers 107, 106, 105 and 104 in the vicinity of end faces adjacent to resonator end faces are removed. An InGaP upper optical waveguide layer 108, having a band gap larger than that of the layer 105, is formed on the removed portions in the vicinity of the end faces and on the InGaP cap layer. Furthermore, a second conductivity-type clad layer 120 is formed on the layer 108.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device, and more particularly to a semiconductor laser device having a window structure.

[0002]

2. Description of the Related Art Conventionally, the oscillation wavelength is 0.7 μm to 1.2 μm.
In the semiconductor laser device of m, it is widely used to provide a current confinement layer and a refractive index guiding mechanism inside the crystal layer in order to obtain a fundamental transverse mode.

For example, Applied Physics Le published in 1998
6.1W continuous wave front-facet power from Al- by JK Wade et al. at tters, Vol.72, No.1.pp.4-6
A free active-region (λ = 805 nm) diode laser has been reported. Here, InG containing no Al in the active region
805n adopting a structure in which aAsP is an active layer, InGaP is an optical waveguide layer, and a clad layer is InAlGaP.
An m band semiconductor laser has been reported. In this document, in order to improve the high output characteristics, the thickness of the optical waveguide layer is increased as a structure for reducing the optical density of the active layer.
A C (Large Optical Cavity) structure has been devised, and an increase in the maximum optical output has been reported. However, the maximum light output is said to be destroyed by the circulation that the end face temperature rises due to the heat generated by the current flowing due to the light absorption at the end face, the band gap at the end face becomes smaller, and the light absorption increases further. COMD (Catastroph
ic optical mirror damage) phenomenon occurs. This COM
The light output reaching D deteriorates with time, and this COMD
As a result, there is a high possibility that the driving of the semiconductor laser will be suddenly stopped, and there is a drawback that high reliability cannot be obtained at the time of high output driving.

On the other hand, when the oscillation wavelength is 0.8 μm, the active layer is A
As a semiconductor laser that becomes l-free, Jap.
In J.Appl.Phys.Vol.34.pp.L1175-1177, the Highly Reliable Operation of High-Power In
GaAsP / InGaP / AlGaAs 0.8μm Separate Confinement Het
erostructure Lasers have been reported. In this semiconductor laser, an n-AlGaAs cladding layer, an i-InGaP optical waveguide layer, an InGaAsP quantum well active layer, an i-InGaP optical waveguide layer, and a p-AlGa layer are formed on an n-GaAs substrate.
A structure in which an As clad layer and a p-GaAs cap layer are laminated is introduced, but there is a problem that the maximum light output is as low as 1.8W.

[0005]

As a means for solving these problems, there is a method of forming a window structure without light absorption on the end face of the cavity. For example, in the 1997 Spring Applied Physics Society Proceedings 29a-PA-19. Proposed. In this document, 9
A semiconductor laser having an oscillation wavelength of 80nm band, a semiconductor laser formed a disordered window structure In _{0. 2} Ga _0.8 As quantum well by Si ion implantation and subsequent heat treatment diffuses the end face region of the ridge structure is reported ing. However, this laser requires a very complicated process of injecting Si ions in the vicinity of the active layer and insulating by H ion injection in order to prevent current from flowing in the vicinity of the end face. There is a drawback that

In view of the above circumstances, it is an object of the present invention to provide a semiconductor laser device having high reliability even under a high output and a manufacturing method thereof.

[0007]

A semiconductor laser device of the present invention comprises a first conductivity type GaAs substrate, a first conductivity type clad layer, a first conductivity type or undoped InGaP lower optical waveguide layer, InGaAsP or InGaAs. Compression strain active layer, second conductivity type or undoped InG
In a semiconductor laser device comprising an aP upper optical waveguide layer and a semiconductor layer in which a second-conductivity-type cladding layer portion is laminated in this order, the compressive strain active layer is provided between the lower optical waveguide layer and the compressive strain active layer. InGaAsP lower barrier layer having a bandgap larger than that of, and an InGaAsP upper barrier layer having a bandgap larger than that of the compressive strain active layer between the compressive strain active layer and the upper optical waveguide layer. And removing portions of the lower barrier layer, the compressive strain active layer and the upper barrier layer, which are adjacent to two opposing end faces constituting the resonator end face, of the end faces formed by cleaving the semiconductor layer. The lower and upper optical waveguide layers have a bandgap larger than the bandgap of the compressive strain active layer, and the lower barrier layer and the compressive strain Sexual layer and the upper barrier layer is removed portions, it is characterized in that the embedded upper optical waveguide layer.

Here, the compressive strain active layer is 0.49y3 <x3.
In with ≦ 0.4 and 0 ≦ y3 ≦ 0.1 _x3Ga_1-x3As_1-y3
P_y3It is desirable to consist of When y3 = 0, P
InGaAs is not included.

The lower and upper barrier layers of InGaAsP may have compressive strain or tensile strain, or may have lattice matching. However, the absolute value of the sum of the product of the strain amount and the film thickness is set to 0.3 nm or less.

A second conductivity type contact layer is formed on a region of the second conductivity type clad layer portion except a region corresponding to a portion where the lower barrier layer, the compressive strain active layer and the upper barrier layer are removed. It is preferable that an insulating film is formed on a region of the second conductivity type cladding layer portion corresponding to a portion where the lower barrier layer, the compressive strain active layer and the upper barrier layer are removed.

Both sides of the stripe-shaped portion of the second conductivity type clad layer portion extending from one side to the other of the cavity end surface are removed from the upper surface side of the second conductivity type clad layer portion to a predetermined position. A ridge portion may be provided.

