Semiconductor light-emitting device

Abstract

To provide a semiconductor light emission device which does not receive restriction of a semiconductor material and a structure and can obtain a good heat dissipation characteristic with a structure not using diffusion of an impurity.SOLUTION: A semiconductor light emission device includes: an element unit 4 configured on one surface side of a light emission element substrate 11 while forming each layer; an n-type electrode 10 formed on the light emission element substrate 11; a p-type electrode 18 arranged at an opposite side of the n-type electrode 10 while sandwiching the element unit 4; a light emission element 2 which has one direction as a resonance direction, and emits light at least one of both end faces in the resonance direction; and a substrate 3 connected with the p-type electrode 18. The p-type electrode 18 has a junction structure between a first electrode arranged at the light emission element 2 side and a second electrode arranged at the substrate side. The junction layers 18d to 18f between the first electrode and the second electrode include at least Au, Sn, and Ni. An Ni concentration being a concentration of the Ni at both ends of in the resonance direction is larger than the Ni concentration at center section being inside of both ends.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor light-emitting device comprising a semiconductor laser. [Background Art]

[0002] In a semiconductor laser, a large number of interface states exist on both end faces. For this reason, it is known that non-radiative recombination causes a temperature rise, which reduces the band gap, leading to light absorption; the light absorption further repeats the temperature rise, resulting in catastrophic optical damage (COD). To address this issue, a structure called a window structure has been proposed, which increases the band gap of both end faces to make light absorption less likely to occur.

[0003] For example, there is a structure in which a semiconductor active layer that generates light is formed of quantum wells, impurities are diffused therein, and the quantum wells are disordered, that is, mixed-crystalized, to increase the band gap. However, since diffusion of impurities requires the material to be a GaAs- or InP-based material, there are restrictions on the material of the active layer, and there are also restrictions on the thickness of the well layer in the active layer structure.

[0004] On the other hand, the same effect can be obtained by containing an impurity with high electronegativity in a GaN-based active layer. Since this structure can be formed by plasma treatment, it has the advantage of being unaffected by heat. However, application of this structure is limited to cases where the active layer is composed of a polarized GaN-based material. Therefore, there are restrictions on the semiconductor materials and element structures.

[0005] In response to this, Patent Document 1 proposes a technique for suppressing COD in nitride-based materials, in which a notch is provided near the end face so that the lower end of the end face of the resonator does not come into contact with the semiconductor substrate, thereby reducing strain. [Prior Art Documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2011-228570 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in the structure proposed in Patent Document 1, while light absorption is suppressed, it is not possible to dissipate the heat generated near the notched end face, and it can only be applied when the active layer is under tensile strain.

[0008] In view of the above points, this disclosure aims to provide a semiconductor light-emitting device that does not involve the diffusion of impurities into the semiconductor layer, is not limited by semiconductor materials or structure, and also achieves good heat dissipation. [Means for solving the problem]

[0009] To achieve the above objective, the invention described in claim 1 is: A semiconductor light-emitting device, A light-emitting element (2) having a light-emitting element substrate (11) made of a first conductivity type semiconductor material, an element section (4) having a first cladding layer (12) of the first conductivity type, a first guide layer (13) of the first conductivity type, an active layer (14), a second guide layer (15) of the second conductivity type, and a second cladding layer (16) of the second conductivity type arranged in order on one side of the light-emitting element substrate, a first conductivity type electrode (10) formed on the side of the light-emitting element substrate opposite to the first cladding layer, and a second conductivity type electrode (18) arranged on the side of the element section opposite to the first conductivity type electrode, with one direction being the resonance direction, and emitting light from at least one of the end faces in the resonance direction, It comprises a substrate (3) connected to a second conductive electrode, The second conductive electrode is a junction structure between a first electrode located on the light-emitting side and a second electrode located on the substrate side, and the junction layer (18d~18f) between the first electrode and the second electrode contains at least Au, Sn, and Ni, and the Ni concentration is higher at both ends in the resonance direction than in the central part further inside. 5mol% or more Growing bigger And, compressive strain is applied to the active layer. .

