Semiconductor laser device

Abstract

This semiconductor laser device comprises a semiconductor substrate, a light emitting unit, a contact layer, an insulating film, and a first electrode. The contact layer has an electrode connection surface facing the Z direction. The insulating film has a pair of contact layer covering parts that cover both end regions of the electrode connection surface in the X direction, and a first opening that exposes a portion of the electrode connection surface. The first electrode is connected to the electrode connection surface exposed from the first opening. The insulation coverage factor, which is the ratio of the width of the pair of contact layer covering parts in the X direction to the width of the electrode connection surface in the X direction, is 10% or less. The thickness of the contact layer in the Z direction is 2 µm or greater.

Description

semiconductor laser device

[0001] The present disclosure relates to a semiconductor laser device.

[0002] Patent Document 1 discloses a semiconductor laser device. This semiconductor laser device has a light-emitting portion including a double heterostructure having an n-type cladding layer, an active layer, and a p-type cladding layer. Such a semiconductor laser device emits laser light from an end facet of the light-emitting portion.

[0003] Japanese Patent Application Laid-Open No. 2019-186387

[0004] However, in order to increase the output power of the semiconductor laser device, it is necessary to increase the width of the light-emitting portion in the horizontal direction. In such a semiconductor laser device, there is room for improvement in terms of uniformity of the light-emitting intensity near the end face of the light-emitting portion.

[0005] A semiconductor laser device according to one aspect of the present disclosure includes a semiconductor substrate having a substrate main surface and a substrate back surface facing the opposite side to the substrate main surface in a first direction orthogonal to the substrate main surface, a light emitting portion protruding from the substrate main surface in the first direction and having a contact layer connection surface facing the first direction and light emitting portion end faces which are both end faces in a second direction orthogonal to the first direction, a contact layer provided on the contact layer connection surface and having an electrode connection surface facing the first direction, and a contact layer covering both side faces of the light emitting portion in a third direction orthogonal to the first direction and both side faces of the contact layer in the third direction. the light-emitting portion comprises an insulating film having a pair of side surface covering portions, a pair of contact layer covering portions covering both end regions of the electrode connection surface in the third direction, an opening formed by the pair of contact layer covering portions and exposing a portion of the electrode connection surface, and an electrode electrically connected to the electrode connection surface exposed from the opening, wherein the light-emitting portion emits laser light from one of the two light-emitting portion end faces, an insulating coverage rate which is the ratio of the width of the pair of contact layer covering portions in the third direction to the width of the electrode connection surface in the third direction is 10% or less, and the thickness of the contact layer in the first direction is 2 μm or more.

[0006] According to the semiconductor laser device of one aspect of the present disclosure, the light emission intensity in the vicinity of the end face of the light emitting portion can be made uniform.

[0007] FIG. 1 is a perspective view showing a semiconductor laser device of an embodiment. FIG. 2 is a cross-sectional view of the semiconductor laser device shown in FIG. 1. FIG. 3 is an explanatory diagram showing an example of the structure of the light-emitting unit shown in FIG. 2. FIG. 4 is an explanatory diagram showing an example of the structure of the active layer shown in FIG. 3. FIG. 5 is an explanatory diagram showing an example of the structure of the tunnel layer shown in FIG. 2. FIG. 6 is an explanatory diagram showing the state of laser light emitted from the semiconductor laser device shown in FIG. 1. FIG. 7 is an explanatory diagram for explaining the relationship between the insulating coverage rate and the thickness of the contact layer and the state of laser light in a semiconductor laser device of an experimental example. FIG. 8A is an explanatory diagram showing the far-field pattern of the semiconductor laser device of an experimental example. FIG. 8B is an explanatory diagram showing the near-field pattern of the semiconductor laser device of an experimental example. FIG. 9A is an explanatory diagram showing the far-field pattern of the semiconductor laser device of an experimental example. FIG. 9B is an explanatory diagram showing the near-field pattern of the semiconductor laser device of an experimental example. FIG. 10A is an explanatory diagram showing the far-field pattern of the semiconductor laser device of an experimental example. FIG. 10B is an explanatory diagram showing the near-field pattern of the semiconductor laser device of an experimental example. Fig. 11A is an explanatory diagram showing a far-field pattern of a semiconductor laser device of an experimental example. Fig. 11B is an explanatory diagram showing a near-field pattern of a semiconductor laser device of an experimental example. Fig. 12 is a cross-sectional view showing a semiconductor laser device of a modified example. Fig. 13 is a cross-sectional view showing a semiconductor laser device of a modified example.

[0008] Hereinafter, embodiments of a semiconductor laser device according to the present disclosure will be described with reference to the accompanying drawings. For simplicity and clarity, components shown in the drawings are not necessarily drawn to scale. For ease of understanding, hatching may be omitted in cross-sectional views. The accompanying drawings are merely illustrative of embodiments of the present disclosure and should not be construed as limiting the present disclosure. In this specification, the terms "parallel," "vertical," "orthogonal," and "constant" do not only refer to strictly parallel, vertical, orthogonal, or constant, but also include roughly parallel, vertical, orthogonal, or constant within the scope of the effects of the present embodiment. In this specification, "equal" refers not only to exact equality but also to slight differences between objects due to dimensional tolerances, etc.

[0009] The statement "at least one of A and B" herein should be understood to mean "A only, or B only, or both A and B." The following detailed description includes apparatuses, systems, and methods embodying example embodiments of the present disclosure. This detailed description is merely illustrative in nature and is not intended to limit the embodiments of the present disclosure or the application and uses of such embodiments.

[0010] [One Embodiment] A semiconductor laser device 1A according to one embodiment will now be described with reference to FIGS. 1 to 6. FIG. 1 is a perspective view showing a semiconductor laser device according to one embodiment. FIG. 2 is a cross-sectional view of the semiconductor laser device shown in FIG. 1. FIG. 3 is an explanatory diagram showing an example of the structure of the light-emitting unit shown in FIG. 2. FIG. 4 is an explanatory diagram showing an example of the structure of the active layer shown in FIG. 3. FIG. 5 is an explanatory diagram showing an example of the structure of the tunnel layer shown in FIG. 2. FIG. 6 is an explanatory diagram showing the radiation pattern of laser light emitted from the semiconductor laser device shown in FIG. 1.

[0011] [Semiconductor Laser Device: Overall Configuration] As shown in FIGS. 1 and 2, the semiconductor laser device 1A includes a semiconductor substrate 10, a light emitting section 20, a contact layer 60, an insulating film 70, a first electrode 81, and a second electrode 82.

[0012] [Semiconductor Substrate] The semiconductor substrate 10 has a substrate main surface 101, a substrate back surface 102, and substrate side surfaces 103, 104, 105, and 106. The substrate main surface 101 and the substrate back surface 102 face opposite each other. A direction perpendicular to the substrate main surface 101 is defined as the Z direction (thickness direction: first direction). A direction perpendicular to the Z direction is defined as the Y direction (second direction). A direction perpendicular to the Z direction and perpendicular to the Y direction is defined as the X direction (third direction). The substrate side surfaces 103 and 104 face opposite each other in the Y direction. The substrate side surfaces 105 and 106 face opposite each other in the X direction. When viewed from the Z direction, the semiconductor substrate 10 is formed in a rectangular shape that is long in the Y direction.

