Semiconductor laser element and method for producing semiconductor laser element

Abstract

A semiconductor laser element (1) comprises a semiconductor layered body (1S). The semiconductor layered body (1S) includes an n-type cladding layer (30) containing In, an active layer (42) containing In, a p-type cladding layer (50) containing In, and a contact layer (70). The semiconductor layered body (1S) has a first end surface (1F) and a second end surface (1R) constituting a resonator, a gain region into which a current is injected, and a window region (Rw) formed between the first end surface (1F) and the gain region. The p-type cladding layer (50) is doped with Mg, and Zn is diffused in the window region (Rw). When the Mg concentration in a portion of the p-type cladding layer (50) located in the gain region is represented by Na, the Mg concentration in a portion of the p-type cladding layer (50) located in the window region (Rw) is represented by Nw, and the Zn concentration in a portion of the p-type cladding layer (50) located in the window region (Rw) is represented by Nz, the relationships Na>10Nw and Nz>Nw are satisfied.

Description

Semiconductor laser element and method for manufacturing semiconductor laser element

[0001] The present disclosure relates to a semiconductor laser device and a method for manufacturing a semiconductor laser device.

[0002] Semiconductor laser elements have been known as compact, high-power light sources. To ensure the reliability of such semiconductor laser elements, a technique has been known in which a window region with an increased energy band gap is formed near the light-emitting end face by impurity diffusion (see, for example, Patent Document 1). This technique aims to suppress the absorption of laser light near the light-emitting end face and the temperature rise that accompanies the absorption of laser light.

[0003] Japanese Patent Application Laid-Open No. 2017-026953

[0004] However, since the laser light is absorbed by the impurities diffused in the window region, the power of the laser light output from the semiconductor laser element and the COD (Catastrophic Optical Damage) level can be suppressed.

[0005] The present disclosure has been made to solve such problems, and has an object to provide a semiconductor laser element and the like that can reduce absorption of laser light in the window region.

[0006] In order to achieve the above object, one aspect of a semiconductor laser device according to the present disclosure is a semiconductor laser device that includes a semiconductor laminate and emits laser light, the semiconductor laminate including an n-type cladding layer made of a III-V semiconductor containing In, an active layer arranged above the n-type cladding layer and made of a III-V semiconductor containing In, a p-type cladding layer arranged above the active layer and made of a III-V semiconductor containing In, and a contact layer arranged above the p-type cladding layer, the semiconductor laminate being located at an end in a direction perpendicular to the stacking direction, the p-type cladding layer is doped with Mg as an impurity, and the window region is diffused with Zn; and the Mg concentration in the portion of the p-type cladding layer located in the gain region is represented by Na, the Mg concentration in the portion of the p-type cladding layer located in the window region is represented by Nw, and the Zn concentration in the portion of the p-type cladding layer located in the window region is represented by Nz, the relationships Na>10Nw and Nz>Nw hold.

[0007] In order to achieve the above object, one aspect of a method for manufacturing a semiconductor laser device according to the present disclosure is a method for manufacturing a semiconductor laser device that emits laser light, the semiconductor laser device including a semiconductor laminate, the semiconductor laminate having an n-type cladding layer made of a III-V group semiconductor containing In, an active layer arranged above the n-type cladding layer and made of a III-V group semiconductor containing In, a p-type cladding layer arranged above the active layer and made of a III-V group semiconductor containing In, and a contact layer arranged above the p-type cladding layer, the semiconductor laminate being located at ends in a direction perpendicular to a stacking direction and including a first end facet and a second end facet that constitute a cavity in which the laser light resonates, a gain region into which a current is injected, and a window region formed between the first end facet and the gain region. a semiconductor layered film including an n-type cladding film made of a III-V semiconductor containing In, an active film disposed above the n-type cladding film and made of a III-V semiconductor containing In, a p-type cladding film disposed above the active film and made of a III-V semiconductor containing In, and a contact film disposed above the p-type cladding film; and a window region forming step of forming the semiconductor layered film by forming the window region, wherein the window region forming step includes a cap layer forming step of forming a cap layer containing In in a region on the contact film that is located above a region corresponding to the window region, and a diffusion source layer forming step of forming a diffusion source layer containing Zn on the cap layer.

[0008] In order to achieve the above object, another aspect of a manufacturing method of a semiconductor laser device according to the present disclosure is a manufacturing method of a semiconductor laser device that emits laser light, the semiconductor laser device including a semiconductor laminate, the semiconductor laminate having an n-type cladding layer made of a III-V group semiconductor containing In, an active layer arranged above the n-type cladding layer and made of a III-V group semiconductor containing In, a p-type cladding layer arranged above the active layer and made of a III-V group semiconductor containing In, and a contact layer arranged above the p-type cladding layer, the semiconductor laminate being located at ends in a direction perpendicular to a stacking direction and including first and second end faces that constitute a cavity in which the laser light resonates, a gain region into which a current is injected, and a contact layer arranged above the first end face. a window region formed between the facet and the gain region, and a manufacturing method of the semiconductor laser element includes a lamination step of forming a semiconductor laminated film having an n-type cladding film made of a III-V semiconductor containing In, an active film arranged above the n-type cladding film and made of a III-V semiconductor containing In, a p-type cladding film arranged above the active film and made of a III-V semiconductor containing In, and a contact film arranged above the p-type cladding film; and a window region forming step of forming the semiconductor laminated film by forming the window region, wherein the window region forming step includes a diffusion source layer forming step of forming a diffusion source layer containing Zn in a region above the p-type cladding film where the contact film is not arranged.

[0009] According to the present disclosure, it is possible to provide a semiconductor laser element or the like that can reduce absorption of laser light in a window region.

[0010] FIG. 1 is a schematic top view showing the configuration of a semiconductor laser element according to a first embodiment. FIG. 2 is a schematic first cross-sectional view showing the configuration of a semiconductor laser element according to the first embodiment. FIG. 3 is a schematic third cross-sectional view showing the configuration of a semiconductor laser element according to the first embodiment. FIG. 4 is a schematic cross-sectional view showing the configuration of an active layer included in the semiconductor laser element according to the first embodiment. FIG. 5 is a schematic cross-sectional view showing the configuration of a p-type barrier relaxation layer included in the semiconductor laser element according to the first embodiment. FIG. 6 is a schematic cross-sectional view showing the configuration of a contact layer included in the semiconductor laser element according to the embodiment. FIG. 7 is a diagram showing the configuration of each layer in a semiconductor laminate included in the semiconductor laser element according to the first embodiment. FIG. 8 is a schematic cross-sectional view showing a lamination step in a method for manufacturing the semiconductor laser element according to the first embodiment. FIG. 9 is a schematic cross-sectional view showing a cap layer formation step included in a window region formation step in a method for manufacturing the semiconductor laser element according to the first embodiment. FIG. 10 is a schematic cross-sectional view showing a diffusion source layer formation step and the like included in a window region formation step in a method for manufacturing the semiconductor laser element according to the first embodiment. FIG. 1 is a schematic first cross-sectional view showing a diffusion source layer removal step included in the window region formation step of the method for manufacturing a semiconductor laser device according to the first embodiment. FIG. 2 is a schematic second cross-sectional view showing the diffusion source layer removal step included in the window region formation step of the method for manufacturing a semiconductor laser device according to the first embodiment. FIG. 3 is a schematic first cross-sectional view showing a contact layer removal step included in the window region formation step of the method for manufacturing a semiconductor laser device according to the first embodiment. FIG. 4 is a schematic second cross-sectional view showing a ridge formation step of the method for manufacturing a semiconductor laser device according to the first embodiment. FIG. 5 is a schematic first cross-sectional view showing a current blocking layer formation step of the method for manufacturing a semiconductor laser device according to the first embodiment. FIG. 6 is a schematic second cross-sectional view showing a p-side electrode formation step of the method for manufacturing a semiconductor laser device according to the first embodiment.1 is a graph showing current-optical output characteristics of a semiconductor laser device according to a first embodiment. 2 is a graph showing a change in optical output with respect to aging time of a semiconductor laser device according to the first embodiment. 3 is a schematic cross-sectional view showing an overall configuration of a semiconductor laser device according to a second embodiment. 4 is a schematic cross-sectional view showing a configuration of a contact layer included in the semiconductor laser device according to the second embodiment. 5 is a schematic cross-sectional view showing a removal step included in a window region formation step in a method for manufacturing a semiconductor laser device according to a third embodiment. 6 is a schematic cross-sectional view showing a diffusion source layer formation step and the like included in the window region formation step in a method for manufacturing a semiconductor laser device according to the third embodiment. 7 is a schematic cross-sectional view showing a heating step included in a window region formation step in a method for manufacturing a semiconductor laser device according to the third embodiment. 8 is a schematic cross-sectional view showing a heating step included in a diffusion source layer removal step in a method for manufacturing a semiconductor laser device according to the third embodiment. 10 is a schematic cross-sectional view showing a configuration of a second p-type cladding layer included in a semiconductor laser element according to a fourth embodiment. FIG. 11 is a graph showing an example of distribution of Mg concentration and Al secondary ion intensity with respect to a position in a stacking direction of a semiconductor laser element according to a fourth embodiment.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement and connection of the components, steps (processes), and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

[0012] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like do not necessarily match in each figure. In each figure, the same reference numerals are used to denote substantially the same components, and redundant explanations will be omitted or simplified.

[0013] In this specification, the terms "above" and "below" do not refer to vertically above and below in absolute spatial recognition, but are used as terms defined by a relative positional relationship based on the stacking order in a stacked configuration. The terms "above" and "below" are used not only when two components are arranged with a gap between them and another component is present between them, but also when two components are arranged in contact with each other.

[0014] Furthermore, in this specification, terms indicating the relationship between elements, such as parallel, perpendicular, and equal, terms indicating the shape of elements, and numerical ranges are not expressions that only express a strict meaning, but are expressions that mean that a substantially equivalent range, for example, a difference of about a few percent, is also included.

[0015] First Embodiment A semiconductor laser device according to a first embodiment and a method for manufacturing the same will be described.

[0016] [1-1. Overall Configuration] The overall configuration of the semiconductor laser device according to this embodiment will be described with reference to FIGS. 1 to 8. FIG. 1 is a schematic top view showing the configuration of the semiconductor laser device 1 according to this embodiment. FIGS. 2 to 4 are schematic cross-sectional views showing the configuration of the semiconductor laser device 1 according to this embodiment. FIG. 2 shows a portion of the cross-section taken along line II-II in FIG. 1. FIG. 3 shows a cross-section taken along line III-III in FIGS. 1 and 2. FIG. 4 shows a cross-section taken along line IV-IV in FIGS. 1 and 2. FIG. 5 is a schematic cross-sectional view showing the configuration of the active layer 42 included in the semiconductor laser device 1 according to this embodiment. FIG. 6 is a schematic cross-sectional view showing the configuration of the p-type barrier buffer layer 60 included in the semiconductor laser device 1 according to this embodiment. FIG. 7 is a schematic cross-sectional view showing the configuration of the contact layer 70 included in the semiconductor laser device 1 according to this embodiment. FIGS. 5 to 7 show partial cross-sections of each layer. Note that each drawing shows an X-axis, a Y-axis, and a Z-axis, which are orthogonal to one another. The X-axis, Y-axis, and Z-axis are in a right-handed Cartesian coordinate system. The stacking direction of the semiconductor laser device 1 is parallel to the Z-axis direction, and the main emission direction of the laser light is parallel to the Y-axis direction. In other words, the resonance direction of the laser light is parallel to the Y-axis direction. FIG. 8 is a diagram showing the configuration of each layer in the semiconductor stack 1S provided in the semiconductor laser device 1 according to this embodiment. FIG. 8 shows the composition, film thickness, refractive index, band gap energy (Eg), impurity, and impurity concentration of each layer in the semiconductor stack 1S. Note that the impurity concentrations shown in FIG. 8 are all impurity concentrations in the gain region, which will be described later.

[0017] The semiconductor laser device 1 according to this embodiment is a device that emits laser light. The semiconductor laser device 1 has a resonator in which laser light resonates in a first direction between a first end facet 1F on the front side and a second end facet 1R on the rear side (see FIG. 1 ). The laser light is mainly emitted from the first end facet 1F. The peak wavelength of the laser light is, for example, not less than 620 nm and not more than 860 nm. In this embodiment, the peak wavelength of the laser light is approximately 638 nm.

[0018] 2 and 4, the semiconductor laser device 1 includes a substrate 10, a semiconductor stack 1S disposed above the substrate 10, and a p-side electrode disposed above the semiconductor stack 1S. In this embodiment, the semiconductor laser device 1 includes, as the p-side electrodes, a first p-side electrode 91, a second p-side electrode 92, and a third p-side electrode 93. The semiconductor laser device 1 further includes a current blocking layer 80, an n-side electrode 94, and facet protective films 2F and 2R (see FIG. 1).

[0019] The substrate 10 is an n-type semiconductor substrate on which the semiconductor laminate 1S of the semiconductor laser device 1 is laminated. In this embodiment, the substrate 10 is an n-type semiconductor substrate containing GaAs, and more specifically, an n-type GaAs substrate.