[0010] In this way, the Ni concentration of the second conductivity electrode is made higher at both ends in the optical resonance direction than at the center, making it possible to apply compressive strain to the active layer. As a result, the band gap is increased at both ends in the optical resonance direction, making it less likely for light absorption to occur and thus suppressing COD. Furthermore, it is not necessary to make notches or other cutouts on the end faces in the optical resonance direction, and the end faces can remain as simple flat surfaces. Therefore, it is possible to create a semiconductor light-emitting device that does not involve the diffusion of impurities into the semiconductor layer, is not limited by semiconductor materials or structure, and also achieves good heat dissipation.

[0011] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0012] [Figure 1] This is a cross-sectional view of a semiconductor light-emitting device according to a first embodiment of the present disclosure. [Figure 2A] Figure 1 is a cross-sectional view showing the manufacturing process of a semiconductor light-emitting device. [Figure 2B] This is a cross-sectional view showing the manufacturing process of a semiconductor light-emitting device, following Figure 2A. [Figure 2C] This is a cross-sectional view showing the manufacturing process of a semiconductor light-emitting device, following Figure 2B. [Figure 2D] This is a cross-sectional view showing the manufacturing process of a semiconductor light-emitting device, following Figure 2C. [Figure 2E] Figure 2D is a cross-sectional view showing the manufacturing process of a semiconductor light-emitting device. [Figure 3A] This is a cross-sectional view showing the manufacturing process of a semiconductor light-emitting device according to a second embodiment of the present disclosure. [Figure 3B] This is a cross-sectional view showing the manufacturing process of a semiconductor light-emitting device, following Figure 3A. [Figure 4] This is a cross-sectional view of a semiconductor light-emitting device according to a third embodiment of the present disclosure. [Figure 5A]It is a cross-sectional view illustrating the manufacturing steps of the semiconductor light-emitting device shown in FIG. 4 [Figure 5B] It is a cross-sectional view illustrating the manufacturing steps of the semiconductor light-emitting device subsequent to FIG. 5A [Figure 5C] It is a cross-sectional view illustrating the manufacturing steps of the semiconductor light-emitting device subsequent to FIG. 5B [Figure 5D] It is a cross-sectional view illustrating the manufacturing steps of the semiconductor light-emitting device subsequent to FIG. 5C [Figure 5E] It is a cross-sectional view illustrating the manufacturing steps of the semiconductor light-emitting device subsequent to FIG. 5D [Figure 6A] It is a cross-sectional view illustrating the manufacturing steps of the semiconductor light-emitting device according to the fourth embodiment of the present disclosure [Figure 6B] It is a cross-sectional view illustrating the manufacturing steps of the semiconductor light-emitting device subsequent to FIG. 6A [Figure 7] It is a cross-sectional view of the semiconductor light-emitting device according to the fifth embodiment of the present disclosure [Figure 8] It is a cross-sectional view illustrating the manufacturing steps of the semiconductor light-emitting device shown in FIG. 7 [Figure 9] It is a cross-sectional view of the semiconductor light-emitting device according to the sixth embodiment of the present disclosure [Figure 10] It is a cross-sectional view illustrating the manufacturing steps of the semiconductor light-emitting device shown in FIG. 9 DETAILED DESCRIPTION OF EMBODIMENTS

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following respective embodiments, portions that are identical or equivalent to each other will be described with the same reference numerals attached thereto

[0014] (First Embodiment) The first embodiment will be described. As shown in FIG. 1, the semiconductor light-emitting device 1 of the present embodiment includes a light-emitting element 2 and a base substrate 3. The semiconductor light-emitting device 1 is applied to, for example, laser radar, LiDAR, and the like. LiDAR is an abbreviation for Light Detection And Ranging

[0015] The light-emitting element 2 is a component of the semiconductor laser and is a light source that generates laser light. As shown in Figure 1, the light-emitting element 2 has an n-type electrode 10, a light-emitting element substrate 11, a first cladding layer 12, a first guide layer 13, an active layer 14, a second guide layer 15, a second cladding layer 16, a contact layer 17, and a p-type electrode 18. The light-emitting element 2 is configured to emit light from at least one of its end faces in one direction, where the left-right direction in Figure 1 is the resonance direction.

