Semiconductor laser light-emitting device

Abstract

To provide a semiconductor laser light-emitting device capable of realizing a high COD level and long-term reliability.SOLUTION: A semiconductor laser light-emitting element emits a laser beam. The semiconductor laser light-emitting element comprises a semiconductor laminate including a front end face and a rear end face and an end face protective layer disposed so as to cover the front end face of the semiconductor laminate. The end face protective layer is a laminate of a plurality of dielectric films. In the plurality of dielectric films, a first dielectric film disposed closest to the front end face contains a nitride or an oxynitride of a first element, and the first dielectric film has a highest rare gas concentration in the plurality of dielectric films.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a semiconductor laser light-emitting element, and more particularly to a semiconductor laser light-emitting element made of a nitride-based semiconductor. [Background technology]

[0002] Conventionally, laser processing has been put to practical use, and in order to expand its applications, there is a demand for even higher output and narrower beam of laser light. As one method for achieving this, a method using a semiconductor laser light-emitting element having multiple light-emitting points (i.e., a laser array element) has been proposed. In this method, a synthesis optical system is constructed that synthesizes multiple laser beams from the semiconductor laser light-emitting element. In this synthesis optical system, an external resonator is formed by the semiconductor laser light-emitting element (synthesizing optical system) and a mirror arranged at a distance from the semiconductor laser light-emitting element. With this configuration, a laser device that emits high-output and high-beam quality laser light can be realized.

[0003] Here, in a semiconductor laser light-emitting element used in an external cavity type laser device, in order to suppress resonance (i.e., internal resonance) inside the semiconductor laser light-emitting element, it is important to reduce the reflectance at the front end face (the main emission end face of the laser light) of the semiconductor laminate in the semiconductor laser light-emitting element as much as possible, and the reflectance is required to be, for example, 1% or less.

[0004] On the other hand, as a method for combining multiple laser beams, there are, for example, a spatial combining method for spatially combining multiple laser beams, and a wavelength combining method for focusing multiple laser beams having different wavelengths on the same optical axis. In order to combine multiple laser beams to realize a narrow beam, the wavelength combining method for focusing multiple laser beams on the same optical axis is more advantageous than the spatial combining method in which multiple optical axes are different from each other.

[0005] In order to realize wavelength synthesis in the wavelength synthesis method, it is necessary to generate laser light of multiple different wavelengths by a semiconductor laser light emitting element. For example, laser light of multiple different wavelengths can be generated by using a laser array element as the semiconductor laser light emitting element. Furthermore, in order to generate many laser lights, it is also possible to use multiple laser array elements.

[0006] In the GaN-based semiconductor laser light-emitting element used in the above-mentioned composite optical system, blue laser light having high optical energy is emitted from the end face of the semiconductor. Therefore, there is a problem that the end face of the semiconductor is easily damaged. Therefore, a protective layer is usually provided on the end face (light-emitting end face) of the semiconductor. Here, Patent Document 1 and Patent Document 2 include descriptions focusing on the rare gas concentration in the protective layer. For example, Patent Document 1 describes that the protective layer is divided into two regions, and the amount of rare gas in the region in contact with the semiconductor is made smaller than the amount of rare gas in the other region. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4621791 [Patent Document 2] International Publication No. 2019 / 159449 Summary of the Invention [Problem to be solved by the invention]

[0008] The protective layer that covers the facets of a semiconductor must be able to prevent oxygen from entering the semiconductor from the outside and diffusing into it. The protective layer itself must also have low light absorption. From the perspective of preventing oxygen diffusion, it is considered effective to include a crystalline nitride film or oxynitride film in the protective layer. On the other hand, from the perspective of reducing the light absorption of the protective layer, it is important to reduce the extinction coefficient (light absorption) of the protective layer.

[0009] The present inventors have conducted extensive research into these issues and have found that the protective layers described in the above Patent Documents 1 and 2 do not have sufficient effects of suppressing oxygen diffusion or reducing the extinction coefficient. In particular, when used as a semiconductor laser light-emitting element that emits high-output, high-beam quality laser light for laser processing applications, the protective layers in the above Patent Documents 1 and 2 have the problem that the semiconductor facets are prone to deterioration.

[0010] The present disclosure has been made to solve such problems, and has an object to provide a semiconductor laser light-emitting element that can suppress deterioration of the facets of a semiconductor laminate over a long period of time. [Means for solving the problem]

[0011] According to the inventors' intensive research, it has been found that the deterioration of the front end face can be suppressed by disposing an end face protection layer made of a plurality of dielectric films so as to cover the front end face for emitting light of the semiconductor (semiconductor laminate) and setting the rare gas concentration of the dielectric film located closest to the front end face to be the highest among the rare gas concentrations of the plurality of dielectric films. Furthermore, the semiconductor laser light emitting element having the structure disclosed herein can maintain a high COD (catastrophic optical damage) level for a long period of time.

[0012] Specifically, the present disclosure provides the following semiconductor laser light-emitting element. [1] A semiconductor laser light-emitting element that emits laser light, comprising: a semiconductor laminate having a front end face and a rear end face; and an end face protection layer arranged to cover the front end face of the semiconductor laminate, wherein the end face protection layer is a laminate of a plurality of dielectric films, a first dielectric film of the plurality of dielectric films that is arranged closest to the front end face contains a nitride or oxynitride of a first element, and the first dielectric film has the highest rare gas concentration of the plurality of dielectric films. [2] The semiconductor laser light-emitting element according to [1], wherein the first element is Si. [3] The semiconductor laser light-emitting element according to [1] or [2], wherein the first dielectric film is a SiN film. [4] The semiconductor laser light-emitting element according to any one of [1] to [3], wherein the rare gas contained in the first dielectric film is Ar, and the concentration of the Ar in the first dielectric film is 4.0 atomic % or more. [5] The semiconductor laser light-emitting element according to any one of [1] to [4], wherein the end face protection layer includes two layers of SiN film, one of the two layers of SiN film being the first dielectric film. [6] The semiconductor laser light-emitting element according to [5], wherein the two SiN films have the same rare gas concentration. [7] The semiconductor laser light emitting element according to any one of [1] to [6], wherein the first dielectric film has a film thickness of 1 nm or less.

[0013] [8] The semiconductor laser light emitting element according to [1], further comprising a second dielectric film disposed on the first dielectric film, the second dielectric film including a nitride or oxynitride of a second element different from the first element. [9] The semiconductor laser light-emitting element according to [8], wherein the second element is Al.

[10] The semiconductor laser light-emitting element described in [8] or [9], wherein the second dielectric film includes hexagonal crystals whose c-axes are oriented in the normal direction of the front end face and hexagonal crystals whose m-axes are oriented in the normal direction of the front end face.

[0014]

[11] The semiconductor laser light emitting element according to any one of [8] to

[10] , further comprising a third dielectric film on the second dielectric film, the third dielectric film including an oxide of the second element.

[12] The semiconductor laser light emitting element according to

[11] , wherein the third dielectric film is an amorphous film, and the second element is Al.

[13] The semiconductor laser light emitting element according to

[11] or

[12] , wherein the rare gas concentration in the second dielectric film is lower than the rare gas concentration in the third dielectric film.

[0015]

[14] The semiconductor laser light emitting element according to any one of

[11] to

[13] , further comprising a fourth dielectric film on the third dielectric film, the fourth dielectric film including a nitride or an oxynitride of the second element.

[15] The semiconductor laser light emitting element according to

[14] , wherein the fourth dielectric film is a polycrystalline film, and the second element is Al.

[0016]

[16] The semiconductor laser light-emitting element according to any one of [1] to

[15] , wherein the end face protection layer further has a reflectance adjustment film.

[17] The semiconductor laser light-emitting element described in

[16] , wherein the reflectance adjustment film is composed of three layers, namely a first film, a second film, and a third film, arranged in that order from the front end face side, and a refractive index n2 of the second film is greater than a refractive index n1 of the first film and a refractive index n3 of the third film.

[0017]

[18] The semiconductor laser light-emitting element according to any one of [1] to

[17] , wherein the reflectance at the front end face of light with a wavelength of 440 nm±15 nm incident on the end face protection layer from the semiconductor laminate is 1% or less.

[19] The semiconductor laser light-emitting element according to any one of [1] to

[18] , wherein the semiconductor laminate contains a GaN-based material.

[20] The semiconductor laser light-emitting element according to any one of [1] to

[19] , wherein the semiconductor laminate has a plurality of light-emitting points for emitting laser light. Effect of the Invention

[0018] According to the present disclosure, a semiconductor laser light-emitting element capable of achieving a high COD level and long-term reliability is provided. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional view showing the configuration of a semiconductor laser light-emitting element according to a first embodiment. [Diagram 2] FIG. 2 is a graph showing actual measurement data obtained by SIMS analysis of various dielectric films. [Diagram 3]FIG. 3 is a schematic cross-sectional view showing the configuration of a semiconductor laser light-emitting element according to the second embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing the configuration of a semiconductor laser light-emitting element according to the third embodiment. [Diagram 5] FIG. 5 is a schematic cross-sectional view showing the configuration of a semiconductor laser light-emitting element according to the fourth embodiment. [Figure 6] FIG. 6 is a schematic plan view showing an optical system configuration of a semiconductor laser device to which the semiconductor laser light-emitting elements according to the first to fourth embodiments are applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, the embodiments of the present disclosure will be described with reference to the drawings. Note that the embodiments described below each show a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, and the arrangement and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present disclosure. In addition, each figure is a schematic diagram and is not necessarily illustrated precisely. Therefore, the scales and the like do not necessarily match in each figure. Note that in each figure, the same reference numerals are given to substantially identical components, and duplicated descriptions are omitted or simplified. In addition, in this specification, the terms "upper" and "lower" do not refer to the upper direction (vertically upward) and the lower direction (vertically downward) in absolute spatial recognition, but are used as terms defined by the relative positional relationship based on the stacking order in the stacking configuration. In addition, the terms "upper" and "lower" are applied not only to the case where two components are arranged at a distance from each other and another component exists between the two components, but also to the case where two components are arranged in contact with each other.

[0021] [First embodiment] A semiconductor laser light emitting element according to a first embodiment will be described.

[0022] [1-1. Overall composition] First, the overall configuration of a semiconductor laser light-emitting element according to the present embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing the configuration of a semiconductor laser light-emitting element 2 according to the present embodiment.

