Semiconductor laser device and method for manufacturing the same

Abstract

To provide a semiconductor laser element which, for example, is capable of suppressing optical damage and has a more improved and novel constitution, and a method for manufacturing the semiconductor laser element.SOLUTION: A semiconductor laser element includes: a layered structure in which, for example, a clad layer of a first conductive type, an active layer, a clad layer of a second conductive type, and a contact layer are layered in a first direction, the layered structure having an end surface which is for outputting laser light and which is in a second direction intersecting the first direction, a non-window region formed in at least a center portion of the second direction, and a window region formed between the non-window region and the end surface and having a bandgap which is greater than that of the non-window region; a first electrode that is electrically connected to the clad layer of the first conductive type; a second electrode that is formed on the contact layer and that constitutes a current path together with the first electrode with the layered structure therebetween; a passivation layer that is formed on the end surface and that has a bandgap greater than that of the window region; and a dielectric reflective film that covers a side of the passivation layer opposite the end surface.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] In edge-emitting semiconductor laser devices, suppressing optical damage at the emitting end facet is an important issue. Optical damage occurs through the following process. That is, when a defect occurs at the emitting end facet, electrons and holes combine through the defect, raising the temperature of the end facet, which in turn reduces the band gap of the semiconductor material at the end facet, resulting in increased light absorption. When light absorption increases, the temperature of the end facet further increases, further reducing the band gap, which in turn increases light absorption, resulting in a cycle that may ultimately lead to the melting of the semiconductor material.

[0003] To suppress such optical damage, a technique is known in which a window region is formed on the facet by impurity diffusion or vacancy diffusion (e.g., Patent Documents 1 and 2). The window region can expand the band gap near the facet, suppressing light absorption and thus suppressing optical damage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 5,703,894 [Patent Document 2] Patent No. 4128898 Summary of the Invention [Problem to be solved by the invention]

[0005] In such a semiconductor laser element, it is undesirable that a configuration for suppressing optical damage causes an undesirable phenomenon such as a decrease in optical output.

[0006] Therefore, one object of the present invention is to provide a semiconductor laser element having a new and improved configuration capable of suppressing optical damage, and a method for manufacturing the semiconductor laser element. [Means for solving the problem]

[0007] The semiconductor laser element of the present invention has a laminated structure in which a first conductivity type cladding layer, an active layer, a second conductivity type cladding layer, and a contact layer are laminated in a first direction, the laminated structure having an end face in a second direction intersecting the first direction and outputting laser light, a non-window region formed in at least a center in the second direction, and a window region formed between the non-window region and the end face and having a band gap larger than that of the non-window region, a first electrode electrically connected to the first conductivity type cladding layer, a second electrode formed on the contact layer and constituting a current path between the first electrode and the laminated structure, a passivation layer formed on the end face and having a band gap larger than that of the window region, and a dielectric reflective film covering the side of the passivation layer opposite to the end face.

[0008] In the semiconductor laser device, the passivation layer may be a layer that is substantially lattice-matched with the laminated structure.

[0009] In the semiconductor laser device, the multilayer structure may be made of a GaAs-based semiconductor material, and the passivation layer may contain GaAs as a layer material.

[0010] In the semiconductor laser device, the laminated structure may be made of a GaAs-based semiconductor material, and the passivation layer may contain a II-IV group compound semiconductor material as a layer material.

[0011] In the semiconductor laser device, the passivation layer may contain ZnSe as a layer material.

[0012] In the semiconductor laser device, the passivation layer may have a thickness of 10 nm or more and 150 nm or less.

[0013] In the semiconductor laser device, the passivation layer may have a thickness of 10 nm or more and 50 nm or less.

[0014] In the semiconductor laser device, the window region may be one in which an impurity is diffused.

[0015] In the semiconductor laser device, the window region may be one in which holes are diffused.

