JP2019129216A - Nitride semiconductor laser element and semiconductor laser device - Google Patents

Abstract

To provide a nitride semiconductor laser element and a semiconductor laser device capable of emitting high output laser light.SOLUTION: A semiconductor laser element 1 is a nitride semiconductor laser element including a laminate structure 20 consisting of a first conductivity type layer, an active layer and a second conductivity type layer. The laminate structure 20 includes a pair of opposite end faces becoming resonator end faces, the second conductivity type layer includes multiple first ridges (light emission ridge R) becoming the current injection paths to the active layer, and a second ridge (dummy ridge S) provided at a position adjacent to at least one ridge out of the multiple first ridges, and does not become the current injection path to the active layer. Assuming the width of the top face of the first ridge is WR, the width between the top face of the first ridge and the top face of the second ridge is WM, and the width between two first ridges with the second ridge in between is WA, following relations are satisfied, 5 μm≤WR≤35 μm, 5 μm≤WM≤30 μm, and (WA/WR)≥7.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a nitride semiconductor laser device and a semiconductor laser device.

  Since semiconductor laser elements have advantages such as long life, high efficiency, and small size, they are used as light sources for various applications including image display devices such as projectors and displays. In recent years, research and development of a high-power semiconductor laser element of a watt class exceeding 1 watt as a light source of a laser processing apparatus has been performed.

  In the semiconductor laser device, laser light is generated by injecting current into the emitter (light emitting portion), but the upper limit of the emitter width is about several tens of μm from the viewpoint of uniformity of current distribution and control of light distribution. is there. On the other hand, when high-power laser light is emitted from one emitter, the optical density of the front end surface from which the laser light is emitted becomes too high, and there is a possibility that COD (Catalytic Optical Damage) occurs on the front end surface. Therefore, a semiconductor laser device having a laser array (multi-emitter) structure in which a plurality of emitters are integrated has been proposed in order to emit laser light with high output.

  Patent Document 1 discloses a conventional semiconductor laser device having such a laser array structure. FIG. 19 shows a cross-sectional structure of a conventional semiconductor laser device 100 disclosed in Patent Document 1.

  In the conventional semiconductor laser device 100 shown in FIG. 19, a laminated structure 120 including a plurality of semiconductor layers is formed on a substrate 110, and a voltage is applied to the p-side electrode 141 and the n-side electrode 142. Current flows in the stacked structure 120. At this time, electrons and holes supplied from the n-type cladding layer 121 and the p-type cladding layer 126 in the stacked structure 120 are recombined in the active layer 123, and are amplified by stimulated emission and reflected by both end faces of the device. The laser is oscillated by (resonance) and emitted as laser light. Since the semiconductor laser device 100 has the ridge portion R, the supply of electrons and holes is performed directly below the ridge portion R. In the ridge stripe semiconductor laser device 100 having the ridge portion R, electrons, holes, and light are confined immediately below the ridge portion R, so that the threshold value of the laser oscillation is lowered and the transverse mode control of the laser beam is performed. Can.

  In the semiconductor laser device 100 having the laser array structure, a plurality of ridge portions R are arranged corresponding to a plurality of emitters. In the semiconductor laser device 100 shown in FIG. 19, the dummy ridge portion S is provided between the adjacent ridge portions R. Since the insulating film 130 exists in the dummy ridge portion S, the current from the p-side electrode 141 is not injected into the active layer 123. Therefore, the active layer 123 immediately below the dummy ridge portion S does not emit light.

  Thus, light emission is achieved by providing the dummy ridge portion S not having the current injection function to the active layer 123 between the original ridge portions R (light emission ridge portion R) having the current injection function to the active layer 123. The ridge spacing can be narrowed for all the ridges including the ridges R and the dummy ridges S. Thereby, when the semiconductor laser element 100 is mounted on a support base such as a submount by the face-down method, the contact area between the semiconductor laser element 100 and the support base can be increased. As a result, it is possible to disperse the stress caused by the distortion remaining in the semiconductor laser device 100 after mounting on the submount.

Japanese Patent Application Laid-Open No. 2007-073669

  As described above, in the semiconductor laser device having the laser array structure, in order to reduce the residual distortion of the light emitting ridge portion that occurs when the semiconductor laser device is mounted on the submount, dummy ridges are provided on both sides of the light emitting ridge portion R. A part S is provided.

  Here, if the distance d2 between the two adjacent light emitting ridges R is smaller than the width d1 of the light emitting ridge R, the laser interference is caused by the laser oscillation of the two adjacent light emitting ridges R. This leads to the generation of thermal saturation during high power operation in the light output characteristics of light.

  In particular, heat generated at the time of laser oscillation in the light emitting ridge portion R is exhausted from the upper portion of the light emitting ridge portion R through the dummy ridge portion S to the back surface of the substrate. If the distance d3 is long, the heat exhaust path from the light emitting ridge portion R to the dummy ridge portion S becomes long, and sufficient heat cannot be exhausted at the time of high output operation. It leads to the occurrence of heat saturation.

  In order to obtain a high wattage light output, the width d1 of the light emitting ridge R, the distance d2 between the two adjacent light emitting ridges R, the distance between the light emitting ridge R and the dummy ridge S However, the semiconductor laser device (nitride semiconductor laser device) composed of a GaN-based nitride semiconductor material has a threshold current density composed of a GaAs-based arsenide semiconductor material. Since it is higher than a semiconductor laser element (arsenide semiconductor laser element) and has a low threshold voltage, the power conversion efficiency (light emission efficiency) is low, so that it is more than a semiconductor laser element composed of other semiconductor materials such as GaAs. There is a lot of power loss. Therefore, the nitride semiconductor laser device generates a large amount of heat as compared to the arsenide semiconductor laser device, so even if the numerical ranges of d1, d2 and d3 disclosed in Patent Document 1 are satisfied, watt-class light is obtained. Output can not be realized.

  The present disclosure has been made to solve such a problem, and an object thereof is to provide a nitride semiconductor laser element and a semiconductor laser device capable of emitting high-power laser light.

  In order to achieve the above object, an aspect of a nitride semiconductor laser device according to the present disclosure includes a first conductivity type layer, an active layer formed on the first conductivity type layer, and an active layer formed on the active layer. A second conductive type layer, wherein the first conductive type layer, the active layer, and the second conductive type layer are made of a nitride semiconductor, and the first conductive type layer, the active layer, and the first conductive layer The laminated structure composed of two conductivity type layers includes a pair of opposed end surfaces serving as resonator end surfaces, and the second conductivity type layer has a longitudinal direction in a direction perpendicular to the pair of end surfaces, and the active layer A plurality of first ridge portions serving as current injection paths to the layer, and a second ridge portion having a longitudinal direction in a direction orthogonal to the pair of end faces and not serving as a current injection path to the active layer, The second ridge portion includes at least two of the plurality of first ridge portions. The width in the direction perpendicular to the longitudinal direction is a width provided between the ridge portions, the width of the upper surface of the first ridge portion is WR, the upper surface of the first ridge portion and the upper surface of the second ridge portion Where WM is the width between them and WA is the width between the upper surfaces of the two first ridges, 5 μm ≦ WR ≦ 35 μm, 5 μm ≦ WM ≦ 30 μm, (WA / WR)) 7.

  An aspect of the semiconductor laser device according to the present disclosure includes the nitride semiconductor laser element and a submount, and the nitride semiconductor laser element includes the first ridge portion side and the second ridge portion. The side is joined to the submount.

  A nitride semiconductor laser device and a semiconductor laser device capable of emitting high-power laser light can be realized.

1 is a perspective view of a semiconductor laser device according to an embodiment. FIG. 2 is a perspective view of the semiconductor laser device with the pad electrode omitted in FIG. It is a top view of the semiconductor laser device according to the embodiment. It is sectional drawing of the semiconductor laser element which concerns on embodiment in the IV-IV line of FIG. (A) of FIG. 5 is an enlarged top view of the semiconductor laser device according to the embodiment, and (b) of FIG. 5 is an enlarged cross-sectional view of the same semiconductor laser device. It is a figure which shows the experimental result of the semiconductor laser element which concerns on embodiment. It is an enlarged top view of the semiconductor laser element concerning the modification of an embodiment. It is a figure which shows the result of the reliability experiment of the semiconductor laser element performed regarding the pitch X and the width | variety Y of the recessed part of a pad electrode. FIG. 1 is a cross-sectional view of a semiconductor laser device according to an embodiment. 6 is an enlarged top view of a semiconductor laser device according to Modification 1. FIG. 10 is an enlarged top view of a semiconductor laser device according to Modification 2. FIG. 10 is an enlarged top view of a semiconductor laser device according to Modification 3. FIG. 10 is an enlarged top view of a semiconductor laser device according to Modification 4. FIG. 10 is a perspective view of a semiconductor laser device according to Modification 5. FIG. 10 is an enlarged top view of a semiconductor laser device according to Modification 5. FIG. FIG. 18 is an enlarged top view of a semiconductor laser device according to another example of the fifth modification. FIG. 16 is an enlarged top view of a semiconductor laser device according to still another example of Modification Example 5; 10 is an enlarged top view of a semiconductor laser device according to Modification 6. FIG. 10 is an enlarged top view of a semiconductor laser device according to Modification 7. FIG. FIG. 1 is a cross-sectional view of a conventional semiconductor laser device disclosed in Patent Document 1;

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Each embodiment described below shows one specific example of the present disclosure. Accordingly, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps (steps) and order of steps, etc. shown in the following embodiments are merely examples and limit the present disclosure. It is not the main point to do. Therefore, among the components in the following embodiments, components that are not described in the independent claims indicating the highest concept of the present disclosure are described as optional components.

  Each figure is a mimetic diagram and is not necessarily illustrated strictly. Therefore, the scale and the like do not necessarily match in each figure. In the drawings, substantially the same components are denoted by the same reference numerals, and redundant description will be omitted or simplified.

Embodiment
First, the configuration of the semiconductor laser device 1 according to the embodiment will be described with reference to FIGS. FIG. 1 is a perspective view of a semiconductor laser device 1 according to an embodiment. FIG. 2 is a perspective view of the semiconductor laser device 1 with the pad electrode 50 omitted in FIG. FIG. 3 is a top view of the semiconductor laser device 1. 4 is a cross-sectional view of the semiconductor laser device taken along line IV-IV in FIG.

  As shown in FIGS. 1 to 4, the semiconductor laser device 1 includes a substrate 10, a stacked structure 20 formed on the substrate 10, an insulating layer 30 covering the stacked structure 20, and the stacked structure 20. A first electrode 41 and a second electrode 42 for injecting a current, and a pad electrode 50 are provided. In the present embodiment, the semiconductor laser element 1 is a nitride semiconductor laser element made of a nitride semiconductor material.