[0023] Fig. 1 shows a cross section of the semiconductor laser light emitting element 2 along the stacking direction (vertical direction in Fig. 1) of semiconductor layers in a semiconductor stack 50 included in the semiconductor laser light emitting element 2 and along the resonance direction of laser light (horizontal direction in Fig. 1). As shown in Fig. 1, the semiconductor laser light emitting element 2 includes a semiconductor stack 50, a front end face protection layer (also simply referred to as "end face protection layer" in this specification) 1F, a rear end face protection layer 1R, a first electrode 56, and a second electrode 57, and emits laser light upon receiving a power supply from an external source.

[0024] [1-1-1. Configuration of semiconductor laminate and electrodes (first electrode and second electrode)] The semiconductor laminate 50 is a laminate in which a plurality of semiconductor layers are laminated, and is a configuration for emitting laser light in the semiconductor laser light emitting element 2. As shown in Fig. 1, the semiconductor laminate 50 has a front end face (front-side resonator end face) 50F and a rear end face (rear-side resonator end face) 50R, which are opposing end faces. A front end face protection layer 1F and a rear end face protection layer 1R, which will be described later, are disposed on the front end face 50F and the rear end face 50R, respectively.

[0025] The semiconductor laminate 50 includes a substrate 51, a first semiconductor layer 52, an active layer 53, a second semiconductor layer 54, and a contact layer 55. In the present embodiment, the semiconductor laminate 50 is made of a gallium nitride material. This makes it possible to realize a semiconductor laser light emitting element 2 that emits laser light having a wavelength in a band of approximately 390 nm or more and 530 nm or less.

[0026] The substrate 51 is a plate-like member serving as the base material of the semiconductor laminate 50. In the present embodiment, the substrate 51 is a GaN single crystal substrate with a thickness of about 100 μm. Note that the thickness of the substrate 51 is not limited to 100 μm, and it may be, for example, any value between 50 μm and 120 μm. Further, the material forming the substrate 51 is not limited to GaN single crystal, and it may be sapphire, SiC, GaAs, InP, Si, or the like.

[0027] The first semiconductor layer 52 is a semiconductor layer of a first conductivity type disposed above the substrate 51. In the present embodiment, the first semiconductor layer 52 is an n-type semiconductor layer disposed on one main surface of the substrate 51 and includes an n-type cladding layer. The n-type cladding layer in the present embodiment is a layer made of n-Al 0.2 Ga 0.8 N. Note that the configuration of the n-type cladding layer is not limited to this. The thickness of the n-type cladding layer may be 0.5 μm or more, and the composition may be n-Al x Ga 1-x N (0 < x < 1).

[0028] The first semiconductor layer 52 may further include an n-type Al x In y Ga 1-x―y N (0 ≤ x + y ≤ 1) guide layer and an undoped Al x In y Ga 1-x―y N (0 ≤ x + y ≤ 1) guide layer.

[0029] The active layer 53 is a light-emitting layer disposed above the first semiconductor layer 52. The active layer 53 in the present embodiment is a quantum well active layer in which a well layer made of In 0.18 Ga 0.82 N with a thickness of 5 nm and a barrier layer made of GaN with a thickness of 10 nm are alternately laminated, and has two well layers. By providing such an active layer 53, the semiconductor laser light-emitting element 2 emits blue laser light with a wavelength of about 440 nm. The configuration of the active layer 53 is not limited to this, and may be a well layer made of In x Ga 1-x N (0 < x < 1) and an Al x Iny Ga 1-x―y A quantum well active layer can be formed by alternately laminating barrier layers composed of GaN(0≦x+y≦1).

[0030] Note that the active layer 53 may include a guide layer on at least one of the upper and lower sides of the quantum well active layer. In this embodiment, the number of well layers is two, but the number of well layers may be any of 1 or more and 4 or less. Also, the In composition of the well layer may be appropriately selected so as to generate light of a desired wavelength within the range of 390 nm or more and 530 nm or less.

[0031] The second semiconductor layer 54 is a second conductivity type semiconductor layer disposed above the active layer 53. The second conductivity type is different from the first conductivity type. In this embodiment, the second semiconductor layer 54 is a p-type semiconductor layer, and the second semiconductor layer 54 includes a p-type cladding layer. The p-type cladding layer of this embodiment is a superlattice layer in which a 3 nm thick layer made of p-Al 0.2 Ga 0.8 N and a 3 nm thick layer made of GaN are alternately laminated 100 layers each. The configuration of the p-type cladding layer is not limited to this, and it may be a layer made of Al x Ga 1-x N(0<x<1) with a thickness of 0.3 μm or more and 1 μm or less. Also, the p-type cladding layer may not be a superlattice layer, but a bulk cladding layer made of Al x Ga 1-x N(0<x<1). Also, the p-type cladding layer may have a structure including a plurality of layers made of Al x Ga 1-x N(0≦x<1). Note that the p-type cladding layer may be formed of another material other than AlGaN having a refractive index suitable for confining light in the active layer 53, for example, a transparent dielectric oxide film such as an ITO film, In2O3, Ga2O3, SnO, InGaO3, etc., which has little light absorption with respect to the laser oscillation wavelength.

[0032] Also, the second semiconductor layer 54 has a p-type Al x In y Ga 1-x―yAn N (0≦x+y≦1) guide layer and undoped Al x In y Ga 1-x―y It may include a plurality of N (0≦x+y≦1) guide layers.

[0033] The contact layer 55 is a semiconductor layer of the second conductivity type that makes ohmic contact with the second electrode 57. In the present embodiment, the contact layer 55 is a p-type semiconductor layer and is a layer made of p-GaN with a thickness of 10 nm. However, the contact layer 55 may be a layer made of p-In x Ga 1-x N (0<x<1). Note that the configuration of the contact layer 55 is not limited to this. The thickness of the contact layer 55 may be 5 nm or more.

[0034] Also, in the present embodiment, one or more ridge portions (not shown) are formed in the second semiconductor layer 54 and the contact layer 55. The region of the active layer 53 corresponding to the ridge portion (that is, the region of the active layer 53 located below the ridge portion) becomes a light-emitting point and emits laser light. When the semiconductor laser light-emitting element 2 is a semiconductor laser array element, the second semiconductor layer 54 and the contact layer 55 have a plurality of ridge portions. And the regions of the active layer 53 corresponding to the respective ridge portions (the regions of the active layer 53 located below the respective ridge portions) become a plurality of light-emitting points, and laser light is emitted from each light-emitting point.

[0035] The first electrode 56 is an electrode disposed on the main surface below the substrate 51 (that is, the main surface on which the first semiconductor layer 52 and the like are not disposed). In the present embodiment, the first electrode 56 is a laminated film in which Ti, Pt, and Au are laminated in order from the substrate 51 side. The configuration of the first electrode 56 is not limited to this. The first electrode 56 may be a laminated film in which Ti and Au are laminated.

[0036] The second electrode 57 is an electrode disposed on the contact layer 55. In this embodiment, the second electrode 57 has a p-side electrode in ohmic contact with the contact layer 55 and a pad electrode disposed on the p-side electrode. The p-side electrode is a laminated film in which Pd and Pt are laminated in this order from the contact layer 55 side. The configuration of the p-side electrode is not limited to this. The p-side electrode may be, for example, a single layer film or a multilayer film formed of at least one of Cr, Ti, Ni, Pd, Pt, and Au. Alternatively, the p-side electrode may be an ITO film, In2O3, Ga2O3, SnO, InGaO3, or the like, which is a transparent oxide electrode.

[0037] The pad electrode in the second electrode 57 is a pad-shaped electrode disposed above the p-side electrode. In this embodiment, the pad electrode is a laminated film in which Ti and Au are laminated in this order from the p-side electrode side, and is disposed in the ridge portion and its periphery. The configuration of the pad electrode is not limited to this, and may be, for example, made of only Au, a laminated film of Ti, Pt and Au, a laminated film of Ni and Au, or a laminated film of other metals.

[0038] Although not shown in Fig. 1, the semiconductor laminate 50 may further include an insulating film such as a SiO2 film or a SiN film that covers the sidewalls of the ridge portion in addition to the above layers. In the present embodiment, each semiconductor layer is made of a GaN-based material, but these may be GaAs-based or InP-based. As described above, the semiconductor laminate 50 may have a single light-emitting point or may have multiple light-emitting points.

[0039] [1-1-2. Composition of the front end protection layer] The (front) end face protection layer 1F is a layer disposed so as to cover the front end face 50F of the semiconductor laminate 50. The end face protection layer 1F is a layer for protecting the front end face 50F of the semiconductor laminate 50. The end face protection layer 1F of this embodiment is a laminate of a plurality of dielectric films, and the end face protection layer 1F includes, in order from the front end face 50F side, a first dielectric film 30, a second dielectric film 31, and a reflectance adjustment film 40. In this embodiment, the reflectance (hereinafter also referred to as "front end face reflectance") at the front end face 50F of light having a wavelength of 440 nm±15 nm (particularly, light having a wavelength of 440 nm, which is the laser oscillation wavelength in this embodiment) incident on the end face protection layer 1F from the semiconductor laminate 50 is 1.0% or less.

[0040] When the front end face reflectance is 1.0% or less, efficient external resonance characteristics can be realized in an external resonance type semiconductor laser device 90 having semiconductor laser light emitting elements 2a, 2b and a partial reflection mirror 97 as shown in FIG. 6 described later. By reducing the reflectance of light at the front end face 50F as much as possible, it is possible to suppress the internal resonance mode of the oscillation of the semiconductor laser light emitting element itself that occurs between the front end face 50F and the rear end face 50R of the semiconductor laser light emitting element 2. This makes it easier for laser oscillation to occur in the external cavity formed by the rear end faces 50R of the semiconductor laser light emitting elements 2a, 2b and the partial reflection mirror 97. As a result, it is possible to improve the external resonance efficiency and stably realize high optical output. However, the front end face reflectance may be greater than 1.0%, and even if it is, for example, 2.0% or less, good external resonance characteristics can be realized.

[0041] (First dielectric film) The first dielectric film 30 is a dielectric film arranged closest to the front end face 50F among the multiple dielectrics constituting the end face protection layer 1F. The first dielectric film 30 is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50, improving adhesion between the end face protection layer 1F and the front end face 50F, and suppressing light absorption by the end face protection layer 1F.