[0016] A method for manufacturing a semiconductor laser element of the present invention includes the steps of: forming a layered structure in which a first conductivity type cladding layer, an active layer, a second conductivity type cladding layer, and a contact layer are layered in a first direction, the layered structure having a non-window region and a window region adjacent to the non-window region in a second direction intersecting the first direction and having a band gap larger than that of the non-window region; cleaving the layered structure at the window region in air to form an end face in the second direction; cleaning the end face in ultra-high vacuum; forming a passivation layer on the cleaned end face in ultra-high vacuum, the passivation layer having a band gap larger than that of the window region; and forming a dielectric reflective film on the side of the passivation layer opposite to the end face.

[0017] In the method for manufacturing a semiconductor laser device, the step of cleaning the end face may include irradiating the end face with plasma to clean the end face.

[0018] A manufacturing method for a semiconductor laser element of the present invention includes the steps of: forming a layered structure on a semiconductor substrate in a first direction, the layered structure including a non-window region and a window region adjacent to the non-window region in a second direction intersecting the first direction and having a band gap larger than that of the non-window region; cleaving the layered structure at the window region in an ultra-high vacuum to form an end face in the second direction; forming a passivation layer on the end face in an ultra-high vacuum; and forming a dielectric reflective film on the side of the passivation layer opposite to the end face.

[0019] In the method for manufacturing a semiconductor laser device, in the step of forming the passivation layer, the passivation layer may be formed by epitaxial growth.

[0020] In the method for manufacturing a semiconductor laser device, the step of forming the passivation layer and the step of forming the dielectric reflective film may be performed in chambers connected to each other.

[0021] In the method for manufacturing a semiconductor laser device, the step of forming the passivation layer and the step of forming the dielectric reflective film may be performed in separate chambers, respectively.

[0022] In the method for manufacturing a semiconductor laser device, in the step of forming the laminated structure, the window region may be formed by impurity diffusion or vacancy diffusion. Effect of the Invention

[0023] According to the present invention, for example, it is possible to obtain a semiconductor laser element having a novel and improved configuration capable of suppressing optical damage, and a method for manufacturing the semiconductor laser element. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is an illustrative schematic perspective view of a semiconductor laser device according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III of FIG. [Figure 4] FIG. 4 is an explanatory diagram showing the band gaps of the non-window region, the window region, and the passivation layer of the embodiment. [Diagram 5] FIG. 5 is a flowchart showing an example of a manufacturing procedure for the semiconductor laser device of the embodiment. [Figure 6] FIG. 6 is an exemplary schematic plan view showing a wafer piece in which a plurality of bars, each including a layered structure of a semiconductor laser device according to an embodiment, are arranged in a matrix. [Figure 7] FIG. 7 is an illustrative schematic perspective view showing a step of forming facets by cleavage in a manufacturing method for a semiconductor laser device according to an embodiment. [Figure 8] FIG. 8 is an illustrative schematic perspective view showing an example of a step of forming a passivation layer using one molecular beam generating unit in a manufacturing method for a semiconductor laser device according to an embodiment. [Figure 9] FIG. 9 is an illustrative schematic perspective view showing an example of a step of forming a passivation layer using two molecular beam generating units in a manufacturing method for a semiconductor laser device according to an embodiment. [Figure 10] FIG. 10 is a flowchart showing an example of a manufacturing procedure for the semiconductor laser device according to the modified embodiment. [Figure 11] FIG. 11 is an illustrative schematic configuration diagram showing an example of a manufacturing apparatus capable of implementing the manufacturing procedure of the modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Exemplary embodiments and modifications of the present invention are disclosed below. The configurations of the embodiments and modifications shown below, as well as the actions and results (effects) brought about by the configurations, are merely examples. The present invention can be realized by configurations other than those disclosed in the following embodiments and modifications. Furthermore, according to the present invention, it is possible to obtain at least one of the various effects (including derivative effects) obtained by the configurations.

[0026] In this specification, ordinal numbers are given for the sake of convenience to distinguish directions, parts, etc., and do not indicate priority or order.

[0027] In each drawing, the X direction is represented by an arrow X, the Y direction is represented by an arrow Y, and the Z direction is represented by an arrow Z. The X direction, Y direction, and Z direction intersect with each other and are perpendicular to each other.