Further, the second conductivity type clad layer portion is
It may be composed of one layer, or may be composed of a plurality of layers, for example, from the upper optical waveguide layer side,
A second conductivity type first cladding layer, a second conductivity type InGaP first etching stop layer, a GaAs second etching stop layer having a stripe-shaped current injection opening extending from one of the resonator end faces to the other, and the resonator end face. First conductivity type InG having stripe-shaped current injection openings extending from one side to the other side
aAlP current confinement layer, first conductivity type I having a stripe-shaped current injection opening extending from one end face of the resonator to the other end face
The nGaP cap layer and the second conductivity type second cladding layer may be provided in this order, or
GaAs having a stripe-shaped current injection opening extending from one side of the resonator end face to the other side from the upper optical waveguide layer side.
Etching Blocking Layer First conductivity type In having stripe-shaped current injection openings extending from one side of the resonator to the other side
A GaAlP current confinement layer, a first conductivity type InGaP cap layer having a stripe-shaped current injection opening extending from one of the cavity end faces to the other, and a second conductivity type clad layer may be provided in this order. .

In each of the semiconductor laser devices described above, the AlG in which the cladding layers are lattice-matched with the GaAs substrate is used.
It is preferably made of any one of aAs, InGaAlP, and InGaAlAsP.

The lower and upper barrier layers are each 0
In _x1 Ga _1-x1 As with ≦ x1 ≦ 0.3 and 0 ≦ y1 ≦ 0.6
_1-y1 P _y1 may be a single layer, or 0 ≦ x2
In _x2 Ga _1-x2 As _{1-y2 with} ≦ 0.3 and x2 = 0.49y2
A P _y2 barrier layer and an In _x4 Ga _1-x4 As _1-y4 P _y4 tensile strain barrier layer in which 0.49y4> x4 ≧ 0 and 0 <y4 ≦ 0.5 may be formed, and may be two layers. If it consists of layers,
Of the two layers, the tensile strain barrier layer is preferably arranged adjacent to the compressive strain active layer.

The method of manufacturing a semiconductor laser device according to the present invention comprises:
A method of manufacturing a semiconductor laser device, comprising a plurality of semiconductor layers including a compressive strain active layer laminated on a substrate, wherein a cavity end face is constituted by two facing end faces, the first conductivity type GaAs substrate A first conductivity type clad layer, a first conductivity type or undoped InGaP having a bandgap larger than that of the compressive strain active layer.
Lower optical waveguide layer, InGaAsP lower barrier layer having a band gap larger than that of the compressive strain active layer, the compressive strain active layer made of InGaAsP or InGaAs, InGaAsP having a band gap larger than that of the compressive strain active layer An upper barrier layer, an InGaP cap layer, and a GaAs cap layer are laminated in this order, and a portion of the GaAs cap layer near the end face adjacent to the cavity end face is removed to remove the GaAs.
Using the cap layer as a mask, a portion of the InGaP cap layer near the end face was removed, and GaA was used as the mask.
At the same time as removing the s cap layer, the InGaP cap layer is used as a mask to remove the end face vicinity portions of the upper barrier layer, the compressive strain active layer and the lower barrier layer, and the removed end face vicinity portions and the InGaP cap are removed. A second conductivity type or undoped InGaP upper optical waveguide layer having a bandgap larger than that of the compressive strain active layer is formed on the layer, and the second conductivity type clad layer portion is further formed on the upper optical waveguide layer. Is formed.

Here, the second conductivity type clad layer portion is
From the upper optical waveguide layer side, the second conductivity type first cladding layer,
Second conductivity type InGaP first etching stop layer, GaAs
A second etching stop layer, a first conductivity type InGaAlP current confinement layer, a first conductivity type InGaP cap layer, and a second GaAs cap layer are laminated in this order, and the second GaAs
A portion of the cap layer corresponding to the stripe-shaped current injection opening is removed, and then the first conductivity type InGaP cap layer, the current confinement layer, and the current injection opening are formed using the second GaAs cap layer as a mask. Is removed, and at the same time the second GaAs cap layer used as the mask is removed, at the same time, the portion of the second etching stop layer that will be the current injection opening is removed using the first conductivity type InGaP cap layer as a mask. It can be formed by forming a second conductivity type second cladding layer so as to cover the current injection opening.

The second conductivity type clad layer portion includes a GaAs etching stop layer, a first conductivity type InGaAlP current confinement layer, and a first conductivity type InG from the upper optical waveguide layer side.
An aP cap layer and a second GaAs cap layer are laminated in this order, a portion of the second GaAs cap layer corresponding to the stripe-shaped current injection opening is removed, and then the second GaAs cap layer is used as a mask. , The second G used as the mask by removing portions of the first conductivity type InGaP cap layer and the current confinement layer which become the current injection openings.
At the same time as removing the aAs cap layer, the first conductivity type InGaP cap layer is used as a mask to remove the portion of the GaAs etching stop layer that will be the current injection opening, and the second conductivity type clad so as to cover the current injection opening. You may form by forming a layer.

[0018]

The semiconductor laser device of the present invention has a band gap larger than that of the compressive strain active layer between the lower optical waveguide layer and the compressive strain active layer and between the compressive strain active layer and the upper optical waveguide layer. An InGaAsP lower barrier layer having a bandgap, and two opposing end faces of the lower barrier layer, the compressive strain active layer, and the upper barrier layer that constitute a resonator end face among the end faces formed by cleaving the semiconductor layer. Has a structure in which an upper optical waveguide layer having a bandgap larger than that of the active layer is embedded in this removed part (so-called window structure). Since it is possible to form a transparent region, it is possible to reduce the current generated by light absorption at the end face. As a result, it is possible to reduce the heat generation of the element on the end face, to significantly improve the end face destruction level due to thermal runaway that occurs on the end face, and to provide a highly reliable semiconductor laser device even during high output operation. Can be provided.