[0042] The first dielectric film 30 is composed of a nitride film or an oxynitride film of a first element. The first element may be Si, Al, or the like, and is preferably Si. In this embodiment, the first dielectric film 30 is a SiN film. When the first dielectric film 30 is a SiN film, oxygen diffusion from the outside of the end face protection layer 1F to the front end face 50F side is particularly likely to be suppressed, and deterioration at the front end face 50F of the semiconductor laminate 50 is likely to be suppressed.

[0043] The concentration of the rare gas (Ar in this embodiment) in the first dielectric film 30 is the highest among the concentrations of the rare gas in each dielectric film constituting the end face protection layer 1F. The first dielectric film 30 is formed by a solid source ECR (Electron Cyclotron Resonance) sputtering plasma deposition apparatus (hereinafter also referred to as "ECR sputtering") as described later. The high rare gas (Ar) concentration in the first dielectric layer 30 means that the rare gas (Ar) concentration is high when the first dielectric film 30 is formed by ECR sputtering. The first dielectric film 30 having a high rare gas concentration has a low light absorption (extinction coefficient) as shown in Table 2 described later, and is unlikely to generate heat even when exposed to laser light from the semiconductor laminate 50. Therefore, when the semiconductor laser light emitting element 2 is used, the temperature of the first dielectric film 30 and therefore the temperature of the front end face 50F are unlikely to rise, and the semiconductor laminate 50 is unlikely to deteriorate. As a result, it is possible to achieve a high COD level and long-term reliability in the semiconductor laser light emitting element 2. The rare gas concentration of each dielectric film constituting the end face protection layer 1F can be confirmed by analyzing each dielectric film by an analysis method such as energy dispersive X-ray spectroscopy (TEM-EDX), a method other than the TEM-EDX method or the SIMS method, for example, Auger electron spectroscopy (AES). Note that the Ar concentration in the first dielectric film 30 (SiN film) of this embodiment measured by the TEM-EDX method is 5.1 atomic %.

[0044] Table 1 below shows the TEM-EDX analysis results of the Ar concentration in each of the representative dielectric films (SiO2 film, Al2O3 film, SiN film, and AlON film) when they are formed by ECR sputtering. The SiN films (1) to (3) are formed under substantially the same conditions as the film formation conditions of the first dielectric layer 30 of the present embodiment. More specifically, the ratio of Ar and nitrogen in the atmosphere during ECR sputtering is adjusted, and the film formation is performed under a relatively high Ar concentration. As shown in Table 1 below, when each dielectric film is formed by ECR sputtering, the Ar concentration of the Al2O3 film is usually likely to be high. However, by adjusting the amount of Ar in the atmosphere during ECR sputtering as in the present embodiment, it is possible to make the Ar concentration of the SiN film higher than that of the Al2O3 film, as shown in Table 1.

[0045] [Table 1]

[0046] Figure 2 shows the results of an experiment in which SiN films were formed by ECR sputtering while changing the Ar concentration in the atmosphere. Figure 2 shows the results of analysis by secondary ion mass spectrometry (SIMS) for SiN (a) formed under high Ar concentration and SiN (b) formed under low Ar concentration. For comparison, an Al2O3 film was formed before and after each SiN film. When the amount of Ar during ECR sputtering is large, the Ar concentration in the SiN film is higher than the Ar concentration in the Al2O3 film, as in SiN (a) in Figure 2. On the other hand, when a SiN film is formed under low Ar concentration, the Ar concentration in the SiN film is lower than the Ar concentration in the Al2O3 film, as in SiN (b) in Figure 2.

[0047] Table 2 below shows the type and extinction coefficient of each film. Table 2 shows the extinction coefficients of the two types of SiN films (SiN(a) and SiN(b)) produced above. As described above, the Ar concentration in the SiN film is higher in SiN(a) than in SiN(b). Table 2 also shows the extinction coefficients of the Al2O3 film, SiO2 film, and AlON film used in this embodiment or other embodiments. All of these are extinction coefficients at a laser oscillation wavelength of 440 nm.

[0048] [Table 2]

[0049] As shown in Table 2 above, the SiN film has a low extinction coefficient when the Ar atomic concentration is high. In particular, it can be said that an Ar concentration of 4.0 atomic % or more shows a good value. The first dielectric film (SiN) 31 of this embodiment also has an Ar atomic concentration of 5.1 atomic %, and as shown in Table 2 above, the extinction coefficient is 9.1×10 -4 In other words, it is clear that the first dielectric film 30 of the present embodiment has a low extinction coefficient that does not affect the oscillation and reliability tests of the high-power semiconductor laser. The extinction coefficient of the first dielectric film 30 is set to 3.0×10 -3 Less than or equal to 1.0×10 is preferred. -3 The following is more preferred:

[0050] Here, in the above evaluation, the amount and concentration of Ar in each dielectric film were analyzed by the TEM-EDX method or the SIMS method, but the analysis method is not limited to these. As described above, the amount and concentration of Ar can be analyzed by methods other than the TEM-EDX method or the SIMS method, for example, Auger electron spectroscopy, and the analysis can be performed by selecting the most suitable analysis method depending on the sample form and the measurement area. In addition, the extinction coefficient can be measured using a spectroscopic ellipsometry method, a reflectance spectroscopy method, a spectrophotometer, and the like, and the analysis can be performed by selecting the most suitable analysis method depending on the sample form and the measurement area.

[0051] Here, the thickness of the first dielectric film 30 in this embodiment is 1 nm or less. Therefore, whether the first dielectric film 30 has crystallinity or is amorphous, it is unlikely to affect the crystallinity of the second dielectric film 31, which will be described later, disposed on the first dielectric film 30. That is, the second dielectric film 31 can be a film having the same crystallinity as the semiconductor laminate 50. If the second dielectric film 31, which will be described later, is a film having the same crystallinity as the semiconductor laminate 50, oxygen is unlikely to diffuse from the outside of the end face protection layer 1F to the front end face 50F side, and deterioration of the semiconductor laminate 50 is more likely to be suppressed. The thickness of the first dielectric film 30 may be more than 1 nm, and for example, 2 nm or less, as long as the crystallinity of the second dielectric film 31 is not impaired. Similarly, as long as the second dielectric film 31 can maintain its crystallinity, the thickness of the first dielectric film 30 may be 5 nm or less, without any problem.

[0052] There are various methods for evaluating the crystallinity and amorphousness of each dielectric film (the first dielectric film 30 and the second dielectric film 31) in the end face protection layer 1F. These can be evaluated by, for example, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), etc., and the analysis can be performed by selecting the most suitable analysis method depending on the sample shape, measurement area, etc.

[0053] The configuration of the first dielectric film 30 is not limited to the SiN film shown above, and may be, for example, a SiON film, an AlON film, or an AlN film.

[0054] (Second dielectric film) The second dielectric film 31 is a dielectric film disposed on the surface of the first dielectric film 30 opposite to the semiconductor laminate 50. The second dielectric film 31 is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50. The second dielectric film 31 is preferably a nitride film or an oxynitride film of a second element different from the first element contained in the first dielectric film 30. If the second dielectric film 31 is an oxide film, the film becomes amorphous. Therefore, it is difficult to obtain a sufficient oxygen diffusion suppression effect. On the other hand, if the second dielectric film 31 is a nitride film or an oxynitride film of the second element, the second dielectric film 31 is likely to become a film having a desired crystallinity, and oxygen diffusion from the outside of the end face protection layer 1F to the front end face 50F side is easily suppressed. In other words, deterioration of the front end face 50F of the semiconductor laminate 50 can be suppressed, and the semiconductor laser light emitting element 2 is likely to operate stably for a long time. The second element may be Si, Al, Ta, Zr, etc., and among these, Al is preferable. The second dielectric film 31 of this embodiment is an AlON film. When the second dielectric film 31 is an AlON film, it is possible to have the same crystallinity as the semiconductor laminate 50. This can further reduce the diffusion of oxygen, and therefore, the deterioration of the front end face 50F of the semiconductor laminate 50 can be further suppressed. In addition, the AlON film exhibits a low extinction coefficient that does not affect the oscillation and reliability test of the high-power semiconductor laser light-emitting element 2, as shown in Table 2 above, for example. Therefore, it is possible to further reduce the light absorption of the end face protection layer 1F.

[0055] The second dielectric film 31 of the present embodiment is a film having hexagonal crystallinity, and is a polycrystalline film including crystals oriented on the c-axis in the normal direction to the front end face 50F (cavity end face) of the semiconductor laminate 50, and crystals oriented on the m-axis in the normal direction. In this way, the second dielectric film 31 having crystal axes with different orientations can reduce stress on the front end face 50F, and can achieve a high COD level and long-term reliability.

[0056] Furthermore, there are no particular limitations on the Ar concentration of the second dielectric film 31 as long as it is lower than the Ar concentration of the first dielectric film 30. Specifically, the Ar concentration of the second dielectric film 31 in this embodiment is 1.4 atomic %.

[0057] The thickness of the second dielectric film 31 in this embodiment is about 20 nm. However, the thickness is not limited to this value, and even if the thickness is about 50 nm, there is no problem as long as the second dielectric film 31 has a low extinction coefficient. The composition of the second dielectric film 31 is not limited to an AlON film. The second dielectric film 31 may be an AlN film, a SiN film, a SiON film, or the like. The second dielectric film 31 may also be composed of multiple layers.

[0058] (Reflectance adjustment film) The reflectance adjustment film 40 is a dielectric film disposed on the outside of the second dielectric film 31 (opposite side to the first dielectric film 30), and the reflectance adjustment film 40 is composed of at least one layer of dielectric film. The reflectance adjustment film 40 is composed of an oxide film, an oxynitride film, a nitride film, or the like, and is a film that plays a role in adjusting the front end face reflectance of the end face protection layer 1F. The reflectance adjustment film 40 needs to have a structure for obtaining a desired reflectance. As long as the desired reflectance can be obtained, the reflectance adjustment film 40 may be composed of only one layer or may be composed of multiple layers. In this embodiment, it is composed of a single layer structure of a SiO2 film with a thickness of about 65 nm. With this configuration, as described above, the front end face reflectance of the end face protection layer 1F in this embodiment can be 1.0% or less for the laser oscillation wavelength of 440 nm.

[0059] Moreover, the Ar concentration of the reflectance adjustment film (SiO2 film) 40 is not particularly limited as long as it is smaller than the Ar concentration of the first dielectric film 30. The Ar concentration of the reflectance adjustment film (SiO2 film) in this embodiment is specifically 0.1 atomic %.