  The substrate 10 is, for example, a semiconductor substrate such as GaN or SiC or a sapphire substrate. The thickness of the substrate 10 is, for example, 50 μm to 120 μm. In the present embodiment, the substrate 10 is a first conductivity type substrate. Specifically, a single crystal n-type GaN substrate with a thickness of 100 μm is used as the substrate 10.

  The laminated structure 20 has a pair of first end face 20 a and second end face 20 b opposed in the cavity length direction of the semiconductor laser device 1. The pair of first end faces 20 a and the second end face 20 b are device end faces of the semiconductor laser device 1. The pair of first end faces 20a and the second end face 20b are resonator end faces of the laser light, and play a role of a reflection surface (mirror) in laser oscillation. In the present embodiment, the first end face 20a is a front end face from which laser light is emitted, and the second end face 20b is a rear end face which is an element end face on the opposite side to the first end face 20a. The first end surface 20a and the second end surface 20b are cleavage surfaces formed by cleavage, for example. The length in the cavity length direction of the multilayer structure 20 (that is, the length of the semiconductor laser 1) is, for example, 0.8 to 4 mm, and is 2 mm in the present embodiment.

  Although not shown, a reflective film made of a dielectric multilayer film is formed on the first end face 20a and the second end face 20b as an end face coat film for controlling the reflectance. Specifically, a reflective film having a low reflectivity is formed on the first end face 20a, and a reflective film having a high reflectivity is formed on the second end face 20b.

  The stacked structure 20 is a semiconductor stacked body made of a semiconductor material, and includes a first conductivity type first cladding layer 21, an active layer 23 formed on the first cladding layer 21, and an active layer 23. And a second cladding layer 26 of the second conductivity type formed. The first cladding layer 21, the active layer 23, and the second cladding layer 26 are made of, for example, a nitride semiconductor.

  In the present embodiment, the laminated structure 20 further includes a first guide layer 22, a second guide layer 24, an electron barrier layer 25, and a contact layer 27. Specifically, the stacked structure 20 includes a first cladding layer 21, a first guide layer 22, an active layer 23, a second guide layer 24, an electron barrier layer 25, The second clad layer 26 and the contact layer 27 are stacked in this order. In addition, the layer which comprises the layer structure of the laminated structure 20 is not limited to said layer, In addition to said layer, the strain relief layer etc. may be formed.

The first cladding layer 21 is formed on the substrate 10. The first cladding layer 21 is a first conductivity type layer made of a semiconductor material of a first conductivity type. For example, the first cladding layer 21 is an n-type cladding layer made of a nitride semiconductor material such as n-type Al _x GaN (0 <x <1) doped with an impurity. In the present embodiment, the first cladding layer 21 is composed of n-AlGaN. The thickness of the first cladding layer 21 is preferably 0.5 μm or more.

The first guide layer 22 is formed on the first cladding layer 21. The first guide layer 22 is an n-side guide layer formed on the n-side. For example, the first guide layer 22 is made of a nitride semiconductor material such as n-type In _x GaN (0 ≦ x <1) or the like which is not intentionally doped with an impurity or undoped. In the present embodiment, the first guide layer 22 is made of n-GaN. The first guide layer 22 may be either a single layer or a plurality of layers, but the total thickness of the first guide layer 22 is preferably 0.2 μm or more.

The active layer 23 (light emitting layer) is formed on the first guide layer 22. The active layer 23 is made of, for example, a single layer or multiple layers of nitride semiconductor material. Specifically, the active layer 23 is a quantum well structure formed of In _x GaN (0 <x <1) and / or Al _x In _y GaN (x, y 1 1). In the present embodiment, the active layer 23 is an InGaN quantum well structure.

The second guide layer 24 is formed on the active layer 23. The second guide layer 24 is a p-side guide layer formed on the p side. For example, the second guide layer 24 is made of a nitride semiconductor material such as undoped or n-type In _x GaN (0 ≦ x <1). In the present embodiment, the second guide layer 24 is made of u-GaN. The second guide layer 24 may be either a single layer or a plurality of layers, but the total thickness of the second guide layer 24 is preferably 0.05 μm or more.

  The electron barrier layer 25, the second cladding layer 26, and the contact layer 27 are second conductivity type layers made of a second conductivity type semiconductor material having a conductivity type different from the first conductivity type. In the present embodiment, the second conductivity type is p-type.

The electron barrier layer 25 is formed on the second guide layer 24. For example, the electron barrier layer 25 is a p-type electron barrier layer made of a nitride semiconductor material such as p-type Al _x GaN (0 ≦ x <1) doped with an impurity. In the present embodiment, the electron barrier layer 25 is made of p-AlGaN. The thickness of the electron barrier layer 25 may be 1 to 50 nm.

The second cladding layer 26 is formed on the electron barrier layer 25. For example, the second cladding layer 26 is a p-type cladding layer made of a nitride semiconductor material such as p-type Al _x GaN (0 ≦ x <1). In the present embodiment, the second cladding layer 26 is made of p-AlGaN. The thickness of the second cladding layer 26 may be 0.3 to 1 μm.

  The contact layer 27 is formed on the second cladding layer 26. For example, the contact layer 27 is a p-type contact layer formed of a p-type nitride semiconductor material. In the present embodiment, the contact layer 27 is made of p-type GaN.

  The laminated structure 20 configured as described above has a ridge waveguide structure having a light emitting ridge portion R as a ridge portion. In the present embodiment, the multilayer structure 20 has a laser array structure constituted by a plurality of light emitting ridge portions R.

  Each of the plurality of light emitting ridge portions R is a first ridge portion serving as an original ridge portion serving as a current injection path to the active layer 23. The current is injected into the active layer 23 by each light emitting ridge portion R so that the active layer 23 emits light. Each of the plurality of light emitting ridge portions R has an elongated shape having a longitudinal direction in a direction orthogonal to the pair of first end surface 20a and second end surface 20b. Specifically, each light emitting ridge portion R extends linearly along the laser resonator length direction (laser light oscillation direction).

The plurality of light emitting ridges R is a light emitting ridge R ₁ and a light emitting ridge from the one end side to the other end side in the width direction (the direction orthogonal to the laser resonator length direction) of the semiconductor laser device 1. part _{R 2,} emitting ridges _R 3, ···, emitting ridge _R i, · · ·, emitting ridge _{R n-2,} the light emitting ridge _{R n-1,} in the order of the light emitting ridge _{R n,} n This is formed (i = 1 to n). The number of light emitting ridges R is, for example, 2 to 50. In the present embodiment, 20 light emitting ridge portions R are formed at equal intervals.

  Furthermore, the stacked structure 20 has a plurality of dummy ridges S as another ridge. Each of the plurality of dummy ridge portions S is a second ridge portion which does not serve as a current injection path to the active layer 23. That is, the dummy ridge portion S has no current injection function. Like the light emitting ridge portion R, each of the plurality of dummy ridge portions S has a long shape having a longitudinal direction in a direction perpendicular to the pair of first end surfaces 20a and second end surfaces 20b. Specifically, each dummy ridge portion S extends linearly along the laser resonator length direction. Therefore, the dummy ridge portion S is formed in parallel with the light emitting ridge portion R.

  Further, the dummy ridge portion S is provided at a position adjacent to at least one light emitting ridge portion R of the plurality of light emitting ridge portions R. The dummy ridge portions S are provided between at least two light emitting ridge portions R of the plurality of light emitting ridge portions R, except for the dummy ridge portions S located at both ends in the width direction of the semiconductor laser element 1. Specifically, the dummy ridge portions S other than the both ends are formed between two adjacent light emitting ridge portions R. In the present embodiment, the dummy ridge portions S other than the both ends are formed one by one between the two adjacent light emitting ridge portions R adjacent to the light emitting ridge portion R.

The plurality of dummy ridges S are arranged from one end in the width direction of the semiconductor laser device 1 toward the other end, such as a dummy ridge S ₀ , a dummy ridge S ₁ , a dummy ridge S ₂ ,. , Dummy ridges S _i ,..., Dummy ridges S _n−2 , dummy ridges S _n−1 , and dummy ridges S _n are formed in this order (i = 0 to n). ). The dummy ridge portion S is formed on each of both ends of the laminated structure 20, and is formed by one more than the light emitting ridge portion R. In the present embodiment, since 20 light emitting ridge portions R are formed, 21 dummy ridge portions S are formed.

  Although the details will be described later, the dummy ridge portions S located at both ends in the width direction of the semiconductor laser device 1 are divided into a plurality. In the present embodiment, the dummy ridge portions S located at both ends are each divided into three. Therefore, when each of the three divided dummy ridges is counted as one, 25 dummy ridges S are formed as a whole.

  Thus, by providing the dummy ridge portion S in addition to the light emitting ridge portion R, when the semiconductor laser device 1 is mounted on a support base such as a submount by the face-down method, the semiconductor laser device 1 and the support base The contact area can be increased. As a result, it is possible to disperse the stress caused by the distortion remaining in the semiconductor laser device 1 after mounting on the support base. Thereby, concentration of stress on the light emitting ridge portion R can be suppressed. Further, by providing the dummy ridge portion S, the heat generated in the light emitting ridge portion R can be dissipated to the support base via the dummy ridge portion S.

  The light emitting ridge portion R and the dummy ridge portion S are formed on the top of the laminated structure 20. In the present embodiment, the light emitting ridge portion R and the dummy ridge portion S are formed in the second conductivity type layer of the laminated structure 20.

  Specifically, the light emitting ridge portion R and the dummy ridge portion S are formed by digging the second cladding layer 26 and the contact layer 27 to form the grooves M and M ′ in the laminated structure 20. The groove M (first groove) is formed between the light emitting ridge portion R and the dummy ridge portion S on one side (left side in the drawing) of the light emitting ridge portion R. On the other hand, the groove M ′ (second groove) is formed between the light emitting ridge portion R and the dummy ridge portion S on the other side (right side in the drawing) of the light emitting ridge portion R. That is, the light emitting ridge portion R and the two dummy ridge portions S adjacent to the light emitting ridge portion R are separated by the grooves M and M ′. In the present embodiment, the light emitting ridge portion R and the dummy ridge portion S are formed in the middle of the second cladding layer 26. That is, the bottoms of the grooves M and M ′ provided between the light emitting ridge portion R and the dummy ridge portion S exceed the contact layer 27 and reach the second cladding layer 26, and the grooves M and M ′ The bottom surface of each of the layers is located in the second cladding layer 26. Each of the light emitting ridge portion R and the dummy ridge portion S formed in this manner has a convex portion of the second cladding layer 26 whose cross section is formed in a convex shape, and is formed on the convex portion with the same width as the convex portion. Contact layer 27 formed.