Further, the InGaP optical waveguide layer and the InGaAs
If the InGaAsP barrier layer is not provided between the P compressive strain active layer and the P compressive strain active layer, it generally takes time to switch the gas from P to As in the manufacturing process, and the substitution of P and As at the interface occurs, resulting in the quality of the interface. Degradation, that is, deterioration of the quality of the active layer was sometimes caused.
By providing the aAsP barrier layer, gas switching and the like can be performed smoothly, so that the quality of the active layer can be improved. In particular, if the InGaAsP barrier layer has tensile strain, there is an advantage that the temperature characteristics of the device can be improved.

A second-conductivity-type contact layer is formed on a region of the second-conductivity-type cladding layer portion except a region corresponding to a portion where the lower barrier layer, the compressive strain active layer and the upper barrier layer are removed, By forming an insulating film in a region corresponding to a portion where the lower barrier layer, the compressive strain active layer, and the upper barrier layer are removed, it is possible to more effectively suppress current injection into the window region. Therefore, the light output can be increased.

The ridge portion is formed by removing a part of the second-conductivity-type clad layer portion, or the second-conductivity-type clad layer portion is formed of a plurality of layers, and a current constriction structure is provided in the ridge portion to refract With the structure in which the index guiding mechanism is provided, the mode control of the laser light can be accurately performed.

According to the method of manufacturing a semiconductor laser device of the present invention, when a plurality of semiconductor layers are stacked to form a window structure or a current injection opening, an In surface that will become a regrowth surface later is formed.
A GaAs cap layer is laminated on the GaP cap layer, and the GaAs cap layer is used as a mask to remove a predetermined portion of the layer below the GaAs cap layer.
By using the step of removing the cap layer,
By preventing a natural oxide film from being formed on the InGaP cap layer and preventing the layer from being transformed by the direct formation of a resist layer, and by preventing the adhesion of organic substances that tend to remain on the regrowth surface, Generation of crystal defects can be suppressed, and device characteristics and reliability can be improved.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to FIGS. In each figure,
(A) is a side sectional view taken along a plane including an active region, and (b) is a sectional view taken along the line AA '(a sectional view of a central portion of a semiconductor laser device in a direction perpendicular to a resonance direction). Yes,
(C) is a BB 'cross-sectional view (a cross-sectional view near the element end face in a direction perpendicular to the resonance direction of the semiconductor laser element).

A first embodiment of the present invention is shown in FIG.
The structure will be described together with the manufacturing process. First, n-Ga is formed on an n-GaAs substrate 101 by metal organic chemical vapor deposition.
_1-z1 Al _z1 As cladding layer 102 (0.57 ≦ z1 ≦ 0.8), n or i-In _0.49 Ga _0.51 P lower optical waveguide layer 103, i-
In _x1 Ga _1-x1 As _1-y1 P _y1 lower barrier layer 104 (0 ≦ x1 ≦
0.3, 0 ≦ y1 ≦ 0.6), In _x3 Ga _1-x3 As _1-y3 P _y3 compressive strain quantum well active layer 105 (0.49y3 <x3 ≦ 0.4, 0 ≦ y3 ≦ 0.
1), i-In _x1 Ga _1-x1 As _1-y1 P _y1 upper barrier layer (5
106), In _0.49 Ga _0.51 P cap layer (10 nm
About 107) are laminated. A resist is applied on this cap layer 107, and by ordinary lithography, at a predetermined resonator long period.

[Equation 1] Stripe-shaped part extending in the direction and having a width of about 40 μm
Of the resist is removed, and this resist is used as a mask.
In hydrochloric acid etching solution_O.49Ga_0.51P cap layer
Etching 107, In_x1Ga_1-x1As_1-y1P_y1Upper part
The barrier layer 106 is exposed. At this time, etching with hydrochloric acid
By using a liquid, In_x1Ga_1-x1As _1-y1P_y1Up
The etching automatically stops on the upper surface of the partial barrier layer 106.
After removing the resist, I
n_O.49Ga_O.51P until the lower optical waveguide layer 103 is exposed
Ching. At this time, use a sulfuric acid-based etching solution.
And by In_O.49Ga_0.51P upper surface of lower optical waveguide layer 103
Etching stops automatically at. In this way,
Layer 105, lower and upper barrier layers 104, 106, In_O.49Ga
_0.51Width of P cap layer 107 including the cavity end face setting position 4
Strip the 0 μm striped part (the part near the end face)
It