[0028] [Embodiment] [Configuration of semiconductor laser element] Fig. 1 is a perspective view of the semiconductor laser device 1 of this embodiment. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. The X direction is the direction in which laser light is emitted from the semiconductor laser device 1. The X direction can also be referred to as the longitudinal direction, and the Y direction can also be referred to as the width direction.

[0029] 1, the semiconductor laser device 1 has a ridge 6 at its Z-direction end portion that protrudes in the Z direction from the Y-direction center portion. The ridge 6 extends in the X direction with a substantially constant width in the Y direction.

[0030] 1, a low-reflection film 3 that spreads across the X direction is formed on an end of the semiconductor laser element 1 in the X direction, while a high-reflection film 2 that spreads across the X direction is formed on an end of the semiconductor laser element 1 in the opposite direction in the X direction. The low-reflection film 3 and the high-reflection film 2 function as reflectors that reflect and resonate the generated laser light 4. The laser light 4 is output in the X direction from the end face in the X direction on which the low-reflection film 3 is formed. The low-reflection film 3 and the high-reflection film 2 are examples of dielectric reflection films. The X direction is an example of the second direction.

[0031] 2 and 3, the semiconductor laser device 1 has a laminated structure 10 in which an n-buffer layer 12 made of a III-V compound, an n-clad layer 13, an n-guide layer 14, an active layer 15, a p-guide layer 16, a p-clad layer 17, a p-contact layer 18, and an insulating layer 19 are laminated in this order in the Z direction on a semiconductor substrate 11, which is an n-type GaAs substrate. An upper electrode 20 is formed on the upper side of the p-contact layer 18, and a lower electrode 21 is formed on the lower side of the semiconductor substrate 11. The p-guide layer 16 formed on the upper side of the active layer 15, the p-clad layer 17 formed on the side where a p-type clad is laminated on the active layer 15, and the p-contact layer 18 formed for injecting holes into the active layer 15 are doped with Zn as an impurity. 2 and 3, the semiconductor laser device 1 has a ridge 6 that confines the current injected into the active layer 15 in a stripe shape and functions as an optical waveguide along the stripe, and is processed into a mesa shape in which the width of the layer region including the upper layer of the p-cladding layer 17 and the p-contact layer 18 in the direction perpendicular to the laser light emission direction is narrowed. The Z direction can also be called the stacking direction. The Z direction is an example of a first direction.

[0032] 3, the semiconductor laser element 1 is provided with a non-window region 24 and a window region 23 that absorbs less laser light compared to the non-window region 24. The non-window region 24 is formed in at least the center in the X direction of the semiconductor laser element 1. On the other hand, the window region 23 is formed between an end face 10a in the X direction and the non-window region 24. The end face 10a is an end face that outputs laser light, and may also be referred to as an emission end face.

[0033] Furthermore, a current path is formed between the lower electrode 21 and the upper electrode 20 via the laminated structure 10. The lower electrode 21 is an example of a first electrode, and the upper electrode 20 is an example of a second electrode. The n-clad layer 13 is an example of a first conductivity type clad layer, and the p-clad layer 17 is an example of a second conductivity type clad layer.

[0034] The semiconductor substrate 11 contains n-GaAs as a material. The n-buffer layer 12 is a buffer layer necessary for growing a stacked structure of high-quality epitaxial layers on the semiconductor substrate 11, and contains n-GaAs as a layer material. The n-cladding layer 13 and the n-guide layer 14 have refractive indices and thicknesses set so as to realize an arbitrary light confinement state in the stacking direction, and contain n-AlGaAs as a layer material. The Al composition of the n-guide layer 14 is preferably 15% or more and less than 45%. In addition, the Al composition of the n-cladding layer 13 is generally made higher than the Al composition of the n-guide layer 14 to reduce the refractive index. In the high-power edge-emitting multimode semiconductor laser element having the window region 23 of this embodiment, the film thickness of the n-guide layer 14 is preferably 200 nm or more, for example, about 400 nm. In addition, the thickness of the n-cladding layer 13 is preferably 1 μm or more, for example, about 3 μm. Although the n-guide layer 14 may be an intentionally undoped layer, if the thickness of the n-guide layer 14 is set to 100 nm or more, the influence of residual impurities is large, and it is better to perform doping. The structure and method of this embodiment can also be applied to an edge-emitting single-mode semiconductor laser element depending on the application.