[0016] The n-type electrode 10 is formed on the light-emitting element substrate 11. The light-emitting element substrate 11 is the base material on which each layer constituting the light-emitting element 2 is formed, and is of n-type. Here, an InP (indium phosphide) substrate is used as the light-emitting element substrate 11. The first cladding layer 12 is made of n-InP and is located on one side of the light-emitting element substrate 11. The first guide layer 13 is made of n-InGaAsP (indium gallium arsenide phosphide) and is located on the opposite side of the light-emitting element substrate 11, sandwiched between the first cladding layer 12. The active layer 14 is made of InGaAsP or the like and is located on the opposite side of the first cladding layer 12, sandwiched between the first guide layer 13. The second guide layer 15 is made of p-InGaAsP and is located on the opposite side of the first guide layer 13, sandwiched between the active layer 14. The second cladding layer 16 is made of p-InGaAsP and is located on the opposite side of the active layer 14, sandwiched between the second guide layer 15. The contact layer 17 is made of p-InGaAs and is positioned on the opposite side of the second guide layer 15, sandwiched between the second cladding layer 16. Thus, the first cladding layer 12, the first guide layer 13, the active layer 14, the second guide layer 15, the second cladding layer 16, and the contact layer 17 are stacked in that order on one side of the light-emitting element substrate 11 that is below the plane of the paper.

[0017] The first cladding layer 12 and the second cladding layer 16 increase the electron density and hole density of the junction region of the active layer 14, and together with the first guide layer 13, the second guide layer 15, and the contact layer 17, they play a role in confining light within the active layer 14.

[0018] The first guide layer 13 and the second guide layer 15 play a role in confining the light emitted in the active layer 14 within the active layer 14.

[0019] The contact layer 17 is formed as needed for low contact. As you move from the active layer 14 towards the p-type electrode 18, the band gap widens with the second guide layer 15 and the second cladding layer 16, increasing the contact resistance. Therefore, the contact layer 17 is formed to narrow the band gap and reduce the contact resistance.

[0020] The active layer 14 resonates and emits light at a wavelength corresponding to the band gap when the injected carriers recombine. The active layer 14, although its detailed structure is omitted here, is a multi-quantum well structure, which is a stacked structure in which multiple quantum dot layers, each containing granular quantum dots formed by, for example, crystal growth or microfabrication, are repeated.

[0021] The element portion 4 of the light-emitting element 2 is composed of the first cladding layer 12, the first guide layer 13, the active layer 14, the second guide layer 15, the second cladding layer 16, and the contact layer 17.

[0022] The p-type electrode 18 is a metal layer that makes contact with the element part 4 and is positioned on the opposite side of the element part 4 from the n-type electrode 10. In this embodiment, the p-type electrode 18 is constructed by stacking the following layers in order from the element part 4 side: a Ti (titanium) layer 18a, a Pt (platinum) layer 18b, a Ni layer 18c, an AuNiSn (gold nickel tin) layer 18d, an Au5Sn layer 18e, an AuSn (gold tin) layer 18f, a Pt layer 18g, and a Ti layer 18h.

[0023] The Ti layer 18a is a layer for making contact with the element part 4. The Pt layer 18b is a layer formed as needed and is a barrier layer that suppresses the arrival of AuSn on the Ti layer 18a side. The Ni layer 18c is a layer that is partially alloyed with the Au layer 181 and AuSn layer 182, which will be described later, during bonding, but only a part of the surface layer is alloyed, and it is composed of the remaining parts that are not alloyed. The AuNiSn layer 18d, Au5Sn layer 18e, and AuSn layer 18f are bonding layers for bonding the element part 4 and the Ti layer 18a and Pt layer 18b to the substrate 3. Before bonding, the AuNiSn layer 18d, Au5Sn layer 18e, and AuSn layer 18f are the Au layer 181, AuSn layer 182, and Au layer 183, which will be described later, but they become these respective layers through alloying by melting. The Pt layer 18g is also formed as needed and acts as a barrier layer to suppress the arrival of AuSn to the Ti layer 18h. The Ti layer 18h is an adhesive auxiliary layer to facilitate adhesion with the substrate 3. As will be described later, the substrate 3 is made of Si, so the Ti layer 18h is used as the adhesive auxiliary layer, but if the substrate 3 is made of a material other than Si, a metal with good adhesion to that material should be selected. Of course, even if the substrate 3 is made of Si, the adhesive auxiliary layer may be made of a metal other than Ti.