[0013] The semiconductor substrate 10 has, for example, a rectangular plate shape. The semiconductor substrate 10 is configured, for example, as an n-type semiconductor substrate (n-GaAs substrate) containing GaAs (gallium arsenide). The semiconductor substrate 10 contains, for example, at least one of Si (silicon), Te (tellurium), and Se (selenium) as an n-type impurity.

[0014] [Light Emitting Section] The light emitting section 20 is provided on the substrate main surface 101 of the semiconductor substrate 10. The light emitting section 20 protrudes from the substrate main surface 101 toward the side opposite to the substrate back surface 102. That is, the light emitting section 20 protrudes from the substrate main surface 101 in the Z direction.

[0015] The light emitting section 20 has a contact layer connection surface 201, a substrate connection surface 202, light emitting section end surfaces 203 and 204, and light emitting section side surfaces 205 and 206. The contact layer connection surface 201 faces the same direction as the substrate main surface 101 in the Z direction. The substrate connection surface 202 faces the semiconductor substrate 10. The substrate connection surface 202 is connected to the substrate main surface 101. The light emitting section end surfaces 203 and 204 are both end surfaces of the light emitting section 20 in the Y direction. The light emitting section end surfaces 203 and 204 face opposite each other in the Y direction. The light emitting section side surfaces 205 and 206 are both side surfaces of the light emitting section 20 in the X direction. The light emitting section side surfaces 205 and 206 face opposite each other in the X direction. The light emitting section side surfaces 205 and 206 connect the contact layer connection surface 201 and the substrate connection surface 202. The light-emitting portion end faces 203 and 204 form cavity end faces. The Y direction can be said to be the cavity direction of the light-emitting portion 20.

[0016] The light emitting section 20 has, for example, a mesa structure. When viewed from the Y direction, the light emitting section 20 is formed in a trapezoidal shape (ridge shape) protruding from the substrate main surface 101. The light emitting section side surface 205 is inclined so as to face the contact layer connection surface 201 side with respect to the direction in which the substrate side surface 105 faces. The light emitting section side surface 206 is inclined so as to face the contact layer connection surface 201 side with respect to the direction in which the substrate side surface 106 faces. When viewed from the Y direction, the light emitting section 20 is formed in a trapezoidal shape in which the width of the contact layer connection surface 201 is narrower than the width of the substrate connection surface 202 that is connected to the substrate main surface 101.

[0017] 1 , the light emitting portion 20 extends in the Y direction. For example, the length of the light emitting portion 20 in the Y direction is equal to the length of the semiconductor substrate 10 in the Y direction. In other words, the light emitting portion end surface 203 of the light emitting portion 20 is flush with the substrate side surface 103 of the semiconductor substrate 10. Furthermore, the light emitting portion end surface 204 of the light emitting portion 20 is flush with the substrate side surface 104 of the semiconductor substrate 10.

[0018] [Contact Layer] The contact layer 60 is provided on the contact layer connection surface 201 of the light-emitting section 20. The contact layer 60 has an electrode connection surface 601, a light-emitting section connection surface 602, contact layer end surfaces 603 and 604, and contact layer side surfaces 605 and 606. The electrode connection surface 601 faces the same direction as the substrate main surface 101 in the Z direction. That is, the electrode connection surface 601 faces the Z direction (first direction). The light-emitting section connection surface 602 faces the semiconductor substrate 10 side. The light-emitting section connection surface 602 is connected to the contact layer connection surface 201 of the light-emitting section 20. The contact layer end surfaces 603 and 604 are both end surfaces of the contact layer 60 in the Y direction. The contact layer end surfaces 603 and 604 face opposite each other in the Y direction. The contact layer side surfaces 605 and 606 are both side surfaces of the contact layer 60 in the X direction. The contact layer side surfaces 605 and 606 face opposite each other in the X direction. The contact layer end surfaces 603 and 604 and the contact layer side surfaces 605 and 606 connect the electrode connection surface 601 and the light emitting unit connection surface 602.

[0019] As shown in FIG. 2 , the contact layer 60 is formed in a trapezoidal (ridge-like) shape when viewed from the Y direction. The contact layer side surface 605 is inclined toward the electrode connection surface 601 with respect to the direction in which the substrate side surface 105 faces. For example, the inclination angle of the contact layer side surface 605 with respect to the substrate main surface 101 is equal to the inclination angle of the light-emitting section side surface 205 with respect to the substrate main surface 101. The contact layer side surface 605 is, for example, flush with the light-emitting section side surface 205. Note that the inclination angle of the contact layer side surface 605 with respect to the substrate main surface 101 may be different from the inclination angle of the light-emitting section side surface 205 with respect to the substrate main surface 101. The contact layer side surface 606 is inclined toward the electrode connection surface 601 with respect to the direction in which the substrate side surface 106 faces. For example, the inclination angle of the contact layer side surface 606 with respect to the substrate main surface 101 is equal to the inclination angle of the light-emitting section side surface 206 with respect to the substrate main surface 101. The contact layer side surface 606 is, for example, flush with the light emitting unit side surface 206. Therefore, the width in the X direction of the light emitting unit connection surface 602 that contacts the contact layer connection surface 201 of the light emitting unit 20 is equal to the width in the X direction of the contact layer connection surface 201. The inclination angle of the contact layer side surface 606 with respect to the substrate main surface 101 may be different from the inclination angle of the light emitting unit side surface 206 with respect to the substrate main surface 101. When viewed from the Y direction, the contact layer 60 is formed in a trapezoidal shape in which the width WC1 of the electrode connection surface 601 is narrower than the width of the light emitting unit connection surface 602 that is connected to the light emitting unit 20.

[0020] 1 , the contact layer 60 extends in the Y direction. For example, the length of the contact layer 60 in the Y direction is equal to the length of the light emitting section 20 in the Y direction. That is, a contact layer end surface 603 of the contact layer 60 is flush with the light emitting section end surface 203 of the light emitting section 20. Furthermore, a contact layer end surface 604 of the contact layer 60 is flush with the light emitting section end surface 204 of the light emitting section 20. Therefore, the length in the Y direction of the light emitting section connection surface 602 that is in contact with the contact layer connection surface 201 of the light emitting section 20 is equal to the length in the Y direction of the contact layer connection surface 201.

[0021] The contact layer 60 is located between the light emitting section 20 and the first electrode 81 in the Z direction. The contact layer 60 is electrically connected to the light emitting section 20 and also electrically connected to the first electrode 81. The contact layer 60 electrically connects the first electrode 81 and the light emitting section 20.

[0022] The contact layer 60 is made of a p-type semiconductor material containing, for example, GaAs. The contact layer 60 contains, as a p-type impurity, at least one of, for example, C (carbon) and Zn (zinc). The impurity concentration of the contact layer 60 is, for example, 1.0×10 １８ cm －３ Above 1.0 x 10 ２０ cm －３ The following is the result.

[0023] 1 and 2, the electrode connection surface 601 has, for example, a rectangular shape that is long in the Y direction when viewed from the Z direction. The width WC1 of the electrode connection surface 601 in the X direction (third direction) is, for example, constant.