[0035] The active layer 15 has a lower barrier layer 15a, a quantum well layer 15b, and an upper barrier layer 15c. The lower barrier layer 15a and the upper barrier layer 15c function as barriers that confine carriers in the quantum well layer 15b, and contain AlGaAs, which is not intentionally doped, as a material. The quantum well layer 15b contains InGaAs, which is not intentionally doped, as a material. The radiative recombination energy of the confined carriers is determined by the In composition and film thickness of the quantum well layer 15b, and the potential well structure determined by the composition of the lower barrier layer 15a and the upper barrier layer 15c. Here, the active layer 15 has been described as having a single quantum well layer (SQW) configuration, but the active layer 15 is not limited to this, and may have a multiple quantum well layer (MQW) configuration in which the quantum well layer 15b, the lower barrier layer 15a, and the upper barrier layer 15c are stacked a predetermined number of times. Although the configuration of layers that are not intentionally doped has been described here, donors and acceptors may be intentionally added to quantum well layer 15b, lower barrier layer 15a, and upper barrier layer 15c. Furthermore, since lower barrier layer 15a and n-guide layer 14 may have the same composition, and upper barrier layer 15c and p-guide layer 16 may have the same composition, lower barrier layer 15a and upper barrier layer 15c do not necessarily need to be formed.

[0036] The p-guide layer 16 and the p-cladding layer 17 are paired with the n-cladding layer 13 and the n-guide layer 14, and their refractive indices and thicknesses are set so as to realize any light confinement state in the stacking direction. The p-guide layer 16 and the p-cladding layer 17 contain p-AlGaAs as a layer material. The Al composition of the p-guide layer 16 is about 20%. The Al composition of the p-cladding layer 17 is generally set higher than the Al composition of the p-guide layer 16. In addition, in order to shift the optical field in the layer toward the n-cladding layer 13 to reduce the waveguide loss, the Al composition of the p-cladding layer 17 is set slightly higher than the n-cladding layer 13. In addition, the Al composition of the p-guide layer 16 is set lower than the Al composition of the p-cladding layer 17.

[0037] In the high-power edge-emitting multimode semiconductor laser element having the window region 23 as in this embodiment, the thickness of the p-guide layer 16 is preferably 200 [nm] or more, and the thickness of the p-cladding layer 17 is preferably about 1 to 2 [μm]. Note that, as the p-guide layer 16, a layer that is not intentionally doped may be formed, but when the thickness of the guide layer is set to be thick, the influence of the conductivity fluctuation due to the residual impurities is large, so it is better to perform intentional doping in order to improve the manufacturing reproducibility. The p-cladding layer 17 is formed of an n-type semiconductor layer. The p-contact layer 18 is doped with a high concentration of p-type impurities because it is necessary to make contact with an electrode in order to inject holes into the active layer 15. Note that a current constriction layer that constricts the injection current to increase the current density in the active layer 15 may be formed in the p-cladding layer 17.

[0038] In the semiconductor laser device 1 of this embodiment, a ridge 6 formed by processing a part of the laminated structure 10 causes current injected from the upper electrode 20 and the lower electrode 21 to concentrate in a part of the active layer 15, and laser light 4 is extracted to the outside of the semiconductor laser device 1. Since the light density of the laser light 4 emitted from the emission region 5 (see FIG. 1) is high, the semiconductor laser device 1 is provided with a window region 23 that absorbs less laser light in a predetermined region including the light emission end face, and other regions are made non-window regions 24, thereby suppressing optical damage.

[0039] In the window region 23, at least a part of the semiconductor layers constituting the stacked structure 10 of the window region 23 is intermixed. In Fig. 2, the intermixed region is hatched. As a result of the intermixing increasing the band gap of the window region 23, a large difference occurs between the band gap of the non-window region 24 and the band gap of the window region 23. This makes it possible to suppress absorption of laser light in the light-emitting end face region of the semiconductor laser device 1 and to suppress optical damage.