[0060] In this embodiment, the reflectance adjustment film 40 is a SiO2 film, but the reflectance adjustment film 40 may be, for example, any one of an Al2O3 film, an AlON film, a SiON film, an AlN film, a SiN film, a SiON film, a TiO2 film, an Nb2O5 film, a Ta2O5 film, and an HfO2 film, or a combination of these.

[0061] [1-1-3. Rear end face protection layer] The rear end face protection layer 1R is a protection layer disposed on the rear end face 50R of the semiconductor laminate 50. The rear end face protection layer 1R protects the rear end face 50R of the semiconductor laminate 50 and has a role of increasing the end face reflectance of the laser light at the rear end face 50R (hereinafter also referred to as "rear end face reflectance"). In this embodiment, the rear end face protection layer 1R is a multilayer film in which multiple pairs of SiO2 films and AlON films are laminated with a thickness of about λ / (4n), where λ is the wavelength of the laser light. Here, n represents the refractive index of each dielectric film. With such a configuration, it is possible to achieve a rear end face reflectance of 90% or more, and it is possible to realize a semiconductor laser light emitting element 2 with high slope efficiency and low threshold current.

[0062] The configuration of the rear end surface protective layer 1R is not limited to this, and may be any configuration that can obtain a desired reflectance. For example, the rear end surface protective layer 1R may include an Al2O3 film as a low refractive index film. In addition, the rear end surface protective layer 1R may include a nitride film or an oxynitride film. The rear end surface protective layer 1R may be configured by stacking multiple pairs of, for example, a SiO2 film and a ZrO2 film, a SiO2 film and a Ta2O5 film, a SiO2 film and an AlN film, a SiO2 film and a SiN film, a SiO2 film and a TiO2 film, a SiO2 film and a HfO2 film, a SiO2 film and a Nb2O5 film, a SiO2 film and an Al2O3 film, etc.

[0063] [1-2. Functions and Effects of End Surface Protective Layer 1F, and Modified Examples] In this embodiment, the semiconductor laminate 50 is made of a gallium nitride material. This makes it possible to realize a semiconductor laser light-emitting element 2 that emits laser light having a wavelength in a band of about 390 nm or more and 530 nm or less. In addition, in this embodiment, a SiN film with low light absorption is used as the first dielectric film 30. Therefore, heat is unlikely to be generated at the front end face 50F during laser light emission, and the semiconductor laminate 50 is unlikely to deteriorate due to heat. This makes it possible to realize a high COD level and long-term reliability of the semiconductor laser light-emitting element 2.

[0064] In addition, in the semiconductor laminate 50 made of a gallium nitride material, oxygen diffusion from the outside of the end face protection layer 1F to the front end face 50F side can also be a problem, but in this embodiment, an AlON film having low light absorption and crystallinity is used as the second dielectric film 31. Therefore, oxygen diffusion from the outside of the end face protection layer 1F to the front end face 50F side can also be suppressed, and long-term reliability of the semiconductor laser light emitting element 2 can be achieved.

[0065] In this embodiment, the semiconductor laminate 50 is a semiconductor laminate made of a gallium nitride material that oscillates blue to green laser light in a wavelength band of about 390 nm to 530 nm. However, the semiconductor laminate 50 may be a semiconductor laminate made of an AlGaInP material that oscillates laser light in a red wavelength band (band of 600 nm to 700 nm). The semiconductor laminate 50 may also be a semiconductor laminate made of a gallium arsenide material that oscillates laser light in an infrared wavelength band (band of 750 nm to 1100 nm). The semiconductor laminate 50 may also be a semiconductor laminate made of an InP material that oscillates laser light in a wavelength band of 1 μm. Furthermore, the semiconductor laser light emitting element 2 may be a laser chip having a single light emitting point, or a laser array having a plurality of light emitting points.

[0066] [1-3. Manufacturing method] A method for manufacturing the semiconductor laser light-emitting element 2 according to this embodiment will be described. In this manufacturing method, first, a semiconductor laminate 50 is formed. When forming the semiconductor laminate 50, a substrate 51 is first prepared, and a first semiconductor layer 52, an active layer 53, a second semiconductor layer 54, and a contact layer 55 are laminated in this order. In this embodiment, an n-type cladding layer 52, an active layer 53, a p-type cladding layer 54, and a contact layer 55 are laminated in this order on the substrate 51. Each layer can be formed by, for example, a metal organic chemical vapor deposition (MOCVD) method.

[0067] Subsequently, a ridge portion (not shown) is formed in the second semiconductor layer 54 and the contact layer 55. The ridge portion can be formed by, for example, ICP (Inductive Coupled Plasma) type reactive ion etching or the like. In this manner, the semiconductor laminate 50 of the semiconductor laser light emitting element 2 can be formed.

[0068] Next, an insulating film (not shown) such as a SiO2 film is formed by, for example, a plasma CVD method. At least a part of the insulating film on the upper surface of the ridge portion is removed by, for example, wet etching. At this time, the insulating film may be formed by a solid source ECR (Electron Cyclotron Resonance) sputter plasma film forming device, or the insulating film may be formed of a SiN film by a similar manufacturing method. Next, a second electrode 57 is formed on the ridge portion by, for example, a vacuum deposition method. Furthermore, a first electrode 56 is formed on the lower surface of the substrate 51 by, for example, a vacuum deposition method.

[0069] Next, in order to form the front end facet 50F and the rear end facet 50R, the semiconductor wafer is primarily cleaved using, for example, a laser scribing device and a breaking device, thereby obtaining a laser bar having laser resonator end faces (front end facet 50F and rear end facet 50R).

[0070] Next, the (front) end face protection layer 1F and rear end face protection layer 1R are formed on the front end face 50F and rear end face 50R of the semiconductor laminate 50, respectively. To form each dielectric film on each of the front end face 50F and rear end face 50R, a solid source ECR sputtering plasma deposition apparatus is used as described above. When depositing the first dielectric film 30 of the end face protection layer 1F, Si is used as a target, and plasma is generated in an atmosphere of nitrogen and Ar to deposit the film. By adjusting the ratio of nitrogen and Ar at this time, the first dielectric film 30 (SiN film) having a high Ar concentration can be deposited. Next, in the same apparatus, Al is used as a target, and plasma is generated in an atmosphere of oxygen, nitrogen, and Ar to deposit the film. This allows the above-mentioned second dielectric film 31 (AlON film) to be deposited. Furthermore, by depositing the film using an ECR sputtering apparatus, the above-mentioned reflectance adjustment film 40 (SiO2 film) can be deposited. The conditions for depositing these films can be appropriately adjusted according to the dielectric film to be deposited. The rear end face protective layer 1R can be formed in the same manner. In this manner, the semiconductor laser light emitting element 2 according to this embodiment can be manufactured.

[0071] [1-4. Application Examples] Next, an application example of the semiconductor laser light-emitting element 2 according to this embodiment will be described. The semiconductor laser light-emitting element 2 according to this embodiment can be applied to, for example, an external cavity type semiconductor laser device 90 that performs wavelength synthesis. Hereinafter, the semiconductor laser device 90 to which the semiconductor laser light-emitting element 2 is applied will be described with reference to Fig. 6. Fig. 6 is a schematic plan view showing the configuration of the semiconductor laser device 90 to which the semiconductor laser light-emitting element 2 according to this embodiment is applied.

[0072] As shown in FIG. 6, a semiconductor laser device 90 includes semiconductor laser light emitting elements 2a and 2b, optical lenses 91a and 91b, a diffraction grating 95, and a partial reflection mirror 97.

[0073] Each of the semiconductor laser light emitting elements 2a and 2b is an example of the semiconductor laser light emitting element 2 according to the present embodiment. Here, the semiconductor laser light emitting elements 2a and 2b are each a laser array element, and each has N (N is an integer of 2 or more) light emitting points E 11 ~E 1N , and N light-emitting points E 21 ~E 2N Each of these light emitting points emits a laser beam. In the semiconductor laser device 90, the wavelength of the laser beam emitted from each light emitting point is determined by a wavelength selection action of an external resonator including a diffraction grating 95, which will be described later. The semiconductor laser light emitting element 2a has a light emitting point E 11 ~E 1N From these, the wavelengths λ 11 ~λ 1N Similarly, the semiconductor laser light emitting element 2b emits a laser beam at a light emitting point E 21 ~E 2N From these, the wavelengths λ 21 ~λ 2N The semiconductor laser light emitting elements 2a and 2b are arranged so that the laser beams propagate within the same plane.

[0074] The optical lenses 91a and 91b are optical elements that focus the laser beams emitted from the semiconductor laser light emitting elements 2a and 2b, respectively, on the diffraction grating 95. The optical lenses 91a and 91b may have a function of collimating the laser beams. The semiconductor laser device 90 may further include a collimating lens (not shown) that collimates the laser beams, in addition to the optical lenses 91a and 91b.

[0075] The diffraction grating 95 is a wavelength dispersion element that combines multiple laser beams having different wavelengths. By appropriately setting the wavelengths and incidence angles of the multiple laser beams incident on the diffraction grating 95 and the intervals between the slits of the diffraction grating 95, multiple laser beams having different propagation directions can be combined on approximately the same optical axis.

[0076] The partial reflection mirror 97 is a mirror that forms an external resonator between itself and the rear end face 50R of each semiconductor laser light emitting element 2, and functions as an output coupler that emits laser light. The reflectance and transmittance of the partial reflection mirror 97 may be appropriately set according to the gain of each semiconductor laser light emitting element 2, etc.

[0077] The operation of the semiconductor laser device 90 having the above configuration will be described. When a current is supplied to each of the semiconductor laser light emitting elements 2a and 2b, the semiconductor laser light emitting elements 2a and 2b emit N laser beams. The N laser beams emitted from the semiconductor laser light emitting element 2a are focused at a focusing point on the diffraction grating 95 by the optical lens 91a. The N laser beams emitted from the semiconductor laser light emitting element 2b are focused at the focusing point on the diffraction grating 95 by the optical lens 91b. Each laser beam transmitted through the diffraction grating 95 is diffracted by the diffraction grating 95 and propagates along substantially the same optical axis toward the partial reflection mirror 97. A part of each laser beam directed toward the partial reflection mirror 97 is reflected by the partial reflection mirror 97, returns to each semiconductor laser light emitting element 2a and 2b via the diffraction grating 95 and the optical lenses 91a and 91b, and is reflected by the rear end surface 50R of each semiconductor laser light emitting element 2a and 2b. In this manner, an external resonator is formed between the rear end face 50R of each of the semiconductor laser light emitting elements 2a and 2b and the partial reflection mirror 97. On the other hand, the laser light transmitted through the partial reflection mirror 97 becomes the output light of the semiconductor laser device 90, and it becomes possible to obtain high-output laser light, for example, by using an optical fiber arranged on the optical axis of the output light.