[0024] The thickness TC1 of the contact layer 60 in the Z direction (first direction) is 2 μm or more. The thickness TC1 is the film thickness of the contact layer 60. For example, the thickness TC1 of the contact layer 60 is 10 μm or less. The thickness TC1 of the contact layer 60 may be greater than 10 μm. The thickness TC1 of the contact layer 60 may be thicker than the thickness of the second p-type cladding layer 37 in the Z direction. The thickness TC1 of the contact layer 60 may be equal to the thickness of the second p-type cladding layer 37 in the Z direction, or may be thinner than the thickness of the second p-type cladding layer 37 in the Z direction.

[0025] [Insulating Film] The insulating film 70 has a pair of side surface covering portions 71, 72 that cover both side surfaces of the light emitting portion 20 in the X direction (third direction) and both side surfaces of the contact layer 60 in the third direction. The insulating film 70 also has a pair of contact layer covering portions 73, 74 that cover both end regions of the electrode connection surface 601 in the third direction. The insulating film 70 may also have, for example, substrate covering portions 75, 76 that cover the substrate main surface 101 of the semiconductor substrate 10.

[0026] The side surface covering portion 71 covers the light emitting portion side surface 205 of the light emitting portion 20 and the contact layer side surface 605 of the contact layer 60. The side surface covering portion 72 covers the light emitting portion side surface 206 of the light emitting portion 20 and the contact layer side surface 606 of the contact layer 60. The side surface covering portion 71 is connected to the contact layer covering portion 73. The side surface covering portion 71 is also connected to the substrate covering portion 75. The side surface covering portion 72 is connected to the contact layer covering portion 74. The side surface covering portion 72 is also connected to the substrate covering portion 76. The insulating film 70 is made of, for example, SiN (silicon nitride), SiO ２ (silicon oxide), etc.

[0027] The insulating film 70 has a first opening 77X (opening) that exposes a portion of the electrode connection surface 601. The first opening 77X is formed by a pair of contact layer covering portions 73 and 74. Specifically, the first opening 77X corresponds to a portion between the end of the contact layer covering portion 73 opposite to the X direction and the end of the contact layer covering portion 74 in the X direction.

[0028] [Contact Layer Covering Portion] A pair of contact layer covering portions 73, 74 cover both end regions of the electrode connection surface 601 in the X direction (third direction). One contact layer covering portion 73 covers an end region of the electrode connection surface 601 in the X direction. The contact layer covering portion 73 extends along the end of the electrode connection surface 601 in the X direction. The other contact layer covering portion 74 covers an end region of the electrode connection surface 601 in the opposite direction to the X direction. The contact layer covering portion 74 extends along the end of the electrode connection surface 601 in the opposite direction to the X direction. Each of the contact layer covering portions 73, 74 is formed in a rectangular shape that is long in the Y direction when viewed from the Z direction. The length of each of the contact layer covering portions 73, 74 in the Y direction is, for example, equal to the length of the electrode connection surface 601 in the Y direction.

[0029] The width WI1 of the contact layer covering portion 73 in the X direction is constant along the Y direction, for example. The width WI2 of the contact layer covering portion 74 in the X direction is constant along the Y direction, for example. The pair of contact layer covering portions 73, 74 have, for example, the same width in the X direction (third direction). That is, the width WI1 of the contact layer covering portion 73 and the width WI2 of the contact layer covering portion 74 may be equal. Note that the width WI1 of the contact layer covering portion 73 and the width WI2 of the contact layer covering portion 74 may be different.

[0030] The ratio of the widths WI1 and WI2 of the pair of contact layer covering portions 73 and 74 in the X direction to the width WC1 of the electrode connection surface 601 in the X direction is defined as the insulation coverage ratio. That is, the insulation coverage ratio is the ratio (%) of the sum of the width WI1 of the contact layer covering portion 73 and the width WI2 of the contact layer covering portion 74 to the width WC1 of the electrode connection surface 601. The insulation coverage ratio is 10% or less. For example, the insulation coverage ratio is higher than 0%.

[0031] [First Electrode] The first electrode 81 is electrically connected to the electrode connection surface 601 exposed from the first opening 77X of the insulating film 70. The first electrode 81 is formed so as to cover the end portion of the insulating film 70 that forms the first opening 77X.

[0032] The first electrode 81 may be provided on the upper surface 701 of the insulating film 70 that covers the electrode connection surface 601 of the contact layer 60. That is, the first electrode 81 may have a portion that covers the contact layer coverings 73, 74. The first electrode 81 may have insulating film coverings 83, 84 in both end regions of the first electrode 81 in the third direction. The insulating film covering portion 83 is located in an end region of the first electrode 81 in the X direction. The insulating film covering portion 83 covers the end face of the contact layer covering portion 73 in the Z direction. In the Z direction, the contact layer covering portion 73 is sandwiched between the insulating film covering portion 83 and the contact layer 60. The insulating film covering portion 84 is located in an end region of the first electrode 81 in the direction opposite to the X direction. The insulating film covering portion 84 covers the end face of the contact layer covering portion 74 in the Z direction. In the Z direction, the contact layer covering portion 74 is sandwiched between the insulating film covering portion 84 and the contact layer 60.

[0033] The first electrode 81 may be composed of multiple electrode layers. For example, the first electrode 81 includes a first electrode layer and a second electrode layer. The first electrode layer and the second electrode layer are stacked in this order from the electrode connection surface 601 side. The first electrode layer is composed of, for example, Ti (titanium) / Au (gold). The second electrode layer is, for example, a plating layer containing Au.

[0034] [Second Electrode] The second electrode 82 is provided on the rear surface 102 of the semiconductor substrate 10. The second electrode 82 covers, for example, the entire surface of the rear surface 102. The second electrode 82 is electrically connected to the semiconductor substrate 10.

[0035] The second electrode 82 may be configured with a plurality of electrode layers. The second electrode 82 may include at least one of a Ni (nickel) layer, an AuGe (gold-germanium alloy) layer, a Ti layer, and an Au layer. For example, the second electrode 82 may include a Ni layer, an AuGe layer, a Ti layer, and an Au layer stacked in this order from the rear surface 102 of the substrate.

[0036] [Configuration Example of Light-Emitting Section] As shown in Fig. 2, the light-emitting section 20 includes light-emitting units 21 stacked on the substrate main surface 101 of the semiconductor substrate 10. The light-emitting units 21 generate light by recombination of holes and electrons. The light-emitting section 20 has, for example, three light-emitting units 21. Note that the light-emitting section 20 may have at least one light-emitting unit 21. In other words, the number of light-emitting units 21 may be one, two, or four or more.

[0037] The width WL1 of the light-emitting section 20 in the X direction (third direction) is, for example, 200 μm or more and 400 μm or less. The width WL1 of the light-emitting section 20 is, for example, the average width of the light-emitting section 20 in the X direction. In a light-emitting section 20 having three light-emitting units 21, the width WL1 of the light-emitting section 20 is the width of the central light-emitting unit 21 in the X direction. The width WL1 of the light-emitting section 20 is, for example, 225 μm. Note that the width WL1 of the light-emitting section 20 is not limited to 225 μm. The width WL1 of the light-emitting section 20 may be smaller than 200 μm or larger than 400 μm.