[0024] The substrate 3 is on which the light-emitting element 2 is mounted via a p-type electrode 18, and in this case, it is a semiconductor substrate made of Si. Wiring patterns that are electrically connected to the p-type electrode 18 are formed on this substrate 3, making it possible to apply a desired voltage to the p-type electrode 18. Note that the substrate 3 may also be made of a material other than Si.

[0025] In the semiconductor light-emitting device 1 configured in this way, the left-right direction of the paper plane is used as the resonance direction of light, and light is resonated and emitted to the outside from at least one end face. At both ends of the resonance direction, the Ni concentration is higher than in the central part further inside. In this embodiment, the thickness of the Ni layer 18c is made thicker at both ends of the resonance direction than in the central part, so that the Ni concentration at those locations is higher than in the central part. Furthermore, the AuNiSn layer 18d formed on the Ni layer 18c is also formed on the Ni layer 18c so that both ends in the left-right direction of the paper plane protrude towards the substrate 3 side more than the central part further inside.

[0026] In this way, by making the Ni concentration higher at both ends of the optical resonance direction in the semiconductor light-emitting device 1 than in the center, for example by making the Ni layer 18c thicker as in this embodiment, it becomes possible to apply compressive strain to the active layer 14, as will be described later. As a result, the band gap becomes larger at both ends of the optical resonance direction, making it less likely for light absorption to occur and thus suppressing COD. Furthermore, by making the Ni concentration higher at both ends of the optical resonance direction than in the center, for example by making the thickness of a part of the electrode material, the Ni layer 18c, thicker at both ends of the optical resonance direction than in the center, the COD suppression effect can be obtained. For this reason, it is not necessary to provide notches or the like on the end faces, and the end faces can remain as simple flat surfaces. Therefore, the semiconductor light-emitting device 1 can be made with a structure that does not involve the diffusion of impurities into the semiconductor layer, and without being limited by semiconductor materials or structure, and with good heat dissipation.

[0027] Next, the manufacturing method of the semiconductor light-emitting device 1 according to this embodiment will be described with reference to Figures 2A to 2E.

[0028] First, as shown in Figure 2A, a light-emitting element substrate 11 is prepared, and each layer constituting the element portion 4 and some metal layers for constituting the p-type electrode 18 are formed on this light-emitting element substrate 11. Specifically, the element portion 4 is formed by sequentially forming a first cladding layer 12, a first guide layer 13, an active layer 14, a second guide layer 15, a second cladding layer 16, and a contact layer 17 on the light-emitting element substrate 11. Then, a Ti layer 18a and a Pt layer 18b are deposited on the contact layer 17, and then a Ni layer 18c is deposited on top of them. For the Ni layer 18c, both ends in one direction, that is, both ends in the resonance direction when it is a semiconductor light-emitting device 1, are made thicker than the central part further inside, and in this embodiment, the Ni layer 18c is formed using the lift-off method.

[0029] More specifically, as shown in Figure 2A, the first layer 18ca of the Ni layer 18c is deposited, then a resist 30 is deposited on top of it, and the resist 30 is exposed so that it remains in the central part of the first layer 18ca but not in the parts at both ends. Then, the second layer 18cb, which will be the remaining part of the Ni layer 18c, is deposited on top of the resist 30. As a result, the second layer 18cb is added at both ends of the first layer 18ca, and the second layer 18cb is formed on top of the resist 30 everywhere else. After this, as shown in Figure 2B, when the resist 30 is removed with a stripping solution or the like, the part of the second layer 18cb that was formed on top of the resist 30 is also removed. This makes it possible to form a Ni layer 18c with increased thickness at both ends in one direction.

[0030] Furthermore, as shown in Figure 2C, an Au layer 181 is formed on top of the Ni layer 18c. This Au layer 181 is formed as needed, and is formed to prevent oxidation because the Ni layer 18c, being on the outermost surface, can be oxidized by the surrounding oxygen.

[0031] In this way, a portion of the metal layer for forming the light-emitting element 2 and the p-type electrode 18 can be formed on the light-emitting element substrate 11. A further part ofThis corresponds to the first electrode.

[0032] On the other hand, separate from the steps shown in Figures 2A to 2C, the steps shown in Figure 2D are performed to sequentially deposit a Ti layer 18h, a Pt layer 18g, an Au layer 183, and an AuSn layer 182 on the substrate 3. This forms the remaining metal layers necessary to constitute the p-type electrode 18. A further part of This corresponds to the second electrode.