[0020] The semiconductor laminate 1S is a laminate in which semiconductor layers are stacked. The semiconductor laminate 1S is located at the end in the direction perpendicular to the stacking direction (the Y-axis direction in each figure) and has a first end facet 1F and a second end facet 1R that constitute a resonator in which laser light resonates. In this embodiment, the length L of the resonator (i.e., the distance between the first end facet 1F and the second end facet 1R) is approximately 1500 μm. As shown in FIGS. 2 to 4 , the semiconductor laminate 1S includes an n-type cladding layer 30, an active layer 42, a p-type cladding layer 50, and a contact layer 70, which are stacked in this order from the substrate 10 side. In this embodiment, the semiconductor laminate 1S further includes a buffer layer 21, an n-type barrier buffer layer 22, an n-side optical guide layer 41, a p-side optical guide layer 43, and a p-type barrier buffer layer 60.

[0021] 1, 3, and 4, a ridge 50R that protrudes upward is formed in the semiconductor laminate 1S. The semiconductor laminate 1S also has a groove 50T that is disposed along the ridge 50R and extends in the Y-axis direction, and two protrusions 50P that protrude upward. The semiconductor laminate 1S also has a groove 50T that is disposed between the protrusion 50P and the end face of the semiconductor laminate 1S in the X-axis direction and extends in the Y-axis direction. In this embodiment, the width (dimension in the X-axis direction) of the ridge 50R is 75 μm.

[0022] The semiconductor stack 1S also has a current injection region Ri, which is a region in the upper surface of the semiconductor stack 1S into which current is injected. The semiconductor stack 1S also has a gain region into which current is injected. The gain region includes a region of the semiconductor stack 1S located below the current injection region Ri. The gain region may be defined as a region located below the current injection region Ri. In the embodiment, the upper surface of the semiconductor stack 1S has a first region Rn in which the contact layer 70 is not disposed between the current injection region Ri and the first end facet 1F. More specifically, the first region Rn refers to a region on the ridge 50R in which the contact layer 70 is not disposed. The upper surface of the semiconductor stack 1S also includes a first region Rn in which the contact layer 70 is not disposed between the current injection region Ri and the second end facet 1R. The semiconductor stack 1S also has a window region Rw below the first region Rn. In other words, the semiconductor stack 1S has a window region Rw formed between the first end facet 1F and the gain region. In this embodiment, the semiconductor laminate 1S further includes a window region Rw formed between the second end facet 1R and the gain region. In the window region Rw, absorption of laser light in the active layer 42 is suppressed.

[0023] The window region Rw is formed by diffusing a window-region-forming impurity. In this embodiment, Zn is used as the window-region-forming impurity. That is, Zn is diffused into the window region Rw. The window region Rw is a region in which the energy band gap of the active layer 42 is expanded by diffusing the window-region-forming impurity into the semiconductor stack 1S near the first end face 1F and the second end face 1R of the semiconductor laser device 1. In the window region Rw, each layer included in the active layer 42 is intermixed with an adjacent layer. The window region Rw is formed by disordering the quantum well structure of the active layer 42. That is, portions of the quantum well structure near the first end face 1F and the second end face 1R are disordered regions.

[0024] In this embodiment, the width of the window region Rw in the resonance direction (i.e., the width in the Y-axis direction) is smaller than the width of the first region Rn in the resonance direction. This makes it possible to suppress current injection into the window region Rw. Therefore, the reactive current injected into the window region Rw can be reduced, thereby improving the power efficiency of the semiconductor laser device 1. As shown in FIG. 2 , the width Dw of the window region Rw in the resonance direction in the active layer 42 is, for example, 40 μm, and the width of the first region Rn in the resonance direction is greater than 40 μm.

[0025] The window region Rw formed in the active layer 42 (i.e., the window region Rw in the same layer as the active layer 42) includes a stability window region having an energy bandgap 30 meV or more larger than the bandgap energy of the active layer 42, and a transition region whose bandgap energy changes continuously. The stability window region and the transition region are arranged in this order along the resonance direction from the first end facet 1F side. The length Dw1 of the stability window region is the distance from the first end facet 1F to the edge of the stability window region in the resonance direction. The length Dw2 of the transition region is the distance from the boundary between the stability window region and the transition region in the resonance direction to the edge of the Zn-diffused region. In this embodiment, the length Dw1 of the stability window region is 15 μm, and the length Dw2 of the transition region is 25 μm. The length Dw of the window region Rw formed in the active layer 42 is the sum of the length Dw1 of the stability window region and the length Dw2 of the transition region.

[0026] The buffer layer 21 is a semiconductor layer disposed above the substrate 10. In this embodiment, as shown in FIG. 5, the buffer layer 21 has a concentration of 5.0×10 １７ cm －３ The n-type GaAs layer is 0.4 μm thick and is doped with an n-type impurity of . The n-type impurity is not particularly limited, and Si, Se, Te, etc. can be used. In this embodiment, Si is used as the n-type impurity.

[0027] The n-type barrier buffer layer 22 is a semiconductor layer disposed above the substrate 10. In this embodiment, the n-type barrier buffer layer 22 is disposed between the buffer layer 21 and the n-type cladding layer 30, and buffers the conduction band barrier between the buffer layer 21 and the n-type cladding layer 30. This reduces the barrier for electrons moving between the buffer layer 21 and the n-type cladding layer 30, thereby reducing the operating voltage of the semiconductor laser device 1. In this embodiment, the n-type barrier buffer layer 22 has a concentration of 7.5×10 １７ cm －３ n-type Al of 0.075 μm thickness doped with n-type impurities ｘｎａ Ga １－ｘｎａ The Al composition ratio of the n-type barrier buffer layer 22 increases with increasing distance from the substrate 10. The Al composition ratio of the n-type barrier buffer layer 22 is 0.05 at the end closer to the substrate 10 (i.e., the end farther from the n-type cladding layer 30) and is 0.63 at the end farther from the substrate 10 (i.e., the end closer to the n-type cladding layer 30).

[0028] The n-type cladding layer 30 is disposed above the substrate 10 and is a semiconductor layer made of a III-V group semiconductor containing In. In this embodiment, the n-type cladding layer 30 is made of AlGaInP. The n-type cladding layer 30 is disposed between the n-type barrier buffer layer 22 and the n-side optical guide layer 41 and is in contact with both the n-type barrier buffer layer 22 and the n-side optical guide layer 41. The average refractive index of the n-type cladding layer 30 is smaller than the average refractive index of the active layer 42. The Zn concentration at the interface of the portion of the n-type cladding layer 30 located in the window region Rw on the side farther from the active layer 42 (i.e., the lower interface) is 1.0×10 １８ cm －３ That is, in the window region Rw, Zn is diffused up to the lower interface of the n-type cladding layer 30. The Zn concentration in the portion of the n-type cladding layer 30 located in the window region Rw is, for example, 1.6×10 １８ cm －３ In this embodiment, the n-type cladding layer 30 includes a first n-type cladding layer 31 , a second n-type cladding layer 32 , and a third n-type cladding layer 33 .

[0029] In the present disclosure, the average refractive index of each layer refers to the refractive index value obtained by integrating the magnitude of the refractive index at a certain position in the stacking direction of the layer in the stacking direction from the position of the interface closer to the substrate 10 in the stacking direction of the layer to the position of the interface farther from the substrate 10, and dividing the result by the film thickness of the layer (the distance from the interface closer to the substrate 10 to the interface farther from the substrate 10). In the following, the average refractive index will also be simply referred to as the refractive index.

[0030] In addition, the concentration of impurities and the like in each layer refers to an average concentration. In the present disclosure, the average concentration of each layer refers to the concentration value obtained by integrating the magnitude of the concentration at a certain position in the stacking direction of the layer in the stacking direction from the position of the interface closer to the substrate 10 in the stacking direction of the layer to the position of the interface farther from the substrate 10, and dividing the result by the film thickness of the layer (the distance from the interface closer to the substrate 10 to the interface farther from the substrate 10).

[0031] The first n-type cladding layer 31 is disposed above the substrate 10. In this embodiment, the first n-type cladding layer 31 is disposed above the n-type barrier buffer layer 22 and is in contact with the n-type barrier buffer layer 22. In this embodiment, the first n-type cladding layer 31 has a concentration of 7.5×10 １７ cm －３ n-type impurity doped with Al ０．８９ Ga ０．１１ ) ０．５１ In ０．４９ This is the P layer.

[0032] The second n-type cladding layer 32 is disposed above the first n-type cladding layer 31. In this embodiment, the second n-type cladding layer 32 is disposed between the first n-type cladding layer 31 and the third n-type cladding layer 33, and is in contact with both the first n-type cladding layer 31 and the third n-type cladding layer 33. In this embodiment, the second n-type cladding layer 32 has a concentration of 5.0×10 １７ cm －３ n-type impurity doped with Al ０．８９ Ga ０．１１ ) ０．５１ In ０．４９ This is the P layer.

[0033] The third n-type cladding layer 33 is disposed above the second n-type cladding layer 32. In this embodiment, the third n-type cladding layer 33 is disposed between the second n-type cladding layer 32 and the n-side light guide layer 41, and is in contact with both the second n-type cladding layer 32 and the n-side light guide layer 41. In this embodiment, the third n-type cladding layer 33 has a concentration of 3.0×10 １７ cm －３ n-type impurity doped with Al ０．８９ Ga ０．１１ ) ０．５１ In ０．４９ This is the P layer.

[0034] The n-side optical guide layer 41 is a semiconductor layer disposed above the n-type cladding layer 30. The n-side optical guide layer 41 is disposed between the n-type cladding layer 30 and the active layer 42, and is in contact with both the n-type cladding layer 30 and the active layer 42. The average refractive index of the n-side optical guide layer 41 is larger than the average refractive index of the n-type cladding layer 30. In this embodiment, the n-side optical guide layer 41 is an undoped (Al ０．５２ Ga ０．４８ ) ０．５１ In ０．４９ The Zn concentration in the portion of the n-side light guide layer 41 located in the window region Rw is, for example, 1.6×10 １８ cm －３ is.

[0035] The active layer 42 is disposed above the n-type cladding layer 30 and is a light-emitting layer made of a III-V group semiconductor containing In. In this embodiment, the active layer 42 is disposed between the n-side optical guiding layer 41 and the p-side optical guiding layer 43 and is in contact with the n-side optical guiding layer 41 and the p-side optical guiding layer 43. The configuration of the active layer 42 is not particularly limited. In this embodiment, the active layer 42 has a quantum well structure including one or more well layers and two or more barrier layers, and each of the one or more well layers is an AlGaInP layer, a GaInP layer, a GaAsP layer, a GaAs layer, or an InGaAs layer.

[0036] The Zn concentration in the active layer 42 located in the window region Rw is 1.0×10 １８ cm －３In this embodiment, the Zn concentration in the portion of the active layer 42 located in the window region Rw is 1.6×10 １８ cm －３ That's it, 6.0 x 10 １８ cm －３ The following is the result.

[0037] As shown in FIGS. 5 and 8, the active layer 42 according to this embodiment includes a barrier layer 42a, a well layer 42b, and a barrier layer 42c.

[0038] The barrier layer 42a is disposed above the n-type cladding layer 30. In this embodiment, the barrier layer 42a is disposed above the n-side optical guide layer 41 and is in contact with the n-side optical guide layer 41. The barrier layer 42a is an undoped (Al ０．５２ Ga ０．４８ ) ０．５１ In ０．４９ This is the P layer.

[0039] The well layer 42b is disposed between the barrier layer 42a and the barrier layer 42c. In this embodiment, the well layer 42b is in contact with both the barrier layer 42a and the barrier layer 42c. The well layer 42b is an undoped GaInP layer with a thickness of 0.0125 μm.

[0040] The barrier layer 42c is disposed above the well layer 42b. In this embodiment, the barrier layer 42c is disposed between the well layer 42b and the p-side optical guiding layer 43, and is in contact with both the well layer 42b and the p-side optical guiding layer 43. The barrier layer 42c is an undoped (Al ０．５２ Ga ０．４８ ) ０．５１ In ０．４９ This is the P layer.

[0041] The p-side optical guide layer 43 is a semiconductor layer disposed above the active layer 42. The p-side optical guide layer 43 is disposed between the active layer 42 and the p-type cladding layer 50, and is in contact with both the active layer 42 and the p-type cladding layer 50. The average refractive index of the p-side optical guide layer 43 is larger than the average refractive index of the p-type cladding layer 50. In this embodiment, the p-side optical guide layer 43 is an undoped (Al ０．５２ Ga ０．４８ ) ０．５１ In ０．４９The Zn concentration in the portion of the p-side optical guide layer 43 located in the window region Rw is 1.6×10 １８ cm.

[0042] The p-type cladding layer 50 is disposed above the active layer 42 and is a semiconductor layer made of a III-V group semiconductor containing In. In this embodiment, the p-type cladding layer 50 is disposed between the p-side optical guide layer 43 and the p-type barrier buffer layer 60, and is in contact with both the p-side optical guide layer 43 and the p-type barrier buffer layer 60. The average refractive index of the p-type cladding layer 50 is smaller than the average refractive index of the active layer 42. The p-type cladding layer 50 is made of AlInP. The Al composition ratio in the p-type cladding layer 50 may be, for example, 0.5 or more and 0.6 or less. In this embodiment, the p-type cladding layer 50 is made of p-type Al ０．５４ In ０．４６ This is the P layer.

[0043] In this embodiment, the p-type cladding layer 50 is doped with Mg as an impurity, and when the Mg concentration in the portion of the p-type cladding layer 50 located in the gain region is represented by Na, the Mg concentration in the portion of the p-type cladding layer 50 located in the window region Rw is represented by Nw, and the Zn concentration in the portion of the p-type cladding layer 50 located in the window region Rw is represented by Nz, the relationships Na>10Nw and Nz>Nw hold.