[0038] The light-emitting section 20 includes, for example, a tunnel layer 22 disposed between adjacent light-emitting units 21. The tunnel layer 22 generates a tunnel current due to a tunnel effect and supplies the tunnel current to the light-emitting units 21. The light-emitting section 20 includes, for example, two tunnel layers 22. The tunnel layer 22 is disposed between the two light-emitting units 21 adjacent to each other.

[0039] [Light-Emitting Unit] Figure 3 shows the configuration of the light-emitting unit 21. The light-emitting unit 21 includes an active layer 31, and an n-type semiconductor layer 32 and a p-type semiconductor layer 33 that sandwich the active layer 31 in the thickness direction of the active layer 31. The n-type semiconductor layer 32 is disposed on the side of the active layer 31 that faces the semiconductor substrate 10 shown in Figures 1 and 2. The p-type semiconductor layer 33 is disposed on the side of the active layer 31 opposite the n-type semiconductor layer 32, that is, on the side of the first electrode 81 shown in Figures 1 and 2. It can be said that the light-emitting unit 21 has a layered structure that includes the n-type semiconductor layer 32, the active layer 31, and the p-type semiconductor layer 33, which are layered in this order from the semiconductor substrate 10 side.

[0040] [N-Type Semiconductor Layer] The n-type semiconductor layer 32 contains AlGaAs (aluminum gallium arsenic). The n-type semiconductor layer 32 contains at least one of Si, Te, and Se as an n-type impurity. The impurity concentration of the n-type semiconductor layer 32 is, for example, 1.0×10 １７ cm －３ Above 1.0 x 10 １９ cm －３ The following is the result.

[0041] The n-type semiconductor layer 32 includes a first n-type cladding layer 34 and a second n-type cladding layer 35. The first n-type cladding layer 34 is disposed adjacent to the active layer 31. The second n-type cladding layer 35 is disposed on the opposite side of the first n-type cladding layer 34 from the active layer 31. In other words, it can be said that the n-type semiconductor layer 32 includes the first n-type cladding layer 34 adjacent to the active layer 31 and the second n-type cladding layer 35 located on the opposite side of the first n-type cladding layer 34 from the active layer 31. It can also be said that the n-type semiconductor layer 32 includes the first n-type cladding layer 34 and the second n-type cladding layer 35 stacked in this order from the active layer 31 side.

[0042] The impurity concentration of the second n-type cladding layer 35 may be different from the impurity concentration of the first n-type cladding layer 34. Specifically, the impurity concentration of the second n-type cladding layer 35 may be higher than the impurity concentration of the first n-type cladding layer 34. The impurity concentration of the second n-type cladding layer 35 may be equal to the impurity concentration of the first n-type cladding layer 34. The impurity concentration of the second n-type cladding layer 35 may also be lower than the impurity concentration of the first n-type cladding layer 34.

[0043] [P-Type Semiconductor Layer] The p-type semiconductor layer 33 contains AlGaAs. The p-type semiconductor layer 33 contains, for example, C as a p-type impurity. The impurity concentration of the p-type semiconductor layer 33 is, for example, 1.0×10 １７ cm －３ Above 1.0 x 10 １９ cm －３ The following is the result.

[0044] The p-type semiconductor layer 33 includes a first p-type cladding layer 36 and a second p-type cladding layer 37. The first p-type cladding layer 36 is disposed adjacent to the active layer 31. The second p-type cladding layer 37 is disposed on the opposite side of the first p-type cladding layer 36 from the active layer 31. In other words, it can be said that the p-type semiconductor layer 33 includes the first p-type cladding layer 36 adjacent to the active layer 31, and the second p-type cladding layer 37 located on the opposite side of the first p-type cladding layer 36 from the active layer 31. It can also be said that the p-type semiconductor layer 33 includes the first p-type cladding layer 36 and the second p-type cladding layer 37 stacked in this order from the active layer 31 side.

[0045] The impurity concentration of the second p-type cladding layer 37 may be different from the impurity concentration of the first p-type cladding layer 36. Specifically, the impurity concentration of the second p-type cladding layer 37 may be higher than the impurity concentration of the first p-type cladding layer 36. The impurity concentration of the second p-type cladding layer 37 may be equal to the impurity concentration of the first p-type cladding layer 36. The impurity concentration of the second p-type cladding layer 37 may also be lower than the impurity concentration of the first p-type cladding layer 36.

[0046] 4 shows an example of the configuration of the active layer 31. The active layer 31 has a multiple quantum well structure including a barrier layer 41, a first well layer 42, and a second well layer 43. The active layer 31 includes, for example, a barrier layer 41, a first well layer 42, a second well layer 43, a first guide layer 44, and a second guide layer 45.

[0047] The first well layer 42 and the second well layer 43 are disposed with a barrier layer 41 sandwiched therebetween. The first well layer 42 is disposed adjacent to the barrier layer 41 on the n-type semiconductor layer 32 side shown in FIG. 3 with respect to the barrier layer 41. The second well layer 43 is disposed on the opposite side of the barrier layer 41 from the first well layer 42. In other words, it can be said that the active layer 31 includes the first well layer 42, the barrier layer 41, and the second well layer 43, which are stacked in this order on the n-type semiconductor layer 32 (first n-type cladding layer 34) shown in FIG. 3 .

[0048] The first guide layer 44 is disposed adjacent to the first well layer 42. The first guide layer 44 is disposed on the opposite side of the first well layer 42 from the barrier layer 41. The second guide layer 45 is disposed adjacent to the second well layer 43. The second guide layer 45 is disposed on the opposite side of the second well layer 43 from the barrier layer 41. The first guide layer 44 and the second guide layer 45 can be said to be disposed so as to sandwich the first well layer 42, the barrier layer 41, and the second well layer 43. The active layer 31 can be said to include the first guide layer 44, the first well layer 42, the barrier layer 41, the second well layer 43, and the second guide layer 45, which are stacked in this order on the n-type semiconductor layer 32 (first n-type cladding layer 34) shown in FIG.

[0049] [Tunnel Layer] FIG. 5 shows an example configuration of the tunnel layer 22. The tunnel layer 22 includes a p-type tunnel layer 51 and an n-type tunnel layer 52. The p-type tunnel layer 51 is disposed adjacent to the p-type semiconductor layer 33 (second p-type cladding layer 37) shown in FIG. 3. The n-type tunnel layer 52 is disposed adjacent to the n-type semiconductor layer 32 (second n-type cladding layer 35) shown in FIG. 3. Therefore, the p-type tunnel layer 51 and the n-type tunnel layer 52 are stacked in this order from the semiconductor substrate 10 side shown in FIGS. 1 and 2. The tunnel layer 22 is disposed between the light-emitting units 21 such that the p-type tunnel layer 51 is electrically connected to the p-type semiconductor layer 33 shown in FIG. 3 and the n-type tunnel layer 52 is electrically connected to the n-type semiconductor layer 32 shown in FIG. 3.

[0050] The p-type tunnel layer 51 includes GaAs. The p-type tunnel layer 51 includes, for example, C as a p-type impurity. The impurity concentration of the p-type tunnel layer 51 is different from the impurity concentration of the p-type semiconductor layer 33. The impurity concentration of the p-type tunnel layer 51 is higher than the impurity concentration of the p-type semiconductor layer 33.