[0078] In addition, it is necessary to suppress internal resonance in each of the semiconductor laser light-emitting elements 2a, 2b. In order to suppress internal resonance in each of the semiconductor laser light-emitting elements 2a, 2b, it is preferable to reduce light reflection at the front end face 50F of each of the semiconductor laser light-emitting elements 2a, 2b as much as possible. In this embodiment, the light reflectance at the front end face 50F, which is the interface between the semiconductor laminate 50 and the end face protection layer 1F, is 1.0% or less. However, the front end face reflectance is not limited to this, and even if it is 2.0% or less, it is possible to realize external resonance characteristics.

[0079] As shown in FIG. 6, the wavelength λ of the semiconductor laser light emitting element 2a 11 Laser light with wavelength λ 1N The semiconductor laser light emitting element 2b, which is disposed at a different position from the semiconductor laser light emitting element 2a, emits light of a different wavelength because the optical path length and the angle of incidence on the diffraction grating 95 are different from those of the semiconductor laser light emitting element 2a. Also, the semiconductor laser light emitting element 2b, which is disposed at a different position from the semiconductor laser light emitting element 2a, emits light of a different wavelength because the optical path length and the angle of incidence on the diffraction grating 95 are different from those of the semiconductor laser light emitting element 2a. In this way, by combining a plurality of laser lights by the wavelength combining method, it is possible to increase the optical output. In addition, for this purpose, laser lights of many wavelengths are required. Therefore, by designing the semiconductor laser light emitting elements 2a and 2b of this embodiment to emit a plurality of laser lights, a small-sized laser device 90 can be realized.

[0080] In the present embodiment, the semiconductor laser device 90 is provided with two semiconductor laser light-emitting elements 2a and 2b, but the number of the semiconductor laser light-emitting elements 2 provided in the semiconductor laser device is not limited to this, and may be three or more. The more the number of the semiconductor laser light-emitting elements 2 is increased, the more the optical output can be increased. In addition, it is also possible to increase the optical output by using a plurality of semiconductor laser devices 90 that have performed wavelength synthesis and synthesizing beams by spatial synthesis. In addition, in the semiconductor laser device 90, each of the semiconductor laser light-emitting elements 2a and 2b has a plurality of light-emitting points, but even if each of the semiconductor laser light-emitting elements 2a and 2b has a single light-emitting point, there is no problem and it is possible to realize an improvement in the optical output.

[0081] [Second embodiment] A semiconductor laser light emitting device according to the second embodiment will be described, but the same parts as those in the first embodiment will be omitted.

[0082] [2-1. Overall composition] First, the overall configuration of the semiconductor laser light-emitting element according to the present embodiment will be described with reference to Fig. 3. Fig. 3 is a schematic cross-sectional view showing the configuration of a semiconductor laser light-emitting element 2 according to the present embodiment. Fig. 3 shows a cross section of the semiconductor laser light-emitting element 2 along the stacking direction (vertical direction in Fig. 3) of a semiconductor stack 50 included in the semiconductor laser light-emitting element 2 and along the resonance direction of laser light (horizontal direction in Fig. 3).

[0083] The semiconductor laser light emitting element 2 is a semiconductor light emitting element that emits laser light. As shown in Fig. 3, the semiconductor laser light emitting element 2 includes a semiconductor laminate 50, a (front) end face protection layer 1F, a rear end face protection layer 1R, a first electrode 56, and a second electrode 57. Note that the semiconductor laminate 50, the first electrode 56, the second electrode 57, and the rear end face protection layer 1R shown in Fig. 3 are similar to the respective configurations of the first embodiment shown in Fig. 1, so that the description here is omitted, and the front end face protection layer 1F will be described below.

[0084] [2-2. Configuration of front end face protection layer 1F] The (front) end face protection layer 1F is a layer disposed so as to cover the front end face 50F of the semiconductor laminate 50. The end face protection layer 1F is a layer for protecting the front end face 50F of the semiconductor laminate 50. The end face protection layer 1F is a laminate of a plurality of dielectric films. The end face protection layer 1F of the present embodiment includes a first dielectric film 30, a second dielectric film 31, a third dielectric film 32, and a reflectance adjustment film 40, and in the present embodiment, the front end face reflectance is 1.0% or less for light having a wavelength of 440 nm±15 nm (particularly, light having a wavelength of 440 nm, which is the laser oscillation wavelength in the present embodiment) incident on the end face protection layer 1F from the semiconductor laminate 50.

[0085] As described above, when the front end facet reflectivity is 1.0% or less, efficient external resonance characteristics can be realized in the external resonance type semiconductor laser device 90 shown in Fig. 6. However, the front end facet reflectivity is not limited to this, and good external resonance characteristics can be realized even if the front end facet reflectivity is 2.0% or less.

[0086] (First dielectric film) The first dielectric film 30 is a dielectric film arranged closest to the front end face 50F among the multiple dielectrics constituting the end face protection layer 1F. The first dielectric film 30 is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50, improving adhesion between the end face protection layer 1F and the front end face 50F, and suppressing light absorption by the end face protection layer 1F.

[0087] The first dielectric film 30 is composed of a nitride film or an oxynitride film of a first element. The first element is the same as the first element in the first dielectric film 30 of the first embodiment described above, such as Si, Al, etc. Among these, Si is preferable, and in this embodiment, the first dielectric film 30 is a SiON film having a film thickness of 1 nm or less. When the first dielectric film 30 is a SiON film, deterioration at the front end face 50F of the semiconductor laminate 50 is particularly likely to be suppressed, and the semiconductor laser light emitting element 2 is likely to achieve stable operation for a long time. Furthermore, in this embodiment in which the first dielectric film 30 is a SiON film, it is possible to reduce the stress on the cavity end face 50F compared to the first embodiment.

[0088] Also in this embodiment, the concentration of the rare gas (Ar in this embodiment) in the first dielectric film 30 is the highest among the concentrations of the rare gas in each dielectric film constituting the end face protection layer 1F. The first dielectric film 30 with a high Ar gas concentration has low light absorption (light extinction coefficient) and is unlikely to generate heat even when exposed to laser light from the semiconductor laminate 50. Therefore, the temperature of the front end face 50F is unlikely to rise, the semiconductor laminate 50 is unlikely to deteriorate due to heat, and the semiconductor laser light emitting element 2 can achieve a high COD level and long-term reliability. The method of forming the first dielectric film 30 is also the same as that of the first dielectric film 30 in the first embodiment, and the Ar concentration can be adjusted by the ratio of Ar and nitrogen during ECR sputtering.

[0089] Here, in this embodiment, the thickness of the first dielectric film 30 is set to 1 nm or less, but the thickness of the first dielectric film 30 may be more than 1 nm, and for example, even if it is 2 nm or less, there is no problem as long as it does not inhibit the crystallinity of the second dielectric film 31 and the second dielectric film 31 can maintain its crystallinity. Similarly, as long as the second dielectric film 31 can maintain its crystallinity, the thickness of the first dielectric film 30 may be 5 nm or less. Furthermore, the composition of the first dielectric film 30 is not limited to a SiON film, and may be, for example, a SiN film, an AlON film, or an AlN film.

[0090] (Second dielectric film) The second dielectric film 31 is a dielectric film disposed on the opposite side of the first dielectric film 30 from the semiconductor laminate 50. The second dielectric film 31 is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50. The second dielectric film 31 is preferably a nitride film or an oxynitride film of a second element different from the first element contained in the first dielectric film 30. The second element is the same as the second element in the second dielectric film 31 of the above-mentioned first embodiment, and is Si, Al, Ta, Zr, etc., but Al is preferable. In this embodiment, the second dielectric film 31 is an AlN film with a film thickness of 15 nm. When the second dielectric film 31 is an AlN film, it is possible to have the same crystallinity as the semiconductor laminate 50. Moreover, the second dielectric film (AlN film) 31 of this embodiment is a film having hexagonal crystallinity, and is a polycrystalline film including crystals oriented along the c-axis in the normal direction to the front end face 50F (cavity end face) of the semiconductor laminate 50, and crystals oriented along the m-axis in the normal direction. By providing crystal axes with different orientations in this way, it is possible to reduce stress on the front end face 50F, and achieve a high COD level and long-term reliability.

[0091] The Ar concentration of the second dielectric film 31 only needs to be lower than that of the first dielectric film 31. The AlN film exhibits a low extinction coefficient that does not affect the oscillation of the high-power semiconductor laser light emitting element 2 or the reliability test.

[0092] The thickness of the second dielectric film 31 in this embodiment is about 15 nm as described above, but the thickness is not limited to this, and there is no problem even if the thickness is about 50 nm as long as the second dielectric film 31 has a low extinction coefficient. The composition of the second dielectric film 31 is not limited to an AlN film. The second dielectric film 31 may be an AlON film, a SiN film, a SiON film, or the like. The second dielectric film 31 may also be composed of multiple layers.

[0093] (Third dielectric film) The third dielectric film 32 is a dielectric film disposed outside the second dielectric film 31, and is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50. The third dielectric film 32 is preferably a film containing the same second element as the second element contained in the above-mentioned second dielectric film 31. In addition, the third dielectric film 32 is more preferably an amorphous oxide film of the second element. When the third dielectric film 32 is an amorphous oxide film, it is easy to reduce the overall stress of the end face protection layer 1F. As a result, deterioration of the front end face 50R of the semiconductor laminate 50 can be suppressed, and the long-term stability of the semiconductor laser light emitting element 2 is improved. The third dielectric film 32 of this embodiment is an Al2O3 film with a thickness of 10 nm. The Al2O3 film has a SiO2 content of 5.0×10 as shown in Table 2. -4 Therefore, when the third dielectric film 32 is an Al2O3 film, the light absorption of the end face protection layer 1F is low, and the oscillation and long-term operation of the high-power semiconductor laser are less likely to be affected, and it is possible to achieve a high COD level and long-term reliability of the semiconductor laser light emitting element 2.