[0044] The p-type cladding layer 50 includes a first p-type cladding layer 51 and a second p-type cladding layer 52 .

[0045] The first p-type cladding layer 51 is disposed above the active layer 42. In this embodiment, the first p-type cladding layer 51 is disposed above the p-side optical guide layer 43 and is in contact with the p-side optical guide layer 43. In this embodiment, the first p-type cladding layer 51 is a p-type AlInP layer doped with a p-type impurity and having a thickness of 0.290 μm. In this embodiment, Mg is used as the p-type impurity. The Mg concentration in the portion of the first p-type cladding layer 51 located in the gain region is 0.5×10 １８ cm －３ For example, the Mg concentration in the portion of the first p-type cladding layer 51 located in the gain region may be 1.1×10 １８ cm－３ In this embodiment, the Zn concentration in the portion of the first p-type cladding layer 51 located in the window region Rw may be 1.6×10 １８ cm －３ is.

[0046] The second p-type cladding layer 52 is disposed above the first p-type cladding layer 51. In this embodiment, the second p-type cladding layer 52 is disposed between the first p-type cladding layer 51 and the p-type barrier buffer layer 60, and is in contact with both the first p-type cladding layer 51 and the p-type barrier buffer layer 60. In this embodiment, the second p-type cladding layer 52 is a p-type AlInP layer doped with a p-type impurity and having a thickness of 0.620 μm. In this embodiment, Mg is used as the p-type impurity. The Mg concentration in the portion of the second p-type cladding layer 52 located in the gain region is 0.6×10 １８ cm －３ The Mg concentration in the portion of the second p-type cladding layer 52 located in the gain region may be 1.0×10 １８ cm －３ In this embodiment, the Mg concentration in the portion of the second p-type cladding layer 52 located in the gain region is 1.5×10 １８ cm －３ In this embodiment, the Zn concentration in the portion of the second p-type cladding layer 52 located in the window region Rw is 1.5×10 １８ cm －３ is.

[0047] The first p-type cladding layer 51 is a region of the p-type cladding layer 50 that is below the lower end of the ridge 50R. The second p-type cladding layer 52 includes a region of the p-type cladding layer 50 that is included in the ridge 50R. In this embodiment, the second p-type cladding layer 52 further includes a region that is included in the protruding portion 50P. In this manner, the lower end of the ridge 50R is located within the p-type cladding layer 50, and more specifically, at the interface between the first p-type cladding layer 51 and the second p-type cladding layer 52.

[0048] The first p-type cladding layer 51 may have an etching stop layer as its uppermost layer. This allows for improved control of the film thickness of the first p-type cladding layer 51 when forming the ridge 50R (and the protruding portion 50P). The etching stop layer may be a single layer made of a p-type GaInP layer or a p-type AlGaInP layer having a lower Al composition ratio than the layers of the first p-type cladding layer 51 located below the etching stop layer. Alternatively, the etching stop layer may have a multilayer periodic structure of GaInP layers and AlGaInP layers, or a multilayer periodic structure of AlGaInP layers and AlInP layers.

[0049] The p-type barrier buffer layer 60 is a semiconductor layer disposed above the p-type cladding layer 50. The p-type barrier buffer layer 60 buffers the valence band barrier between the p-type cladding layer 50 and the contact layer 70. The bandgap energy of the p-type barrier buffer layer 60 is greater than the bandgap energy of the contact layer 70 but less than the maximum bandgap energy of the p-type cladding layer 50. By disposing such a p-type barrier buffer layer 60 between the p-type cladding layer 50 and the contact layer 70, the barrier in the valence band is buffered. In other words, the height of the barrier formed at the boundary between the p-type cladding layer 50 and the contact layer 70 is reduced. This makes it possible to suppress an increase in the electrical resistance of the semiconductor laser device 1 due to the barrier. Therefore, the operating voltage of the semiconductor laser device 1 can be reduced.

[0050] In this embodiment, the p-type barrier buffer layer 60 has a thickness of 0.06 μm or less. By reducing the thickness of the p-type barrier buffer layer 60 in this manner, the electrical resistance of the p-type barrier buffer layer 60 can be reduced, and therefore an increase in operating voltage caused by inserting the p-type barrier buffer layer 60 between the p-type cladding layer 50 and the contact layer 70 can be suppressed.

[0051] 6 , the p-type barrier buffer layer 60 includes a first p-type barrier buffer layer 61 and a third p-type barrier buffer layer 63. The third p-type barrier buffer layer 63 is disposed between the contact layer 70 and the first p-type barrier buffer layer 61. In the present embodiment, the first p-type barrier buffer layer 61 is in contact with the p-type cladding layer 50, and the third p-type barrier buffer layer 63 is in contact with the contact layer 70. In the present embodiment, the p-type barrier buffer layer 60 includes a second p-type barrier buffer layer 62 disposed between the first p-type barrier buffer layer 61 and the third p-type barrier buffer layer 63, and having a composition different from that of each of the first p-type barrier buffer layer 61 and the third p-type barrier buffer layer 63.

[0052] The first p-type barrier buffer layer 61 is disposed above the p-type cladding layer 50. The first p-type barrier buffer layer 61 is a layer disposed between the p-type cladding layer 50 and the third p-type barrier buffer layer 63, and has a bandgap energy smaller than the maximum bandgap energy of the p-type cladding layer 50. The bandgap energy of the first p-type barrier buffer layer 61 is also larger than the energy corresponding to the peak wavelength of the laser light emitted by the semiconductor laser device 1. This reduces the absorption of laser light in the first p-type barrier buffer layer 61, thereby reducing waveguide loss in the semiconductor laser device 1.

[0053] In this embodiment, the first p-type barrier buffer layer 61 is disposed between the p-type cladding layer 50 and the second p-type barrier buffer layer 62, and is in contact with both the p-type cladding layer 50 and the second p-type barrier buffer layer 62. The first p-type barrier buffer layer 61 is, for example, an AlGaInP layer. In this embodiment, the first p-type barrier buffer layer 61 is a p-type (Al ０．７０ Ga ０．３０ ) ０．５１ In ０．４９ In this embodiment, Mg is used as a p-type impurity. The Mg concentration in the portion of the first p-type barrier buffer layer 61 located in the gain region is 1.2×10 １８ cm －３ is.

[0054] The second p-type barrier buffer layer 62 is disposed above the p-type cladding layer 50. In this embodiment, the second p-type barrier buffer layer 62 is disposed between the first p-type barrier buffer layer 61 and the third p-type barrier buffer layer 63, and has a different composition from the first p-type barrier buffer layer 61 and the third p-type barrier buffer layer 63. In this embodiment, the second p-type barrier buffer layer 62 is disposed between the first p-type barrier buffer layer 61 and the third p-type barrier buffer layer 63, and is in contact with the first p-type barrier buffer layer 61 and the third p-type barrier buffer layer 63. The second p-type barrier buffer layer 62 is, for example, an AlGaInP layer. In this embodiment, the second p-type barrier buffer layer 62 is a p-type (Al ０．４０ Ga ０．６０ ) ０．５１ In ０．４９ In this embodiment, Mg is used as the p-type impurity. The Mg concentration in the portion of the second p-type barrier buffer layer 62 located in the gain region is 1.2×10 １８ cm －３ is.

[0055] The third p-type barrier buffer layer 63 is disposed above the p-type cladding layer 50. In this embodiment, the third p-type barrier buffer layer 63 is disposed between the second p-type barrier buffer layer 62 and the contact layer 70, and is in contact with both the second p-type barrier buffer layer 62 and the contact layer 70. The third p-type barrier buffer layer 63 is, for example, an AlGaInP layer. In this embodiment, the third p-type barrier buffer layer 63 is a p-type (Al ０．１２ Ga ０．８８ ) ０．５１ In ０．４９ In this embodiment, Mg is used as the p-type impurity. The Mg concentration in the portion of the third p-type barrier buffer layer 63 located in the gain region is 1.2×10 １８ cm －３ is.

[0056] The contact layer 70 is a semiconductor layer disposed above the p-type cladding layer 50. In this embodiment, the contact layer 70 is disposed above the p-type barrier buffer layer 60 and is in contact with the p-side electrode. The contact layer 70 is in contact with the p-type barrier buffer layer 60 and the first p-side electrode 91. The contact layer 70 has a thickness of, for example, 0.2 μm. In this embodiment, the contact layer 70 is doped with C as an impurity. The contact layer 70 may have a thickness of 0.1 μm or less. The bandgap energy of the GaAs layer (second contact layer 72) included in the contact layer 70 is smaller than the energy corresponding to the peak wavelength of the laser light emitted by the semiconductor laser device 1. Therefore, the laser light is absorbed in the contact layer 70. However, by setting the thickness of the contact layer 70 to 0.1 μm or less, the absorption of the laser light in the contact layer 70 can be suppressed. Therefore, an increase in waveguide loss in the semiconductor laser device 1 can be suppressed. In addition, when forming the window region Rw, the GaAs layer, in which Zn has a slow diffusion rate, becomes thinner, thereby shortening the time required for Zn diffusion and suppressing the concentration of Zn diffusing into the window region Rw, thereby reducing the absorption of laser light in the window region Rw.

[0057] When the contact layer 70 includes a GaAs layer and the well layer 42b is a GaInP layer, as in the present embodiment, the difference in bandgap energy between the contact layer 70 and the well layer 42b is very large. Therefore, the absorption of laser light in the contact layer 70 has a significant effect on the waveguide loss. Therefore, in the present embodiment, the effect of reducing the waveguide loss by setting the film thickness of the contact layer 70 to 0.1 μm or less is significant.

[0058] In this embodiment, as shown in FIGS. 7 and 8, the contact layer 70 includes a first contact layer 71 and a second contact layer 72 .

[0059] The first contact layer 71 is disposed above the p-type barrier buffer layer 60. In this embodiment, the first contact layer 71 is disposed between the p-type barrier buffer layer 60 and the second contact layer 72, and is in contact with both the p-type barrier buffer layer 60 and the second contact layer 72. The first contact layer 71 is an AlGaAs layer. The bandgap energy of the first contact layer 71 is greater than the energy corresponding to the peak wavelength of the laser light emitted by the semiconductor laser device 1. This reduces the absorption of laser light in the first contact layer 71, thereby reducing waveguide loss in the semiconductor laser device 1.

[0060] Furthermore, the bandgap energy of the first contact layer 71 is smaller than the maximum bandgap energy of the p-type cladding layer 50 .

[0061] The band gap energy of the first contact layer 71 may be larger than the band gap energy of the well layer 42b.

[0062] In this embodiment, the first contact layer 71 has a concentration of 1.2×10 １８ cm －３ p-type Al doped with p-type impurities of 0.020 μm in thickness ｘ Ga １－ｘ The first contact layer 71 is an As layer. In this embodiment, C is used as the p-type impurity. The Al composition ratio of the first contact layer 71 decreases with increasing distance from the substrate 10. The Al composition ratio of the first contact layer 71 is 0.55 at the end closer to the substrate 10 (i.e., the end closer to the p-type cladding layer 50) and is 0.05 at the end farther from the substrate 10 (i.e., the end farther from the p-type cladding layer 50).

[0063] The second contact layer 72 has a concentration of 3.0×10 １９ cm －３The contact layer 70 is a p-type GaAs layer having a thickness of 0.20 μm and doped with a p-type impurity of C. In this embodiment, C is used as the p-type impurity. In this embodiment, the contact layer 70 is a GaAs layer, but the configuration of the contact layer 70 is not limited to this. For example, the contact layer 70 may be a GaInAsP layer having a refractive index higher than that of the third p-type barrier buffer layer 63 and a band gap energy higher than that of a GaAs layer.

[0064] The current blocking layer 80 is disposed above the semiconductor stack 1S and is a dielectric film made of an (electrically) insulating material. In this embodiment, the current blocking layer 80 has an opening 80a at a position corresponding to the upper surface of the ridge 50R, as shown in FIGS. 1, 2, and 4. The current blocking layer 80 covers almost the entire upper surface of the semiconductor stack 1S except for the region corresponding to the opening 80a. Specifically, the current blocking layer 80 continuously covers from the right end of the top surface of the ridge 50R shown in FIG. 4 to the right side surface of the ridge 50R (i.e., the end surface of the ridge 50R on the positive side in the X-axis direction), the groove 50T adjacent to the right side of the ridge 50R, the left side surface of the right-side protrusion 50P (i.e., the end surface of the right-side protrusion 50P on the negative side in the X-axis direction), the top surface of the right-side protrusion 50P, the right side surface of the right-side protrusion 50P (i.e., the end surface of the right-side protrusion 50P on the positive side in the X-axis direction), and partway through the groove 50T at the right end (the end on the positive side in the X-axis direction). 4 , the current blocking layer 80 continuously covers from the left end of the top surface of the ridge 50R to the left side surface of the ridge 50R (i.e., the end surface of the ridge 50R on the negative side in the X-axis direction), the groove 50T adjacent to the left side of the ridge 50R, the right side surface of the left protrusion 50P (i.e., the end surface of the left protrusion 50P on the positive side in the X-axis direction), the top surface of the left protrusion 50P, the left side surface of the left protrusion 50P (i.e., the end surface of the left protrusion 50P on the negative side in the X-axis direction), and up to partway through the groove 50T at the left end (end on the negative side in the X-axis direction). The current blocking layer 80 is not particularly limited as long as it is a dielectric film, and may be any suitable material such as SiN, SiO ２ , TiO ２ , ZrO ２ , Al ２ O ３ , Nb ２ O ５ , Ta ２ O ５In this embodiment, the current blocking layer 80 is a SiN film with a thickness of about 180 nm.