  In the present embodiment, the height of the light emitting ridge portion R and the height of the dummy ridge portion S are equal. That is, the distance from the upper surface of the active layer 23 to the upper surface of the light emitting ridge portion R is equal to the distance from the upper surface of the active layer 23 to the upper surface of the dummy ridge portion S. The upper surface of the part S is at the same height. The depth of the groove M and the depth of the groove M 'are the same. That is, the position of the bottom of the groove M and the position of the bottom of the groove M ′ are the same.

  In the laminated structure 20 configured as described above, when a current is injected into the laminated structure 20, laser light is emitted from an emitter E (light emitting point) below each light emitting ridge portion R as shown in FIG. Do. In the present embodiment, laser light is emitted from each of the plurality of emitters E. That is, the semiconductor laser element 1 in the present embodiment is a multi-emitter laser including a plurality of emitters E. The plurality of emitters E are arranged in a line on the straight line in the lateral direction, and a plurality of laser beams arranged in a line on the line in the horizontal direction are emitted from the laminated structure 20.

  Each of the plurality of emitters E corresponds to each of the plurality of light emitting ridges R. That is, the emitter E and the light emitting ridge portion R correspond to each other in a one-to-one manner. Therefore, the number of emitters E is the same as the number of light emitting ridge portions R.

  In addition, the laminated structure 20 is covered by the insulating layer 30. In the present embodiment, the insulating layer 30 is formed so as to cover all the ridge portions of the multilayer structure 20 including all the light emitting ridge portions R and all the dummy ridge portions S. Specifically, so as to cover the side surfaces of the light emitting ridge portion R and the dummy ridge portion S and the flat portion (the bottom surfaces of the grooves M and M ′) between the light emitting ridge portion R and the dummy ridge portion S, It is formed along the surface of the laminated structure 20.

  Furthermore, the insulating layer 30 covers the entire upper surface of the dummy ridge portion S in the dummy ridge portion S, but covers a part of the upper surface of the light emitting ridge portion R in the light emitting ridge portion R. Specifically, a part of the insulating layer 30 on the light emitting ridge portion R is opened. A current is injected into the stacked structure 20 through the opening of the insulating layer 30. In this embodiment, the insulating layer 30 covers a part of the upper surface of the light emitting ridge portion R, but does not cover the upper surface of the light emitting ridge portion R at all, and passes through the entire upper surface of the light emitting ridge portion R. A configuration in which a current is injected into the laminated structure 20 may also be employed.

  Further, by covering the side surface of the light emitting ridge portion R with the insulating layer 30, the current injected from the first electrode 41 through the opening of the insulating layer 30 can be narrowed. That is, by covering the side surface of the light emitting ridge portion R with the insulating layer 30, it is possible to suppress the current injected from the first electrode 41 from flowing into the region between the two adjacent light emitting ridge portions R.

The insulating layer 30 is made of an insulating material. For example, the insulating layer 30 is made of a dielectric material such as SiO ₂ . In the present embodiment, the insulating layer 30 is a SiO ₂ film. The thickness of the insulating layer 30 is, for example, 100 to 500 nm.

  The first electrode 41 is a p-side electrode, and is formed on each light emitting ridge portion R. Specifically, the first electrode 41 is formed so as to fill the opening provided in the insulating layer 30, and is in contact with the contact layer 27 on the contact layer 27 which is the uppermost layer of the light emitting ridge portion R. It is formed. The first electrode 41 is an ohmic electrode in ohmic contact with the contact layer 27. Although the first electrode 41 is formed at the same height as the insulating layer 30 so as to fill only the opening of the insulating layer 30, it is not limited thereto.

  The first electrode 41 is composed of a single layer or a plurality of layers formed using at least one metal material such as Cr, Ti, Ni, Pd, Pt, and Au. In the present embodiment, the first electrode 41 has a two-layer structure of Pd / Pt. The width of the first electrode 41 is narrower than the width of the light emitting ridge portion R, but may be the same as the width of the light emitting ridge portion R.

  As shown in FIG. 2, the first electrode 41 is formed on the light emitting ridge portion R, but is not formed on the dummy ridge portion S. That is, the first electrode 41 is formed only on the light emitting ridge portion R for each light emitting ridge portion R. Therefore, a plurality of first electrodes 41 are formed in parallel to one another. That is, the plurality of first electrodes 41 are not connected to each other but are formed separately.

  The second electrode 42 is an n-side electrode. The second electrode 42 is a metal layer (first metal layer) formed on the lower surface (back surface) of the substrate 10. The second electrode 42 is an ohmic electrode that is in ohmic contact with the substrate 10 that is a semiconductor substrate. The second electrode 42 is one electrode common to the plurality of light emitting ridges R, and is formed on substantially the entire lower surface of the substrate 10.

  The second electrode 42 is composed of a single layer or a plurality of layers formed using at least one metal material such as Cr, Ti, Ni, Pd, Pt, and Au. The second electrode 42 may be made of an Au-based material containing Au. The second electrode 42 may be composed of a plurality of layers such as Ti / Au and Ti / Pt / Au. In the present embodiment, the second electrode 42 has a three-layer structure of Ti / Pt / Au.

  The pad electrodes 50 are formed on the respective first electrodes 41 and the insulating layer 30 so as to be in contact with the plurality of first electrodes 41. The pad electrode 50 is a metal layer (second metal layer) made of a metal material. The pad electrode 50 may be made of an Au-based material containing Au. In addition, the pad electrode 50 may be configured of a plurality of layers such as Ti / Au, Ti / Pt / Au, and the like. In the present embodiment, the pad electrode 50 has a three-layer structure of Ti / Pt / Au.

  In the present embodiment, the pad electrode 50 is made of a material different from that of the first electrode 41 (p-side electrode), but may be made of the same material as the first electrode 41. In this case, a combination of the pad electrode 50 and the first electrode 41 may be called a p-side electrode or a pad electrode. The pad electrode 50 is made of the same material as the second electrode 42 (n-side electrode), but may be made of a material different from the second electrode 42.

  The pad electrode 50 is formed continuously on the plurality of light emitting ridges R and at least one dummy ridge S. In the present embodiment, the pad electrode 50 is continuously formed on all the light emitting ridge portions R and all the dummy ridge portions S. That is, the pad electrode 50 is formed in a wide range on the upper surface of the multilayer structure 20 so as to cover all the ridge portions of the multilayer structure 20 including all the light emitting ridge portions R and all the dummy ridge portions S. .

  Thus, the pad electrode 50 is not formed for each of the light emitting ridge portion R and the dummy ridge portion S, but is formed over the entire ridge portion including the light emitting ridge portion R and the dummy ridge portion S. As compared with the case where each ridge portion is formed, the complexity of the configuration of the semiconductor laser device 1 can be suppressed. That is, if pad electrodes 50 are formed for each light emitting ridge portion R and each dummy ridge portion S, a plurality of pad electrodes 50 will be present, and wires need to be connected for each pad electrode 50, The electrical connection to each pad electrode 50 is complicated.

  Moreover, by forming the pad electrode 50 continuously on the plurality of light emitting ridge portions R and the plurality of dummy ridge portions S, the pad electrode 50 and the sub electrode are mounted when the semiconductor laser device 1 is mounted on the submount. Since the contact area with the mount can be gained, the bonding strength between the semiconductor laser device 1 and the submount can be increased.

  In the semiconductor laser device 1 configured as above, when a voltage is applied to the first electrode 41 and the second electrode 42, a current flows between the first electrode 41 and the second electrode 42. That is, current is injected into the laminated structure 20. The current injected into the stacked structure 20 is narrowed and flows only under the light emitting ridge portion R. As a result, the narrowed current is injected into the active layer 23 below the light emitting ridge portion R, and electrons and holes recombine in the active layer 23 to emit light.

  The light generated in the active layer 23 is, in the substrate vertical direction (longitudinal direction), the first cladding layer 21, the first guide layer 22, the active layer 23, the second guide layer 24, the electron barrier layer 25, and the second cladding layer. 26 and the refractive index difference between the layers of the contact layer 27, and in the substrate horizontal direction (lateral direction), the inside of the light emitting ridge portion R (the second cladding layer 26, the contact layer 27) and the outside of the light emitting ridge portion R It is confined by the refractive index difference with (insulation layer 30).

  Then, the light generated in the active layer 23 reciprocates between the first end face 20a and the second end face 20b, resonates and amplifies it, and gain is obtained by the injection current to obtain a high-intensity laser whose phases are aligned. The light is emitted from the first end face 20 a of the emitter E. In the present embodiment, since 20 light emitting ridge portions R are formed, laser light is emitted from each of 20 emitters E. That is, twenty laser beams are emitted from the laminated structure 20.

  Next, a detailed configuration of the semiconductor laser element 1 in the present embodiment will be described below with reference to FIGS.

  First, the detailed configuration of the pad electrode 50 will be described with reference to FIG. FIG. 5A is an enlarged top view of the semiconductor laser device 1 according to the embodiment, and FIG. 5B is an enlarged cross-sectional view of the semiconductor laser device 1.

In FIG 5, among the plurality of light emitting ridges R and a plurality of dummy ridge portions S, and the dummy ridge portions S _i, and the light emitting ridge R _i adjacent to the left side of the dummy ridge portions S _i, the dummy ridge portions S _i and the light emitting ridge R _{i + 1} adjacent to the right side of the light-emitting ridge R and part of the dummy ridge portions S _i-1 adjacent to the left side of _i, the light emitting ridge R _{i + 1} of the dummy ridge portions S _i adjacent to right _-1 is shown in part.

  As shown in FIG. 5A, when the semiconductor laser device 1 is viewed from above, the pad electrode 50 is separated from the pair of first end surface 20a and second end surface 20b by a first distance d1 on the light emitting ridge portion R. It has a part that is. Further, in the top view of the semiconductor laser device 1, the pad electrode 50 has a portion separated from the first end face 20 a and the second end face 20 b by the second distance d 2 on the dummy ridge portion S. The second distance d2 in the dummy ridge portion S is larger than the first distance d1 in the light emitting ridge portion R. As an example, the first distance d1 is 4 to 8 μm, and the second distance d2 is 15 to 25 μm.

  Specifically, in the top view of the semiconductor laser device 1, the pad electrode 50 has recesses 51 on both sides of the pair of the first end face 20 a and the second end face 20 b on the dummy ridge portion S. The recess 51 of the pad electrode 50 is a portion on the dummy ridge portion S that is separated from the pair of first end surface 20a and second end surface 20b by a second distance d2. The recessed portion 51 of the pad electrode 50 is not formed on the light emitting ridge portion R.

  In the present embodiment, the recess 51 is formed in the pad electrode 50 on the dummy ridge portion S for all of the plurality of dummy ridge portions S. By forming the recess 51 in the pad electrode 50 in this manner, on the dummy ridge portion S, a part of the side on the first end face 20 a side of the pad electrode 50 is retracted toward the second end face 20 b, A part of the side of the electrode 50 on the second end face 20b side is set back to the first end face 20a side.