[0033] Subsequently, in the process shown in Figure 2E, the light-emitting element substrate 11, on which some of the metal layers for forming the light-emitting element 2 and the p-type electrode 18 have been formed through the process shown in Figure 2C, and the substrate 3, on which the remaining part of the metal layers for forming the p-type electrode 18 have been formed through the process shown in Figure 2D, are joined together. Each of the metal layers for forming the p-type electrode 18 is positioned facing each other, and the joining is performed by heating at, for example, 280°C or higher.

[0034] At this time, the AuSn and Ni contained in the AuSn layer 182 and the Ni layer 18c undergo the reaction shown in the following chemical formula. In addition, the Au constituting the Au layers 181 and 183 is used in this reaction as appropriate. As a result, the Au layers 181, 182, and 183 become the Au5Sn layer 18e and the AuSn layer 18f. Furthermore, the Ni in the Ni layer 18c diffuses to the AuSn layer 182 and reacts with AuSn to form the AuNiSn layer 18d. These AuNiSn layers 18d, 18e, and 18f then function as junction layers, joining the first electrode and the second electrode. Although Ni3Sn2 is not shown in Figure 1, it is formed at the interface between the AuNiSn layer 18d and the Ni layer 18c, among other places.

[0035] [C1] 7Au 0.71 Sn 0.29 +1.53Ni→0.51Ni3Sn2+Au5Sn Here, it is known that when the reaction described in the above chemical formula occurs, 22 mol% of Ni reacts, resulting in a volume shrinkage of 3.2% (see Materials Science & Engineering A 773 (2020) 138738). A 1% shrinkage occurs in one axial direction.

[0036] Therefore, by increasing the Ni content in the AuNiSn layer 18d, which forms a junction layer near the end face in the resonance direction, the compressive strain on the active layer 14 can be increased. In other words, as in this embodiment, by increasing the thickness of both ends of the Ni layer 18c, the amount of Ni diffusion and Ni concentration at those locations increase, and the volume shrinkage rate increases, thus increasing the compressive strain. When compressive strain is applied, the band gap of the light-emitting layer of the optical device can be increased (Phys, Rev.B (43) 12 pp9649-9661). Consequently, it becomes possible to suppress COD suppression due to light absorption at the end face.

[0037] Furthermore, the energy spread of the emitted light from a semiconductor laser is less than 10 meV. By generating a band shift of 10 meV or more, a greater COD suppression effect can be expected. In that case, it is preferable to add a compressive strain of 0.25%, and by incorporating 5 mol% or more of Ni into the junction layer, that is, by making the difference in Ni concentration between the ends and the center of the junction layer in the resonance direction 5 mol% or more, it is possible to further suppress COD.

[0038] Although the subsequent steps are not shown in the diagram, the semiconductor light-emitting device 1 is completed by forming the n-type electrode 10 on the light-emitting element substrate 11.

[0039] As explained above, in the semiconductor light-emitting device 1 of this embodiment, by making the Ni concentration higher at the ends than in the center, for example, by making the Ni layer 18c thicker as in this embodiment, it becomes possible to apply compressive strain to the active layer 14, as will be described later. As a result, the band gap becomes larger at both ends in the direction of optical resonance, making it less likely for light absorption to occur and thus suppressing COD. Furthermore, by making the Ni concentration higher at both ends in the direction of optical resonance than in the center, for example, by making the thickness of a part of the electrode material, the Ni layer 18c, thicker at both ends in the direction of optical resonance than in the center, the COD suppression effect can be obtained. For this reason, it is not necessary to provide notches or the like on the end faces, and the end faces can remain as simple flat surfaces. Therefore, the semiconductor light-emitting device 1 can be made with a structure that does not involve the diffusion of impurities into the semiconductor layer, and without being limited by semiconductor materials or structures, and with good heat dissipation.

[0040] (Second Embodiment) A second embodiment will now be described. This embodiment is a modification of the configuration of the Au layer 183 compared to the first embodiment, and is otherwise the same as the first embodiment. Therefore, only the parts that differ from the first embodiment will be described.