[0040] Impurities or vacancies are diffused in the window region 23. The impurities are, for example, at least one of Zn, Si, and Mg. The length of the window region 23 in the X direction is generally set to about several μm in the case of impurity diffusion, and to about several tens of μm in the case of vacancy diffusion.

[0041] In this embodiment, a passivation layer 30 is formed by stacking a material having a larger band gap than the window region 23 by end face growth on the end face 10a on which the window region 23 is formed. The passivation layer 30 is a layer having a larger band gap than the window region 23, and this can further improve the effect of suppressing optical damage. FIG. 4 is an explanatory diagram showing the band gaps of the non-window region 24, the window region 23, and the passivation layer 30 of this embodiment. Here, the band gap of the non-window region 24 is the band gap in the active layer 15, and the band gap of the window region 23 is the band gap in the layer corresponding to the active layer 15. As shown in FIG. 4, the band gap V2 of the window region 23 is larger than the band gap V1 of the non-window region 24, and the band gap V3 of the passivation layer 30 is larger than the band gap V2 of the window region 23.

[0042] In this embodiment, a low reflection film 3 is provided as a dielectric reflection film so as to cover the side of the passivation layer 30 opposite to the end face 10a.

[0043] Conventionally, a semiconductor laser element has been known in which a mixed crystallization region (window region) is formed by impurity diffusion at the end of the stacked structure 10 in the X direction, and a dielectric reflection film is formed on the end face of the mixed crystallization region in the X direction without forming a passivation layer as in the present embodiment. In this configuration, the mixed crystallization region is difficult to elongate in the X direction because light loss occurs in the mixed crystallization region. As a result, the length of the active layer adjacent to the center side in the X direction relative to the mixed crystallization region becomes long in the X direction, and a section in which no current flows is generated in the active layer adjacent to the mixed crystallization region. In such a section where no current flows, light is absorbed, which causes a decrease in optical output and an increase in energy loss.

[0044] Also, conventionally, a semiconductor laser element is known in which a passivation layer is formed without forming a window region at the end of the active layer in the X direction. In this configuration, since a current cannot flow at the interface between the passivation layer and the active layer, it is necessary to provide a section in the active layer adjacent to the passivation layer where no current flows. As described above, light is absorbed in the section where no current flows, which causes a decrease in optical output and an increase in energy loss.

[0045] In this embodiment, as shown in Figures 3 and 4, the non-window region 24, the window region 23, the passivation layer 30, and the low-reflection film 3 are formed in this order in the X direction, so that the section in the active layer 15 where no current flows can be shortened or eliminated, and thus the decrease in optical output and the increase in energy loss can be suppressed or avoided. In particular, in the case of the window region 23 where vacancies are diffused, the probability that the section in the active layer 15 where no current flows can be further shortened or eliminated is increased. From this viewpoint, it has been found that the thickness of the passivation layer 30 is preferably 10 nm or more and 150 nm or less, and more preferably 10 nm or more and 50 nm or less.

[0046] [Manufacturing method] Fig. 5 is a flow chart showing a manufacturing procedure of the semiconductor laser device 1 of this embodiment. As shown in Fig. 5, first, the above-mentioned layered structure 10 is formed (S11).

[0047] 6 is a plan view showing a wafer piece 100 in which a plurality of bars 101, each including a layered structure 10 of the semiconductor laser device 1, are arranged in a matrix in S11. The wafer piece 100 is a part of a wafer (not shown) cut out from the wafer.

[0048] In S11, a plurality of bars 101 each including the above-mentioned laminated structure 10, window region 23, and non-window region 24 are formed on a wafer (wafer piece 100) by a known semiconductor process. In other words, the laminated structure 10, the window region 23, and the non-window region 24 are formed on the wafer (wafer piece 100), thereby forming the plurality of bars 101 collectively.