Then, p or i-In _O.49 Ga _O.51 P is _formed so as to fill the removed portion in the vicinity of the end face.
The upper optical waveguide layer 108 is grown, and p-Ga _{1 -z 1} Al is further grown.
_z1 As first cladding layer 109, p-In _0.49 G _0.51 P first etching stop layer (about 10 nm) 110, GaAs second etching stop layer (about 10 nm) 111, n-In _O.5 (Ga
_1-z2 Al _z2 ) _0.5 P current confinement layer 112 (0.2 ≦ z2 ≦ 1), n
-In _0.49 Ga _0.51 P cap layer 113 and GaAs
A cap layer (not shown) is formed. After that, after applying a resist, the resist in the stripe region corresponding to the current injection opening having a width of about 1 to 3 μm in the <011> direction perpendicular to the previously removed stripe portion is removed, and this resist is used as a mask. Then, the striped portion of the GaAs cap layer exposed from the resist, which corresponds to the current injection opening, is removed with a sulfuric acid-based etching solution. At this time, In _O.49
The etching automatically stops on the upper surface of the Ga _O.51 P cap layer 113. After that, the resist is removed, and the GaAs cap layer is used as a mask to etch GaAs with a hydrochloric acid-based etching solution.
In _O.49 Ga exposed on the striped portion of the cap layer
The striped portion of the _O.51 P cap layer 113 was removed to form a current injection opening, and then n-In _O.5 (Ga
The striped portion of the _1-z2 Al _z2 ) _0.5 P current confinement layer 112 is removed to form a current injection opening. Then, the GaAs cap layer used as the mask is removed with a sulfuric acid-based etching solution, and at the same time, the GaAs second etching stop layer 111 is removed.
The striped portion is removed to form a current injection opening.

Subsequently, a p-Ga _{1 -z 1} Al _z1 As second cladding layer 115 and a p-GaAs contact layer 116 are grown, a p-side electrode 117 is formed on the contact layer 116, and then the substrate 101 is polished. Then, the n-side electrode 118 is formed on this polished surface. Here, the p-type first clad layer 109 to the p-type second clad layer 115 constitute a p-type clad layer portion (second conductivity type clad layer portion) 120.

After that, a high reflectivity coat is applied to one of the resonator faces formed by cleaving the sample at the cavity end face setting position, and a low reflectivity coat is applied to the other face, and further a chip is formed to complete a semiconductor laser device.

The film thickness of the p-type first cladding layer 109, p
The composition of the first and second clad layers 109 and 115 is such that the fundamental transverse mode oscillation can be realized up to a high output. That is, the equivalent refractive index step is 1.5 × 10 ⁻³ to 7 × 10
Set it to be ^-3 . The composition of each clad layer may be any composition having a bandgap larger than the bandgap of the optical waveguide layer. In addition to the above-mentioned GaAlAs, InG that lattice-matches the GaAs substrate 101 is used.
It is also possible to use the aAlP or InGaAlAsP system. Also, the active layer may be a multiple quantum well.

Further, in the manufacturing process for removing the portion near the end face, Ga is _{formed on} the In _O.49 Ga _O.51 P cap layer 107.
The As cap layer (about 10 nm) is laminated, and this GaAs
Apply a resist on the cap layer and apply ordinary lithography at a specified resonator long period.

[Equation 2] Direction, the resist of the striped portion having a width of about 40 μm is removed, and this resist is used as a mask.
The GaAs cap layer is striped with a sulfuric acid-based etching solution, and after removing the resist, the GaAs cap layer is used as a mask and the hydrochloric acid-based etching solution is used to _{remove InO.49GaO.51.}
After removing the P cap layer 107, the entire GaAs cap layer used as the mask was removed with a sulfuric acid-based etching solution, and at the same time, the In _O.49 Ga _O.51 P lower optical waveguide layer 103 was removed.
You may use the process of etching until it is exposed. By using the step of _{forming the} GaAs cap layer on the In _O.49 Ga _0.51 P cap layer 107 and removing the GaAs cap layer later, it is possible to prevent the adhesion of organic substances and the like remaining on the regrowth surface. .

A second embodiment of the present invention is shown in FIG.
Only the differences from the semiconductor laser device according to the first embodiment will be described, the same layers will be denoted by the same reference numerals, and detailed description thereof will be omitted.

The steps up to the formation of the p-GaAs contact layer 116 are exactly the same as the manufacturing steps of the first embodiment. After forming the p-GaAs contact layer 116, the active layer 105
The p-GaAs contact layer 116 in the striped region corresponding to the region (the portion near the end face) from which is removed is removed, and the contact layer removed portion is covered with the insulating film 119. That is,
Instead of the contact layer 116, an insulating film 119 is provided near the end face.
To form. Thereby, the injection of current into the window region (portion near the end face) can be significantly suppressed, and the light output can be increased.

A third embodiment of the present invention is shown in FIG.
The structure will be described together with the manufacturing process. First, n-Ga is formed on the n-GaAs substrate 121 by metalorganic vapor phase epitaxy.
_1-z1 Al _z1 As cladding layer 122 (0.57 ≦ z1 ≦ 0.8), n or i-In _O.49 Ga _O.51 P lower optical waveguide layer 123, i-
In _x2 Ga _1-x2 As _1-y2 P _y2 lower barrier layer 124 (O ≦ x2 ≦ 0.
3, x2 = 0.49y2, about 10 nm), i-In _x4 Ga _1-x4 A
s _1-y4 P _y4 lower tensile strain barrier layer 125 (0.49y4> x4 ≧ 0,
0 <y4 ≦ 0.5), In _x3 Ga _1-x3 As _1-y3 P _y3 compressive strain quantum well active layer 126 (0.49y3 <x3 ≦ 0.4, 0 ≦ y3 ≦ 0.1),
i-In _x4 Ga _1-x4 As _1-y4 P _y4 upper tensile strain barrier layer 12
7, i-In _x2 Ga _1-x2 As _1-y2 P _y2 upper barrier layer (10n
128, In _O.49 Ga _O.51 P cap layer (5 nm)
Degree) 129 is laminated. A resist is coated on this cap layer 129, and by a normal lithography, at a predetermined resonator long period.