  The top view shape of the recess 51 is, for example, a rectangle. In the present embodiment, the top view shape of the recess 51 is trapezoidal. Specifically, the top view shape of the recess 51 is a trapezoidal shape in which the side on the bottom of the recess 51 is shorter than the side on the opening of the recess 51. The inclination angle of the side of the trapezoid forming the recess 51 is, for example, about 45 °, but is not limited thereto.

Incidentally, as shown in FIG. 3, the recess 51 located outermost on the dummy ridge S positioned at both ends (first dividing ridge S _0a and recesses 51 on the S _na described later), the dummy ridge portions Of the two sides of the trapezoid on S, the outer side is not present, and the recess 51 is cut out to the outer end of the dummy ridge portion S.

  Next, a detailed configuration of the dummy ridge portion S will be described with reference to FIGS.

As shown in FIGS. 2 and 3, the plurality of dummy ridges S formed in the stacked structure 20 includes at least the dummy ridges S provided on both ends in the arrangement direction of the plurality of light emitting ridges R. _{i (i} = 0, n) a is the end-side ridge, the dummy ridge portions provided between every two light-emitting ridge portion R adjacent the plurality of light emitting ridges R S _{i (i} = 1~n- 1) and an intermediate ridge portion.

Specifically, an end-side ridge dummy ridge portions _{S i (i = 0, n} ) is an end-side ridge portion _{S 0} and _{S n.} Further, an intermediate ridge dummy ridge portions _{S i (i = 1~n-1} ) is an end-side ridge portion _{S 0} and _{S n} than the dummy ridge portions S, the dummy ridge portions _{S 1, S} 2, S ₃ ,..., S _n-3 , S _n-2 and S _n−1 . In the present embodiment, the dummy ridge portions S that are intermediate ridge portions have the same shape and the same width, and are formed at equal intervals. The widths of the light emitting ridge portion R and the dummy ridge portion S are the lengths in the direction perpendicular to the longitudinal direction of the light emitting ridge portion R (the dummy ridge portion S).

Among all the dummy ridge portions S, each of the end side ridge portions S ₀ and S _n is the dummy ridge portion located on the outermost side in each of the left and right direction (direction orthogonal to the cavity length direction) of the semiconductor laser device 1 S. 2 and 3, the end-side ridge portion S _{0 (first} end side ridge portion) is located at the left end of the laminated structure 20, the end-side ridge portion S _{n (second} end side ridge Part) is located at the right end of the laminated structure 20. Therefore, for the dummy ridge portions S (S ₁ , S ₂ ,..., S _n−2 , S _n−1 ) that are intermediate ridge portions, the light emitting ridge portions R are present on both sides, but the end The light emitting ridges R are present only on one side of the side ridges S ₀ and S _n .

The left end ridge S ₀ and the right end ridge S _n are separated into a plurality of divided ridges by a groove m. In other words, by forming the groove m in the end side ridge portion S ₀ and S _n, each of the end-side ridge portion S ₀ and S _n are divided into a plurality of divided ridges (sub dummy ridge portions). As a result, when each of the plurality of divided ridge portions is counted as one dummy ridge portion S, each of the both end portions in the width direction of the stacked structure 20 has a plurality of dummy ridge portions with the divided ridge portion as a dummy ridge portion. It is formed continuously. In the present embodiment, each of the end side ridge portions S ₀ and S _n is separated into three or more divided ridge portions, and three or more divided ridge portions are continuously arranged.

Specifically, the end-side ridge portion S ₀ of the left, by two grooves m, the first dividing ridge S _0a, is separated into three second dividing ridge S _0b and third dividing ridge S _0c ing. Among these, the second divided ridge portion _S0b is located at the center, the first divided ridge portion _S0a is located on the left side of the second divided ridge portion _S0b , and the third divided ridge portion _S0c is the second divided ridge portion _S0c . It is located on the right side of the split ridge portion S 0 _b . In the present embodiment, the first divided ridge portion S _{0 a} and the third divided ridge portion S _{0 c} are located at both ends of the end ridge portion S ₀ . The first divided ridge portion S _{0 a} is located at the leftmost end portion of the left end side ridge portion S ₀ .

Similarly, the right end ridge portion _Sn is separated by the two grooves m into a first divided ridge portion S _na , a second divided ridge portion S _nb, and a third divided ridge portion S _nc . . Specifically, the second divided ridge portion S _nb is located at the center, the first divided ridge portion S _na is located on the right side of the second divided ridge portion S _nb , and the third divided ridge portion S _nc is It is located on the left side of the second divided ridge portion _Snb . Right end side ridge portion even S _n, first dividing ridge S _na and third dividing ridge S _nc is located at both ends of the end ridge portion S _n. The first dividing ridge S _0a, in the right end side ridge portion S _n, are positioned at the rightmost end.

In the present embodiment, the end side ridge portions S ₀ and S _n are formed in symmetrical shapes. That is, the grooves m for _dividing each of the end side ridge portions S ₀ and S _n into a plurality are formed at symmetrical positions.

Groove m to separate each of the end-side ridge portion S ₀ and S _n in plurality, like the grooves M and M 'for separating the light emitting ridge R and the dummy ridge portions S, the second cladding of the laminated structure 20 It is formed by digging the layer 26 and the contact layer 27. In the present embodiment, the depth of the groove m is the same as the depth of the grooves M and M ′. That is, the position of the bottom of the groove m and the position of the bottom of the grooves M and M ′ are the same.

  The dummy ridge portion S which is an intermediate ridge portion is a non-divided ridge portion which is not divided by the groove m.

  Next, regarding the stacked structure 20 in which the light emitting ridge portion R and the dummy ridge portion S are formed, the width of the light emitting ridge portion R and the dummy ridge portion S, the width and depth of the grooves M and M ′, and the light emitting ridge portion. An example of the width WA (interval) between R ridges is shown in Table 1.

As shown in Table 1, in any light emitting ridge portion R _i (i = 1 to n), the width (ridge width) WR _i of the light emitting ridge portion is, for example, 5 μm or more and 35 μm or less. By setting 5 μm ≦ WR _i , it is possible to suppress the generation of COD on the first end face 20a that is the laser light emission end face. In addition, by setting WR _i ≦ 35 μm, a gain for causing laser oscillation can be easily obtained.

In the present embodiment, the widths WR _i of all the light emitting ridge portions R are equal. That is, the width WR _i of all the light emitting ridge portions R is uniform. Thus, by making the widths WR _i of all the light emitting ridge portions R uniform, it is possible to inject current uniformly into all the light emitting ridge portions R. As a result, laser beams having a uniform beam diameter are output from all the emitters E. Thereby, a plurality of laser beams emitted from the semiconductor laser device 1 can be condensed on an optical component such as a lens or a fiber with high efficiency. The width WR _i of the light emitting ridge R is if not uniform, with the difference in light output occurs for each emitter E, partially difference in degradation occurs in the laminated structure 20. In particular, the emitter E with a large light output is deteriorated more. On the other hand, by making the widths WR _i of all the light emitting ridge portions R uniform, it is possible to suppress the occurrence of a difference in deterioration in the stacked structure 20 due to the light output difference of the emitter E. In the present embodiment, the width WR _i of all the light emitting ridge portions R is set to 30 μm.

Further, in any dummy ridge portion S _i (i = 0 to n), the width WS _i of the dummy ridge portion S is, for example, not less than 25 μm and not more than 500 μm.

Specifically, the width WS _i of an intermediate ridge existing between the light emitting ridge R dummy ridge portions _{S i (i = 1~n-1} ) is, for example, 25μm or more 500μm or less. In the present embodiment, it has a width WS _i of all intermediate ridge portion other than the end-side ridge portion _{S 0} and _{S n} to 370 .mu.m.

On the other hand, in the end-side ridge portions S ₀ and S _n divided into a plurality, the widths of the first divided ridge portions S _0a and S _na are, for example, 25 μm or more and 300 μm or less (in this embodiment, 180 μm), The widths of the two divided ridges S _0b and S _nb are, for example, 5 μm or more and 35 μm or less (30 μm in the present embodiment), and the widths of the third divided ridges S _0c and S _nc are, for example, 25 μm or more and 500 μm or less ( In this embodiment, it is 370 μm).

  In addition, the width WM of the groove M and the width WM ′ of the groove M ′ are, for example, 5 μm or more and 30 μm or less for the optional grooves M and M ′ separating the light emitting ridge portion R and the dummy ridge portion S. The depth of the groove M and the depth of the groove M ′ are, for example, 0.1 μm or more and 0.6 μm or less (all 0.5 μm in the present embodiment). By setting 5 μm ≦ WM and WM ′, it is possible to suppress the occurrence of voids without the solder getting wet when the semiconductor laser device 1 is mounted on the submount by the face-down method. Further, by setting WM and WM ′ ≦ 30 μm, the heat generated in the emitter E corresponding to the light emitting ridge portion R can be efficiently exhausted through the dummy ridge portion S.

For the groove m that separates the end-side ridge portions S ₀ and _Sn into a plurality, the width of the groove m is, for example, 5 μm or more and 15 μm or less (all 10 μm in this embodiment), and the depth of the groove m However, it is, for example, 0.1 μm or more and 0.6 μm or less (all 0.5 μm in this embodiment).

Further, a width WA (= WS _i + WR _i ) between the ridges of two adjacent light emitting ridge portions R is, for example, 35 μm or more and 560 μm or less. In the present embodiment, the width WA between the ridges of the light emitting ridge portion R is all 390 μm.

  The ratio (WA / WR) of the width WA between the two adjacent light emitting ridges R to the width WR of the light emitting ridges R preferably satisfies WA / WR ≧ 7. By satisfying the relationship of WA / WR ≧ 7, it is possible to suppress thermal saturation due to thermal interference in high power operation in two adjacent light emitting ridges R, and light necessary for high power laser oscillation of watt class Output characteristics can be easily obtained.

Here, with respect to the end side ridge portions S ₀ and S _n , Table 2 shows a pattern example of the combination of the widths of the divided ridge portions.

As shown in Table 2, in the pattern 1, for each has been end-side ridge portion S ₀ and S _n divided three or more, a ridge width of the divided ridge of the center side, the ridge of the division ridge portion at both ends It is larger than the width. That is, in each of the end side ridge portions S ₀ and S _n , the ridge widths of the plurality of divided ridge portions are wider toward the center. In this embodiment, the ridge width of the end-side ridge portion _{S 0} and _S the second dividing ridge portion of the center of _{n S} 0b _{(S nb)} is first divided ridge outer side in the end-side ridge portion _{S 0} and _{S n} The ridge width of the portion S _0a (S _na ) is larger than the ridge width of the third divided ridge portion S _0c (S _nc ) at the end side ridge portions S ₀ and S _n . Yes. In the pattern 1, the ridge width of the first divided ridge portion S _0a (S _na ) and the ridge width of the third divided ridge portion S _0c (S _nc ) are the same, but the present invention is not limited thereto.