[0049] The window region 23 is formed in the wafer piece 100 so as to extend in the Y direction with a substantially constant width w in the X direction, centered on the position (imaginary line PL) where the scribe 100a (scratch) is provided. The line PL is a position that will become the longitudinal end of the bar 101 in the later step S12.

[0050] As shown in FIG. 5, after S11, in this embodiment, the wafer piece 100 is cleaved in the atmosphere to form an end face 10a in the X direction in each bar 101 included in the array 102 (S12).

[0051] FIG. 7 is a perspective view showing the step (S12) of forming the end surface 10a by cleavage. As shown in FIG. 7, the wafer piece 100 is cleaved using a blade B or the like to form a plurality of arrays 102. At this time, the blade B is aligned with a scribe 100a (see FIG. 6) that has been provided in advance. As a result, the wafer piece 100 is cleaved at the position where the scribe 100a is provided, that is, at the line PL, and is divided into a plurality of arrays 102. Here, the scribe 100a and the line PL are located approximately in the center of the width w of the window region 23, so that the end surface 10a is formed in the window region 23. Also, as shown in FIG. 7, the divided arrays 102 are stacked in the Z direction.

[0052] 5, after S12, in this embodiment, the end faces 10a are cleaned in ultra-high vacuum (S13). In S13, plasma such as hydrogen plasma is irradiated onto the end faces 10a of the stacked arrays 102.

[0053] As shown in FIG. 5, after S13, in this embodiment, a passivation layer 30 is formed on the end face 10a in ultra-high vacuum (S13).

[0054] The passivation layer 30 is a layer that is approximately lattice-matched to the laminated structure 10. The passivation layer 30 is formed by epitaxial growth. As described above, the laminated structure 10 is made of a GaAs-based semiconductor material. Correspondingly, the passivation layer 30 contains, as a layer material (semiconductor material), for example, a III-V compound such as GaAs or a II-IV compound such as ZnSe.

[0055] The passivation layer 30 is formed in an edge growth chamber 1003 (see FIG. 11) that is kept in an ultra-high vacuum state. The arrays 102 are heated to a processing temperature of, for example, about 300° C. by a heater or the like provided in the edge growth chamber 1003.

[0056] Fig. 8 is a perspective view showing an example of the step (S13) of forming the passivation layer 30. As shown in Fig. 8, the passivation layer 30 is formed collectively on a plurality of arrays 102 stacked with the end faces 10a aligned substantially flush in the Z direction.

[0057] In the example of FIG. 8, the passivation layer 30 is formed by irradiating the end face 10 a of the array 102 with a molecular beam generated by one molecular beam generating unit 1031 .

[0058] When forming the passivation layer 30 containing a ZnSe compound as a II-IV group compound, the molecular beam generating unit 1031 can be realized by using, for example, a Knudsen cell. In this case, the molecular beam generating unit 1031 generates a molecular beam of Zn and low molecular weight Se from the ZnSe compound raw material held inside, and irradiates the molecular beam toward the end face 10a of the multiple arrays 102. As a result, a ZnSe film is formed on the end face 10a by epitaxial growth. Since the rate of epitaxial growth is determined by the molecular beam component with the smaller molecular beam intensity, a high-quality ZnSe film can be obtained even by epitaxial growth using one molecular beam generating unit 1031.

[0059] Fig. 9 is a perspective view showing another example of the step (S13) of forming the passivation layer 30. As shown in Fig. 9, in this case as well, the passivation layer 30 is formed collectively on a plurality of arrays 102 stacked with the end faces 10a aligned substantially flush in the Z direction.

[0060] In the example of FIG. 9, the passivation layer 30 is formed by irradiating the end face 10 a of the array 102 with molecular beams generated by two molecular beam generating units 1031 .

[0061] When forming the passivation layer 30 containing a ZnSe compound as a II-IV group compound, the two molecular beam generating units 1031 can be realized using a Knudsen cell or a valved cell. As an example, one molecular beam generating unit 1031 generates and irradiates a molecular beam of Zn, and the other molecular beam generating unit 1031 generates and irradiates a molecular beam of Se. As a result, a ZnSe film is formed on the end face 10a by epitaxial growth. Note that the molecular beam generating unit 1031 that irradiates a molecular beam of Sn is preferably realized using a valved cracking cell in order to reduce Se to smaller molecules.