[Equation 3] Stripe-shaped part extending in the direction and having a width of about 40 μm
Of the resist is removed, and this resist is used as a mask.
In hydrochloric acid etching solution_O.49Ga_0.51P cap layer
Etching 129, In_x2Ga_1-x2As_1-y2P_y2Upper part
The barrier layer 128 is exposed. At this time, etching with hydrochloric acid
By using a liquid, In_x2Ga_1-x2As _1-y2P_y2Up
The etching automatically stops on the upper surface of the partial barrier layer 128.
After removing the resist, I
n_O.49Ga_O.51P until the lower optical waveguide layer 123 is exposed
Ching. At this time, use a sulfuric acid-based etching solution.
And by In_O.49Ga_O.51P Upper surface of lower optical waveguide layer 123
Etching stops automatically at. In this way,
Layer 126, lower and upper tensile strain barrier layers 125, 127, lower
And upper barrier layers 124, 128, In_O.49Ga_0.51P Cap
The strike layer 129 has a width of 40 μm including the cavity end face setting position.
The lip-shaped portion (portion near the end face) is removed.

Subsequently, p or i-In _0.49 Ga _0.51 P is formed so as to fill the removed portion in the vicinity of the end face.
The upper optical waveguide layer 130 is grown, and p-Ga _{1 -z 1} Al is further grown.
_z1 As first cladding layer 131, p-In _O.49 Ga _O.51 P first etching stop layer (about 10 nm) 132, GaAs second etching stop layer (about 10 nm) 133, n-In _O.5 (G
a _1-z2 Al _z2 ) _0.5 P current confinement layer 134 (O.2 ≦ z2 ≦ 1),
An n-In _O.49 Ga _O.51 P cap layer 135 is formed. After that, after applying a resist, the resist in the stripe region corresponding to the current injection opening having a width of about 1 to 3 μm in the <011> direction perpendicular to the previously removed stripe portion is removed, and this resist is used as a mask. , N-In _O.49 Ga
_O.51 P cap layer 135, n-In _O.5 (Ga _{1-z 2} Al _{z 2} ).
The stripe-shaped portion of the _O.5P current confinement layer 134 is removed to form a current injection opening. At this time, etching automatically stops on the upper surface of the GaAs second etching stop layer 133. After that, the resist is removed and a Ga-based etching solution is used to remove Ga.
The striped portion of the As second etching stop layer 133 is removed to form a current injection opening.

Subsequently, a p-Ga _{1 -z 1} Al _z1 As second cladding layer 137 and a p-GaAs contact layer 138 are grown, a p-side electrode 139 is formed on the contact layer 138, and then the substrate 121 is polished. Then, the n-side electrode 140 is formed on this polished surface.

After that, a high reflectivity coat is applied to one of the resonator faces formed by cleaving the sample at the cavity end face setting position, and a low reflectivity coat is applied to the other face, and further a chip is formed to complete a semiconductor laser device.

The film thickness of the p-type first clad layer 131 and the composition of the p-type second clad layer are set such that fundamental transverse mode oscillation can be realized up to a high output. That is, set to the equivalent refractive index step is 7 × lO ^-3 from 1.5 × 10 ^-3.
Further, the composition of each clad layer may be any composition having a bandgap larger than that of the optical waveguide layer. In addition to the above-mentioned GaAlAs, InGaAlP or InGaA lattice-matched to the GaAs substrate 101 can be used.
The lAsP system can also be used. The active layer may be a multi-quantum well, but the absolute value of the sum of the product of the strain amount and the thickness of the tensile strain barrier layer and the compressive strain active layer is within 0.3 nm.

A fourth embodiment of the present invention is shown in FIG.
The structure will be described together with the manufacturing process. First, n-Ga is formed on the n-GaAs substrate 141 by metal organic chemical vapor deposition.
_1-z1 Al _z1 As cladding layer 142 (0.57 ≦ z1 ≦ 0.8), n or i-In _O.49 Ga _0.51 P lower optical waveguide layer 143, i-
In _x1 Ga _1-x1 As _1-y1 P _y1 lower barrier layer 144 (0 ≦ x1 ≦
0.3,0 ≦ y1 ≦ 0.6), In _x3 Ga _1-x3 As _1-y3 P _y3 compressive strain quantum well active layer 145 (O.49y3 <x3 ≦ O.4, O ≦ y3 ≦ 0.
1), i-In _x1 Ga _1-x1 As _1-y1 P _y1 upper barrier layer (5
146, In _0.49 Ga _O.51 P cap layer ( _{10 n}
Approximately m) 147 is laminated. A resist is applied on the cap layer 147, and by a normal lithography, at a predetermined resonator long period.

[Equation 4] Stripe-shaped part extending in the direction and having a width of about 40 μm
Of the resist is removed, and this resist is used as a mask.
In hydrochloric acid etching solution_0.49Ga_0.51P cap layer
Etching 147, In_x1Ga_1-x1As_1-y1P_y1Upper part
Barrier layer 146 is exposed. At this time, etching with hydrochloric acid
By using a liquid, In_x1Ga_1-x1As _1-y1P_y1Up
The etching automatically stops on the upper surface of the partial barrier layer 146.
After removing the resist, I
n_O.49Ga_O.51P until the lower optical waveguide layer 143 is exposed
Ching. At this time, use a sulfuric acid-based etching solution.
And by In_O.49Ga_O.51P upper surface of lower optical waveguide layer 143
Etching stops automatically at. In this way,
Layer 145, lower and upper barrier layers 144,146, In_O.49Ga
_0.51Width of the P cap layer 147 including the cavity end face setting position 4
Strip the 0 μm striped part (the part near the end face)
It