In pattern 2, the plurality of divided the end side ridge portion S ₀ and S _n, the ridge width of the plurality of divided ridges are equal all. Specifically, the widths of the first divided ridge portion S _0a (S _na ), the second divided ridge portion S _0b (S _nb ), and the third divided ridge portion S _0c (S _nc ) are all equal.

In pattern 3, the ridge width of the split ridge portion on the center side is smaller than the ridge width of the split ridge portions on both ends of the end ridge portions S ₀ and S _n divided into three or more. . That is, in each of the end side ridge portions S ₀ and S _n , the ridge widths of the plurality of divided ridge portions are narrower toward the center. Specifically, the ridge width of the end-side ridge portion _{S 0} and _S the second dividing ridge portion of the center of _{n S} 0b _{(S nb)} is first divided ridge portion of the outer side in the end-side ridge portion _{S 0} and _{S n} S _0a is smaller than the ridge width of the _{(S na),} and is smaller than the ridge width of the third split ridge _S 0c inside the end-side ridge portion _{S 0} and _{S n (S nc)} . In the pattern 3, the ridge width of the third divided ridge portion S _0c (S _nc ) on the inner side is larger than the ridge width of the first divided ridge portion S _0a (S _na ) on the outer side. Not limited to.

Further, the pattern 3, the ridge width of the end-side ridge portion _{S 0} and _S third dividing ridge portion of the inner side of _{n S} 0c _{(S nc)} comprises a ridge width of the intermediate ridge _S i (i = _1~n) The ridge width of the second divided ridge portion S _0b (S _nb ) at the center in the end side ridge portions S ₀ and S _n is the same as the ridge width of the light emitting ridge portion R. With this configuration, it is possible to mass-produce a plurality of types of semiconductor laser devices 1 having different numbers of light emitting ridges R (number of emitters) at low cost.

Specifically, the ridge width of the third divided ridge portion S _0c (S _nc ) and the ridge width of the intermediate ridge portion S _i (i = 1 to n) are made the same, and the second divided ridge portion S _0b ( When the ridge width of S _nb ) and the ridge width of the light emitting ridge portion R are the same, in the state where the step of forming the insulating layer 30 is completed, the plurality of light emitting ridge portions R having the same width on the wafer have the same width. Since a plurality of dummy ridge portions S are periodically and alternately arranged one by one, depending on which light emitting ridge portion R the first electrode 41 (p-side electrode) is formed in the next step The dummy ridge portion S corresponding to the second divided ridge portion S _0b (S _nb ) may also be a light emitting ridge portion R. As a result, even if the reliability is somewhat inferior due to the user's request, if it is desired to increase the number of emitters to achieve a higher output, the second ridge portion S _0b (S _nb ) is placed on the ridge portion corresponding to the second divided ridge portion S _0b (S _nb ). By forming the one electrode 41, the ridge portion can be made to function not as the dummy ridge portion S but as the light emitting ridge portion R, so that the semiconductor laser device 1 with higher output can be realized. Conversely, by not forming the first electrode 41 in the ridge corresponding to the light emitting ridge R, the ridge where the first electrode 41 is not formed becomes a dummy ridge that is the second divided ridge S _0b (S _nb ). It can function as the part S. For example, a first electrode is formed on M (N> M) ridge portions out of N ridge portions having the same width as the light emission ridge portion R to function as the light emission ridge portion R, and (N−M) The ridge portion can function as the dummy ridge portion S. Thus, the stress can be relaxed by the groove of the adjacent dummy ridge portion S, so that the semiconductor laser device 1 with higher reliability can be realized. In this way, after the process of forming the insulating layer 30 is completed, a large number of wafers in which a plurality of light emitting ridge portions R having the same width and a plurality of dummy ridge portions S having the same width are arranged alternately one by one are arranged. The number of light emitting ridges R (the number of emitters) and the dummy ridges serving as support parts at the time of mounting are adjusted by adjusting the presence / absence of the first electrode 41 and the cleaving position according to the user's request. The number of S can be arbitrarily changed. Thereby, productivity improvement and cost reduction can be expected by process commonization.

In the pattern 4, the ridge widths of the plurality of divided ridge portions increase with distance from the light emitting ridge portion R in the plurality of divided end side ridge portions S ₀ and S _n . That is, the ridge width of the divided ridge portion increases as it is farther from the light emitting ridge portion R (as the end of the semiconductor laser device 1), and conversely, the ridge width of the divided ridge portion decreases as it is closer to the light emitting ridge portion R. Yes. Specifically, the distance from the light emitting ridge R adjacent to the end side ridge portion _{S 0} and _{S n,} third dividing ridge _S 0c _{(S nc),} second dividing ridge _S 0b _{(S nb)} and the The ridge width is gradually increased in the order of the one-part ridge portion S _0a (S _na ).

In the pattern 5, the ridge widths of the plurality of divided ridge portions decrease with increasing distance from the light emitting ridge portion R with respect to the end side ridge portions S ₀ and S _n divided into a plurality. In other words, the ridge width of the divided ridge portion becomes smaller as it is farther from the light emitting ridge portion R (as the end of the semiconductor laser device 1), and conversely, the ridge width of the divided ridge portion becomes larger as it is closer to the light emitting ridge portion R. Yes. Specifically, the distance from the light emitting ridge R adjacent to the end side ridge portion _{S 0} and _{S n,} third dividing ridge _S 0c _{(S nc),} second dividing ridge _S 0b _{(S nb)} and the The ridge width is gradually narrowed in the order of the one-divided ridge portion S _0a (S _na ).

Further, in the present embodiment, the sum of the ridge widths of the plurality of divided ridge portions in each of the end side ridge portions S ₀ and S _n is an intermediate ridge portion S _i (i = 1 to n) which is a non-divided ridge portion. It is larger than the width of. Specifically, in this embodiment, since the ridge width of the intermediate ridge portion S _i (i = 1 to n) is 370 μm, the patterns 1 to 3 correspond to this. In this case, the sum of the ridge width of a plurality of divided ridges at each end-side ridge portion S ₀ and S _n is about 210μm larger than the ridge width of the intermediate ridge. Thus, by the end-side ridge portion S ₀ and S _n wider than the intermediate ridge portion, the semiconductor laser element 1 and the submount when mounting the semiconductor laser element 1 to the submount by the face-down method Since the contact area (junction area) can be increased, the junction strength between the semiconductor laser device 1 and the submount can be increased. The semiconductor laser device 1 shown in FIG. 1 is illustrated as an example of the pattern 3.

The total ridge width of a plurality of divided ridges at each end-side ridge portion S ₀ and S _n may be equal to the width of the intermediate ridge portions to be not dividing ridge. In this case, in the present embodiment, since the ridge width of the middle ridge portion S _i (i = 1 to n) is 370 μm, the pattern 4 corresponds.

The total ridge width of a plurality of divided ridges at each end-side ridge portion S ₀ and S _n may be less than the width of the intermediate ridge is not divided ridge. In this case, in the present embodiment, since the ridge width of the intermediate ridge portion S _i (i = 1 to n) is 370 μm, the pattern 5 corresponds.

  Next, the effects of the semiconductor laser device 1 according to the present embodiment will be described including the background to the present disclosure.

  In the arsenide semiconductor laser device made of a GaAs arsenide semiconductor material, as described in Patent Document 1 above, the width of the light emitting ridge portion R is d1, and two adjacent light emitting ridge portions R are used. Assuming that the distance between the upper surfaces is d2, good laser characteristics can be realized by satisfying the conditions of d1 ≧ 40 and d1 ≦ 0.49 × d2.

  However, when the present inventors actually experimented on a nitride semiconductor laser element composed of a GaN-based nitride semiconductor material, the nitride semiconductor laser element satisfies the above-described conditions disclosed in Patent Document 1. Even so, it has been found that due to differences in semiconductor materials, laser oscillation does not occur due to (i) high threshold current density and (ii) low emission efficiency due to high threshold voltage.

  As a result of repeated experiments, the inventors have found that in the nitride semiconductor laser element having a laser array structure, the width WR of the upper surface of the light emitting ridge portion R, the upper surface of the light emitting ridge portion R, and the upper surface of the dummy ridge portion S With respect to the width WM between the two and the width WA between the upper surfaces of the two light emitting ridges R sandwiching the dummy ridge portion S, a range in which laser oscillation is performed and good high output characteristics can be realized is found.

  Specifically, as shown in Table 3 below, the inventors have determined the width WR of the light emitting ridge portion R, the width WS of the intermediate ridge portion of the dummy ridge portion S, the light emitting ridge portion R, Five sample semiconductor laser elements 1 are prepared in which the width WM of the grooves M and M ′ between the dummy ridge portion S and the width WA between the two light emitting ridge portions R are changed. An experiment was conducted to determine whether or not to

  As shown in Table 3, Samples 4 and 5 did not oscillate, but Samples 1 to 3 oscillated. In particular, samples 4 and 5 did not reach laser oscillation due to thermal interference due to thermal interference of two adjacent light emitting ridges R during high power operation, but samples 1 to 3 were high power operation Also, no thermal saturation occurred due to thermal interference between two adjacent light emitting ridge portions R.

  The experimental results are shown in FIG. As shown in FIG. 6, it can be seen that laser oscillation does not occur when the width WR of the light emitting ridge portion R exceeds 35 μm. This point will be described below.

  As in the present embodiment, the semiconductor laser device 1 which is a GaN-based nitride semiconductor laser device is different from the GaAs-based arsenide semiconductor laser device in the difference in physical properties of GaN / GaAs and the InGaN quantum device. The threshold current density is increased three times or more due to non-uniformity of the In composition in the well layer. For this reason, in the GaN-based semiconductor laser device 1, if the width WR of the top surface of the light-emitting ridge portion R is too large, the gain for laser oscillation can not be obtained, compared to the GaAs-based semiconductor laser device. The width WR of the ridge portion R needs to be set narrow.

  According to the above experiment, in the GaN-based semiconductor laser device 1, when the width WR of the light emitting ridge exceeds 35 μm, the gain intensity for laser oscillation cannot exceed the light absorption, and laser oscillation does not occur. I found it experimentally. That is, in the GaN-based semiconductor laser device 1, by setting the width WR of the light emitting ridge portion R to 35 μm or less, laser oscillation can be performed, and the light emission efficiency necessary to obtain high light output characteristics can be obtained.

  On the other hand, if the width WR of the light emitting ridge portion R is too narrow, COD is generated due to light density concentration on the first end face 20a that is the emission end face of the laser beam of the laminated structure 20, but according to the experiments by the present inventors, In the semiconductor laser device 1 according to the present embodiment, COD at the first end face 20a can be suppressed by setting the width WR of the light emitting ridge portion R to 5 μm or more, and high watt-class light output characteristics can be obtained. I found that.