[0065] The first p-side electrode 91 is an example of a p-side electrode disposed above the semiconductor laminate 1S. The first p-side electrode 91 is in ohmic contact with the contact layer 70. In the present embodiment, the first p-side electrode 91 is disposed above the ridge 50R, as shown in FIGS. 3 and 4 . More specifically, the first p-side electrode 91 is disposed on the upper surface of the ridge 50R at a position corresponding to the opening 80a in the current blocking layer 80. In the present embodiment, the first p-side electrode 91 covers almost the entire upper surface of the semiconductor laminate 1S, as shown in FIGS. 3 and 4 . In other words, the first p-side electrode 91 is disposed above the current blocking layer 80 and the contact layer 70. The first p-side electrode 91 extends from the middle of the groove 50T at the left end (the end on the negative side in the X-axis direction) shown in FIG. 4 to the left side surface of the left protrusion 50P (i.e., the end face on the negative side in the X-axis direction of the left protrusion 50P), the top surface of the left protrusion 50P, the right side surface of the left protrusion 50P (i.e., the end face on the positive side in the X-axis direction of the left protrusion 50P), the groove 50T adjacent to the left side of the ridge 50R, the left side surface of the ridge 50R (i.e., the end face on the negative side in the X-axis direction of the ridge 50R), It continuously covers the top surface of the ridge 50R, the right side surface of the ridge 50R (i.e., the end surface of the ridge 50R on the positive side in the X-axis direction), the groove 50T adjacent to the right side of the ridge 50R, the left side surface of the right protrusion 50P (i.e., the end surface of the right protrusion 50P on the negative side in the X-axis direction), the top surface of the right protrusion 50P, the right side surface of the right protrusion 50P (i.e., the end surface of the right protrusion 50P on the positive side in the X-axis direction), and partway through the groove 50T at the right end (the end on the positive side in the X-axis direction).

[0066] The first p-side electrode 91 includes at least one of Pt, Pd, Mo, W, Ni, Cr, and Ti, for example. For example, the first p-side electrode 91 may be a stacked film including a 50-nm-thick Ti film, a 150-nm-thick Pt film disposed above the Ti film, and a 200-nm-thick Au film.

[0067] The second p-side electrode 92 is an example of a p-side electrode disposed above the semiconductor laminate 1S. Furthermore, the second p-side electrode 92 is an example of a pad electrode disposed above the first p-side electrode 91. In this embodiment, the second p-side electrode 92 is disposed above the first p-side electrode 91 and is in contact with the first p-side electrode 91. The second p-side electrode 92 is disposed above the current injection region Ri. In this embodiment, as shown in FIG. 1 , the second p-side electrode 92 covers the entire opening 80a of the current blocking layer 80. The second p-side electrode 92 is disposed continuously from above the current injection region Ri to above the first region Rn. As shown in FIG. 2 , the end of the second p-side electrode 92 may have an inverted tapered shape. For example, in the cross section shown in FIG. 2 , the lower end of the second p-side electrode 92 may be farther away from the first end facet 1F in the Y-axis direction than the upper end. 1 and 3, the second p-side electrode 92 is not disposed near the first end facet 1F or the second end facet 1R. As shown in Fig. 4, the second p-side electrode 92 continuously covers the entire surface from the top surface of one protrusion 50P to the top surface of the other protrusion 50P. In this embodiment, the second p-side electrode 92 is an Au film with a thickness of 3.0 µm.

[0068] The third p-side electrode 93 is an example of a p-side electrode disposed above the second p-side electrode 92. In the present embodiment, as shown in FIGS. 1 and 2 , the third p-side electrode 93 is disposed above the first p-side electrode 91 and the second p-side electrode 92. As shown in FIGS. 1 to 4 , the third p-side electrode 93 may be disposed above the entire first p-side electrode 91 and the second p-side electrode 92. As shown in FIG. 2 , the third p-side electrode 93 contacts the second p-side electrode 92 on the second p-side electrode 92. The third p-side electrode 93 has a region electrically connected to the first p-side electrode 91 via the second p-side electrode 92 and a region in contact with the first p-side electrode 91. Furthermore, the third p-side electrode 93 may be discontinuous between a portion disposed at an end of the second p-side electrode 92 and a portion disposed on the first p-side electrode 91. As shown in FIGS. 3 and 4 , the third p-side electrode 93 continuously covers the entire surface of one protrusion 50P from the top surface of the other protrusion 50P. Alternatively, the third p-side electrode 93 may be disposed on the current blocking layer 80 (in contact with the current blocking layer 80) at the end in the X-axis direction. In this embodiment, the third p-side electrode 93 includes a 50-nm-thick Ti film, a 150-nm-thick Pt film, and a 200-nm-thick Au film disposed above the Pt film. The third p-side electrode 93 is bonded to a base such as a submount using, for example, AuSn solder. This allows the semiconductor laser device 1 to be junction-down mounted (i.e., flip-chip mounted) on the base. In this case, the third p-side electrode 93 functions as a barrier electrode that prevents Sn contained in the AuSn solder from diffusing into the second p-side electrode 92 or the like.

[0069] The n-side electrode 94 is a conductive layer disposed on the lower main surface of the substrate 10 (i.e., the main surface of the substrate 10 on the back side of the main surface on which the semiconductor laminate 1S is laminated). The configuration of the n-side electrode 94 is not particularly limited. In the present embodiment, the n-side electrode 94 includes, laminated in this order from the substrate 10 side, a 90-nm-thick AuGe film, a 20-nm-thick Ni film, a 50-nm-thick Au film, a 100-nm-thick Ti film, a 50-nm-thick Pt film, a 50-nm-thick Ti film, a 100-nm-thick Pt film, and a 500-nm-thick Au film.

[0070] [1-2. Manufacturing Method] A manufacturing method of the semiconductor laser device 1 according to this embodiment will be described with reference to FIGS. 1 to 4 and 9 to 21. FIGS. 9 to 21 are schematic cross-sectional views showing each step of the manufacturing method of the semiconductor laser device 1 according to this embodiment. FIGS. 9 to 13, 15, 18, and 20 show cross sections at the same positions as in FIG. 2. FIGS. 14, 16, 17, 19, and 21 show cross sections at the same positions as in FIG. 4.

[0071] First, as shown in FIG. 9 , a semiconductor laminated film 1Sm is formed on a substrate 10 (lamination process). The semiconductor laminated film 1Sm includes an n-type cladding film 30m made of a III-V semiconductor containing In, an active film 42m made of a III-V semiconductor containing In and disposed above the n-type cladding film 30m, a p-type cladding film 50m made of a III-V semiconductor containing In and disposed above the active film 42m, and a contact film 70m disposed above the p-type cladding film 50m. A window region Rw is formed in the semiconductor laminated film 1Sm to form a semiconductor laminate 1S. In other words, the n-type cladding film 30m, the active film 42m, the p-type cladding film 50m, and the contact film 70m have the same configurations as the n-type cladding layer 30, the active layer 42, the p-type cladding layer 50, and the contact layer 70 in the gain region, respectively.

[0072] The n-type cladding film 30m has a first n-type cladding film 31m, a second n-type cladding film 32m arranged above the first n-type cladding film 31m, and a third n-type cladding film 33m arranged above the second n-type cladding film 32m.

[0073] The p-type cladding film 50m has a first p-type cladding film 51m and a second p-type cladding film 52m disposed above the first p-type cladding film 51m.

[0074] In this embodiment, the semiconductor laminated film 1Sm further includes a buffer film 21m, an n-type barrier buffer film 22m, an n-side light guide film 41m, a p-side light guide film 43m, and a p-type barrier buffer film 60m. The buffer film 21m, the n-type barrier buffer film 22m, the n-side light guide film 41m, the p-side light guide film 43m, and the p-type barrier buffer film 60m have the same configurations as the buffer layer 21, the n-type barrier buffer layer 22, the n-side light guide layer 41, the p-side light guide layer 43, and the p-type barrier buffer layer 60 in the gain region, respectively. The layers constituting the semiconductor laminated film 1Sm are deposited by, for example, metalorganic chemical vapor deposition (MOCVD).

[0075] Next, a window region Rw is formed in the semiconductor laminated film 1Sm to form the semiconductor laminated body 1S (window region forming step). The window region forming step will be described with reference to FIGS.

[0076] In the window region forming process, first, as shown in FIG. 10 , a cap layer containing In is formed in a region above the contact film 70m that corresponds to the window region Rw (i.e., the region that will become the window region Rw after the window region forming process) (cap layer forming process). In this embodiment, a cap layer 11 is formed above the contact film 70m in contact with the contact film 70m, and a cap covering layer 12 is formed on the cap layer 11. The cap layer 11 is a p-type semiconductor layer that is doped with, for example, Zn or Mg as an impurity and contains In. The thickness of the cap layer 11 is, for example, 30 nm or more and 100 nm or less. If the thickness of the cap layer 11 is too thin, the effect of diffusing Zn into the contact film 70m and below it is weakened, and the time required for Zn diffusion cannot be shortened. As a result, the Zn concentration in the window region Rw cannot be suppressed. Furthermore, if the thickness of the cap layer 11 is too thick, the cap layer 11 is altered by heat treatment when the cap layer 11 is removed after the window region Rw is formed, making it difficult to remove. １８ cm －３If the impurity concentration of the cap layer 11 is too high, the Zn concentration in the window region Rw increases, and the absorption of laser light in the window region increases. The cap layer 11 is made of, for example, p-type GaInP or p-type AlGaInP. In this embodiment, the cap layer 11 has a concentration of 7×10 １７ cm －３ The cap coating layer 11 is a 75 nm thick GaInP layer doped with Zn. The cap coating layer 12 is a p-type semiconductor layer that covers the cap layer 11. For example, a p-type GaAs layer can be used as the cap coating layer 12. The cap layer 11 and the cap coating layer 12 are stacked by, for example, an MOCVD method. Note that the stacking step and the cap layer formation step of forming the cap layer 11 and the cap coating layer 12 may be performed consecutively as a series of film formation steps.

[0077] Next, as shown in FIG. 11 , the cap coating layer 12 and a portion of the cap layer 11 are removed. A region of the cap layer 11 that is a predetermined length from the first end face 1F in the resonance direction is left. Although not shown, a region of the cap layer 11 that is a predetermined length from the second end face 1R in the resonance direction is also left. In other words, the region of the cap layer 11 other than the predetermined length regions near the first end face 1F and the second end face 1R is removed. In this embodiment, the predetermined length is 10 μm or more. The portion of the cap layer 11 is removed, for example, using photolithography and etching.

[0078] Furthermore, a protective layer 13 is formed on the upper surface of the contact film 70m to cover the region not covered by the cap layer 11 and a part of the upper surface of the cap layer 11. In this embodiment, the protective layer 13 is made of SiO ２ The protective layer 13 is a layer. The distance Dd from the first end face 1F to the protective layer 13 (and the distance from the second end face 1R to the protective layer 13) is, for example, 10 μm. The protective layer 13 is formed using, for example, a low-pressure CVD (Chemical Vapor Deposition) method. The protective layer 13 may also be formed using, for example, an atmospheric pressure CVD method. A portion of the protective layer 13 is removed using, for example, photolithography and etching.

[0079] Subsequently, a diffusion source layer 14 containing Zn is formed on the cap layer 11 (diffusion source layer forming step). The diffusion source layer 14 may be, for example, a ZnO layer, a ZnSiO layer, or a layer of ZnO and SiO ２ A mixed crystal layer made of, for example, ZnO or ZnO can be used. In this embodiment, a ZnO layer is formed as the diffusion source layer 14. The diffusion source layer 14 may be a ZnO layer having a refractive index of 1.5 or more and 1.8 or less. That is, while the refractive index of a typical ZnO layer is approximately 1.9 or more and 2.0 or less, the refractive index of the ZnO layer used as the diffusion source layer 14 may be lower. A ZnO layer with such a low refractive index has a lower density than a ZnO layer with a high refractive index. In other words, a ZnO layer with a low refractive index is a sparser film than a ZnO layer with a high refractive index. Therefore, by using a ZnO layer with a low refractive index as the diffusion source layer 14, Mg is more easily absorbed by the diffusion source layer 14 during interdiffusion of Zn and Mg. This reduces the Mg concentration in the window region Rw. In this embodiment, the diffusion source layer 14 is a ZnO layer with a refractive index of 1.7.

[0080] The diffusion source layer 14 may also be formed on the protective layer 13. The diffusion source layer 14 may be formed by, for example, sputtering. The diffusion source layer 14 may also be formed by, for example, atmospheric pressure CVD or low-pressure CVD.