Subsequently, p or i-In _O.49 Ga _O.51 P is _formed so as to fill the removed portion in the vicinity of the end face.
Upper optical waveguide layer 148, GaAs etching stop layer (about 10 nm) 149, n-In _O.5 (Ga _{1-z 2} Al _{z 2} ) _0.5 P current confinement layer 150 (0.2 ≦ _{z 2} ≦ 1), n-In _O.49 A Ga _O.51 P cap layer 151 and a GaAs cap layer (not shown) are formed. After this, a resist is applied, and then a region resister having a width of 1 to 3 μm is removed in the <011> direction perpendicular to the previously stripped portion, and the resist is used as a mask to remove the GaAs cap with a sulfuric acid-based etching solution. The striped portion of the layer is removed to form a current injection opening. At this time, the etching automatically stops on the upper surface of the In _O.49 Ga _O.51 P cap layer 151. Then remove the resist,
The GaAs cap layer as a mask, a hydrochloric acid-based etching solution, In _O.49 Ga _O.51 P cap layer 151, n-In _O.5
The striped portion of the (Ga _{1 -z 2} Al _{z 2} ) _O.5 P current confinement layer 150 is removed to form a current injection opening. The GaAs cap layer used also as a mask is removed and GaA
s Striped portions of the etching stop layer 149 are removed to form current injection openings.

Subsequently, a p-Ga _{1 -z 1} Al _z1 As second cladding layer 153 and a p-GaAs contact layer 154 are grown, a p-side electrode 155 is formed on the contact layer 154, and then the substrate 141 is polished. Then, the n-side electrode 156 is formed on this polished surface.

Thereafter, one side of the cavity surface formed by cleaving the sample at the cavity end face setting position is coated with a high reflectance and the other side is coated with a low reflectance, and the semiconductor laser device is completed by chipping.

The thickness of the upper optical waveguide layer 148 and p
The composition of the mold second clad layer 153 is set to a thickness capable of realizing fundamental transverse mode oscillation up to high output. That is, the equivalent refractive index step is set to be 1.5 × 10 ⁻³ to 7 × 10 ⁻³ .

A fifth embodiment of the present invention is shown in FIG.
The structure will be described together with the manufacturing process. First, n-Ga is formed on an n-GaAs substrate 161 by a metal organic chemical vapor deposition method.
_1-z1 Al _z1 As cladding layer 162 (0.57 ≦ z1 ≦ 0.8), n or i-In _O.49 Ga _O.51 P lower optical waveguide layer 163 (5n
m), i-In _x1 Ga _1-x1 As _1-y1 P _y1 lower barrier layer
164 (0 ≦ x1 ≦ 0.3, 0 ≦ y1 ≦ 0.6, about 10 nm), In
_x3 Ga _1-x3 As _1-y3 P _{y 3} compressive strained quantum well active layer 165 (O.4
9y3 <x3 ≦ O.4, O ≦ y3 ≦ 0.1), i-In _x1 Ga _{1 -x1} As
_1-y1 P _y1 upper barrier layer (about 10 nm) 166, In _O.49 Ga
_{An O.51} P cap layer (about 5 nm) 167 is laminated. A resist is applied on this cap layer 167, and by a normal lithography, at a predetermined resonator long period.

[Equation 5] Stripe-shaped part extending in the direction and having a width of about 40 μm
Of the resist is removed, and this resist is used as a mask.
In hydrochloric acid etching solution_O.49Ga_O.51P cap layer
Etching 167, In_x1Ga_1-x1As_1-y1P_y1Upper part
The barrier layer 166 is exposed. At this time, etching with hydrochloric acid
By using a liquid, In_x1Ga_1-x1As _1-y1P_y1Up
The etching automatically stops on the upper surface of the partial barrier layer 166.
After removing the resist, I
n_O.49Ga_0.51P until the lower optical waveguide layer 163 is exposed
Ching. At this time, use a sulfuric acid-based etching solution.
And by In_O.49Ga_O.51P upper surface of lower optical waveguide layer 163
Etching stops automatically at. In this way,
Layer 165, lower and upper barrier layers 164,166, In_O.49Ga
_0.51Width of P cap layer 167 including the cavity end face setting position 4
Strip the 0 μm striped part (the part near the end face)
It

Subsequently, p or i-In _O.49 Ga _O.51 P is _formed so as to fill the removed portion near the end face.
Upper optical waveguide layer _{168, p-Ga 1-z1} Al z1 As first cladding layer _{169, p-In O.49 Ga 0.51} P etching stop layer (1
170 nm, p-Ga _{1-z 1} Al _z1 As second cladding layer 171, and p-GaAs contact layer 172 are grown. Further, an insulating film (not shown) is formed, and 1 to 3 μm of this insulating film is formed.
The striped portion in the <011> direction of about m is left, and the other portions are removed. Using this insulating film as a mask,
P-GaAs contact layer 17 with sulfuric acid etching solution
2. The ridge is formed by removing both sides of the stripe-shaped portion of the p-Ga _{1 -z 1} Al _z1 As second cladding layer 171. Subsequently, the insulating film 173 is formed, and the current injection opening is formed only in the upper portion of the ridge by ordinary lithography. A p-side electrode 174 is formed so as to cover the current injection opening, and then the substrate 161 is formed.
Then, the n-side electrode 175 is formed on the polished surface.

Thereafter, one side of the cavity surface formed by cleaving the sample at the cavity end face setting position is coated with a high reflectance and the other side is coated with a low reflectance, and the semiconductor laser element is completed by chipping.