  As described above, the width WR of the light emitting ridge portion R preferably satisfies the relational expression of 5 μm ≦ WR ≦ 35 μm.

  Next, the width WM between the light emitting ridge portion R and the dummy ridge portion S will be described.

  In the GaN-based semiconductor laser device 1, heat generated when laser oscillation occurs in the light emitting ridge portion R is high. This is because the GaN based semiconductor laser device 1 has a higher threshold voltage than the GaAs based semiconductor laser due to the energy band gap, so that the light emission efficiency is low and the heat generation is large.

  Here, the heat generated in the light emitting ridge portion R is exhausted from the upper portion of the light emitting ridge portion R to the back surface of the substrate 10 through the dummy ridge portion S. If the width WM between the upper surface and the upper surface is too long, the heat exhaust path from the light emitting ridge portion R to the dummy ridge portion S becomes long, so that sufficient heat exhaust cannot be performed at the time of high output operation. It leads to the occurrence of thermal saturation in the light output characteristics.

  As a result of experiments conducted by the present inventors on this point, the width WM between the light emitting ridge portion R and the dummy ridge portion S is set to 30 μm or less so that the heat generated in the light emitting ridge portion R is sufficiently transmitted through the dummy ridge portion S. It has been found that a semiconductor laser device 1 can be realized that can ensure a heat removal path capable of heat removal and can achieve watt-class light output characteristics without thermal saturation occurring up to a high light output region.

  On the other hand, if the width WM between the light emitting ridge portion R and the dummy ridge portion S is too narrow, the light emitting ridge portion R and the dummy ridge portion are formed when the semiconductor laser device 1 is mounted on a support substrate such as a submount by the face down method. In the region of width WM between S (i.e., the region of groove width), the solder does not get wet well and a void is generated, the thermal resistance increases, and the heat dissipation may be reduced.

  As a result of experiments conducted by the present inventors on this point, by setting the width WM between the light emitting ridge portion R and the dummy ridge portion S to 5 μm or more, the semiconductor laser device 1 can be sub-assembled in a face-down manner without generating voids. It has been found that it can be mounted on a support base such as a mount and high light output characteristics can be obtained without reducing the heat dissipation.

  As described above, the width WM between the light emitting ridge portion R and the dummy ridge portion S preferably satisfies the relational expression of 5 μm ≦ WM ≦ 30 μm.

  The width WM between the light emitting ridge portion R and the dummy ridge portion S may further satisfy 5 μm ≦ WM ≦ 15 μm. As a result, the heat generated in the light emitting ridge portion R can be more efficiently exhausted through the dummy ridge portion S, so that watt-class light output characteristics can be obtained without generating heat saturation up to a higher light output region. Be

Next, the relationship between the width WR of the light emitting ridge R and the width WA between the top surfaces of two adjacent light emitting ridges R _i and R _{i + 1} will be described.

  As described above, the dummy ridge portion S avoids stress concentration on the light emitting ridge portion R when the semiconductor laser device 1 is mounted on the submount by the face down method, and the heat generated in the light emitting ridge portion R. However, if the width WS of the dummy ridge portion S is too narrow, thermal interference occurs between two adjacent light emitting ridge portions R, and heat is generated during high output operation. There is a possibility that saturation occurs and laser oscillation does not occur. It has been found that this thermal interference depends on the width WR of the light emitting ridge portion R as described above (this is used in a state where the light output of the laser light is larger as the WR of the light emitting ridge portion R is larger. This is because that). Therefore, it is important to design in consideration of the ratio (WA / WR) between the width WA between two adjacent light emitting ridges R and the width WR of the light emitting ridges R.

  This ratio (WA / WR) is preferably 7 or more as shown in FIG. As described above, by satisfying the relationship WA / WR ≧ 7 with respect to the width WR of the light emitting ridge portion R and the width WA between the two light emitting ridge portions R, the high output operation in the two adjacent light emitting ridge portions R is achieved. It is possible to suppress the thermal saturation due to the thermal interference at the same time, and to obtain the light output characteristics necessary for high-power laser oscillation of watt-class.

  In the present embodiment, since the width WR of the light emitting ridge portion R is 30 μm, the width WA between the two light emitting ridge portions R is required to be at least 210 (= 30 × 7) μm or more. In the embodiment, the width WA is 370 μm. That is, WA / WR = 12.3.

  If WA / WR is too large (that is, if WA is too large), the size of the optical lens at the time of condensing a plurality of laser beams emitted from the semiconductor laser device 1 of the laser array structure becomes large or the semiconductor laser device Although there is a possibility that problems such as an increase in cost due to an increase in size of 1 itself may occur, but such problems do not occur if WA / WR = 12.3 or so.

  As described above, the semiconductor laser device 1 in the present embodiment is a nitride semiconductor laser device, and the second conductivity type layer of the multilayer structure 20 is a plurality of light emitting ridge portions R (first ridge portions). And a plurality of dummy ridge portions S (second ridge portions). The width of the upper surface of the light emitting ridge portion R is WR, the width between the upper surface of the light emitting ridge portion R and the upper surface of the dummy ridge portion S is WM, and the upper surfaces of the two light emitting ridge portions R sandwiching the dummy ridge portion S. Assuming that the width between the two is WA, the following relational expressions (Expression 1), (Expression 2) and (Expression 3) are satisfied.

  5 μm ≦ WR ≦ 35 μm (Expression 1)

  5 μm ≦ WM ≦ 30 μm (Equation 2)

  (WA / WR) ≧ 7 (Equation 3)

  As a result, it is possible to suppress thermal saturation due to thermal interference during the high output operation of the two adjacent light emitting ridge portions R, and to increase the distance of the heat exhaust path from the light emitting portion ridge portion R to the dummy ridge portion S. Since the accompanying thermal saturation can be suppressed, it is possible to realize the semiconductor laser device 1 excellent in heat dissipation capable of obtaining watt-class light output characteristics without generating thermal saturation even in high-output operation.

  Further, in the semiconductor laser device 1 according to the present embodiment, as shown in FIG. 5, the pad electrode 50 formed continuously on the plurality of light emitting ridges R and the dummy ridges S is a light emitting ridge R On the dummy ridge portion S, a portion separated from the first end face 20a and the second end face 20b by the first distance d1 is provided, and the dummy ridge portion S is separated from the first end face 20a and the second end face 20b by the second distance d2 In addition, the second distance d2 is larger than the first distance d1.

  In this manner, by making the second distance d2 on the dummy ridge portion S larger than the first distance d1 on the light emitting ridge portion R, the vicinity of the element end surface (on the first end surface 20a side and the second end surface) in the dummy ridge portion S. The pad electrode 50 in the vicinity of the 20 b side can be recessed more than the pad electrode 50 in the vicinity of the element end face in the light emitting ridge portion R. That is, in plan view, part of the side on the first end face 20 a side of the pad electrode 50 and part of the side on the second end face 20 b side of the pad electrode 50 are respectively retracted to the opposite side.

  As a result, even if heat is generated at the element end face of the emitter E corresponding to the light emitting ridge part R due to dangling bonds existing in the vicinity of the element end face of the light emitting ridge part R, it is generated between the element end faces of two adjacent emitters E. It is possible to suppress the propagation of the generated heat to the dummy ridge portion S adjacent to the light emitting ridge portion R via the pad electrode 50. Therefore, it is possible to suppress that the heat generated at the element end faces of two adjacent emitters E interfere with each other through the pad electrode 50.

  Further, the second distance d2 on the dummy ridge portion S is made larger than the first distance d1 on the light emitting ridge portion R so that the pad electrode 50 in the vicinity of the element end surface in the dummy ridge portion S is located in the vicinity of the element end surface in the light emitting ridge portion R. Even if heat generated at the element end face of the emitter E corresponding to the light emitting ridge portion R propagates to the dummy ridge portion S by being recessed from the pad electrode 50, the pad near the element end face in the dummy ridge portion S The thermal expansion of the electrode 50 can be suppressed. That is, by providing a region (concave portion 51) where the pad electrode 50 does not exist on the dummy ridge portion S, thermal expansion of the pad electrode 50 in this region can be eliminated. As a result, it is possible to suppress the light emitting ridge portion R from being compressed from both sides due to thermal expansion by the pad electrode 50 existing in the vicinity of the element end face in the dummy ridge portion S. Therefore, the generation of crystal defects in the light emitting ridge portion R can be suppressed by the compressive stress of the light emitting ridge portion R.

  As described above, according to the semiconductor laser device 1 of the present embodiment, it is possible to suppress the thermal interference between two adjacent emitters E via the pad electrode 50, and the crystal of the light emitting ridge portion R due to the thermal expansion of the pad electrode 50. Defects can be suppressed. Therefore, the semiconductor laser device 1 with high reliability can be realized.

  In the region inside (inside) the pad electrode 50 that is separated from the first end surface 20a and the second end surface 20b, the light propagates from the light emitting ridge portion R to the dummy ridge portion S adjacent to the light emitting ridge portion R through the pad electrode 50. Although there is heat, this heat is diffused widely by a region inside the pad electrode 50 that is widely formed across the light emitting ridge portion R and the dummy ridge portion S, so that the heat density is low and the temperature rise is small. For this reason, since the thermal expansion of the pad electrode 50 due to the diffused heat is small, the compressive stress received by the light emitting ridge portion R is also small. Further, in the light emitting ridge portion R and the dummy ridge portion S in the region inside the pad electrode 50, there are not many dangling bonds in the first place. For this reason, in the region inside the pad electrode 50, crystal defects do not occur in the light emitting ridge portion R very much.

  Further, in the present embodiment, the pad electrode 50 has the recess 51 on the side of the first end face 20a and the second end face 20b on the dummy ridge portion S, and this recess 51 is the first end face. This is a portion that is separated from 20a and the second end face 20b by a second distance d2.

Specifically, as shown in FIG. 7, the side of the first end face 20a side of the pad electrode 50 on the light emitting ridge R _i is left groove M _i and the right of the groove M _'i of the light emitting ridge R _i The first end face with a slope of about 45 ° on the dummy ridges S _i-1 and S _i after extending horizontally to the left dummy ridge S _i-1 and the right dummy ridge S _i A recess 51 is formed in the pad electrode 50 on the dummy ridges S _i-1 and S _{i by} leaving (recessing) from 20a.

  As described above, by forming the recess 51 in the pad electrode 50 on the dummy ridge portion S, the second distance d2 on the dummy ridge portion S can be easily made larger than the first distance d1 on the light emitting ridge portion R. Can. Then, in the semiconductor laser device 1 according to the present embodiment, the heat interference between two adjacent emitters E via the pad electrode 50 and the crystal defects of the light emitting ridge portion R due to the thermal expansion of the pad electrode 50 are caused by the recess 51. It can be suppressed.