[0041] In the first embodiment, when the Ni layer 18c is formed by the lift-off method, the first layer 18ca of the Ni layer 18c is exposed when it is formed. For this reason, as shown in Figure 3A, a portion of the Au layer 181 may be formed on the first layer 18ca, and then, after forming the resist 30 and the second layer 18cb, the remaining portion of the Au layer 181 may be formed on the second layer 18cb. In this case, as shown in Figure 3B, when removing the resist 30, the remaining portion of the second layer 18cb and the Au layer 181 on top of the resist 30 can also be removed. Thus, the Au layer 181 may be formed on the first layer 18ca and the second layer 18cb respectively.

[0042] (Third embodiment) A second embodiment will now be described. This embodiment is a modification of the configuration of the Au layer 183 compared to the first embodiment, and is otherwise the same as the first embodiment. Therefore, only the parts that differ from the first embodiment will be described.

[0043] As shown in Figure 4, the semiconductor light-emitting device 1 of this embodiment also has a configuration comprising a light-emitting element 2 and a substrate 3, but the stacking order of the metal layers constituting the p-type electrode 18 is different from that of the first embodiment.

[0044] Specifically, in this embodiment, the p-type electrode 18 is constructed from a laminated structure consisting of a Ti layer 18a, a Pt layer 18b, an AuSn layer 18f, an Au5Sn layer 18e, an AuNiSn layer 18d, a Ni layer 18c, and a Ti layer 18h, in that order from the element portion 4. The Ni layer 18c, which has increased thickness at both ends, is formed on the substrate 3 side and then joined to some of the metal layers that constitute the p-type electrode 18 on the element portion 4 side. Although the stacking order of the metal layers constituting the p-type electrode 18 differs from that of the first embodiment, the role of each metal layer is the same as in the first embodiment. In addition, in this embodiment, a Pt layer 18g is not formed on the surface of the Ti layer 18h formed on the substrate 3, but it can be formed.

[0045] A semiconductor light-emitting device 1 with this structure can be manufactured through the processes shown in Figures 5A to 5E.

[0046] First, as shown in Figures 5A to 5C, a substrate 3 with a wiring pattern and the like is prepared, and a part of the metal layer for forming the p-type electrode 18 is formed on this substrate 3. Specifically, as shown in Figures 5A and 5B, a Ti layer 18h is deposited on the substrate 3, and then a Ni layer 18c is deposited on top of it. The Ni layer 18c is made so that both ends in one direction, that is, both ends in the resonance direction when it is a semiconductor light-emitting device 1, are thicker than the central part further inside, and in this embodiment, the Ni layer 18c is formed using the lift-off method.

[0047] More specifically, as shown in Figure 5A, the first layer 18ca of the Ni layer 18c is deposited, then a resist 30 is deposited on top of it, and the resist 30 is exposed so that it remains on the central part of the first layer 18ca and not on the ends. Then, the second layer 18cb, which will be the remaining part of the Ni layer 18c, is deposited on top of the resist 30. As a result, the second layer 18cb is added to both ends of the first layer 18ca, and the second layer 18cb is formed on top of the resist 30 everywhere else. After this, as shown in Figure 5B, when the resist 30 is removed with a stripping solution or the like, the portion of the second layer 18cb that was formed on top of the resist 30 is also removed. This makes it possible to form a Ni layer 18c with increased thickness at both ends in one direction.

[0048] Furthermore, as shown in Figure 5C, if necessary, an Au layer 181 is formed on top of the Ni layer 18c to prevent oxidation of the Ni layer 18c.

[0049] In this way, a portion of the metal layer for forming the p-type electrode 18 can be formed on the substrate 3. A further part of This corresponds to the second electrode.

[0050] On the other hand, separate from the processes shown in Figures 5A to 5C, the process shown in Figure 5D is performed to form the light-emitting element 2 and the remaining metal layers for forming the p-type electrode 18. Specifically, each layer constituting the element part 4 is formed on the light-emitting element substrate 11. Then, the remaining metal layers for forming the p-type electrode 18 are formed by forming the Ti layer 18a, Pt layer 18b, Au layer 183, and AuSn layer 182 on the contact layer 17. A further part of This corresponds to the first electrode.