[0081] Next, a diffusion source covering layer 15 is formed to cover the diffusion source layer 14. In this embodiment, the diffusion source covering layer 15 is a SiN layer that covers the entire upper surface of the diffusion source layer 14. The diffusion source covering layer 15 may be a SiN layer having a refractive index of 1.8 or more but less than 2.0. That is, while the refractive index of a typical SiN layer is 2.0, the refractive index of the SiN layer used as the diffusion source covering layer 15 may be lower. Such a low-refractive-index SiN layer has a lower density than a high-refractive-index SiN layer. In other words, a low-refractive-index SiN layer is a sparser film than a high-refractive-index SiN layer. Therefore, by using a low-refractive-index SiN layer as the diffusion source covering layer 15, peeling or cracking of the diffusion source covering layer 15 can be suppressed even if the diffusion source layer 14 is altered due to Mg absorption. In this embodiment, the diffusion source covering layer 15 is a SiN layer having a refractive index of 1.9. The diffusion source covering layer 15 is formed using, for example, a low-pressure CVD method. The diffusion source covering layer 15 may be formed by, for example, atmospheric pressure CVD.

[0082] Next, the semiconductor laminated film 1Sm and the diffusion source layer 14 are heated (heating step). ２ The semiconductor laminated film 1Sm and the diffusion source layer 14 are heated at 560°C for 90 minutes in a Zn atmosphere. As a result, Zn diffuses into the semiconductor laminated film 1Sm, forming a window region Rw as shown in FIG. 12 . That is, a semiconductor laminated body 1S having a window region Rw is formed. In other words, the buffer film 21m, the n-type barrier buffer layer 22m, the n-type cladding film 30m, the n-side light guide film 41m, the active film 42m, the p-side light guide film 43m, the p-type cladding film 50m, the p-type barrier buffer layer 60m, and the contact film 70m become the buffer layer 21, the n-type barrier buffer layer 22, the n-type cladding layer 30, the n-side light guide layer 41, the active layer 42, the p-side light guide layer 43, the p-type cladding layer 50, the p-type barrier buffer layer 60, and the contact layer 70, respectively.

[0083] The bandgap energy of the well layers 42b in the window regions Rw is 190 meV greater than the bandgap energy of the gain region, thereby reducing the absorption of laser light in the well layers 42b.

[0084] 13 and 14, the diffusion source layer 14 is removed (diffusion source layer removal step). More specifically, the cap layer 11, diffusion source layer 14, protective layer 13, and diffusion source covering layer 15 are all removed. These layers can be removed by, for example, etching. This completes the window region formation step.

[0085] Next, as shown in FIGS. 15 and 16 , a portion of the contact layer 70 is removed (contact layer removal process). Specifically, as shown in FIG. 15 , the contact layer 70 located above the window region Rw is removed. A region of the contact layer 70 with a predetermined length Dc in the resonance direction from the first end facet 1F and the second end facet 1R is removed. The predetermined length Dc is, for example, 40 μm. Furthermore, as shown in FIG. 16 , a region of the contact layer 70 corresponding to the groove 50T is also removed. The portion of the contact layer 70 is removed using, for example, photolithography and etching.

[0086] 17, a ridge 50R is formed (ridge formation step). In this embodiment, a protrusion 50P is also formed. The ridge 50R is formed using, for example, photolithography and etching.

[0087] 18 and 19, the current blocking layer 80 is formed (current blocking layer forming step). The current blocking layer 80 is formed by, for example, low-pressure CVD. The current blocking layer 80 may also be formed by, for example, atmospheric pressure CVD. The opening 80a of the current blocking layer 80 is formed by, for example, photolithography and etching.

[0088] 20 and 21 , p-side electrodes are formed (p-side electrode formation step). Specifically, a first p-side electrode 91, a second p-side electrode 92, and a third p-side electrode 93 are formed. Each p-side electrode is formed by, for example, electron beam evaporation.

[0089] 2 to 4, the n-side electrode 94 is formed (n-side electrode forming step). The n-side electrode 94 is formed by using, for example, electron beam evaporation.

[0090] Subsequently, the semiconductor laminate 1S and the substrate 10 are singulated as necessary, and then end face protective films 2F, 2R are formed as shown in Figures 1 and 2. Through the above steps, the semiconductor laser device 1 can be manufactured.

[0091] [1-3. Effects, etc.] The effects of the semiconductor laser device 1 according to this embodiment and the manufacturing method thereof will be described.

[0092] The semiconductor laser device 1 according to this embodiment includes a semiconductor laminate 1S. The semiconductor laminate 1S has a gain region into which current is injected, a first facet 1F, and a window region Rw formed between the gain region and the first facet 1F. The p-type cladding layer 50 is doped with Mg as an impurity, and Zn is diffused into the window region Rw. If the Mg concentration in the portion of the p-type cladding layer 50 located in the gain region is represented by Na, the Mg concentration in the portion of the p-type cladding layer 50 located in the window region Rw is represented by Nw, and the Zn concentration in the portion of the p-type cladding layer 50 located in the window region Rw is represented by Nz, the following relationships hold: Na > 10Nw, and Nz > Nw.

[0093] Thus, the Mg concentration Nw in the window region Rw of the p-type cladding layer 50 is lower than the Mg concentration Na in the gain region. This is thought to be due to the fact that, when Zn is diffused, the Mg doped in the p-type cladding film 50m and Zn interdiffuse, substituting the Mg for Zn. As a result, the Zn concentration Nz becomes higher than the Mg concentration Nw. It has been confirmed that the Mg substituted for Zn reaches the diffusion source layer 14 formed when Zn is diffused from each layer disposed above the p-type cladding layer 50. In particular, in this embodiment, it has been confirmed that the use of a ZnO layer with a low refractive index (i.e., density) as the diffusion source layer 14 allows for even greater absorption of Mg (in other words, absorption).

[0094] The above-mentioned Mg concentration, Na concentration, Nw concentration, and Zn concentration can be achieved by adjusting the configuration of the p-type cladding layer 50, the configuration of the contact layer 70, the configuration of the diffusion source layer 14 used in the window region formation process, the configuration of the diffusion source covering layer 15, the temperature and time of the heating process, etc.

[0095] As described above, the Mg concentration Nw in the portion of the p-type cladding layer 50 located in the window region Rw can be reduced to less than 1 / 10 of the Mg concentration Na in the portion located in the gain region. This reduces the absorption of laser light by Mg in the window region Rw, thereby improving the COD level.

[0096] Furthermore, by making the Mg concentration Nw lower than the Zn concentration in the window region Rw of the p-type cladding layer 50, the absorption of laser light by Mg can be reduced while realizing the formation of the window region Rw by Zn diffusion, thereby further improving the COD level.

[0097] In the semiconductor laser device 1 according to this embodiment, the contact layer 70 may be doped with C as an impurity.

[0098] Since C is an impurity that does not easily diffuse into the window region Rw, the amount of C diffused into the window region Rw is small, which makes it possible to further reduce the absorption of laser light by impurities in the window region Rw.

[0099] The p-type cladding layer 50 of the semiconductor laser device 1 may be made of AlInP.

[0100] This increases the diffusion rate of the impurity Zn for forming the window region Rw, thereby reducing the time required for Zn diffusion and reducing the amount of Zn accumulated in the p-type cladding layer 50 and the like. This further reduces the absorption of laser light by the impurities in the window region Rw.

[0101] In the semiconductor laser device 1, the p-type cladding layer 50 may include a first p-type cladding layer 51 and a second p-type cladding layer 52 disposed above the first p-type cladding layer 51. The Mg concentration in the portion of the second p-type cladding layer 52 located in the gain region is 1.0×10 １８ cm －３ It may be higher.

[0102] This reduces the electrical resistance of the region of the p-type cladding layer 50 that is far from the active layer 42, thereby reducing the operating voltage of the semiconductor laser device 1. Furthermore, by increasing the impurity concentration in the region of the p-type cladding layer 50 that is far from the active layer 42, it is possible to reduce the absorption of laser light by impurities.

[0103] In addition, the Mg concentration in the p-type cladding layer 50 is 1.0×10 １８ cm －３ Since the active layer 42 is higher, the Fermi level in the p-type cladding layer 50 becomes smaller. Accordingly, the energy of the conduction band in the p-type cladding layer 50 becomes higher. This region with high energy in the conduction band functions as a barrier to electrons, so that leakage of electrons from the active layer 42 to the contact layer 70 can be suppressed. Therefore, the current utilization efficiency of the semiconductor laser device 1 can be improved.

[0104] In the semiconductor laser device 1, the n-type cladding layer 30 may be made of AlInP.

[0105] This increases the diffusion rate of the impurity Zn for forming the window region Rw. This reduces the time required for Zn diffusion. For example, this reduces the time required for the heating step in the window region formation process. This reduces the amount of Zn that accumulates in the n-type cladding layer 30 and the like. This further reduces the absorption of laser light by the impurities in the window region Rw.

[0106] In the semiconductor laser device 1 according to the present embodiment, the Zn concentration at the interface of the n-type cladding layer 30 located in the window region Rw on the side farther from the active layer 42 is 1.0×10 １８ cm －３ It may be more than that.

[0107] This allows a sufficient amount of Zn to be diffused to form the window regions Rw, thereby reliably increasing the bandgap energy of the portions of the active layer 42 located in the window regions Rw, thereby reducing the absorption of laser light in the window regions Rw.

[0108] This effect will be explained with reference to Fig. 22. Fig. 22 is a graph showing the current-optical output characteristics of the semiconductor laser device 1 according to this embodiment. In Fig. 22, the current-optical output characteristics of the semiconductor laser device 1 according to this embodiment are shown by a solid line, and the current-optical output characteristics of the semiconductor laser device of Comparative Example 1 are also shown by a dashed line. In the semiconductor laser device of Comparative Example 1, Zn does not reach the interface of the n-type cladding layer 30 on the side farther from the active layer 42 in the portion where the window region Rw is located (i.e., the interface between the n-type cladding layer 30 and the n-type barrier buffer layer 22), and the Zn concentration at this interface is 1.0 × 10 １８ cm －３ The semiconductor laser device 1 of Comparative Example 1 differs from the semiconductor laser device 1 of the present embodiment in that the band gap energy of the well layer 42b is less than 1.0×10. In the semiconductor laser device 1 of the present embodiment, the amount of shift in the band gap energy of the well layer 42b due to the formation of the window region is 190 meV, whereas in the semiconductor laser device of Comparative Example 1, the amount of shift in the band gap energy of the well layer 42b due to the formation of the window region is 160 meV. Thus, the amount of shift in the band gap energy of the well layer 42b due to the formation of the window region varies depending on the Zn concentration in the n-type cladding layer 30. In this embodiment, Zn reaches the interface of the n-type cladding layer 30 farther from the active layer 42 in the portion where the window region Rw is located (i.e., the interface between the n-type cladding layer 30 and the n-type barrier buffer layer 22), and the Zn concentration at the interface is 1.0×10 １８ cm －３ As a result, the amount of shift in the bandgap energy of the well layer 42b due to the formation of the window region can be made sufficiently large. As a result, as shown in Fig. 22, the semiconductor laser device 1 according to this embodiment can significantly improve the current-optical output characteristics compared to Comparative Example 1. Specifically, the maximum optical output can be increased by approximately 1.3 times.

[0109] Note that the heating time in the window region formation step may be extended to increase the Zn concentration in the n-type cladding layer 30 and ensure a sufficient shift in bandgap energy. However, it is preferable not to extend the heating time more than necessary. The effect of heating time on the semiconductor laser device 1 will be described with reference to FIG. 23 . FIG. 23 is a graph showing the change in optical output with aging time for the semiconductor laser device 1 according to the present embodiment. In FIG. 23 , the characteristics (two examples) of the semiconductor laser device 1 according to the present embodiment are shown by solid lines, and the characteristics (two examples) of the semiconductor laser device of Comparative Example 2 are also shown by dashed lines. The semiconductor laser device of Comparative Example 2 differs from the semiconductor laser device 1 according to the present embodiment in the heating time in the window region formation step. In the semiconductor laser device 1 according to the present embodiment, the heating time in the window region formation step is 90 minutes, while in the semiconductor laser device of Comparative Example 2, the heating time in the window region formation step is 120 minutes. Accordingly, in the semiconductor laser device of Comparative Example 2, the shift in bandgap energy of the well layer 42b due to the formation of the window region is 205 meV. During the aging, the temperature of each semiconductor laser element was maintained at 25° C., and the element was continuously driven while being supplied with a constant current in the pre-aging state. The initial optical output of each semiconductor laser element (i.e., the optical output before aging) was 1.2 W.

[0110] In the semiconductor laser device according to Comparative Example 2, the amount of Zn accumulated in the window region Rw is large, and therefore the amount of reduction in optical output is larger than that in the semiconductor laser device 1 according to the present embodiment, as shown in Fig. 23. As such, it is better not to make the heating time in the window region formation step longer than necessary.

[0111] The method for manufacturing the semiconductor laser device 1 according to this embodiment includes a lamination step of forming a semiconductor laminated film 1Sm and a window region forming step of forming a window region Rw in the semiconductor laminated film 1Sm to form a semiconductor laminated body 1S. The window region forming step includes a cap layer forming step of forming a cap layer 11 containing In on the contact film 70m and a diffusion source layer forming step of forming a diffusion source layer 14 containing Zn on the cap layer 11.

[0112] If the contact film 70m includes, for example, a GaAs layer, forming the diffusion source layer 14 directly on the contact film 70m would require a relatively long time for Zn diffusion due to the slow diffusion rate of Zn in the GaAs layer. This would result in a high Zn concentration in the window region Rw, potentially leading to increased absorption of laser light. In contrast, in this embodiment, a cap layer 11 containing In, which has a fast Zn diffusion rate, is formed between the contact film 70m and the diffusion source layer 14, thereby facilitating the diffusion of Zn into the contact film 70m and the layers below it. This shortens the time required for Zn diffusion, thereby suppressing the Zn concentration accumulated in the window region Rw. This reduces the absorption of laser light in the window region Rw.