  In the present embodiment, the recess 51 of the pad electrode 50 is not formed on the light emitting ridge portion R. Therefore, even if the recess 51 is formed in the pad electrode 50, it does not hinder the injection of the current into the light emitting ridge portion R.

In the present embodiment, the planar view shape of the recess 51 of the pad electrode 50 is a trapezoid as shown in FIG. 5A, but is not limited thereto. For example, the planar view shape of the recess 51 of the pad electrode 50 may be a rectangle as shown in FIG. In this case, the recess 51, the light emitting ridge R first end face 20a side of the sides of the pad electrode 50 on the _i is, the light emitting ridge R _i right groove M 'dummy ridge portions in the horizontal direction beyond the _i S _i of After spreading to the dummy ridge portion S _i , it is formed in a rectangular shape by being separated from the first end face 20 a in a step-like manner with an inclination of about 90 °.

  Thus, by making the shape of the concave portion 51 in a plan view rectangular, the width of the concave portion 51 in the left-right direction (the direction orthogonal to the resonator length direction) can be increased. While being able to suppress further the thermal interference of two emitters E, the crystal defect of the light emission ridge part R by the thermal expansion of the pad electrode 50 can be suppressed further.

  Further, as shown in FIG. 5A and FIG. 7, assuming that the pitch of two adjacent recesses 51 is X and the width of the recesses 51 is Y, it is preferable to satisfy the relationship of 0.667X ≦ Y ≦ X. . This point will be described with reference to FIG.

  FIG. 8 is a diagram showing the result of a reliability experiment of the semiconductor laser device 1 performed with respect to the pitch X and width Y of the recess 51. In this experiment, a plurality of semiconductor laser devices 1 in which the pitch X and the width Y of the concave portions 51 are changed are manufactured, and each semiconductor laser device is operated to have an initial 3 W output per light emitting ridge portion R. A product with a deterioration rate (output reduction rate) of not more than 30% after 20,000 hours was regarded as a non-defective product, and a product with a deterioration rate of 20,000 hours after 30% was evaluated as a non-defective product.

  As a result, as shown in FIG. 8, it was experimentally found that it is necessary to satisfy the relationship of 0.667X ≦ Y <X in order to obtain a non-defective product. In this experiment, the first distance d1 between the side of the pad electrode 50 in the light emitting ridge portion R and the first end surface 20a (second end surface 20b) is 6 μm, and the bottom side of the recess 51 of the pad electrode 50 in the dummy ridge portion S is used. The second distance d2 between the first end face 20a (second end face 20b) and 20 μm.

  Further, when the semiconductor laser device 1 configured as described above is incorporated into equipment such as a laser processing apparatus, as shown in FIG. 9, the semiconductor laser device 2 is formed into a module form. FIG. 9 is a cross-sectional view of the semiconductor laser device 2 according to the embodiment.

  As shown in FIG. 9, the semiconductor laser device 2 includes the semiconductor laser element 1 described above and a submount 60. The semiconductor laser element 1 is mounted on the submount 60 by a face down method (junction down method). That is, in the semiconductor laser device 1, the ridge portion side (light emitting ridge portion R side, dummy ridge portion S) is joined to the submount 60. Specifically, the pad electrode 50 of the semiconductor laser device 1 is connected to a bonding layer (not shown) stacked on the submount 60.

  The submount 60 includes, for example, a base made of a semiconductor material such as SiC, a ceramic material such as AlN, a high thermal conductive material such as diamond or a diamond composite, and a metal layer formed on the surface of the base. . The semiconductor laser device 1 and the metal layer of the submount 60 are bonded via a bonding layer made of a solder layer such as AuSn.

  In order to strengthen the bonding between the semiconductor laser device 1 and the submount 60, that is, to reduce the contact thermal resistance and the contact electrical resistance between the pad electrode 50 and the submount 60, the pad electrode 50 can be made as close as possible. It is good to enlarge.

  As shown in FIG. 9, the semiconductor laser device 2 in the present embodiment further includes a first heat radiating member 71 and a second heat radiating member 72, and the joined body of the semiconductor laser element 1 and the submount 60 is It is sandwiched between the first heat radiation member 71 and the second heat radiation member 72. The first heat radiating member 71 and the second heat radiating member 72 are heat sinks for radiating heat generated by the semiconductor laser device 1. The first heat radiation member 71 and the second heat radiation member 72 may be conductors for supplying a current to the semiconductor laser device 1. Therefore, as the first heat radiating member 71 and the second heat radiating member 72, it is preferable to use a metal block or the like made of a metal material such as copper which is excellent in electrical conductivity and thermal conductivity.

  Thus, by sandwiching the joined body of the semiconductor laser element 1 and the submount 60 between the first heat radiating member 71 and the second heat radiating member 72, the heat conducted from the light emitting ridge portion R to the pad electrode 50 is It spreads at 50 and is transmitted to the first heat dissipation member 71 via the submount 60. Thereby, the heat dissipation of the heat generated in the semiconductor laser device 1 can be improved, and the highly reliable semiconductor laser device 2 can be realized.

  Further, in the semiconductor laser device 1 according to the present embodiment, the height of the light emitting ridge portion R and the height of the dummy ridge portion S are equal, and the upper surface of the light emitting ridge portion R and the upper surface of the dummy ridge portion S have the same height. Position.

  With this configuration, when the semiconductor laser element 1 is mounted on the submount 60 by the face-down method, the mounting surface of the semiconductor laser element 1 is flat, so that the semiconductor laser element 1 can be easily mounted on the submount 60. be able to. Further, since the height of the light emitting ridge portion R and the height of the dummy ridge portion S are equal to each other, the light emitting ridge portion R and the dummy ridge portion S can be easily formed in the laminated structure 20.

Furthermore, in the semiconductor laser device 1 according to the present embodiment, as shown in FIGS. 2 and 3, the end side ridge portion S ₀ (S _n ) of the plurality of dummy ridge portions S is divided into a plurality of divisions by the groove m. Separated into ridges.

As described above, the end-side ridge portion S ₀ (S _n ) is separated into a plurality of pieces, whereby the strain m caused by the stress can be relieved by the grooves m between the plurality of divided ridge portions. With this configuration, a difference in thermal expansion occurs with a difference in linear expansion coefficient between the laminated structure 20 of the semiconductor laser device 1 and the submount 60 due to a temperature difference etc. during mounting, and the width of the laminated structure 20 of the semiconductor laser device 1 Even if stress is generated at the end of the direction, the stress can be absorbed by the groove m between the plurality of split ridges. As a result, the strain caused in the dummy ridge portion S due to the stress due to the thermal expansion difference can be alleviated, so that the generation of crystal defects in the dummy ridge portion S can be suppressed. As a result, it is possible to suppress the occurrence of crystal defects in the light emitting ridge portion R by propagating crystal defects in the dummy ridge portion S to the light emitting ridge portion R adjacent to the dummy ridge portion S. Therefore, the semiconductor laser device 1 with high reliability can be realized.

In the present embodiment, both end-side ridge portion S ₀ and S _n is the plurality of separated, only one end side ridge portion S ₀ and S _n may be the plurality of separated.

(Modification)
As described above, the semiconductor laser element 1 and the semiconductor laser device 2 according to the present disclosure have been described based on the embodiments, but the present disclosure is not limited to the above embodiments.

  For example, in the above embodiment, the portion of the pad electrode 50 which is separated from the element end face (the first end face 20a and the second end face 20b) on the light emitting ridge R by the first distance d1 is the first end face 20a side and Although it formed in both the 2nd end surface 20b side, it is not restricted to this, You may form in the at least one element end surface side of the 1st end surface 20a and the 2nd end surface 20b.

  Similarly, the portions of the pad electrode 50 that are separated from the element end surfaces (first end surface 20a, second end surface 20b) on the dummy ridge portion S by the second distance d2 are the first end surface 20a side and the second end surface 20b side. However, the present invention is not limited to this, and may be formed on at least one of the first end surface 20a and the second end surface 20b. That is, in the above embodiment, the recessed portion 51 which constitutes the amount of retraction (the amount of recess) from the side of the pad electrode 50 which is the second distance d2 in the dummy ridge portion S is the side on the first end face 20a side and the second end face It may be formed on at least one of the sides on the 20b side.

  Specifically, in the above embodiment, the recess 51 of the pad electrode 50 is formed on both sides of the first end face 20a and the second end face 20b, either of the first end face 20a and the second end face 20b. It may be formed only on one side. As described above, by forming the recess 51 of the pad electrode 50 only on one side of the first end surface 20a side and the second end surface 20b side, the area of the pad electrode 50 can be increased compared to the above embodiment. can do. Thus, the contact area with the submount 60 can be increased, so that a semiconductor laser device with higher reliability can be realized.

  When the second distance d2 in the dummy ridge portion S is increased by, for example, increasing the amount of retraction of the recess 51, the length in the cavity length direction of the pad electrode 50 connecting adjacent light emitting ridge portions R is shortened. As a result, the resistance of the pad electrode 50 partially rises to generate ineffective power and heat is generated by the ineffective power. Therefore, the amount of retraction of the recess 51 should not be too large, and may be set to an optimum value.

  Further, when the recess 51 of the pad electrode 50 is formed only on either the first end face 20a side or the second end face 20b side, the first end face 20a from which the laser light is emitted is reflected by the second light. Since the temperature is higher than that of the end face 20b, as shown in FIG. 10, the recess 51 of the pad electrode 50 is preferably formed only on the first end face 20a side.

  Further, in the above-described embodiment, the recess 51 of the pad electrode 50 is formed in all of the plurality of dummy ridges S, but the present invention is not limited to this. For example, as shown in FIG. 11, the recess 51 of the pad electrode 50 has a pair of first end surface 20 a and second end surface on the dummy ridge portion S on the center side (center portion) among the plurality of dummy ridge portions S. On the dummy ridges S on the left and right end sides in the width direction of the semiconductor laser element, one end face of the pair of first end face 20a and second end face 20b is formed on both end face sides of 20b. It may be formed only on the side. In a semiconductor laser element having a laser array structure, heat tends to accumulate in the central portion. Therefore, as shown in FIG. 11, on the dummy ridge portion S on the central side, the sides on both end surfaces of the first end surface 20a and the second end surface 20b. By forming the recess 51, the influence of thermal expansion at the central portion can be reduced. On the other hand, on the left and right dummy ridge portions S, the first end surface 20a and the second end surface 20b are formed by forming the recess 51 only on one end surface side of the first end surface 20a and the second end surface 20b. The contact area between the pad electrode 50 and the submount 60 can be increased and the bonding strength between the pad electrode 50 and the submount 60 can be increased as compared with the case where the concave portions 51 are formed on the both end face sides. be able to. As a result, it is possible to realize a more reliable semiconductor laser device which is excellent in heat dissipation and bonding strength.