[0062] When forming a passivation layer 30 containing a ZnSe compound, the combination of the two molecular beam generating units 1031 is not limited to the above-mentioned combination, and can be set in various ways. For example, one molecular beam generating unit 1031 may irradiate a molecular beam of ZnSe, and the other molecular beam generating unit 1031 may irradiate a molecular beam of either Zn or Se. Also, each of the two molecular beam generating units may irradiate a molecular beam of ZnSe.

[0063] Furthermore, when forming the passivation layer 30 containing a ZnSe compound, the end face 10a may first be irradiated with only a molecular beam of Zn from the molecular beam generating unit 1031. This makes it possible to suppress the occurrence of threading dislocations at the interface between the stacked structure 10 made of a GaAs-based semiconductor material and the passivation layer 30 containing a ZnSe compound, thereby further improving the reliability of the semiconductor laser device 1.

[0064] When forming the passivation layer 30 containing a GaAs compound as a III-V group compound using two molecular beam generating units 1031, one molecular beam generating unit 1031 irradiates a molecular beam of Ga, and the other molecular beam generating unit 1031 irradiates a molecular beam of As. In this case, as an example, the molecular beam generating unit 1031 irradiating the molecular beam of Ga can be realized by using a Knudsen cell, and the molecular beam generating unit 1031 irradiating the molecular beam of As can be realized by using a valved cracking cell. By irradiating the molecular beam from the molecular beam generating unit 1031, a GaAs film is formed on the end face 10a by epitaxial growth.

[0065] By using a plurality of molecular beam generating units 1031, it is possible to reduce variations in the components and thickness of the passivation layer 30 depending on the location on the end face 10a, compared to the case where only one molecular beam generating unit 1031 is used. Note that the number of molecular beam generating units 1031 is not limited to two, and may be three or more.

[0066] The passivation layer 30 is formed on the end face 10a in the X direction of the array 102, and is also formed on the end face 10a in the opposite direction in the X direction of the array 102. In order to form the passivation layer 30 on both end faces 10a, the support device 1032 is equipped with, for example, a turntable that can rotate at least 180° around a central axis C extending in the Z direction.

[0067] 5, after S14, in this embodiment, a low-reflection film 3 is formed on the passivation layer 30 formed on the end face 10a in the X direction, and a high-reflection film 2 is formed on the passivation layer 30 formed on the end face 10a in the opposite direction to the X direction (S15). The low-reflection film 3 and the high-reflection film 2 can be formed by a sputtering device or a plasma CVD device provided separately from the end face growth chamber 1003 in which the epitaxial growth was performed. Since the end face 10a is protected by the passivation layer 30 formed in S14, even if the array 102 is exposed to the atmosphere during the transition from S14 to S15, deterioration of the end face 10a is unlikely to occur.

[0068] As described above, in this embodiment, a passivation layer 30 having a band gap larger than that of the window region 23 is formed on the end face 10a provided in the window region 23, and a low-reflection film 3 (dielectric reflective film) is formed on the passivation layer 30 on the opposite side of the end face 10a.

[0069] According to such a configuration and method, for example, the section where no current flows in the active layer 15 can be shortened or eliminated, so that it is possible to suppress or avoid the occurrence of undesirable phenomena such as a decrease in optical output and an increase in energy loss caused in the conventional structure by the existence of a section where no current flows in the active layer 15. That is, according to the present embodiment, it is possible to obtain a semiconductor laser device 1 having a new and improved configuration capable of suppressing optical damage, and a method for manufacturing the semiconductor laser device 1.