[0113] In the method for manufacturing the semiconductor laser device 1 according to the present embodiment, the cap layer 11 may be made of GaInP or AlGaInP.

[0114] This promotes the diffusion of Zn into the contact film 70m and the layers below it, thereby reducing the time required for Zn diffusion and suppressing the Zn concentration in the window region Rw, thereby reducing the absorption of laser light in the window region Rw.

[0115] In the method for manufacturing the semiconductor laser device 1 according to the present embodiment, the contact film 70m may be doped with C as an impurity.

[0116] This reduces the time required for Mg in the window region Rw to be replaced with Zn due to interdiffusion of Mg and Zn from the contact film 70m. This reduces the amount of Mg in the window region Rw and the amount of Zn accumulated in the window region Rw. This reduces the absorption of laser light by Mg and Zn in the window region Rw.

[0117] (Embodiment 2) The configuration of a semiconductor laser device according to embodiment 2 and a manufacturing method thereof will be described. The semiconductor laser device according to this embodiment differs from the semiconductor laser device 1 according to embodiment 1 mainly in the configurations of the p-type cladding layer and the n-type cladding layer. The semiconductor laser device according to this embodiment and a manufacturing method thereof will be described below, focusing on the differences from the semiconductor laser device 1 according to embodiment 1 and a manufacturing method thereof.

[0118] [2-1. Overall Configuration] The overall configuration of the semiconductor laser device according to this embodiment will be described with reference to FIG. 24. FIG. 24 is a schematic cross-sectional view showing the overall configuration of the semiconductor laser device 101 according to this embodiment. Like FIG. 2, FIG. 24 shows a part of a cross section parallel to the stacking direction and resonance direction of the semiconductor laser device 101. FIG. 25 is a schematic cross-sectional view showing the configuration of the contact layer 170 included in the semiconductor laser device 101 according to this embodiment. Like FIG. 7, FIG. 25 shows a part of a cross section perpendicular to the resonance direction of the contact layer 170.

[0119] 24, the semiconductor laser device 101 according to the present embodiment includes a substrate 10, a semiconductor stack 101S, a first p-side electrode 91, a second p-side electrode 92, a third p-side electrode 93, a current blocking layer 80, an n-side electrode 94, and an end face protective film 2F. Although not shown in FIG. 24, the semiconductor laser device 101 also includes an end face protective film 2R, similar to the semiconductor laser device 1 according to the first embodiment.

[0120] The semiconductor laminate 101S according to this embodiment has an n-type cladding layer 130, an active layer 42, a p-type cladding layer 150, and a contact layer 170, which are stacked in this order from the substrate 10 side. In this embodiment, the semiconductor laminate 101S further has a buffer layer 21, an n-type barrier buffer layer 22, an n-side optical guide layer 41, a p-side optical guide layer 43, and a p-type barrier buffer layer 60.

[0121] The n-type cladding layer 130 according to this embodiment is disposed above the substrate 10 and is a semiconductor layer made of a III-V group semiconductor containing In. In this embodiment, the n-type cladding layer 130 is made of AlInP. More specifically, the n-type cladding layer 130 is an n-type AlInP layer doped with Si and having a thickness of 1.3 μm. The Al composition ratio in the n-type cladding layer 130 may be, for example, 0.5 or more and 0.6 or less. In this embodiment, the n-type cladding layer 130 is made of n-type Al ０．５４ In ０．４６ The Si concentration of the n-type cladding layer 130 is 4.0×10 １７ cm －３ In this embodiment, the Si concentration of the n-type cladding layer 130 is 3.5×10 １７ cm －３ is.

[0122] The p-type cladding layer 150 according to this embodiment is disposed above the active layer 42 and is a semiconductor layer made of a III-V group semiconductor containing In. The p-type cladding layer 150 includes a first p-type cladding layer 151 and a second p-type cladding layer 52.

[0123] The first p-type cladding layer 151 according to this embodiment is disposed above the active layer 42. In this embodiment, the first p-type cladding layer 151 is disposed above the p-side optical guide layer 43 and is in contact with the p-side optical guide layer 43. In this embodiment, the first p-type cladding layer 151 is a p-type AlInP layer doped with a p-type impurity and having a thickness of 0.290 μm. In this embodiment, Mg is used as the p-type impurity. The Mg concentration in the portion of the first p-type cladding layer 151 located in the gain region is 1.0×10 １８ cm －３ In this embodiment, the Mg concentration in the gain region of the first p-type cladding layer 151 is 0.8×10 １８ cm －３ In addition, the Mg concentration in the portion of the p-side optical guide layer 43 located in the gain region, which is disposed between the active layer 42 and the p-type cladding layer 150, is 3.0×10 １７ cm －３ Lower.

[0124] In this embodiment, as in the first embodiment, when the Mg concentration in the portion of the p-type cladding layer 150 located in the gain region is represented by Na, the Mg concentration in the portion of the p-type cladding layer 150 located in the window region Rw is represented by Nw, and the Zn concentration in the portion of the p-type cladding layer 150 located in the window region Rw is represented by Nz, the relationships Na>10Nw and Nz>Nw hold.

[0125] The contact layer 170 according to this embodiment is a semiconductor layer disposed above the p-type cladding layer 150. As shown in FIG. 25 , the contact layer 170 includes a first contact layer 171 and a second contact layer 172.

[0126] In this embodiment, the first contact layer 171 has a concentration of 1.2×10 １８ cm －３ C-doped p-type Al with a thickness of 0.020 μm ｘ Ga １－ｘ The Al composition ratio of the first contact layer 171 decreases with increasing distance from the substrate 10. The Al composition ratio of the first contact layer 171 is 0.55 at the end closer to the substrate 10 (i.e., the end closer to the p-type cladding layer 150) and is 0.05 at the end farther from the substrate 10 (i.e., the end farther from the p-type cladding layer 150).

[0127] The second contact layer 172 has a concentration of 3.0×10 １９ cm －３ The layer is a C-doped p-type GaAs layer having a thickness of 0.200 μm.

[0128] [2-2. Manufacturing Method] A method for manufacturing the semiconductor laser device 101 according to this embodiment will be described. The method for manufacturing the semiconductor laser device 101 according to this embodiment differs from that of the first embodiment in the window region forming step.

[0129] In this embodiment, by adopting the configuration of the semiconductor laminate 101S, the time for the heating step can be shortened compared to the first embodiment. ２Heating is performed in a 560° C. atmosphere for 60 minutes. In this manner, in this embodiment, the heating step time can be shortened by 30 minutes compared to the embodiment.

[0130] [2-3. Effects, etc.] The effects of the semiconductor laser device 101 according to this embodiment will be described.

[0131] In this embodiment, as in the first embodiment, the relationships Na>10Nw and Nz>Nw hold true.

[0132] This reduces the absorption of laser light by Mg in the window region Rw, as in the first embodiment. Furthermore, while achieving the formation of the window region Rw by Zn diffusion, it is possible to reduce the absorption of laser light by Mg. This contributes to an improvement in the COD level.

[0133] In the semiconductor laser device 101 according to the present embodiment, the Mg concentration in the portion of the first p-type cladding layer 151 located in the gain region is 1.0×10 １８ cm －３ The Mg concentration at the interface of the first p-type cladding layer 151 located in the gain region and close to the active layer 42 is 3.0×10 １７ cm －３ It may be lower.

[0134] In this way, by reducing the Mg concentration in the first p-type cladding layer 151 of the p-type cladding layer 150, which is closer to the active layer 42 (i.e., has a higher optical density), it is possible to reduce the absorption of laser light by Mg. Therefore, it is possible to reduce the waveguide loss of the semiconductor laser element 101, and therefore to improve the slope efficiency of the semiconductor laser element 101.

[0135] In the semiconductor laser device 101 according to this embodiment, the n-type cladding layer 130 may be made of AlInP.

[0136] In this way, by using AlInP, which has a high Zn diffusion rate, for the n-type cladding layer 130, the time required for Zn diffusion in the window region formation process can be reduced. Therefore, the Zn concentration accumulated in the window region Rw can be reduced, thereby reducing the absorption of laser light by Zn. Furthermore, by using AlInP, which has a lower refractive index than AlGaInP, for the n-type cladding layer 130, it is possible to improve light confinement in the active layer 42. Therefore, the temperature characteristics of the semiconductor laser device 101 can be improved.

[0137] In the semiconductor laser device 101 according to the present embodiment, the Si concentration of the n-type cladding layer 130 is 4.0×10 １７ cm －３ It may be lower.

[0138] The Si doped in the n-type cladding layer 130 inhibits the diffusion of Zn. Therefore, by reducing the Si concentration, the diffusion rate of Zn can be increased. Therefore, the Zn concentration accumulated in the window region Rw can be reduced, thereby reducing the absorption of laser light by Zn. The Si concentration in the n-type cladding layer 130 is 2.0×10 １７ cm －３ This can suppress an increase in the operating voltage of the semiconductor laser element 101. Also, it can suppress a decrease in the temperature characteristics of the semiconductor laser element 101 due to an increase in carrier leakage.

[0139] In the semiconductor laser device 101 according to this embodiment, the above-described configuration allows the heating time in the window region forming step to be shortened.

[0140] (Embodiment 3) A method for manufacturing a semiconductor laser device according to this embodiment will be described. The method for manufacturing a semiconductor laser device according to this embodiment differs from the method for manufacturing the semiconductor laser device 1 according to embodiment 1 in the window region formation step. The method for manufacturing the semiconductor laser device 1 according to this embodiment will be described below with reference to FIGS. 26 to 29, focusing on the differences from the method for manufacturing the semiconductor laser device 1 according to embodiment 1. FIGS. 26 to 29 are schematic cross-sectional views showing the steps of the method for manufacturing the semiconductor laser device 1 according to this embodiment. FIGS. 26 to 29 show cross sections at the same positions as in FIG. 2.

[0141] First, similarly to the first embodiment, the semiconductor laminated film 1Sm is formed (lamination step).

[0142] Next, a window region Rw is formed in the semiconductor laminate film 1Sm to form the semiconductor laminate body 1S (window region forming process). In this embodiment, as shown in FIG. 26 , the contact film 70m is not disposed in the region where the window region Rw is to be formed. In this embodiment, the window region forming process includes a removal process of removing a portion of the contact film 70m. In the removal process, the contact film 70m disposed in the region where the window region Rw is to be formed is removed. In this embodiment, a region of the contact film 70m with a predetermined length Dc in the resonance direction from the first end facet 1F and the second end facet 1R is removed. The predetermined length Dc is, for example, 10 μm. The portion of the contact film 70m is removed using, for example, photolithography and etching.

[0143] 27, a protective layer 13 is formed to cover the upper surface of the contact film 70m and the region of the upper surface of the semiconductor laminated film 1Sm that is not covered with the contact film 70m. In this embodiment, the protective layer 13 is made of SiO ２ The protective layer 13 is a layer. The distance Dd from the first end facet 1F to the protective layer 13 (and the distance from the second end facet 1R to the protective layer 13) is, for example, less than 15 μm. The protective layer 13 is formed using, for example, a low-pressure CVD method. The protective layer 13 may also be formed using, for example, an atmospheric pressure CVD method. A portion of the protective layer 13 is removed using, for example, photolithography and etching.

[0144] Next, a diffusion source layer 14 containing Zn is formed in a region above the p-type cladding film 50m where the contact film 70m is not disposed (diffusion source layer formation process). In this embodiment, the diffusion source layer 14 containing Zn is formed in a region of the upper surface of the semiconductor laminated film 1Sm where the contact film 70m and the protective layer 13 are not formed (i.e., a region where the p-type barrier buffer film 60m is exposed) (diffusion source layer formation process). In this embodiment, a ZnO layer is formed as the diffusion source layer 14. The diffusion source layer 14 may also be formed on the protective layer 13. The diffusion source layer 14 is formed using, for example, a sputtering method. The diffusion source layer 14 may be formed by, for example, a low-pressure CVD method or an atmospheric-pressure CVD method.

[0145] Next, a diffusion source covering layer 15 is formed to cover the diffusion source layer 14. In this embodiment, the diffusion source covering layer 15 is a SiN layer that covers the entire upper surface of the diffusion source layer 14. The diffusion source covering layer 15 is formed by, for example, a low-pressure CVD method. The diffusion source covering layer 15 may also be formed by, for example, an atmospheric pressure CVD method.

[0146] Next, the semiconductor laminated film 1Sm and the diffusion source layer 14 are heated (heating step). ２ The semiconductor laminated film 1Sm and the diffusion source layer 14 are heated at 560° C. for 40 minutes in a Zn atmosphere. As a result, Zn diffuses into the semiconductor laminated film 1Sm, and a window region Rw is formed as shown in FIG. 28 . Specifically, the bandgap energy of the well layer 42b in the window region Rw is increased by 190 meV compared to the bandgap energy of the gain region. This reduces the absorption of laser light in the well layer 42b.

[0147] 29, the diffusion source layer 14 is removed (diffusion source layer removal step). More specifically, the diffusion source layer 14, the protective layer 13, and the diffusion source covering layer 15 are all removed. These layers can be removed by, for example, etching. This completes the window region formation step.