[0051] The n-type tunnel layer 52 includes GaAs. The n-type tunnel layer 52 includes at least one of Si, Te, and Se as an n-type impurity. The impurity concentration of the n-type tunnel layer 52 is different from the impurity concentration of the n-type semiconductor layer 32. The impurity concentration of the n-type tunnel layer 52 is higher than the impurity concentration of the n-type semiconductor layer 32.

[0052] (Operation of the Embodiment) Next, the operation of the semiconductor laser device 1A of this embodiment will be described. The semiconductor laser device 1A of this embodiment includes a semiconductor substrate 10 having a substrate main surface 101 and a substrate back surface 102 facing the opposite side to the substrate main surface 101 in the Z direction (first direction) perpendicular to the substrate main surface 101. The semiconductor laser device 1A also includes a light-emitting portion 20 that protrudes in the Z direction from the substrate main surface 101 and has a contact layer connection surface 201 facing the Z direction and light-emitting portion end faces 203, 204 that are both end faces in the Y direction (second direction) perpendicular to the Z direction. The semiconductor laser device 1A also includes a contact layer 60 that is provided on the contact layer connection surface 201 and has an electrode connection surface 601 facing the Z direction. The semiconductor laser device 1A also includes an insulating film 70. The insulating film 70 has a pair of side surface covering portions 71, 72 that cover both side surfaces of the light emitting portion 20 in an X direction (third direction) that is orthogonal to the Z direction and orthogonal to the Y direction and both side surfaces of the contact layer 60 in the X direction. The insulating film 70 also has a pair of contact layer covering portions 73, 74 that cover both end regions of the electrode connection surface 601 in the X direction. The insulating film 70 also has a first opening 77X formed by the pair of contact layer covering portions 73, 74 and exposing a portion of the electrode connection surface 601. The semiconductor laser device 1A also has a first electrode 81 (electrode) electrically connected to the electrode connection surface 601 exposed from the first opening 77X. The light emitting portion 20 emits laser light L1 from light emitting portion end faces 203, 204.

[0053] In the active layer 31 of this semiconductor laser device 1A, electrons from the n-type semiconductor layer 32 and holes from the p-type semiconductor layer 33 recombine in the active layer 31. This generates light in the active layer 31. The light generated in the active layer 31 is resonated and amplified by repeated stimulated emission between the light-emitting portion end faces 203, 204 of the light-emitting portion 20, which are the end faces of the active layer 31, as the resonator end faces. Then, a portion of the amplified light is emitted as laser light L1 from the light-emitting portion end face 203 of the light-emitting portion 20, which is the resonator end face.

[0054] Fig. 6 shows an outline of laser light L1 emitted from the light-emitting section 20. Note that Fig. 6 shows laser light L1 emitted from one light-emitting unit 21. As shown in Fig. 6, the shape of laser light L1 emitted from the light-emitting section 20 at the light-emitting section end surface 203 of the light-emitting section 20 is an ellipse elongated in a direction parallel to the active layer 31 (X direction). In contrast, the shape of laser light L1 at a position away from the light-emitting section end surface 203 of the light-emitting section 20 is an ellipse elongated in a direction perpendicular to the active layer 31 (Z direction).

[0055] The radiation pattern characteristic (spread) of the laser light L1 irradiated from the light-emitting end surface 203 of the light-emitting unit 20 is represented by the angle of the far-field pattern (FFP). The FFP of the laser light L1 is represented by a first angle θh (degrees) in a direction parallel to the active layer 31 and a second angle θv (degrees) in the thickness direction of the active layer 31. The first angle θh and the second angle θv are angles at which the light intensity of the laser light L1 becomes full width half maximum (FWH).

[0056] The semiconductor laser device 1A is used in laser systems such as LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging), which is an example of three-dimensional distance measurement, and two-dimensional distance measurement. In such laser systems, the laser light L1 emitted from the semiconductor laser device 1A is coupled to a lens. When a scanning measurement method is used in which the laser light L1 is scanned to detect the distance, direction, and properties of a measurement target, the laser light L1 coupled to the lens is, for example, a parallel beam. In this case, it is desirable that the intensity of the laser light L1 be uniform within the range of the spot diameter. When a flash measurement method is used in which the laser light L1 is scanned over a peripheral area without scanning, the laser light L1 coupled to the lens is, for example, a diverging beam. In this case, it is desirable that the laser light L1 be uniformly irradiated within the irradiation range. For these reasons, in both the scanning and flash measurement methods, it is desirable that the emission intensity be uniform within the range of the width WL1 of the light-emitting unit 20 in the X direction.

[0057] Furthermore, in such a laser system, if the FFP in the X direction has a side peak different from the central peak at a position shifted from the central peak, noise light may be included in the laser light L1 that has passed through the lens, which may result in a decrease in measurement accuracy in the laser system.

[0058] In the semiconductor laser device 1A of this embodiment, the insulation coverage, which is the ratio of the widths WI1 and WI2 of the pair of contact layer covering portions 73 and 74 in the X direction to the width WC1 of the electrode connection surface 601 in the X direction, is 10% or less. The thickness TC1 of the contact layer 60 in the Z direction is 2 μm or more. Therefore, the current supplied to the contact layer 60 via the first electrode 81 is likely to reach both ends of the contact layer 60 in the X direction. Therefore, the current flowing through the contact layer 60 is supplied to both end regions of the light-emitting portion 20 in the X direction. Therefore, the light-emitting portion 20 generates light throughout the entire X direction. As a result, the relative emission intensity can be increased from the center portion of the light-emitting portion 20 to both end regions in the X direction. Furthermore, the occurrence of side peaks in the FFP in the X direction can be suppressed.

[0059] [Experimental Example] Here, an experimental example of a semiconductor laser device will be described. FIG. 7 is an explanatory diagram illustrating the relationship between the insulating coverage rate and the thickness TC1 of the contact layer 60 and the state of the laser light L1 in the semiconductor laser device of the experimental example. FIGS. 8A to 11A are explanatory diagrams showing the far-field patterns of the semiconductor laser device of the experimental example. FIGS. 8B to 11B are explanatory diagrams showing the near-field patterns of the semiconductor laser device of the experimental example. In FIGS. 8A to 11A, the horizontal axis represents the angle centered on the front face of the light-emitting unit 20, and the vertical axis represents the emission intensity (output of the laser light L1). In FIGS. 8B to 11B, the horizontal axis represents the distance in the X direction (third direction) from one end of the light-emitting unit 20, and the vertical axis represents the emission intensity (output of the laser light L1).

[0060] In the semiconductor laser device of each experimental example, the insulating coverage rate and the thickness TC1 of the contact layer 60 were changed, and the FFP and near field pattern (NFP) in the X direction were measured.

[0061] The NFP indicates the emission intensity of the laser light L1 near the light-emitting end surface 203 of the light-emitting unit 20. This NFP can be used as an index for determining whether the emission intensity of the light-emitting unit 20 is uniform. In each experimental example shown in FIG. 7 , the emission intensity at the center position of the light-emitting unit 20 in the X direction was used as the reference (100%) for the NFP. The average emission intensity of the light-emitting unit 20 in the X direction may also be used as the reference. Here, the distance in the X direction from the point where the emission intensity of the NFP changes from a predetermined value (e.g., 90%) to 0% in each of the end regions of the light-emitting unit 20 in the X direction is defined as the "emission foot width." Incidentally, the narrower the emission foot width, the closer the light-emitting unit 20 is to emitting light in the X direction to the vicinity of its end. Therefore, it can be said that the emission intensity in the X direction is uniform throughout the light-emitting unit 20 with respect to the emission width of the laser light L1 emitted from the light-emitting unit 20.