The film thickness of the p-type second clad layer is set to a value that can realize fundamental transverse mode oscillation up to high output. That is, the equivalent refractive index step is set to be 1.5 × 10 ⁻³ to 7 × 10 ⁻³ .

A sixth embodiment of the present invention is shown in FIG.
Here, only the differences from the semiconductor laser device of the fifth embodiment will be described, the same layers will be given the same reference numerals, and detailed description thereof will be omitted.

The semiconductor laser device of the sixth embodiment is
The upper optical waveguide layer 16 of the semiconductor laser device of the fifth embodiment
P-Ga _1-z1 Al _z1 As first cladding layer 169, p-In _O.49 Ga _O.51 P etching stop layer 1 formed on
It does not have 70. In this way, the p-type clad layer portion may be composed of only one p-type clad layer.

In this case, the thickness of the upper optical waveguide layer 168 is set to a value capable of realizing fundamental transverse mode oscillation up to high output. That is, the equivalent refractive index step is from 1.5 × 10 ⁻³ to 7 × 10
Set it to ^-3 .

Semiconductor According to Each Embodiment of the Present Invention
The laser element is In_x3Ga_1-x3As _y3P_1-y3Compressive strain activity
Control layer composition in the range of 0.49y3 <x3≤0.4, 0≤y3≤0.1
The oscillation wavelength is 900 <λ <1200 (n
It can be controlled in the range of m).

As a method for growing each of the above semiconductor layers, a molecular beam epitaxial growth method using a solid or gas as a raw material may be used.

In particular, a suffix with no range specified
x, y, z, etc. are numerical values in the range of 0 or more and 1 or less, and are appropriately determined depending on the lattice matching or mismatching conditions, the size of the band gap, the size of the refractive index with respect to the oscillation wavelength, and the like.

Although the n-type conductive substrate is used as the GaAs substrate in the above-mentioned embodiments, a p-type conductive substrate may be used. In that case, the conductivity of each layer is reversed. It may be stacked.

The semiconductor laser device of each of the above-mentioned embodiments is
Both of them can generate laser light with a high level of optical output while maintaining the basic transverse mode. INDUSTRIAL APPLICABILITY The present invention can obtain similar effects not only in a laser that oscillates in a fundamental transverse mode but also in a semiconductor laser device that oscillates in a multimode having an oscillation region width of 3 μm or more, and enables high-power oscillation with low noise. A highly reliable multi-mode oscillation semiconductor laser can be obtained.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a semiconductor laser device according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a semiconductor laser device according to a third embodiment of the present invention.

FIG. 4 is a sectional view showing a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view showing a semiconductor laser device according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view showing a semiconductor laser device according to a sixth embodiment of the present invention.

[Explanation of symbols]

101 n-GaAs substrate 102 n-Ga _1-z1 Al _z1 As clad layer 103 n or i-In _0.49 Ga _0.51 P lower optical waveguide layer 104 i-In _x1 Ga _1-x1 As _1-y1 P _y1 lower barrier layer 105 In _x3 Ga _1-x3 As _1-y3 P _y3 compressive strain quantum well active layer 106 i-In _x1 Ga _1-x1 As _1-y1 P _y1 upper barrier layer 107 In _0.49 Ga _0.51 P cap layer 108 p or i-In _0.49 Ga _0.51 P upper optical waveguide layer 109 p-Ga _{1 -z1} Al _z1 As first cladding layer 110 p-In _0.49 Ga _0.51 P first etching stop layer 111 GaAs second etching stop layer 112 n-In _0.5 (Ga _{1 -z2} A1 _z2 ) _0.5 P current constriction layer 113 n-In _0.49 Ga _0.51 P cap layer 115 p-Ga _1-z1 Al _z1 As second cladding layer 116 p-GaAs contact layer 117 p-side electrode 118 n-side electrode 119 insulation Membrane 120 Second conductivity type clad layer

Claims (12)