[0148] Subsequently, similarly to the manufacturing method of the semiconductor laser device 1 according to the first embodiment, the contact layer removal step, the ridge formation step, the current blocking layer formation step, the p-side electrode formation step, the n-side electrode formation step, etc. are performed, thereby manufacturing the semiconductor laser device 1.

[0149] As described above, the window region forming step in the method for manufacturing the semiconductor laser device 1 according to this embodiment includes a diffusion source layer forming step of forming the diffusion source layer 14 containing Zn in a region above the p-type cladding film 50 m where the contact film 70 m is not disposed. In this embodiment, the window region forming step also includes a removal step of removing a portion of the contact film 70 m.

[0150] In this way, the contact film 70m is not disposed in the region where the window region Rw is formed, and the diffusion source layer 14 is formed in the region where the contact film 70m is not disposed. As a result, even if the contact film 70m includes a GaAs layer in which the Zn diffusion rate is slow, it is not affected by the contact film 70m. This increases the Zn diffusion rate. Therefore, the time required for Zn diffusion can be shortened, thereby suppressing the Zn concentration in the window region Rw. This reduces the absorption of laser light in the window region Rw. For example, in this embodiment, the time required for the heating step to diffuse Zn can be shortened by 40 minutes compared to the first embodiment.

[0151] In the method for manufacturing the semiconductor laser device 1 according to the present embodiment, the contact film 70m may be doped with C as an impurity.

[0152] This reduces the diffusion of Mg from the contact film 70m near the first end face 1F and the second end face 1R to the window region Rw, thereby reducing the Mg concentration in the window region Rw and reducing the absorption of laser light by Mg in the window region Rw.

[0153] (Fourth Embodiment) The configuration of a semiconductor laser device according to a fourth embodiment will be described. The semiconductor laser device according to this embodiment differs from the semiconductor laser device 101 according to the second embodiment mainly in the configurations of the active layer, each optical guide layer, and p-type cladding layer. The following description of the semiconductor laser device according to this embodiment will focus on the differences from the semiconductor laser device 101 according to the second embodiment.

[0154] [4-1. Overall Configuration] The overall configuration of the semiconductor laser device according to this embodiment will be described with reference to FIGS. 30 to 35. FIG. 30 is a schematic cross-sectional view showing the overall configuration of the semiconductor laser device 201 according to this embodiment. Like FIGS. 2 and 24, FIG. 30 shows a portion of a cross section parallel to the stacking direction and resonance direction of the semiconductor laser device 201. FIGS. 31, 32, 33, and 34 are schematic cross-sectional views showing the configurations of the n-side optical guiding layer 241, the active layer 242, the p-side optical guiding layer 243, and the second p-type cladding layer 252 included in the semiconductor laser device 201 according to this embodiment, respectively. FIGS. 31, 32, 33, and 34 show portions of cross sections perpendicular to the resonance direction of the n-side optical guiding layer 241, the active layer 242, the p-side optical guiding layer 243, and the second p-type cladding layer 252, respectively. 35 is a graph showing an example of the distribution of Mg concentration and Al secondary ion intensity with respect to the stacking direction position in the semiconductor laser device 201 according to this embodiment. FIG. 35 is a graph showing an example of the results of measuring the Mg concentration and Al secondary ion intensity at the stacking direction position in the semiconductor stack 201S included in the semiconductor laser device 201 by secondary ion mass spectrometry (SIMS). The stacking direction position on the horizontal axis of FIG. 35 represents the position corresponding to the depth in the measurement, the left vertical axis represents the Mg concentration, and the right vertical axis represents the Al secondary ion intensity. Note that the horizontal axis of FIG. 35 sets the center position of the active layer 242 in the stacking direction to 0 μm. On the horizontal axis of FIG. 35 , stacking direction positions above the center position are represented by negative values, and stacking direction positions below the center position are represented by positive values.

[0155] 30 , the semiconductor laser device 201 according to the present embodiment includes a substrate 10, a semiconductor stack 201S, a first p-side electrode 91, a second p-side electrode 92, a third p-side electrode 93, a current blocking layer 80, an n-side electrode 94, and an end face protective film 2F. Although not shown in FIG. 30 , the semiconductor laser device 201 also includes an end face protective film 2R, similar to the semiconductor laser device 1 according to the first embodiment.

[0156] The semiconductor laminate 201S according to this embodiment has an n-type cladding layer 130, an active layer 242, a p-type cladding layer 250, and a contact layer 170, which are stacked in this order from the substrate 10 side. In this embodiment, the semiconductor laminate 201S further has a buffer layer 21, an n-type barrier buffer layer 22, an n-side optical guide layer 241, a p-side optical guide layer 243, and a p-type barrier buffer layer 60.

[0157] The n-side light guiding layer 241 according to this embodiment is a semiconductor layer disposed above the n-type cladding layer 130. In this embodiment, the n-side light guiding layer 241 has a first n-side light guiding layer 241a and a second n-side light guiding layer 241b, as shown in FIG.

[0158] The first n-side light guiding layer 241a is in contact with the active layer 242. The first n-side light guiding layer 241a is disposed between the active layer 242 and the second n-side light guiding layer 241b. In this embodiment, the first n-side light guiding layer 241a is made of a III-V group semiconductor containing In. The first n-side light guiding layer 241a further contains Al. The first n-side light guiding layer 241a has a refractive index smaller than that of the barrier layer 242a and a refractive index larger than that of the second n-side light guiding layer 241b. The Al composition ratio of the first n-side light guiding layer 241a is larger than that of the barrier layer 242a and smaller than that of the second n-side light guiding layer 241b. The first n-side light guiding layer 241a according to this embodiment is made of AlGaInP. More specifically, the first n-side light guiding layer 241a is made of an undoped (AlGaInP) layer with a thickness of 0.057 μm. ０．６２ Ga ０．３８ ) ０．５１ In ０．４９ This is the P layer.

[0159] The second n-side light guiding layer 241b is in contact with the n-type cladding layer 130. The second n-side light guiding layer 241b is disposed between the n-type cladding layer 130 and the first n-side light guiding layer 241a. The second n-side light guiding layer 241b is made of a III-V group semiconductor containing In. In this embodiment, the second n-side light guiding layer 241b further contains Al. The second n-side light guiding layer 241b has a refractive index smaller than that of the first n-side light guiding layer 241a and a refractive index larger than that of the n-type cladding layer 130. The Al composition ratio of the second n-side light guiding layer 241b is larger than that of the first n-side light guiding layer 241a and smaller than that of the n-type cladding layer 130. The second n-side light guiding layer 241b in this embodiment is made of AlGaInP. More specifically, the second n-side light guide layer 241b is an n-type (Al) doped with n-type impurities and having a thickness of 0.025 μm. ０．８５ Ga ０．１５ ) ０．５１ In ０．４９ In this embodiment, Si is used as the n-type impurity. The Si concentration of the second n-side light guide layer 241b is 3.5×10 １７ cm －３ is.

[0160] 30 , the active layer 242 according to this embodiment is a light emitting layer made of a III-V group semiconductor containing In, and is disposed above the n-type cladding layer 130. In this embodiment, the active layer 242 is disposed between the n-side optical guiding layer 241 and the p-side optical guiding layer 243, and is in contact with the n-side optical guiding layer 241 and the p-side optical guiding layer 243.

[0161] As shown in FIG. 32, the active layer 242 includes a barrier layer 242a, a well layer 242b, and a barrier layer 242c.

[0162] The barrier layer 242a is disposed above the n-type cladding layer 130. In this embodiment, the barrier layer 242a is disposed above the n-side optical guide layer 241 and is in contact with the n-side optical guide layer 241. The barrier layer 242a is an undoped (Al ０．５６ Ga ０．４４ ) ０．５０８ In ０．４９２ This is the P layer.

[0163] The well layer 242b is disposed between the barrier layer 242a and the barrier layer 242c. In this embodiment, the well layer 242b is in contact with both the barrier layer 242a and the barrier layer 242c. The well layer 242b is an undoped GaInP layer with a thickness of 0.0115 μm.

[0164] The barrier layer 242c is disposed above the well layer 242b. In this embodiment, the barrier layer 242c is disposed between the well layer 242b and the p-side optical guiding layer 243, and is in contact with both the well layer 242b and the p-side optical guiding layer 243. The barrier layer 242c is an undoped (Al ０．５６ Ga ０．４４ ) ０．５０８ In ０．４９２ This is the P layer.

[0165] As shown in Fig. 30, the p-side light guiding layer 243 according to this embodiment is a semiconductor layer disposed above the active layer 242. In this embodiment, as shown in Fig. 33, the p-side light guiding layer 243 has a first p-side light guiding layer 243a and a second p-side light guiding layer 243b.

[0166] The first p-side light guiding layer 243a is in contact with the active layer 242. The first p-side light guiding layer 243a is disposed between the active layer 242 and the second p-side light guiding layer 243b. In this embodiment, the first p-side light guiding layer 243a is made of a III-V group semiconductor containing In. The first p-side light guiding layer 243a further contains Al. The first p-side light guiding layer 243a has a refractive index smaller than that of the barrier layer 242a and a refractive index larger than that of the second p-side light guiding layer 243b. The Al composition ratio of the first p-side light guiding layer 243a is larger than that of the barrier layer 242c and smaller than that of the second p-side light guiding layer 243b. The first p-side light guiding layer 243a in this embodiment is made of AlGaInP. More specifically, the first p-side light guiding layer 243a is made of a p-type (AlGaInP) layer having a thickness of 0.057 μm and doped with p-type impurities. ０．６２ Ga ０．３８ ) ０．５１ In ０．４９ In this embodiment, Mg is used as a p-type impurity. The Mg concentration of the first p-side light guide layer 243a is 1.0×10 １７ cm －３That's it, 4.0 x 10 １７ cm －３ The average Mg concentration of the first p-side light guide layer 243a is 3.0×10 １７ cm －３ 35, the Mg concentration in the first p-side light guide layer 243a decreases toward the active layer 242.

[0167] The second p-side light guiding layer 243b is in contact with the n-type cladding layer 130. The second p-side light guiding layer 243b is disposed between the n-type cladding layer 130 and the first n-side light guiding layer 241a. In this embodiment, the second p-side light guiding layer 243b is made of a III-V group semiconductor containing In. The second p-side light guiding layer 243b further contains Al. The second p-side light guiding layer 243b has a refractive index smaller than that of the first n-side light guiding layer 241a and a refractive index larger than that of the n-type cladding layer 130. The Al composition ratio of the second p-side light guiding layer 243b is larger than that of the first p-side light guiding layer 243a and smaller than that of the p-type cladding layer 250. The second p-side light guiding layer 243b in this embodiment is made of AlGaInP. More specifically, the second p-side light guide layer 243b is a p-type (Al) doped with p-type impurities and having a thickness of 0.025 μm. ０．８５ Ga ０．１５ ) ０．５１ In ０．４９ In this embodiment, Mg is used as a p-type impurity. The Mg concentration of the second p-side light guide layer 243b is 3.0×10 １７ cm －３ That's it, 5.0 x 10 １７ cm －３ The average Mg concentration of the second p-side light guide layer 243b is 4.0×10 １７ cm －３ 35, the Mg concentration in the second p-side light guide layer 243b decreases toward the active layer 242.

[0168] 30 , the p-type cladding layer 250 according to this embodiment is disposed above the active layer 242 and is a semiconductor layer made of a III-V group semiconductor containing In. The p-type cladding layer 250 has a first p-type cladding layer 251 and a second p-type cladding layer 252.

[0169] The first p-type cladding layer 251 is disposed above the active layer 242. In this embodiment, the first p-type cladding layer 251 is disposed above the p-side optical guide layer 243 and is in contact with the p-side optical guide layer 43. In this embodiment, the first p-type cladding layer 251 is a p-type AlInP layer doped with a p-type impurity and having a thickness of 0.018 μm. In this embodiment, Mg is used as the p-type impurity. The Mg concentration in the portion of the first p-type cladding layer 251 located in the gain region is 1.0×10 １８ cm －３ In this embodiment, as shown in FIG. 35, the Mg concentration of the first p-type cladding layer 251 is 0.4×10 １８ cm －３ That's it, 0.7 x 10 １８ cm －３ The Mg concentration in the first p-type cladding layer 251 decreases as it approaches the active layer 242.

[0170] The second p-type cladding layer 252 is disposed above the first p-type cladding layer 251. In this embodiment, the second p-type cladding layer 252 is disposed between the first p-type cladding layer 251 and the p-type barrier buffer layer 60, and is in contact with both the first p-type cladding layer 251 and the p-type barrier buffer layer 60. In this embodiment, the second p-type cladding layer 252 is a p-type AlInP layer doped with a p-type impurity and having a thickness of 0.942 μm. In this embodiment, Mg is used as the p-type impurity. The Mg concentration in the portion of the second p-type cladding layer 252 located in the gain region is 0.6×10 １８ cm －３ In this embodiment, the Mg concentration in the portion of the second p-type cladding layer 252 located in the gain region is 0.7×10 １８ cm －３ That's it, 0.8 x 10 １８ cm －３ The following is the result.

[0171] 34, the second p-type cladding layer 252 has a lower layer 252a and an upper layer 252b. The Mg concentration of the lower layer 252a decreases toward the active layer 242. In the example shown in FIG. 35, the Mg concentration of the lower layer 252a is 0.6×10 １８ cm －３ That's it, 0.8 x 10 １８ cm －３ The Mg concentration in the upper layer 252b increases toward the active layer 242. In this way, the Mg concentration reaches a maximum in the region including the interface between the lower layer 252a and upper layer 252b of the second p-type cladding layer 252.