  As described above, since the first end face 20a from which the laser light is emitted is at a higher temperature than the second end face 20b from which the laser light is reflected, the dummy ridge portions on the left and right end sides in the width direction of the semiconductor laser element In the case where the concave portion 51 is formed only on one end face side of the first end face 20a and the second end face 20b on S, as shown in FIG. 11, a pair of the first end face 20a and the second end face 20b It is preferable to form the recess 51 only in the side on the side of the first end face 20a.

  In the above embodiment, the width and depth of the recess 51 of the pad electrode 50 (the amount of receding from the end surface) are uniform in all of the plurality of dummy ridges S. The width and depth of the recess 51 of the electrode 50 may be modulated for each of the plurality of dummy ridge portions S. Thereby, the bonding between the pad electrode 50 and the submount 60 can be strengthened, and the contact thermal resistance and the contact electrical resistance between the pad electrode 50 and the submount 60 can be effectively reduced.

  For example, as shown in FIG. 12, with respect to the recess 51 of the pad electrode 50, the width of the recess 51 on the dummy ridge S on the center side among the plurality of dummy ridges S is set to the left and right of the plurality of dummy ridges S. The width may be larger than the width of the recess 51 on the dummy ridge portion S on the end side. That is, the width of the recess 51 of the pad electrode 50 may be wider toward the center. As a result, the contact area between the pad electrode 50 and the submount 60 is increased to reduce the contact thermal resistance and the contact electrical resistance between the pad electrode 50 and the submount 60, and the heat at the center where heat is likely to accumulate. The influence of expansion can be reduced. In FIG. 12, the depths of all the recesses 51 in the pad electrode 50 are constant.

  Alternatively, as shown in FIG. 13, with respect to the concave portion 51 of the pad electrode 50, the depth of the concave portion 51 on the dummy ridge portion S on the center side among the plurality of dummy ridge portions S It is preferable that the depth of the recess 51 on the dummy ridge portion S on the end side of the groove is larger than the depth of the recess 51. That is, the depth of the concave portion 51 of the pad electrode 50 may be configured to be deeper toward the central portion. Also in this case, the contact area between the pad electrode 50 and the submount 60 is increased to reduce the contact thermal resistance and the contact electrical resistance between the pad electrode 50 and the submount 60, and at the central portion where heat is likely to accumulate. The influence of thermal expansion can be reduced. In FIG. 13, the width of all the recesses 51 in the pad electrode 50 is constant.

  Alternatively, although not shown, both of FIG. 12 and FIG. 13 may be combined to change both the width and the depth of the recess 51 of the pad electrode 50.

  In the above embodiment, the recess 51 of the pad electrode 50 is formed by recessing only a part of the side of the pad electrode 50 on the dummy ridge portion S on the first end face 20a side and the second end face 20b side. (That is, the other part of the side of the pad electrode 50 on the side of the first end face 20a and the side of the second end face 20b on the dummy ridge portion S is the first end face 20a side of the pad electrode 50 on the light emitting ridge portion R). And the second end face 20b is left flush with the side on the second end face 20b side), but is not limited thereto. For example, as shown in FIGS. 14A and 14B, the recess 51 of the pad electrode 50 is formed by denting all the sides of the pad electrode 50 on the first end surface 20a side and the second end surface 20b side on the dummy ridge portion S. It may be formed. In FIGS. 14A and 14B, the number of light emitting ridges R and the number of dummy ridges S are reduced for simplification. By configuring the recess 51 of the pad electrode 50 in this way, it is possible to minimize the thermal interference between two adjacent emitters E via the pad electrode 50 and the influence of the thermal expansion of the pad electrode 50. Further, in this modification, the pad electrode 50 may have a step in the middle in the width direction of the grooves M and M ′ between the light emitting ridge portion R and the dummy ridge portion S. In this case, the recess 51 may be formed so as to recede by a stepped step in the middle of the grooves M and M ′, as shown in FIG. 15, or as shown in FIG. It may be formed so as to recede with an inclined step in the middle of '. From the viewpoint of the process of forming pad electrode 50, the shape of recess 51 is preferably the shape shown in FIG. 16 rather than the shape shown in FIG. This is because, as shown in FIG. 16, the step is inclined in the middle of the grooves M and M ′, so that the photoresist when patterning the pad electrode 50 having the recess 51 is harder to cut than in the case of FIG. It is because

  14A and 14B, the dummy ridge portions S (end-side ridge portions) located at the left and right ends of the width direction of the semiconductor laser element are not divided. As described above, the dummy ridge portions S located at both the left and right ends may not be divided. This can be applied to other variations.

  Moreover, in this modification shown to FIG. 14A and FIG. 14B, although formed on dummy ridge part S of the both ends on either side, it does not restrict to this. For example, as shown in FIG. 17, the pad electrode 50 is not formed on the left and right dummy ridge portions S, and may be formed only on the light emitting ridge portions R on the left and right ends. . As described above, the pad electrode 50 may not be formed to cover all the light emitting ridges R and all the dummy ridges S, and a part of the plurality of light emitting ridges R and the plurality of dummy ridges S may be used. It may be formed to cover a part of the This can be applied to the above embodiment and other modifications.

  In the above embodiment, the first end surface 20a and the second end surface 20b are flat surfaces. However, the present invention is not limited to this, and in the dummy ridge portion S, the pad electrode 50 is separated by the second distance d2. The end face on the side having the portion may have a groove 20 c extending downward from the upper surface of the dummy ridge portion S. For example, as shown in FIG. 18, a groove 20c extending downward from the upper surface of the dummy ridge S may be formed on both the first end surface 20a and the second end surface 20b of the dummy ridge S. In this way, by forming the groove 20c, it is possible to further suppress the thermal interference between two adjacent emitters E via the pad electrode 50.

  The depth of the groove 20c is a length that reaches the substrate 10 from the upper surface of the dummy ridge S toward the substrate 10, but the groove 20c reaches the substrate 10 from the upper surface of the dummy ridge S. It is possible to form only up to the middle layer (for example, the first cladding layer 21) of the stacked structure 20 without doing so. Although the surface of the groove 20 c is exposed in FIG. 18, the surface of the groove 20 c may be covered with the insulating layer 30.

  Further, in the above embodiment, the first electrode 41 (p-side electrode) is formed in the light emitting ridge portion R and not formed on the dummy ridge portion S, but the present invention is not limited to this. For example, the first electrode 41 may be formed on both the light emitting ridge portion R and the dummy ridge portion S. However, in this case, an insulating film is formed between the dummy ridge portion S and the first electrode 41 or an insulating layer is formed in the dummy ridge portion S, and the active layer 23 below the dummy ridge portion S is formed. It is necessary to form in the dummy ridge portion S a current injection blocking structure in which no current is injected. When the first electrode 41 is also formed on the dummy ridge portion S, a plurality of first electrodes 41 may be formed for each ridge portion R and each dummy ridge portion S, or all the ridge portions may be formed. One first electrode 41 may be formed so as to cover R and all the dummy ridge portions S. In the latter case, the first electrode 41 may be used as the pad electrode without providing the pad electrode 50 separately.

  In the above embodiment, the width WR of the light emitting ridge portion R and the width WS of the dummy ridge portion S are different from each other. However, the present invention is not limited to this. That is, the width WR of the light emitting ridge portion R and the width WS of the dummy ridge portion S may be the same.

  Further, in the above embodiment, the semiconductor laser device 1 is mounted on the submount 60 by the face down method, but the present invention is not limited to this. For example, the semiconductor laser element 1 may be mounted on a support base such as the submount 60 by a face-up method.

  In addition, modes obtained by applying various modifications that those skilled in the art may think on the above embodiment and modifications, and components and functions in the embodiments and modifications without departing from the spirit of the present disclosure. An embodiment realized by arbitrarily combining is also included in the present disclosure.

  The semiconductor laser device and the semiconductor laser device according to the present disclosure can be used as a light source of various devices such as a laser processing device or an image display device, and in particular, as a light source of a device requiring a relatively high light output. It is useful.

DESCRIPTION OF SYMBOLS 1 Semiconductor laser element 2 Semiconductor laser apparatus 10 Substrate 20 Laminated structure 20a 1st end surface 20b 2nd end surface 20c Groove part 21 1st cladding layer 22 1st guide layer 23 Active layer 24 2nd guide layer 25 Electronic barrier layer 26 2nd cladding Layer 27 Contact layer 30 Insulating layer 41 First electrode 42 Second electrode 50 Pad electrode 51 Recess 60 Submount 71 First heat radiating member 72 Second heat radiating member R Light emitting ridge portion S Dummy ridge portion M, M ′, m Groove E Emitter

Claims (8)

A first conductivity type layer;
An active layer formed on the first conductivity type layer;
A second conductivity type layer formed on the active layer,
The first conductivity type layer, the active layer, and the second conductivity type layer are made of a nitride semiconductor,
The laminated structure composed of the first conductivity type layer, the active layer, and the second conductivity type layer includes a pair of opposed end surfaces serving as resonator end surfaces,
The second conductivity type layer is
A plurality of first ridge portions having a longitudinal direction in a direction orthogonal to the pair of end faces and serving as a current injection path to the active layer;
A second ridge portion having a longitudinal direction in a direction orthogonal to the pair of end faces and not serving as a current injection path to the active layer,
The second ridge portion is provided between at least two of the first ridge portions of the plurality of first ridge portions,
The length in the direction orthogonal to the longitudinal direction is the width,
The width of the top surface of the first ridge is WR, the width between the top surface of the first ridge and the top surface of the second ridge is WM, and the width between the top surfaces of the two first ridges is WA If you
5 μm ≦ WR ≦ 35 μm,
5 μm ≦ WM ≦ 30 μm,
(WA / WR) ≧ 7,
A nitride semiconductor laser device. The nitride semiconductor laser element according to claim 1, wherein 5 μm ≦ WM ≦ 15 μm. The nitride semiconductor laser device according to claim 1, wherein a height of the first ridge portion is equal to a height of the second ridge portion. A metal layer is continuously formed on the first ridge portion and the second ridge portion.
The nitride semiconductor laser device according to any one of claims 1 to 3. A groove is provided between the first ridge portion and the second ridge portion, the bottom surface being the second conductive layer,
The first ridge portion and the second ridge portion are separated by the groove,
The nitride semiconductor laser device according to any one of claims 1 to 4. In all of the plurality of first ridges, the widths WR of the upper surfaces are equal,
The nitride semiconductor laser device according to any one of claims 1 to 5. The nitride semiconductor laser device according to any one of claims 1 to 6,
A submount, and
In the nitride semiconductor laser element, the first ridge portion side and the second ridge portion side are joined to the submount. And a first heat radiation member and a second heat radiation member,
The semiconductor laser device according to claim 7, wherein a bonded body of the semiconductor laser element and the submount is sandwiched between the first heat radiating member and the second heat radiating member.

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