[0094] Here, the Ar concentration of the third dielectric film 32 may be higher than the Ar concentration of the second dielectric film 31, but is lower than the Ar concentration of the first dielectric film 30. In this embodiment, the Ar concentration of the third dielectric film 32 is 3.7 atomic %.

[0095] Here, in this embodiment, the thickness of the third dielectric film 32 is set to 10 nm, but it is not limited to this thickness, and even if it is, for example, 30 nm, there is no problem as long as the third dielectric film 32 has a low extinction coefficient. In addition, the composition of the third dielectric film 32 is not limited to Al2O3. For example, it may be an oxide film other than Al, may be an oxide film of Si system (SiO2 film, etc.), or may be an oxide film of various metals, such as ZrO2 film, Ta2O5 film, TiO2 film, HfO2 film, Nb2O5 film, etc. Furthermore, the third dielectric film 32 may be a nitride film or an oxynitride film, and may be an AlON film, an AlN film, a SiON film, a SiN film, etc. In addition, the third dielectric film 32 may be composed of a plurality of films.

[0096] (Reflectance adjustment film) The reflectance adjustment film 40 is a dielectric film disposed outside the second dielectric film 31, and is composed of at least one dielectric film. The reflectance adjustment film 40 is composed of an oxide film, an oxynitride film, a nitride film, or the like, and serves to adjust the facet reflectance of the facet protective layer 1F. The reflectance adjustment film 40 of this embodiment has a single-layer structure of a SiO2 film with a thickness of about 65 nm, and is similar to the reflectance adjustment film 40 of the first embodiment described above. The Ar concentration is also similar to that of the reflectance adjustment film 40 of the first embodiment.

[0097] [2-3. Function and effect of end face protection layer 1F] In this embodiment, the semiconductor laminate 50 is made of a gallium nitride material. This makes it possible to realize a semiconductor laser light-emitting element 2 that emits laser light having a wavelength in a band of about 390 nm or more and 530 nm or less. In addition, in this embodiment, a SiON film with low light absorption is used as the first dielectric film 30. Therefore, heat is unlikely to be generated at the front end face 50F during laser light emission, and the semiconductor laminate 50 is unlikely to deteriorate due to heat. This makes it possible to realize a high COD level and long-term reliability of the semiconductor laser light-emitting element 2.

[0098] In addition, in the semiconductor laminate 50 made of a gallium nitride material, oxygen diffusion from the outside of the end face protection layer 1F to the front end face 50F side can also be a problem, but in this embodiment, an AlON film having low light absorption and crystallinity is used as the second dielectric film 31. Therefore, oxygen diffusion from the outside of the end face protection layer 1F to the front end face 50F side can also be suppressed, and long-term reliability of the semiconductor laser light emitting element 2 can be achieved.

[0099] Furthermore, the semiconductor laser light-emitting element 2 of this embodiment includes an amorphous aluminum oxide film as the third dielectric film 32 of the end face protection layer 1F. This makes it possible to reduce the overall stress of the end face protection layer 1F, suppress deterioration of the front end face 50F, and achieve a high COD level and long-term reliability of the semiconductor laser light-emitting element 2.

[0100] In the semiconductor laser light-emitting element 2 of this embodiment, the semiconductor laminate 50 may be made of a material other than gallium nitride, and may be a semiconductor laminate of various materials as described in the first embodiment. In addition, the semiconductor laser light-emitting element 2 may be a laser chip having a single light-emitting point, or a laser array having a plurality of light-emitting points.

[0101] The manufacturing method and application examples of the semiconductor laser light-emitting element 2 of the present embodiment are similar to the manufacturing method and application examples of the semiconductor laser light-emitting element 2 of the first embodiment.

[0102] [Third embodiment] A semiconductor laser light emitting device according to the third embodiment will be described, but the same parts as those in the first embodiment will be omitted.

[0103] [3-1. Overall composition] First, the overall configuration of the semiconductor laser light-emitting element according to the present embodiment will be described with reference to Fig. 4. Fig. 4 is a schematic cross-sectional view showing the configuration of a semiconductor laser light-emitting element 2 according to the present embodiment. Fig. 4 shows a cross-section of the semiconductor laser light-emitting element 2 along the stacking direction (vertical direction in Fig. 4) of the semiconductor stack 50 included in the semiconductor laser light-emitting element 2 and the resonance direction of the laser light (horizontal direction in Fig. 4).

[0104] The semiconductor laser light emitting element 2 is a semiconductor light emitting element that emits laser light. As shown in Fig. 4, the semiconductor laser light emitting element 2 includes a semiconductor laminate 50, a (front) end face protection layer 1F, a rear end face protection layer 1R, a first electrode 56, and a second electrode 57. Note that the semiconductor laminate 50, the first electrode 56, the second electrode 57, and the rear end face protection layer 1R shown in Fig. 4 are similar to the respective configurations of the first embodiment shown in Fig. 1, so that the description here is omitted, and the front end face protection layer 1F will be described below.

[0105] [3-2. Configuration of the front end face protection layer 1F] The (front) end face protection layer 1F is a layer disposed so as to cover the front end face 50F of the semiconductor laminate 50. The end face protection layer 1F is a layer for protecting the front end face 50F of the semiconductor laminate 50. The end face protection layer 1F is a laminate of a plurality of dielectric films. The end face protection layer 1F of this embodiment includes a first dielectric film 30, a second dielectric film 31, a third dielectric film 32, a fourth dielectric film 33, and a reflectance adjustment film 40, and in this embodiment, the front end face reflectance is 1.0% or less for light having a wavelength of 440 nm±15 nm (particularly, light having a wavelength of 440 nm, which is the laser oscillation wavelength in this embodiment) incident on the end face protection layer 1F from the semiconductor laminate 50.

[0106] As described above, when the front end facet reflectivity is 1.0% or less, efficient external resonance characteristics can be realized in the above-mentioned external resonance type semiconductor laser device. However, the front end facet reflectivity is not limited to this, and good external resonance characteristics can be realized even if the front end facet reflectivity is 2.0% or less.

[0107] (First dielectric film) The first dielectric film 30 is a dielectric film arranged closest to the front end face 50F among the multiple dielectrics constituting the end face protection layer 1F. The first dielectric film 30 is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50, improving adhesion between the end face protection layer 1F and the front end face 50F, and suppressing light absorption by the end face protection layer 1F.

[0108] The first dielectric film 30 is composed of a nitride film or an oxynitride film of a first element. The first element is the same as the first element in the first dielectric film 30 of the first embodiment described above, such as Si, Al, etc. Among these, Si is preferable. The first dielectric film 30 of this embodiment is a SiN film having a thickness of 1 nm or less, and is the same as the first dielectric layer 30 of the first embodiment, and has a similar Ar concentration. Therefore, although a detailed description is omitted, also in this embodiment, the concentration of the rare gas (Ar in this embodiment) in the first dielectric film 30 is the highest among the concentrations of the rare gas in each dielectric film constituting the end face protection layer 1F.

[0109] (Second dielectric film) The second dielectric film 31 is a dielectric film disposed on the opposite side of the first dielectric film 30 from the semiconductor laminate 50. The second dielectric film 31 is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50. The second dielectric film 31 is preferably a nitride film or an oxynitride film of a second element different from the first element contained in the first dielectric film 30. The second element is the same as the second element in the second dielectric film 31 of the above-mentioned first embodiment, and is Si, Al, Ta, Zr, etc., but Al is preferable. In this embodiment, the second dielectric film 31 is an AlON film with a thickness of about 20 nm, which is the same as the second dielectric layer 31 of the first embodiment and has the same Ar concentration. Therefore, a detailed description will be omitted.

[0110] (Third dielectric film) The third dielectric film 32 is a dielectric film disposed outside the second dielectric film 31, and is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50. The third dielectric film 32 is preferably a film containing a second element similar to the second element contained in the above-mentioned second dielectric film 31, and more preferably an amorphous oxide film of the second element. In this embodiment, it is an Al2O3 film with a film thickness of 10 nm. When the third dielectric film 32 is an amorphous oxide film, it is easy to reduce the overall stress of the end face protection layer 1F. As a result, deterioration of the front end face 50R of the semiconductor laminate 50 can be suppressed, and the long-term stability of the semiconductor laser light emitting element 2 is improved.

[0111] In addition, the Al2O3 film has a 5.0×10 -4 Therefore, when the third dielectric film 32 is an Al2O3 film, the light absorption of the end face protection layer 1F is low, and the oscillation and long-term operation of the high-power semiconductor laser are less likely to be affected, and it is possible to achieve a high COD level and long-term reliability of the semiconductor laser light emitting element 2.

[0112] The Ar concentration of the third dielectric film 32 is higher than the Ar concentration of the second dielectric film 31 and the Ar concentration of a fourth dielectric film 33 described below, but is lower than the Ar concentration of the first dielectric film 30. In this embodiment, it is 3.7 atomic %.

[0113] It is preferable that the thickness of the third dielectric film 32 is thin in order to realize the crystallinity of the nitride or oxynitride of the fourth dielectric film 33 described later, but if it is too thin, the stress relaxation property of the third dielectric film 32 is likely to be reduced. Therefore, the thickness of the third dielectric film 32 is preferably about 5 nm to 30 nm, and is set to 10 nm in this embodiment. However, the thickness is not limited to 10 nm, and even if it is 30 nm, there is no problem as long as the third dielectric film 32 has a low extinction coefficient.

[0114] The composition of the third dielectric film 32 is not limited to Al2O3. For example, it may be an oxide film other than Al, a Si-based oxide film (SiO2 film, etc.), or an oxide film of various metals, such as a ZrO2 film, a Ta2O5 film, a TiO2 film, a HfO2 film, or a Nb2O5 film. Furthermore, the third dielectric film 32 may be a nitride film or an oxynitride film, or may be an AlON film, an AlN film, a SiON film, a SiN film, or the like. The third dielectric film 32 may be composed of a plurality of films.