[0062] As shown in Figure 7, in the experiment, the FFP and NFP were measured for insulation coverage rates of 20%, 15%, 10%, 5%, and 2% with the thickness TC1 of the contact layer 60 varied to 0.3 μm, 0.7 μm, 2.0 μm, 3.0 μm, and 4.0 μm. In each experimental example, the width WL1 of the light-emitting portion 20 in the X direction was 225 μm. In each experimental example, the maximum emission intensity in each experimental example was used as the reference (100%) for the FFP. The presence or absence of side peaks was confirmed with reference to the FFP. The emission foot width was also measured with reference to the NFP.

[0063] 7, a "◯" is marked with an "○" for combinations of the insulation coverage and the thickness TC1 of the contact layer 60 where no side peaks occur in the FFP and the emission foot width is less than 10 μm at both end regions of the light emitting section 20 in the X direction. Also, in FIG. 7, a "△" is marked with an "△" for combinations of the insulation coverage and the thickness TC1 of the contact layer 60 where no side peaks occur in the FFP or the emission foot width is less than 10 μm at both end regions of the light emitting section 20 in the X direction. Also, in FIG. 7, an "X" is marked with an "X" for combinations of the insulation coverage and the thickness TC1 of the contact layer 60 where side peaks occur in the FFP and the emission foot width is 10 μm or more at both end regions of the light emitting section 20 in the X direction.

[0064] Referring to Figure 7, when the insulation coverage rate is 10% or less and the thickness TC1 of the contact layer 60 is 2.0 μm or more, no side peaks occur in the FFP, and the emission foot width is less than 10 μm in each of the end regions of the light-emitting section 20 in the X direction.

[0065] 8A shows the measurement results of the FFP in the X direction for a semiconductor laser device having an insulating coverage of 10% and a thickness TC1 of 2.0 μm for the contact layer 60. Also, FIG. 8B shows the measurement results of the NFP in the X direction for a semiconductor laser device having an insulating coverage of 10% and a thickness TC1 of 2.0 μm for the contact layer 60.

[0066] 9A shows the measurement results of the FFP in the X direction for a semiconductor laser device having an insulation coverage of 2% and a thickness TC1 of 4.0 μm for the contact layer 60. Also, FIG. 9B shows the measurement results of the NFP in the X direction for a semiconductor laser device having an insulation coverage of 2% and a thickness TC1 of 4.0 μm for the contact layer 60.

[0067] 10A shows the measurement results of the FFP in the X direction for a semiconductor laser device having an insulating coverage of 10% and a thickness TC1 of 0.3 μm for the contact layer 60. Also, FIG. 10B shows the measurement results of the NFP in the X direction for a semiconductor laser device having an insulating coverage of 10% and a thickness TC1 of 0.3 μm for the contact layer 60.

[0068] 11A shows the measurement results of the FFP in the X direction for a semiconductor laser device having an insulating coverage of 20% and a thickness TC1 of 2.0 μm for the contact layer 60. Also, FIG. 11B shows the measurement results of the NFP in the X direction for a semiconductor laser device having an insulating coverage of 20% and a thickness TC1 of 2.0 μm for the contact layer 60.

[0069] In Figures 8A to 11A, the horizontal axis represents the angle centered on the front of the light-emitting unit 20. In Figures 8A to 11A, the vertical axis represents the emission intensity. Furthermore, in Figures 8B to 11B, the horizontal axis represents the distance in the X direction (third direction) from one end of the light-emitting unit 20. For example, the end of the light-emitting unit 20 opposite the X direction is set to 0 μm. The horizontal axis represents the distance in the X direction from the end of the light-emitting unit 20 opposite the X direction. In Figures 8B to 11B, the vertical axis represents the emission intensity (laser light output). In Figures 8B to 11B, dots are added to the areas corresponding to the emission foot width. In Figures 8B to 11B, widths WLS1 to WLS4 represent the width in the X direction of the region in the light-emitting unit 20 of the semiconductor laser device of each experimental example where the emission intensity is 90% or higher.

[0070] 8A, it can be seen that in a semiconductor laser device having an insulating coverage of 10% and a contact layer 60 thickness TC1 of 2.0 μm, the laser light L1 has a single peak 1SP at the center. Also, in FIG. 8B, it can be seen that in the same semiconductor laser device, the emission foot widths WT11 and WT12 are each about 9 μm.

[0071] 9A, it can be seen that in a semiconductor laser device in which the insulating coverage is 2% and the thickness TC1 of the contact layer 60 is 4.0 μm, the laser light L1 has a single peak 2SP at the center. Also, in FIG. 9B, it can be seen that in the same semiconductor laser device, the emission foot widths WT21 and WT22 are each about 8 μm.

[0072] 10A, in a semiconductor laser device having an insulating coverage of 10% and a contact layer 60 thickness TC1 of 0.3 μm, it can be seen that the laser light L1 has a peak 3SP at the center and side peaks 1NP and 2NP on both sides of the peak 3SP. Also, in FIG. 10B, it can be seen that in the same semiconductor laser device, the emission foot widths WT31 and WT32 are each about 30 μm.

[0073] Referring to FIG. 11A, in a semiconductor laser device with an insulation coverage of 20% and a contact layer 60 thickness TC1 of 2.0 μm, the laser light L1 has a peak 4SP at the center and a peak 5SP offset from the peak 4SP. Referring to FIG. 11B, in the same semiconductor laser device, the emission foot widths WT41 and WT42 are each approximately 35 μm. Note that peak 5SP occurs at an angle close to the center of the light-emitting section 20 (i.e., close to 0°). Therefore, for the semiconductor laser device of this experimental example, it was determined that no side peaks occurred in the FFP and that the emission foot width was 10 μm or more at both end regions of the light-emitting section 20 in the X direction. Therefore, in FIG. 7, the column for the combination of an insulation coverage of 20% and a contact layer 60 thickness TC1 of 2.0 μm is marked with a "△."

[0074] 8B and 10B , it can be seen that the emission foot widths WT11 and WT12 in the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 2.0 μm are narrower than the emission foot widths WT31 and WT32 in the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 0.3 μm. Furthermore, width WLS1 is wider than width WLS3. Therefore, it can be seen that the light-emitting section 20 in the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 2.0 μm emits light closer to the end in the X direction than the light-emitting section 20 in the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 0.3 μm. Therefore, it can be said that the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 2.0 μm has a more uniform emission intensity of the laser light L1 in the X direction across the entire light-emitting section 20 than the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 0.3 μm.

[0075] 8B and 11B , it can be seen that the emission foot widths WT11 and WT12 in the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 2.0 μm are narrower than the emission foot widths WT41 and WT42 in the semiconductor laser device having an insulation coverage of 20% and a contact layer 60 thickness TC1 of 2.0 μm. Furthermore, width WLS1 is wider than width WLS4. Therefore, it can be seen that the light-emitting section 20 in the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 2.0 μm emits light closer to the end in the X direction than the light-emitting section 20 in the semiconductor laser device having an insulation coverage of 20% and a contact layer 60 thickness TC1 of 2.0 μm. Therefore, it can be said that the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 2.0 μm has a more uniform emission intensity of the laser light L1 in the X direction across the entire light-emitting section 20 than the semiconductor laser device having an insulation coverage of 20% and a contact layer 60 thickness TC1 of 2.0 μm.