[Claims] 1. A first-conductivity-type GaAs substrate, a first-conductivity-type clad layer, a first-conductivity-type or undoped InGaP lower optical waveguide layer, a compressive strain active layer made of InGaAsP or InGaAs, a second-conductivity-type or undoped InGaP upper optical waveguide layer, and a semiconductor laser device comprising a semiconductor layer in which a second conductivity type cladding layer portion is laminated in this order, wherein the compressive strain active layer is provided between the lower optical waveguide layer and the compressive strain active layer. An InGaAsP lower barrier layer having a bandgap larger than that of the layer, the InGaAsP upper barrier having a bandgap larger than that of the compressive strain active layer between the compressive strain active layer and the upper optical waveguide layer. A layer, wherein the semiconductor layer of the lower barrier layer, the compressive strain active layer and the upper barrier layer is A portion of the opened end face adjacent to two opposite end faces constituting the cavity end face is removed, and the lower and upper optical waveguide layers have a band gap larger than that of the compressive strain active layer. The semiconductor laser device is characterized in that the upper optical waveguide layer is embedded in a portion where the lower barrier layer, the compressive strain active layer and the upper barrier layer are removed. 2. The compressive strain active layer is 0.49y3 <x3 ≦ 0.4.
And a _{0 ≦ y3 ≦ 0.1 In x3 Ga} 1-x3 As 1-y3 P y3
The semiconductor laser device according to claim 1, comprising: 3. A contact layer of the second conductivity type in a region on the second conductivity type clad layer portion except a region corresponding to a portion where the lower barrier layer, the compressive strain active layer and the upper barrier layer are removed. And an insulating film is formed on a region of the second conductivity type clad layer portion corresponding to a portion where the lower barrier layer, the compressive strain active layer and the upper barrier layer are removed. The semiconductor laser device according to claim 1 or 2. 4. The second conductivity type clad layer portion is formed by removing both sides of a striped portion extending from one side to the other of the cavity end surface to a predetermined position from the upper surface side of the second conductivity type clad layer portion. 4. The semiconductor laser device according to claim 1, further comprising a ridge portion formed therein. 5. The second-conductivity-type cladding layer portion is provided from one of the upper optical waveguide layer side, the second-conductivity-type first cladding layer, the second-conductivity-type InGaP first etching stop layer, and one of the resonator end faces. A GaAs second etching stop layer having a stripe-shaped current injection opening extending to the other side; a first conductivity type InGaAlP current confinement layer having a stripe-shaped current injection opening extending from one of the resonator end faces to the other; A first conductivity type InGaP cap layer having a stripe-shaped current injection opening extending from one to the other;
4. The semiconductor laser device according to claim 1, further comprising a second conductivity type second cladding layer in this order. 6. The GaAs etching stop layer, wherein the second conductivity type clad layer portion has a stripe-shaped current injection opening extending from one side of the cavity end face to the other from the upper optical waveguide layer side, the cavity end face. A first conductivity type InGaAlP current confinement layer having a stripe-shaped current injection opening extending from one side to the other; a first conductivity type InGaP cap layer having a stripe-shaped current injection opening extending from one side of the resonator end face to the other side;
4. The semiconductor laser device according to claim 1, further comprising a second conductivity type cladding layer in this order. 7. The AlGaAs, InGaAlP, InGa in which each of the cladding layers is lattice-matched with the GaAs substrate.
7. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is made of any one of AlAsP. 8. The lower and upper barrier layers, respectively,
In _x1 Ga _{1 -x1} A with 0 ≦ x1 ≦ 0.3 and 0 ≦ y1 ≦ 0.6
_8. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is made of s _{1 -y1} P _y1 . 9. The lower and upper barrier layers, respectively,
In _x2 Ga ₁ -x2 A with 0 ≦ x2 ≦ 0.3 and x2 = 0.49y2
s _1-y2 P _y2 barrier layer and 0.49y4> x4 ≧ 0 and 0 <y4 ≦ 0.
5 of In _x4 Ga _1-x4 As _1-y4 P _y4 tensile strain barrier layer, and the tensile strain barrier layer of the two layers is arranged adjacent to the compressive strain active layer. 8. The semiconductor laser device according to claim 1, wherein the semiconductor laser device is a semiconductor laser device. 10. A method of manufacturing a semiconductor laser device, comprising: a substrate, a plurality of semiconductor layers including a compressive strain active layer, which are stacked, and a cavity end face formed by two opposing end faces. A first conductivity type clad layer on a first conductivity type GaAs substrate; a first conductivity type or undoped InG having a bandgap larger than that of the compressive strain active layer;
aP lower optical waveguide layer, InGaAsP lower barrier layer having a band gap larger than the band gap of the compressive strain active layer, the compressive strain active layer made of InGaAsP or InGaAs, having a band gap larger than the band gap of the compressive strain active layer. An InGaAsP upper barrier layer, an InGaP cap layer, and a GaAs cap layer are laminated in this order, a portion of the GaAs cap layer near the end face adjacent to the resonator end face is removed, and the InGaP layer is used as a mask.
A portion of the cap layer near the end face is removed, and at the same time, the GaAs cap layer used as the mask is removed, and at the same time, the InGaP cap layer is used as a mask to near the end face of the upper barrier layer, the compressive strain active layer, and the lower barrier layer. Removing the portion, and forming a second conductivity type or undoped InGaP upper optical waveguide layer having a bandgap larger than the bandgap of the compressive strain active layer on the removed end face vicinity portion and the InGaP cap layer, A method of manufacturing a semiconductor laser device, further comprising forming a second conductivity type clad layer portion on the upper optical waveguide layer. 11. A second conductivity type first clad layer, a second conductivity type InGaP first etching stop layer, a GaAs second etching stop layer, the second conductivity type clad layer portion from the upper optical waveguide layer side. First conductivity type InGaAlP current confinement layer, first conductivity type InGaP cap layer, and second GaAs
A cap layer is laminated in this order, a portion of the second GaAs cap layer corresponding to the stripe-shaped current injection opening is removed, and then the first conductivity type InGaP cap is formed using the second GaAs cap layer as a mask. Layer, the current confinement layer, and the portion to be the current injection opening are removed, and the second GaAs cap layer used as the mask is removed. At the same time, the second conductivity type InGaP cap layer is used as the mask. 11. The semiconductor laser device according to claim 10, wherein a portion which becomes the current injection opening is removed, and a second conductivity type second cladding layer is formed so as to cover the current injection opening. Production method. 12. The GaAs etching stop layer, the first conductivity type InGaAlP current confinement layer, the first conductivity type InGaP cap layer, and the second GaAs from the upper optical waveguide layer side in the second conductivity type clad layer portion.
A cap layer is laminated in this order, a portion of the second GaAs cap layer corresponding to the stripe-shaped current injection opening is removed, and then the first conductivity type InGaP cap is formed using the second GaAs cap layer as a mask. Layer and the portion of the current confinement layer to be the current injection opening are removed, and the second GaAs cap layer used as the mask is removed. At the same time, the first conductivity type InGaP cap layer is used as a mask to remove the GaAs etching stop layer. 2. A part which becomes the current injection opening is removed, and a second conductivity type clad layer is formed so as to cover the current injection opening.
0. A method for manufacturing a semiconductor laser device described in 0.