[0115] (fourth dielectric film) The fourth dielectric film 33 is a dielectric layer laminated on the outside of the third dielectric film 32, and is a layer that plays a role in further suppressing deterioration of the front end face 50F of the semiconductor laminate 50. The fourth dielectric film 33 is preferably a nitride film or oxynitride film of the second element, similar to the second dielectric film 31. This allows the fourth dielectric film 33 to have crystallinity, and oxygen diffusion from the front end face 50F direction to the semiconductor laminate 50 is further reduced. Therefore, deterioration of the front end face 50F of the semiconductor laminate 50 can be further suppressed, and the semiconductor laser light emitting element 2 can be realized with longer-term stability. In addition, when the fourth dielectric film 33 is a nitride film or oxynitride film of the second element, these have a low extinction coefficient and can realize low light absorption. The fourth dielectric film 33 of this embodiment is an AlON film with a thickness of about 10 nm.

[0116] In this embodiment, the semiconductor laminate 50 is a GaN-based material, and the second dielectric film 31 is an AlON film having hexagonal crystallinity similar to that of the semiconductor laminate 50. The third dielectric film 32 is an amorphous Al2O3 film, and the fourth dielectric film 33 is a film having crystallinity.

[0117] Moreover, the Ar concentration of the fourth dielectric film 33 in this embodiment is not particularly limited as long as it is lower than the Ar concentration of the first dielectric film 30. Specifically, the Ar concentration of the fourth dielectric film 33 in this embodiment is 1.4 atomic %.

[0118] The thickness of the fourth dielectric film 33 in this embodiment is not limited to 10 nm, and there is no problem as long as the fourth dielectric film has a sufficiently low extinction coefficient, and may be, for example, 50 nm. The composition of the fourth dielectric film 33 is not limited to AlON, and the fourth dielectric film 33 may be an Al-based nitride film, such as an AlN film, a SiN film, or a SiON film. The fourth dielectric film 33 may be composed of multiple layers.

[0119] (Reflectance adjustment film) The reflectance adjusting film 40 is a dielectric film disposed on the outer side of the second dielectric film 31, and is composed of at least one dielectric film. The reflectance adjusting film 40 is composed of an oxide film, an oxynitride film, a nitride film, or the like, and serves to adjust the facet reflectance of the facet protective layer 1F. The reflectance adjusting film 40 of this embodiment has a two-layer structure consisting of an Al2O3 film with a thickness of about 100 nm and a SiO2 film with a thickness of about 70 nm.

[0120] Moreover, the Ar concentration of the reflectance adjustment film (Al2O3 film and SiO2 film) 40 is not particularly limited as long as it is smaller than the Ar concentration of the first dielectric film 30. Specifically, the Ar concentrations of the reflectance adjustment films (Al2O3 film and SiO2 film) in this embodiment are 3.7 atomic % and 0.1 atomic %.

[0121] However, the reflectance adjusting film 40 is not limited to an Al2O3 film and a SiO2 film, and may be a combination of two or more layers selected from the group consisting of a SiO2 film, an Al2O3 film, and an AlON film, a SiON film, an AlN film, a SiON film, a TiO2 film, a Nb2O5 film, a Ta2O5 film, and a HfO2 film.

[0122] [3-3. Function and effect of end face protection layer 1F] In this embodiment, the semiconductor laminate 50 is made of a gallium nitride material. This makes it possible to realize a semiconductor laser light-emitting element 2 that emits laser light having a wavelength in a band of about 390 nm or more and 530 nm or less. In addition, in this embodiment, a SiN film with low light absorption is used as the first dielectric film 30. Therefore, heat is unlikely to be generated at the front end face 50F during laser light emission, and the semiconductor laminate 50 is unlikely to deteriorate due to heat. This makes it possible to realize a high COD level and long-term reliability of the semiconductor laser light-emitting element 2.

[0123] In addition, the semiconductor laminate 50 made of a gallium nitride material may be subject to degradation due to oxygen diffusion from the end facets, but in this embodiment, a nitride film or oxynitride film having low light absorption and crystallinity is used as the second dielectric film 31 and the fourth dielectric film 33. This reduces oxygen diffusion from the outside of the end face protection layer 1F to the front end facet 50F side, and achieves long-term reliability of the semiconductor laser light-emitting element 2. Furthermore, by providing a total of five or more end face protection layers 1F with a reflectance adjustment layer, it is possible to achieve low reflectance over a wide wavelength range, and it is possible to provide a semiconductor laser light-emitting element having long-term reliability, stable external resonance characteristics, and high optical output.

[0124] In the semiconductor laser light-emitting element 2 of this embodiment, the semiconductor laminate 50 may be made of a material other than gallium nitride, and may be a semiconductor laminate of various materials as described in the first embodiment. In addition, the semiconductor laser light-emitting element 2 may be a laser chip having a single light-emitting point, or a laser array having a plurality of light-emitting points.

[0125] The manufacturing method and application examples of the semiconductor laser light-emitting element 2 of the present embodiment are similar to those of the semiconductor laser light-emitting element 2 of the first embodiment.

[0126] [Fourth embodiment] A semiconductor laser light emitting device according to the fourth embodiment will be described, but the same parts as those in the first embodiment will be omitted.

[0127] [4-1. Overall composition] First, the overall configuration of the semiconductor laser light-emitting element according to the present embodiment will be described with reference to Fig. 5. Fig. 5 is a schematic cross-sectional view showing the configuration of a semiconductor laser light-emitting element 2 according to the present embodiment. Fig. 5 shows a cross-section of the semiconductor laser light-emitting element 2 along the stacking direction (vertical direction in Fig. 5) of the semiconductor stack 50 included in the semiconductor laser light-emitting element 2 and along the resonance direction of the laser light (horizontal direction in Fig. 5).

[0128] The semiconductor laser light emitting element 2 is a semiconductor light emitting element that emits laser light. As shown in Fig. 5, the semiconductor laser light emitting element 2 includes a semiconductor laminate 50, a (front) end face protection layer 1F, a rear end face protection layer 1R, a first electrode 56, and a second electrode 57. Note that the semiconductor laminate 50, the first electrode 56, the second electrode 57, and the rear end face protection layer 1R shown in Fig. 4 are similar to the respective configurations of the first embodiment shown in Fig. 1, so that the description here is omitted, and the front end face protection layer 1F will be described below.

[0129] [4-2. Configuration of the front end face protection layer 1F] The (front) end face protection layer 1F is a layer disposed so as to cover the front end face 50F of the semiconductor laminate 50. The end face protection layer 1F is a layer that protects the front end face 50F of the semiconductor laminate 50 and transmits the laser light from the front end face 50F without causing significant end face reflection. The end face protection layer 1F is a laminate of a plurality of dielectric films. The end face protection layer 1F of this embodiment includes a first dielectric film 30, a second dielectric film 31, a third dielectric film 32, a fourth dielectric film 33, and a reflectance adjustment film 40 (a first film 41, a second film 42, and a third film 43). In this embodiment, the front end face reflectance is 1.0% or less for light having a wavelength of 440 nm±15 nm (particularly, light having a wavelength of 440 nm, which is the laser oscillation wavelength in this embodiment) incident on the end face protection layer 1F from the semiconductor laminate 50.

[0130] As described above, when the front end facet reflectivity is 1.0% or less, efficient external resonance characteristics can be realized in the above-mentioned external resonance type semiconductor laser device. However, the front end facet reflectivity is not limited to this, and good external resonance characteristics can be realized even if the front end facet reflectivity is 2.0% or less.

[0131] (First dielectric film) The first dielectric film 30 is a dielectric film arranged closest to the front end face 50F among the multiple dielectrics constituting the end face protection layer 1F. The first dielectric film 30 is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50, improving adhesion between the end face protection layer 1F and the front end face 50F, and suppressing light absorption by the end face protection layer 1F.

[0132] The first dielectric film 30 is composed of a nitride film or an oxynitride film of a first element. The first element is the same as the first element in the first dielectric film 30 of the first embodiment described above, such as Si, Al, etc. Among these, Si is preferable. The first dielectric film 30 of this embodiment is a SiN film having a thickness of 1 nm or less, and is the same as the first dielectric layer 30 of the first embodiment, and has a similar Ar concentration. Therefore, although a detailed description is omitted, also in this embodiment, the concentration of the rare gas (Ar in this embodiment) in the first dielectric film 30 is the highest among the concentrations of the rare gas in each dielectric film constituting the end face protection layer 1F.

[0133] However, in this embodiment, as described later, the reflectance adjustment film 40 includes a SiN film (second film 42), which has a rare gas (Ar) concentration equivalent to that of the first dielectric film 30. In this specification, a film having a rare gas (Ar) concentration equivalent to that of the first dielectric film 30 may be included in the end face protection layer 1F other than the first dielectric film 30, provided that the film has the same composition as the first dielectric film 30 (here, a SiN film). In this specification, even in such a case, the rare gas (Ar) concentration of the first dielectric film 30 is treated as being the highest. Note that "equivalent" means that the rare gas (Ar) concentration of the film is within a range of ±5.0% of the rare gas (Ar) concentration of the first dielectric film 30.

[0134] (Second dielectric film) The second dielectric film 31 is a dielectric film disposed on the opposite side of the first dielectric film 30 from the semiconductor laminate 50. The second dielectric film 31 is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50. The second dielectric film 31 is preferably a nitride film or an oxynitride film of a second element different from the first element contained in the first dielectric film 30. The second element is the same as the second element in the second dielectric film 31 of the above-mentioned first embodiment. In this embodiment, the second dielectric film 31 is an AlON film with a thickness of about 20 nm, which is the same as the second dielectric layer 31 of the first embodiment, and the Ar concentration is also the same. Therefore, a detailed description will be omitted.

[0135] (Third dielectric film) The third dielectric film 32 is a dielectric film disposed outside the second dielectric film 31, and is a layer that plays a role in suppressing deterioration of the front end face 50F of the semiconductor laminate 50. The third dielectric film 32 is preferably a film containing a second element similar to the second element contained in the above-mentioned second dielectric film 31, and is more preferably an amorphous oxide film of the second element. In this embodiment, it is an Al2O3 film with a film thickness of 10 nm, which is the same as the third dielectric layer 32 of the third embodiment, and its Ar concentration is also the same. Therefore, a detailed description will be omitted.

[0136] (fourth dielectric film) The fourth dielectric film 33 is a dielectric layer laminated on the outside of the third dielectric film 32, and is a layer that plays a role in further suppressing deterioration of the front end face 50F of the semiconductor laminate 50. The fourth dielectric film 33 is preferably a nitride film or oxynitride film of the second element, similar to the second dielectric film 31. This further reduces oxygen diffusion from the front end face 50F direction to the semiconductor laminate 50. Therefore, deterioration of the front end face 50F of the semiconductor laminate 50 can be further suppressed, and the semiconductor laser light emitting element 2 can be realized with longer-term stability. In addition, the fourth dielectric film 33 can have crystallinity, a low extinction coefficient, and low light absorption. The fourth dielectric film 33 of this embodiment is an AlON film with a thickness of about 10 nm, which is the same as the third dielectric layer 32 of the third embodiment, and the Ar concentration is also the same. Therefore, detailed explanation is omitted.