[0076] 9B and 10B , it can be seen that the emission foot widths WT21 and WT22 in the semiconductor laser device having an insulation coverage of 2% and a contact layer 60 thickness TC1 of 4.0 μm are narrower than the emission foot widths WT31 and WT32 in the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 0.3 μm. Furthermore, width WLS2 is wider than width WLS3. Therefore, it can be seen that the light-emitting section 20 in the semiconductor laser device having an insulation coverage of 2% and a contact layer 60 thickness TC1 of 4.0 μm emits light closer to the end in the X direction than the light-emitting section 20 in the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 0.3 μm. Therefore, it can be said that the semiconductor laser device having an insulation coverage of 2% and a contact layer 60 thickness TC1 of 4.0 μm has a more uniform emission intensity of the laser light L1 in the X direction across the entire light-emitting section 20 than the semiconductor laser device having an insulation coverage of 10% and a contact layer 60 thickness TC1 of 0.3 μm.

[0077] 9B and 11B , it can be seen that the emission foot widths WT21 and WT22 of the semiconductor laser device having an insulation coverage of 2% and a contact layer 60 thickness TC1 of 4.0 μm are narrower than the emission foot widths WT41 and WT42 of the semiconductor laser device having an insulation coverage of 20% and a contact layer 60 thickness TC1 of 2.0 μm. Furthermore, width WLS2 is wider than width WLS4. Therefore, it can be seen that the light-emitting section 20 of the semiconductor laser device having an insulation coverage of 2% and a contact layer 60 thickness TC1 of 4.0 μm emits light closer to the end in the X direction than the light-emitting section 20 of the semiconductor laser device having an insulation coverage of 20% and a contact layer 60 thickness TC1 of 2.0 μm. Therefore, it can be said that the semiconductor laser device having an insulation coverage of 2% and a contact layer 60 thickness TC1 of 4.0 μm has a more uniform emission intensity of the laser light L1 in the X direction across the entire light-emitting section 20 than the semiconductor laser device having an insulation coverage of 20% and a contact layer 60 thickness TC1 of 2.0 μm.

[0078] Effects of the Embodiment As described above in detail, the present embodiment provides the following effects. (1) The semiconductor laser device 1A includes a semiconductor substrate 10 having a substrate main surface 101 and a substrate back surface 102 facing the side opposite to the substrate main surface 101 in the Z direction (first direction) perpendicular to the substrate main surface 101. The semiconductor laser device 1A also includes a light-emitting portion 20 that protrudes in the Z direction from the substrate main surface 101 and has a contact layer connection surface 201 facing the Z direction and light-emitting portion end faces 203, 204 that are both end faces in the Y direction (second direction) perpendicular to the Z direction. The semiconductor laser device 1A also includes a contact layer 60 that is provided on the contact layer connection surface 201 and has an electrode connection surface 601 facing the Z direction. The semiconductor laser device 1A also includes an insulating film 70. The insulating film 70 has a pair of side surface covering portions 71, 72 that cover both side surfaces of the light emitting portion 20 in an X direction (third direction) that is orthogonal to the Z direction and orthogonal to the Y direction and both side surfaces of the contact layer 60 in the X direction. The insulating film 70 also has a pair of contact layer covering portions 73, 74 that cover both end regions of the electrode connection surface 601 in the X direction. The insulating film 70 also has a first opening 77X formed by the pair of contact layer covering portions 73, 74 and exposing a portion of the electrode connection surface 601. The semiconductor laser device 1A also has a first electrode 81 (electrode) electrically connected to the electrode connection surface 601 exposed from the first opening 77X. The light emitting portion 20 emits laser light L1 from one of the two light emitting portion end surfaces 203, 204, the light emitting portion end surface 203. The insulation coverage, which is the ratio of the widths WI1 and WI2 of the pair of contact layer covering portions 73 and 74 in the X direction to the width WC1 of the electrode connection surface 601 in the X direction, is 10% or less. The thickness TC1 of the contact layer 60 in the Z direction is 2 μm or more.

[0079] With this configuration, the current supplied to the contact layer 60 via the first electrode 81 is more likely to reach both ends of the contact layer 60 in the X direction. Therefore, the current flowing through the contact layer 60 is supplied to both end regions of the light-emitting unit 20 in the X direction. Therefore, the light-emitting unit 20 generates light throughout the entire area in the X direction. As a result, the relative light emission intensity can be increased from the center of the light-emitting unit 20 to both end regions in the X direction. Furthermore, the occurrence of side peaks in the FFP in the X direction can be suppressed. As a result, the light emission intensity near the end face of the light-emitting unit 20 can be made uniform. Furthermore, the generation of noise light included in the laser light L1 emitted from the light-emitting unit end face 203 of the light-emitting unit 20 can be suppressed.

[0080] (2) In the semiconductor laser device 1A of this embodiment, the insulation coverage rate is higher than 0%. This configuration makes it easy to manufacture the insulating film 70 having the contact layer coverages 73, 74. Even if the width WC1 of the electrode connection surface 601 varies within the dimensional tolerance range, the insulating film 70 having the contact layer coverages 73, 74 can be easily manufactured.

[0081] (3) In the semiconductor laser device 1A of this embodiment, the thickness TC1 of the contact layer 60 in the Z direction is 10 μm or less. With this configuration, the contact layer 60 can be manufactured more easily than when the thickness TC1 of the contact layer 60 is greater than 10 μm.

[0082] (4) In the semiconductor laser device 1A of this embodiment, the pair of contact layer covering portions 73, 74 have the same widths WI1, WI2 in the X direction. This configuration makes it easier for the current supplied to the contact layer 60 via the first electrode 81 to spread evenly to both end regions of the contact layer 60 in the X direction.

[0083] (5) In the semiconductor laser device 1A of this embodiment, the width WL1 of the light-emitting portion 20 in the X direction (third direction) is 200 μm or more and 400 μm or less. Conventionally, semiconductor laser devices with a light-emitting portion width of 200 μm or more in the X direction have had the problem of side peaks occurring in the FFP even if the light-emitting intensity can be made uniform in the X direction. In contrast, the semiconductor laser device 1A of this embodiment can make the light-emitting intensity uniform near the end face of the light-emitting portion 20 even if the width WL1 is 200 μm or more. Furthermore, the generation of noise light included in the laser light L1 emitted from the light-emitting portion end face 203 of the light-emitting portion 20 can be suppressed.

[0084] (Modifications) The above embodiment can be modified, for example, as follows. The above embodiment and each of the following modifications can be combined with each other as long as no technical contradiction occurs. In the following modifications, parts that are common to the above embodiment will be assigned the same reference numerals as in the above embodiment, and their description will be omitted.