[0051] Next, in the process shown in Figure 5E, the substrate 3, on which some of the metal layers for forming the p-type electrode 18 have been formed via the process shown in Figure 5C, is joined to the light-emitting element 2 and the remaining metal layers for forming the p-type electrode 18, which have been formed via the process shown in Figure 5D. Each of the metal layers for forming the p-type electrode 18 is positioned facing each other, and the joining is performed by heating at, for example, 280°C or higher. This completes the semiconductor light-emitting device 1 of this embodiment shown in Figure 4.

[0052] Thus, even with a structure in which a Ni layer 18c with increased thickness at both ends is formed on the substrate 3 side and then joined to a portion of the metal layer for forming the p-type electrode 18 on the element part 4 side, the compressive strain on the active layer 14 near the end face in the resonance direction can be increased. As a result, the amount of Ni diffusion at that location increases, and the volume contraction rate increases, thus increasing the compressive strain and increasing the band gap of the light-emitting layer of the optical device. Therefore, it becomes possible to suppress COD suppression due to light absorption at the end face, and the same effect as in the first embodiment can be obtained.

[0053] (Modified versions of the first and third embodiments) In the first and third embodiments described above, a structure in which the ends of the Ni layer 18c are thicker than the central part was achieved using the lift-off method. This structure may also be achieved by other methods. For example, although not shown, after forming the Ni layer 18c thickly across the entire surface, a mask is placed that covers both ends of the Ni layer 18c while leaving the central part open, and the Ni layer 18c is etched up to a certain thickness while the Ni layer 18c is covered with the mask. In this way, a structure in which the ends of the Ni layer 18c are thicker than the central part can also be achieved.

[0054] (Fourth Embodiment) A fourth embodiment will now be described. This embodiment is a modification of the configuration of the Au layer 181 compared to the third embodiment, and is otherwise the same as the third embodiment. Therefore, only the parts that differ from the third embodiment will be described.

[0055] In the third embodiment, when the Ni layer 18c is formed by the lift-off method, the first layer 18ca of the Ni layer 18c is exposed when it is formed. For this reason, as shown in Figure 6A, a portion of the Au layer 181 may be formed on the first layer 18ca, and then, after forming the resist 30 and the second layer 18cb, the remaining portion of the Au layer 181 may be formed on the second layer 18cb. In this case, as shown in Figure 6B, when removing the resist 30, the remaining portion of the second layer 18cb and the Au layer 181 on top of the resist 30 can also be removed. Thus, the Au layer 181 may be formed on the first layer 18ca and the second layer 18cb, respectively.

[0056] (Fifth embodiment) A fifth embodiment will now be described. This embodiment is a modification of the Ni layer 18c configuration compared to the first embodiment, and is otherwise the same as the first embodiment. Therefore, only the differences from the first embodiment will be described.

[0057] As shown in Figure 7, in this embodiment, the thickness of the Ni layer 18c is made approximately uniform, while the Ni layer 18c is divided into multiple stripes in the resonance direction, and the width of the Ni layer 18c is wider at both ends than at the center. In other words, the amount of Ni layer 18c distributed is greater at both ends than at the center.

[0058] As shown in Figure 8, when forming the Ni layer 18c, the Ni layer 18c is divided into multiple stripes in the resonance direction, and an Au layer 181 is deposited on top of the Ni layer 18c to join the element part 4 side and the substrate 3 side.

[0059] In this example, the Ni layer 18c is divided into multiple stripes in the resonance direction, but the shape is not limited to stripes and can be arbitrary. The goal is to create an in-plane distribution in the Ni layer 18c such that the amount of Ni layer 18c distributed is greater at both ends in the resonance direction than at the center.

[0060] (Sixth Embodiment) A sixth embodiment will now be described. This embodiment is similar to the fifth embodiment in that the Ni layer 18c configuration is modified compared to the fourth embodiment, and is otherwise the same as the fourth embodiment. Therefore, only the parts that differ from the fourth embodiment will be described.

[0061] As shown in Figure 9, in this embodiment, the thickness of the Ni layer 18c is made approximately uniform, while the Ni layer 18c is divided into multiple stripes in the resonance direction, and the width of the Ni layer 18c is wider at both ends than at the center. In other words, the amount of Ni layer 18c distributed is greater at both ends than at the center.

[0062] As shown in Figure 10, when forming the Ni layer 18c, the Ni layer 18c is divided into multiple stripes in the resonance direction, and an Au layer 181 is deposited on top of the Ni layer 18c, and the element part 4 side and the substrate 3 side are joined together.