[0137] (Reflectance adjustment film) The reflectance adjustment film 40 is a dielectric film disposed outside the second dielectric film 31, and is composed of at least one dielectric film. The reflectance adjustment film 40 is composed of an oxide film, an oxynitride film, a nitride film, or the like, and is a film that adjusts the facet reflectance of the facet protection layer 1F. In this embodiment, the reflectance adjustment film 40 has a three-layer structure in order to obtain a desired reflectance for the wavelength of the laser light emitted from the front facet 50F, and has a three-layer structure of a first film 41 made of an Al2O3 film with a thickness of about 100 nm, a second film made of a SiN film with a thickness of about 40 nm, and a third film made of a SiO2 film with a thickness of about 70 nm. The Ar concentration of each layer is 3.7 atomic % for the first film, 4.9 atomic % for the second film, and 0.1 atomic % for the third film.

[0138] In this embodiment, the refractive index n2 of the second film 42 is higher than the refractive index n1 of the first film 41 and the refractive index n3 of the third film 43 for the wavelength of the laser light emitted from the front end face 50F. This makes it possible to realize an end face protection layer 1F having an end face reflectance of 1% or less over a wide range, specifically, in a wavelength band of 80 nm or more. In particular, it is possible to realize a front end face reflectance of 1.0% or less for the wavelength range of 440 nm±40 nm, which is the laser oscillation wavelength in this embodiment.

[0139] In this embodiment, the second film 42 is a SiN film having a thickness of about 40 nm. The second film 42 may be any dielectric film having a higher refractive index than the first film 41 and the third film 43. The second film 42 may include at least one of an AlN film, an AlON film, a ZrO2 film, a SiON film, a TiO2 film, a Nb2O5 film, a Ta2O5 film, and a HfO2 film. This allows the second film 42 to have a relatively high refractive index. In addition, by providing a SiN film as the second film, in this embodiment, two SiN films are included in addition to the SiN film of the first dielectric film 30, and oxygen diffusion from the outside of the front end face protection layer 1F to the front end face 50F can be suppressed, making it possible to achieve long-term reliability. Furthermore, since the rare gas (Ar in this embodiment) in the two layers of SiN film has the same concentration, it is possible to realize a low extinction coefficient as shown in Table 2, a high COD level, and long-term reliability. As described above, it is also possible to simultaneously realize a facet reflectance of 1% or less over a wide range, specifically, in the wavelength band of 80 nm or more.

[0140] In this embodiment, the first film is an Al2O3 film having a thickness of about 100 nm, and the third film 43 is a SiO2 film having a thickness of about 100 nm. The first film 41 and the third film 43 may be any dielectric film having a refractive index lower than that of the second film 42, and may be, for example, a film selected from the group consisting of a SiO2 film, an Al2O3 film, an AlON film, and a SiON film.

[0141] [4-3. Function and effect of end face protection layer 1F] In this embodiment, the semiconductor laminate 50 is made of a gallium nitride material. This makes it possible to realize a semiconductor laser light-emitting element 2 that emits laser light having a wavelength in a band of about 390 nm or more and 530 nm or less. In addition, in this embodiment, a SiN film with low light absorption is used as the first dielectric film 30. Therefore, heat is unlikely to be generated at the front end face 50F during laser light emission, and the semiconductor laminate 50 is unlikely to deteriorate due to heat. This makes it possible to realize a high COD level and long-term reliability of the semiconductor laser light-emitting element 2.

[0142] In addition, the semiconductor laminate 50 made of a gallium nitride material may be subject to degradation due to oxygen diffusion from the end facets, but in this embodiment, a nitride film or oxynitride film having low light absorption and crystallinity is used as the second dielectric film 31 and the fourth dielectric film 33. This reduces oxygen diffusion from the outside of the end face protection layer 1F to the front end facet 50F side, and achieves long-term reliability of the semiconductor laser light-emitting element 2. Furthermore, by providing a total of five or more end face protection layers 1F with a reflectance adjustment layer, it is possible to achieve low reflectance over a wide wavelength range, and it is possible to provide a semiconductor laser light-emitting element having long-term reliability, stable external resonance characteristics, and high optical output.

[0143] Furthermore, in this embodiment, two layers of SiN film are included in the facet protection layer 1F. Since the SiN film is a high refractive index material among dielectric films, it is possible to configure a facet protection layer with low reflectance over a wide wavelength range, and it is possible to realize an external cavity laser with high efficiency.

[0144] In the semiconductor laser light-emitting element 2 of this embodiment, the semiconductor laminate 50 may be made of a material other than gallium nitride, and may be a semiconductor laminate of various materials as described in the first embodiment. In addition, the semiconductor laser light-emitting element 2 may be a laser chip having a single light-emitting point, or a laser array having a plurality of light-emitting points.

[0145] The manufacturing method and application examples of the semiconductor laser light-emitting element 2 of the present embodiment are similar to those of the semiconductor laser light-emitting element 2 of the first embodiment.

[0146] [Additional information] Each end face protection layer may be formed using a sputtering apparatus or a deposition apparatus other than a solid source ECR sputter plasma deposition apparatus, or may be formed using an ablation deposition apparatus using PLD (Pulse Laser Deposition) or ALD (Atomic Layer Deposition), or an epitaxial growth apparatus using MOCVD, or the like.

[0147] Furthermore, each semiconductor laser light-emitting element may be a laser chip having a single light-emitting point, or a laser array having a plurality of light-emitting points. Although a transmission type diffraction grating is used as the wavelength dispersion element in the semiconductor laser device, the wavelength dispersion element is not limited to this. For example, a prism or a reflection type diffraction grating may be used as the wavelength dispersion element.

[0148] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments that would come to mind by a person skilled in the art, and forms realized by arbitrarily combining the components and functions of the above-described embodiments within the scope of the present disclosure. [Industrial Applicability]

[0149] The semiconductor laser light-emitting element of the present disclosure can be used, for example, as a light source for industrial laser equipment, such as industrial lighting, facility lighting, vehicle headlamps, and laser processing machines, which particularly require high output of the W class, and for image display devices, such as laser displays and projectors. [Explanation of symbols]

[0150] 1F (front) end face protection layer 1R Rear end protection layer 2, 2a, 2b Semiconductor laser light emitting element 30 First dielectric film 31 Second dielectric film 32 Third dielectric film 33 Fourth Dielectric Film 40 Reflectance adjustment film 41 1st membrane 42 Second membrane 43 Third membrane 50 Semiconductor laminate 50F Front end face 50R Rear end face 51 Substrate 52 First semiconductor layer 53 Active layer 54 Second semiconductor layer 55 Contact layer 56 1st electrode 57 2nd electrode 90 Semiconductor laser device 91a, 91b Optical lenses 95 Diffraction Grating 97 Partially Reflecting Mirror

Claims

1. A semiconductor laser light emitting element that emits laser light, a semiconductor laminate having a front end face and a rear end face; an end face protection layer disposed to cover the front end face of the semiconductor laminate; the end face protection layer is a laminate of a plurality of dielectric films, a first dielectric film disposed closest to the front end face among the plurality of dielectric films includes a nitride or an oxynitride of a first element, the first dielectric film has the highest rare gas concentration among the plurality of dielectric films; Semiconductor laser light emitting element.

2. The first element is Si.

2. The semiconductor laser light emitting device according to claim 1.

3. The first dielectric film is a SiN film.

2. The semiconductor laser light emitting device according to claim 1.

4. the rare gas contained in the first dielectric film is Ar; The concentration of Ar in the first dielectric film is 4.0 atomic % or more.

2. The semiconductor laser light emitting device according to claim 1.

5. the end face protection layer includes two layers of SiN films, One of the two SiN films is the first dielectric film.

2. The semiconductor laser light emitting device according to claim 1.

6. The two layers of SiN film have the same rare gas concentration. The semiconductor laser light emitting device according to claim 5 .

7. The first dielectric film has a thickness of 1 nm or less.

2. The semiconductor laser light emitting device according to claim 1.

8. a second dielectric film on the first dielectric film, the second dielectric film including a nitride or an oxynitride of a second element different from the first element; 2. The semiconductor laser light emitting device according to claim 1.

9. The second element is Al. The semiconductor laser light emitting device according to claim 8 .

10. the second dielectric film includes hexagonal crystals whose c-axes are oriented in a normal direction to the front end face, and hexagonal crystals whose m-axes are oriented in a normal direction to the front end face. The semiconductor laser light emitting device according to claim 8 .

11. a third dielectric film on the second dielectric film, the third dielectric film including an oxide of the second element; The semiconductor laser light emitting device according to claim 8 .

12. the third dielectric film is an amorphous film, The second element is Al. The semiconductor laser light emitting device according to claim 11 .

13. the rare gas concentration of the second dielectric film is lower than the rare gas concentration of the third dielectric film; The semiconductor laser light emitting device according to claim 11.

14. a fourth dielectric film on the third dielectric film, the fourth dielectric film including a nitride or an oxynitride of the second element; The semiconductor laser light emitting device according to claim 11.

15. the fourth dielectric film is a polycrystalline film; The second element is Al. The semiconductor laser light emitting device according to claim 14 .

16. The end surface protection layer further has a reflectance adjustment film.

2. The semiconductor laser light emitting device according to claim 1.

17. the reflectance adjustment film is composed of three layers, a first film, a second film, and a third film, which are arranged in this order from the front end face side, The refractive index n2 of the second film is greater than the refractive index n1 of the first film and the refractive index n3 of the third film; The semiconductor laser light emitting device according to claim 16 .

18. the reflectance at the front end face of light having a wavelength of 440 nm±15 nm incident on the end face protection layer from the semiconductor laminate is 1% or less; 2. The semiconductor laser light emitting device according to claim 1.

19. The semiconductor laminate contains a GaN-based material.

2. The semiconductor laser light emitting device according to claim 1.

20. The semiconductor laminate has a plurality of light emitting points for emitting laser light.

2. The semiconductor laser light emitting device according to claim 1.

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