[0172] In the present disclosure, the Mg concentration is determined by fitting a curve to a graph showing the relationship between the measured value of the Mg concentration and the position in the stacking direction, as shown by the thick solid line in FIG.

[0173] [4-2. Effects] The effects of the semiconductor laser device 201 according to this embodiment will be described.

[0174] In the gain region of the semiconductor laminate 201S of the semiconductor laser device 201 according to this embodiment, the average Mg concentration of the p-side optical guiding layer 243 is lower than the average Mg concentration of the first p-type cladding layer 251, which is lower than the average Mg concentration of the second p-type cladding layer 252.

[0175] As described above, in this embodiment, the average Mg concentration in the gain region is gradually decreased toward the active layer 242. Here, the intensity of the laser light increases toward the active layer 242. Therefore, in this embodiment, by reducing the average Mg concentration in the region close to the active layer 242, it is possible to reduce the absorption of the laser light by Mg. This allows the gain of the semiconductor laser device 201 to be increased.

[0176] In addition, in this embodiment, the Al composition ratio of each barrier layer and each optical guide layer is larger than that of each barrier layer and each optical guide layer according to embodiment 2. In this embodiment, the Al composition ratio of each optical guide layer is larger than that of each barrier layer.

[0177] In this way, by increasing the Al composition ratio in the active layer 242 and its vicinity, the diffusion rate of Zn in the active layer 242 and its vicinity can be increased. This reduces the time required for Zn diffusion in the window region formation process. Therefore, the Zn concentration accumulated in the window region Rw can be suppressed. This reduces the absorption of laser light in the window region Rw. This increases the gain of the semiconductor laser device 201.

[0178] In this embodiment, the Al composition ratio of the first n-side light guiding layer 241 a is smaller than that of the second n-side light guiding layer 241 b, and the Al composition ratio of the barrier layer 242 a is smaller than that of the first n-side light guiding layer 241 a. The Al composition ratio of the first p-side light guiding layer 243 a is smaller than that of the second p-side light guiding layer 243 b, and the Al composition ratio of the barrier layer 242 c is smaller than that of the first p-side light guiding layer 243 a.

[0179] As described above, the Al composition ratios of the barrier layers 242a and the n-side optical guiding layer 241 decrease toward the well layer 242b, while the Al composition ratios of the barrier layers 242c and the p-side optical guiding layer 243 decrease toward the well layer 242b. This causes the refractive index of each barrier layer and each optical guiding layer to increase toward the well layer 242b. This increases the optical confinement factor of the active layer 242. Furthermore, by gradually increasing the Al composition ratio of the p-side optical guiding layer 243 relative to the barrier layer 242c, the conduction band energy of the p-side optical guiding layer can be gradually increased relative to the conduction band energy of the barrier layer 242c. Therefore, the p-side optical guiding layer 243 functions as a barrier to electrons, thereby suppressing electron leakage from the active layer 242. This improves the temperature characteristics of the semiconductor laser device 201.

[0180] (Modifications, etc.) Although the semiconductor laser device and the manufacturing method thereof according to the present disclosure have been described above based on the respective embodiments, the present disclosure is not limited to the above-described respective embodiments.

[0181] For example, in each of the above embodiments, the Mg concentration in the portion of the second p-type cladding layer 52 located in the gain region may be higher than the Zn concentration in the portion of the second p-type cladding layer 52 located in the window region Rw. A window region having such a Zn concentration can be achieved, for example, by adjusting the time of the heat treatment process in the window region formation process. Specifically, in the method for manufacturing the semiconductor laser device 1 according to the first embodiment, the amount of Zn diffusion in the window region Rw can be reduced by setting the time of the heat treatment process to approximately 30 minutes. This allows the formation of a window region Rw having the above-described Zn concentration. In the window region Rw, the refractive index distribution in the stacking direction of the semiconductor stack 1S differs from the refractive index distribution in the gain region. Therefore, in the window region Rw, the optical confinement factor of the active layer 42 is reduced, and light is distributed over a wider region in the stacking direction. Accordingly, the optical intensity in the p-type cladding layer 50 in the window region Rw is greater than the optical intensity in the p-type cladding layer 50 in the gain region. Therefore, by reducing the total concentration of Mg and Zn in the p-type cladding layer 50 in the window region Rw, the absorption of laser light in the window region Rw can be further reduced, thereby reducing heat generation in the vicinity of the first facet 1F and improving the COD level.

[0182] Furthermore, the p-type cladding layer may be doped with Zn in a portion located in the gain region. That is, before the window region forming step, the entire p-type cladding film may be doped with Zn. That is, the entire p-type cladding layer may be doped with Zn. The Zn concentration in the portion of the p-type cladding layer located in the gain region may be, for example, 1×10 １７ cm －３ is less than.

[0183] This facilitates interdiffusion of Mg and Zn in the window region formation step, thereby reducing the time required for Zn diffusion and, therefore, reducing the amount of Zn accumulated in the window region Rw, thereby reducing the absorption of laser light by Zn.

[0184] The configuration of the p-type cladding layer in the semiconductor laser device according to the first embodiment is not limited to the above-described configuration. For example, the Mg concentration in the portion of the first p-type cladding layer and the second p-type cladding layer located in the gain region may be 1.0×10 １８ cm －３ For example, the Mg concentration in the portions of the first p-type cladding layer and the second p-type cladding layer located in the gain region may be 0.7×10 or less. １８ cm －３ This can reduce the absorption of laser light by Mg in the gain region, thereby increasing the gain of the semiconductor laser device.

[0185] This disclosure also includes forms obtained by applying various modifications to the above-mentioned embodiments that a person skilled in the art would conceive, and forms realized by arbitrarily combining the components and functions of the above-mentioned embodiments within the scope of the present disclosure.

[0186] For example, the configuration of the active layer 242 and each optical guide layer according to the fourth embodiment may be applied to other embodiments. Also, the configuration of the p-type cladding layer 250 according to the fourth embodiment may be applied to other embodiments.

[0187] The semiconductor laser device according to the present disclosure has low absorption of laser light in the window region, and is therefore particularly applicable as a high-light output light source for, for example, displays, head-up displays, biomedical applications, and projectors.

[0188] REFERENCE SIGNS LIST 1, 101, 201 Semiconductor laser element 1F First end facet 1R Second end facet 1S, 101S, 201S Semiconductor laminate 1Sm Semiconductor laminate film 2F, 2R End face protective film 10 Substrate 11 Cap layer 12 Cap covering layer 13 Protective layer 14 Diffusion source layer 15 Diffusion source covering layer 21 Buffer layer 21m Buffer film 22 n-type barrier relaxation layer 22m n-type barrier relaxation film 30, 130 n-type cladding layer 30m n-type cladding film 31 First n-type cladding layer 31m First n-type cladding film 32 Second n-type cladding layer 32m Second n-type cladding film 33 Third n-type cladding layer 33m Third n-type cladding film 41, 241 n-side optical guide layer 41m n-side optical guide film 42, 242 Active layer 42m Active film 42a, 42c, 242a, 242c Barrier layer 42b, 242b Well layer 43, 243 P-side light guide layer 43m P-side light guide film 50, 150, 250 P-type cladding layer 50m P-type cladding film 50P Protrusion 50R Ridge 50T Groove 51, 151, 251 First p-type cladding layer 51m First p-type cladding film 52, 252 Second p-type cladding layer 52m Second p-type cladding film 60 P-type barrier buffer layer 60m P-type barrier buffer film 61 First p-type barrier buffer layer 62 Second p-type barrier buffer layer 63 Third p-type barrier buffer layer 70, 170 Contact layer 70m Contact film 71, 171 First contact layer 72, 172 Second contact layer 80 Current blocking layer 80a Opening 91 First p-side electrode 92 Second p-side electrode 93 Third p-side electrode 94 N-side electrode 241a First n-side light guide layer 241b Second n-side light guide layer 243a First p-side light guide layer 243b Second p-side light guide layer 252a Lower layer 252b Upper layer Ri Current injection region Rn First region Rw Window region

Claims

1. A semiconductor laser device comprising a semiconductor laminate and emitting laser light, wherein the semiconductor laminate comprises: an n-type cladding layer made of a III-V semiconductor containing In; an active layer arranged above the n-type cladding layer and made of a III-V semiconductor containing In; a p-type cladding layer arranged above the active layer and made of a III-V semiconductor containing In; and a contact layer arranged above the p-type cladding layer; the semiconductor laminate has first and second end faces located at ends in a direction perpendicular to the lamination direction and constituting a resonator in which the laser light resonates; a gain region into which current is injected; and a window region formed between the first end face and the gain region; the p-type cladding layer is doped with Mg as an impurity; and Zn is diffused in the window region; the Mg concentration in the portion of the p-type cladding layer located in the gain region is represented by Na; and the Mg concentration in the portion of the p-type cladding layer located in the window region is represented by Nw; When the Zn concentration in the portion of the p-type cladding layer located in the window region is represented by Nz, the following relationships hold: Na>10Nw and Nz>Nw.

2. The semiconductor laser device according to claim 1, wherein the contact layer is doped with C as an impurity.

3. The semiconductor laser device according to claim 1 or 2, wherein the p-type cladding layer is made of AlInP.

4. The p-type cladding layer includes a first p-type cladding layer and a second p-type cladding layer disposed above the first p-type cladding layer, and the Mg concentration in the portion of the second p-type cladding layer located in the gain region is 0.7×10 １８ cm －３ The semiconductor laser device according to any one of claims 1 to 3, wherein the .lambda.

5. The semiconductor laminate includes a p-side optical guide layer disposed between the p-type cladding layer and the active layer, and the Mg concentration in the portion of the first p-type cladding layer located in the gain region is 1.0×10 １８ cm －３ The Mg concentration in the portion of the p-side optical guide layer located in the gain region is lower than 3.0×10 １７ cm －３ The semiconductor laser device according to claim 4, wherein 6. A semiconductor laser device according to any one of claims 1 to 3, wherein the p-type cladding layer comprises a first p-type cladding layer and a second p-type cladding layer disposed above the first p-type cladding layer, and the Mg concentration in a portion of the second p-type cladding layer located in the gain region is higher than the Zn concentration in a portion of the second p-type cladding layer located in the window region.

7. The semiconductor laser device according to any one of claims 1 to 6, wherein the n-type cladding layer is made of AlInP.

8. The Si concentration of the n-type cladding layer is 4.0×10 １７ cm －３ The semiconductor laser device according to any one of claims 1 to 7, wherein 9. The semiconductor laser device according to any one of claims 1 to 8, wherein the portion of said p-type cladding layer located in said gain region is doped with Zn.

10. The Zn concentration at the interface of the n-type cladding layer located in the window region on the side farther from the active layer is 1.0×10 １８ cm －３ The semiconductor laser device according to any one of claims 1 to 9, wherein:

11. A method for manufacturing a semiconductor laser device that emits laser light, wherein the semiconductor laser device comprises a semiconductor laminate, the semiconductor laminate having: an n-type cladding layer made of a III-V semiconductor containing In; an active layer arranged above the n-type cladding layer and made of a III-V semiconductor containing In; a p-type cladding layer arranged above the active layer and made of a III-V semiconductor containing In; and a contact layer arranged above the p-type cladding layer, the semiconductor laminate having first and second end faces located at ends in a direction perpendicular to the lamination direction and constituting a cavity in which the laser light resonates; a gain region into which current is injected; and a window region formed between the first end face and the gain region, and the method for manufacturing the semiconductor laser device comprises: a window region forming step of forming the semiconductor laminated film by forming the window region in the semiconductor laminated film, wherein the window region forming step comprises: a cap layer forming step of forming a cap layer containing In in a region on the contact film that is located above a region corresponding to the window region; and a diffusion source layer forming step of forming a diffusion source layer containing Zn on the cap layer.

12. The method for manufacturing a semiconductor laser device according to claim 11, wherein the cap layer is made of GaInP or AlGaInP.

13. A method for manufacturing a semiconductor laser device that emits laser light, wherein the semiconductor laser device comprises a semiconductor laminate, the semiconductor laminate having: an n-type cladding layer made of a III-V semiconductor containing In; an active layer arranged above the n-type cladding layer and made of a III-V semiconductor containing In; a p-type cladding layer arranged above the active layer and made of a III-V semiconductor containing In; and a contact layer arranged above the p-type cladding layer, the semiconductor laminate having first and second end faces located at ends in a direction perpendicular to the lamination direction and constituting a cavity in which the laser light resonates; a gain region into which current is injected; and a window region formed between the first end face and the gain region, and the method for manufacturing the semiconductor laser device comprises: a semiconductor layered film including an n-type cladding film made of a III-V semiconductor containing In, an active film disposed above the n-type cladding film and made of a III-V semiconductor containing In, a p-type cladding film disposed above the active film and made of a III-V semiconductor containing In, and a contact film disposed above the p-type cladding film; and a window region forming step of forming the semiconductor layered body by forming the window region in the semiconductor layered film, wherein the window region forming step includes a diffusion source layer forming step of forming a diffusion source layer containing Zn in a region above the p-type cladding film where the contact film is not disposed.

14. The method for manufacturing a semiconductor laser device according to claim 13, wherein the window region forming step includes a removing step of removing a part of the contact film.

15. The method for manufacturing a semiconductor laser device according to any one of claims 11 to 14, wherein the contact film is doped with C as an impurity.

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