[0063] In this example, the Ni layer 18c is divided into multiple stripes in the resonance direction, but the shape is not limited to stripes and can be arbitrary. The goal is to create an in-plane distribution in the Ni layer 18c such that the amount of Ni layer 18c distributed is greater at both ends in the resonance direction than at the center.

[0064] (Other embodiments) This disclosure is written in accordance with the embodiments described above, but is not limited to those embodiments and includes various modifications and variations within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

[0065] For example, in the above embodiment, not all metal layers constituting the p-type electrode 18 are necessary; they may be provided only as needed, and the materials can be changed as appropriate. Similarly, the semiconductor materials constituting the element portion 4 and substrate 3 of the light-emitting element 2 are merely examples, and other semiconductor materials may be used. In particular, the active layer does not have to be GaAs or InP-based materials; nitride-based semiconductor materials can also be used.

[0066] Furthermore, in each of the above embodiments, the first conductivity type is n-type and the second conductivity type is p-type, and the light-emitting element substrate 11 side is n-type, but it may also be p-type. In other words, any structure in which the first cladding layer 12 and first guide layer 13 of the first conductivity type, the active layer 14, the second guide layer 15 and second cladding layer 16 of the second conductivity type, and the first electrode are formed in order on the light-emitting element substrate 11 of the first conductivity type and joined to the second electrode formed on the substrate 3 side is acceptable. [Explanation of Symbols]

[0067] 1...Semiconductor light-emitting device, 2...Light-emitting element, 3...Substrate, 4...Element part, 10...n-type electrode 11...Light-emitting element substrate, 12...First cladding layer, 13...First guide layer 14...Active layer, 15...Second guide layer, 16...Second cladding layer 17...Contact layer, 18...p-type electrode, 18a...Ti layer, 18b...Pt layer 18c...Ni layer, 18ca...1st layer, 18cb...2nd layer, 18d...AuNiSn layer 18e...Au5Sn layer, 18f...AuSn layer, 18g...Pt layer, 18h...Ti layer, 30... Resist, 181... Au layer, 182... AuSn layer, 183... Au layer

Claims

1. A semiconductor light-emitting device, A light-emitting element (2) having a light-emitting element substrate (11) made of a first conductivity type semiconductor material, an element portion (4) having a first cladding layer (12) of the first conductivity type, a first guide layer (13) of the first conductivity type, an active layer (14), a second guide layer (15) of the second conductivity type, and a second cladding layer (16) of the second conductivity type arranged in order on one side of the light-emitting element substrate, a first conductivity type electrode (10) formed on the side of the light-emitting element substrate opposite to the first cladding layer, and a second conductivity type electrode (18) arranged on the side of the element portion opposite to the first conductivity type electrode, with one direction being the resonance direction, and emitting light from at least one of the end faces in the resonance direction, The device comprises a substrate (3) connected to the second conductive electrode, The second conductive electrode has a junction structure between a first electrode disposed on the light-emitting side and a second electrode disposed on the substrate side, and the junction layer (18d to 18f) between the first electrode and the second electrode contains at least Au, Sn, and Ni, and the Ni concentration is 5 mol% or more greater at both ends of the resonance direction than in the central part which is inward from there, and compressive strain is applied to the active layer, in a semiconductor light-emitting device.

2. The semiconductor light-emitting apparatus according to claim 1, wherein the first electrode includes a Ni layer (18c).

3. The semiconductor light-emitting apparatus according to claim 2, wherein the Ni layer is thicker at both ends in the resonance direction than at the central part.

4. The semiconductor light-emitting apparatus according to claim 2, wherein the Ni layer has a greater distribution at both ends in the resonance direction than at the center.

5. The semiconductor light-emitting apparatus according to claim 1, wherein the second electrode includes a Ni layer (18c).

6. The semiconductor light-emitting apparatus according to claim 5, wherein the Ni layer is thicker at both ends in the resonance direction than at the central part.

7. The semiconductor light-emitting apparatus according to claim 5, wherein the Ni layer has a greater distribution at both ends in the resonance direction than at the center.

8. The semiconductor light-emitting apparatus according to any one of claims 1 to 7, wherein the active layer is composed of a nitride-based semiconductor material.

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