[0085] The configuration of the semiconductor laser device 1A of the above embodiment may be modified as appropriate. Fig. 12 shows a modified semiconductor laser device 1B. In this semiconductor laser device 1B, the first electrode 81 extends from the electrode connection surface 601 of the contact layer 60 to the substrate covering portion 76 of the insulating film 70 that covers the substrate main surface 101. In this way, the semiconductor laser device 1B can be driven by connecting a pillar, a wire, or the like to the first electrode 81 extending to the substrate main surface 101.

[0086] FIG. 13 shows a modified semiconductor laser device 1C. Similar to the semiconductor laser device 1B shown in FIG. 12 , this modified semiconductor laser device 1C includes a first electrode 81 extending from the electrode connection surface 601 of the contact layer 60 to the substrate covering portion 76 of the insulating film 70 that covers the substrate main surface 101. Furthermore, the semiconductor laser device 1C includes a second opening 78X in the substrate covering portion 75 of the insulating film 70 that exposes a portion of the substrate main surface 101 of the semiconductor substrate 10. The second electrode 82 is electrically connected to the semiconductor substrate 10 exposed through the second opening 78X in the insulating film 70. The light-emitting portion 20 is connected to the substrate main surface 101 of the semiconductor substrate 10. In other words, the second electrode 82 is electrically connected to the light-emitting portion 20 via the semiconductor substrate 10. The light-emitting portion 20 is connected between the first electrode 81 and the second electrode 82. In this manner, the semiconductor laser device 1C can be driven by the first electrode 81 and the second electrode 82 arranged on the substrate main surface 101 side. Furthermore, since the first electrode 81 and the second electrode 82 are located on the main surface 101 side of the substrate, it is possible to connect wires or the like from the same direction, or to perform flip-chip mounting using pillars or the like.

[0087] In the semiconductor laser device 1C of this modified example, the shape of the first electrode 81 may be the same as the shape of the first electrode 81 in the semiconductor laser device 1A of the above embodiment. Also, the shapes of the first electrode 81 and the second electrode 82 may be changed as appropriate.

[0088] In the above embodiment, an example has been described in which the light-emitting section 20 includes three light-emitting units 21 and two tunnel layers 22. However, the number of light-emitting units 21 is not limited to three and can be any number. One, two, three, or more than three light-emitting units 21 may be formed. Furthermore, the number of tunnel layers 22 is not limited to two and can be adjusted according to the number of light-emitting units 21.

[0089] The above description is merely illustrative. Those skilled in the art will recognize that many more possible combinations and permutations are possible other than the components and methods (manufacturing processes) listed for the purpose of describing the technology of the present disclosure. The present disclosure is intended to embrace all alternatives, modifications, and variations that fall within the scope of the present disclosure, including the claims and appended notes.

[0090] 1A, 1B, 1C Semiconductor laser device 10 Semiconductor substrate 101 Substrate main surface 102 Substrate back surface 103 to 106 Substrate side surface 20 Light emitting portion 21 Light emitting unit 22 Tunnel layer 201 Contact layer connection surface 202 Substrate connection surface 203, 204 Light emitting portion end surface 205, 206 Light emitting portion side surface 31 Active layer 32 n-type semiconductor layer 33 p-type semiconductor layer 34 First n-type cladding layer 35 Second n-type cladding layer 36 First p-type cladding layer 37 Second p-type cladding layer 41 Barrier layer 42 First well layer 43 Second well layer 44 First guide layer 45 Second guide layer 51 P-type tunnel layer 52 N-type tunnel layer 60 Contact layer 601 Electrode connection surface 602 Light emitting portion connection surface 603, 604 Contact layer end face 605, 606 Contact layer side face 70 Insulating film 71, 72 Side face covering portion 73, 74 Contact layer covering portion 75, 76 Substrate covering portion 77X First opening (opening) 78X Second opening 81 First electrode 82 Second electrode 83, 84 Insulating film covering portion θh First angle θv Second angle L1 Laser light TC1 Thickness WC1 Width (width of electrode connection surface in the third direction) WI1, WI2 Width (width of contact layer covering portion in the third direction) WL1 Width (width of light emitting portion in the third direction) WLS1, WLS2, WLS3, WLS4 Width WT11, WT12, WT21, WT22, WT31, WT32, WT41, WT42 Light emitting base width 1SP, 2SP, 3SP, 4SP, 5SP Peak 1NP, 2NP Side Peak

Claims

1. a semiconductor substrate having a substrate main surface and a substrate back surface facing the opposite side to the substrate main surface in a first direction perpendicular to the substrate main surface; a light emitting portion protruding from the substrate main surface in the first direction and having a contact layer connection surface facing the first direction and light emitting portion end surfaces which are both end surfaces in a second direction perpendicular to the first direction; a contact layer provided on the contact layer connection surface and having an electrode connection surface facing the first direction; an insulating film including a pair of side surface covering portions covering both side surfaces of the light emitting portion in a third direction perpendicular to the first direction and perpendicular to the second direction and both side surfaces of the contact layer in the third direction, a pair of contact layer covering portions covering both end regions of the electrode connection surface in the third direction, and an opening formed by the pair of contact layer covering portions and exposing a portion of the electrode connection surface; an electrode electrically connected to the electrode connection surface exposed from the opening; Equipped with the light emitting unit emits laser light from one of the two light emitting unit end faces, an insulation coverage ratio, which is a ratio of a width of the pair of contact layer covering portions in the third direction to a width of the electrode connection surface in the third direction, is 10% or less; The thickness of the contact layer in the first direction is 2 μm or more. Semiconductor laser device.

2. The insulation coverage is greater than 0%.

2. The semiconductor laser device according to claim 1.

3. The thickness of the contact layer in the first direction is 10 μm or less.

2. The semiconductor laser device according to claim 1.

4. The pair of contact layer covering portions have the same width in the third direction.

2. The semiconductor laser device according to claim 1.

5. The light emitting portion has at least one light emitting unit including an active layer and an n-type semiconductor layer and a p-type semiconductor layer sandwiching the active layer in the first direction.

2. The semiconductor laser device according to claim 1.

6. The light-emitting section has a plurality of the light-emitting units stacked in the first direction, the n-type semiconductor layer in each of the light emitting units includes a first n-type cladding layer adjacent to the active layer, and a second n-type cladding layer located on an opposite side of the first n-type cladding layer to the active layer; The p-type semiconductor layer in each of the light emitting units includes a first p-type cladding layer adjacent to the active layer, and a second p-type cladding layer located on the opposite side of the first p-type cladding layer to the active layer.

6. The semiconductor laser device according to claim 5.

7. The plurality of light-emitting units are stacked with a tunnel layer interposed therebetween.

6. The semiconductor laser device according to claim 5.

8. The width of the light emitting portion in the third direction is 200 μm or more and 400 μm or less.

8. The semiconductor laser device according to claim 1, wherein the first and second electrodes are arranged parallel to each other.

9. The electrode has a portion covering the contact layer covering portion.

8. The semiconductor laser device according to claim 1, wherein the first and second electrodes are arranged parallel to each other.

10. The contact layer is made of a p-type semiconductor material including GaAs.

8. The semiconductor laser device according to claim 1, wherein the first and second electrodes are arranged parallel to each other.

11. The semiconductor substrate is an n-type semiconductor substrate containing GaAs.

8. The semiconductor laser device according to claim 1, wherein the first and second electrodes are arranged parallel to each other.