[0070] [Variations] Fig. 10 is a flow chart showing a manufacturing procedure of the semiconductor laser device 1 according to a modification of this embodiment. As will be clear from comparing Fig. 10 with Fig. 5, in this modification, instead of S11 and S12 in the embodiment, the end face 10a is formed by cleaving the wafer piece 100 in the window region 23 in an ultra-high vacuum (S22). According to this procedure, it is possible to suppress the formation of a natural oxide film on the end face 10a and the adhesion of particles to the end face 10a without performing a process for purifying the end face 10a in an ultra-high vacuum, thereby further improving reliability.

[0071] 11 is a configuration diagram showing an example of a manufacturing apparatus 1000 capable of implementing the manufacturing procedure of the modified example. The manufacturing apparatus 1000 includes a load lock chamber 1001, a cleavage chamber 1002, an end face growth chamber 1003, and a coating chamber 1004.

[0072] Between each chamber, a gate valve 1005 is provided for opening and closing the chambers and for providing an airtight seal when closed. The manufacturing apparatus 1000 is provided with a transfer mechanism 1006 for transferring the wafer piece 100 or the array 102 between the chambers. The transfer mechanism 1006 can be configured as, for example, a transfer trolley or a transfer arm.

[0073] The load lock chamber 1001 has an opening and closing door (not shown). In the load lock chamber 1001, the wafer piece 100 is loaded and the array 102 is unloaded.

[0074] In the cleaving chamber 1002, cleaving (S12) as illustrated in FIG. 7 is carried out under ultra-high vacuum conditions.

[0075] The end face growth chamber 1003 is an epitaxial growth apparatus. In the end face growth chamber 1003, the formation of the passivation layer 30 as shown in Fig. 8 and Fig. 9, i.e., end face growth (S22), is performed. The end face growth chamber 1003 is provided with a molecular beam generation unit 1031 and a support device 1032 having a heater and a turntable.

[0076] In the coating chamber 1004, the low reflection film 3 and the high reflection film 2 are formed (S15). In this modification, the end face growth chamber 1003 and the coating chamber 1004 are connected to each other, but this is not limiting, and the end face growth chamber 1003 and the coating chamber 1004 may be independent from each other. In this case, the array 102 may be exposed to the atmosphere between the end face growth chamber 1003 and the coating chamber 1004.

[0077] Although the embodiment and the modified examples of the present invention have been illustrated above, the above-mentioned embodiment and the modified examples are merely examples and are not intended to limit the scope of the invention. The above-mentioned embodiment and the modified examples can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the gist of the invention. In addition, the specifications of each configuration, shape, and the like (structure, type, direction, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be appropriately changed and implemented.

[0078] For example, the semiconductor laser device does not need to have a ridge. [Explanation of symbols]

[0079] 1...Semiconductor laser element 2...Highly reflective film (dielectric reflective film) 3...Low reflection coating (dielectric reflection coating) 4...Laser light 5...Emission area 6. Ridge 10…Laminated structure 10a...end face 11...Semiconductor substrate 12...n-buffer layer 13...n-clad layer (first conductive type clad layer) 14...n-guide layer 15…Active layer 15a…Lower barrier layer 15b...Quantum well layer 15c…Upper barrier layer 16...p-guide layer 17...p-cladding layer (second conductive type cladding layer) 18...p-contact layer 19…Insulating layer 20...Top electrode (second electrode) 21...Lower electrode (first electrode) 23…Window area 24…Non-window area 30…passivation layer 100...wafer piece 100a…Scribe 101…Bar 102…Array 1000…Manufacturing equipment 1001...Load lock chamber 1002...cleavage chamber 1003...Edge growth chamber 1004...coating chamber 1005...Gate valve 1006...Transport mechanism 1031...Molecular beam generation section 1032...Support device B...Blade C…Central axis V1, V2, V3...Band gap w…width X…direction (second direction) Y...Direction Z…direction (first direction)

Claims

1. a laminated structure in which a first conductive type cladding layer, an active layer, a second conductive type cladding layer, and a contact layer are laminated in a first direction, the laminated structure having an end face in a second direction intersecting the first direction and outputting laser light, a non-window region formed at least in a center portion in the second direction, and a window region formed between the non-window region and the end face and having a band gap larger than that of the non-window region; a first electrode electrically connected to the first conductivity type cladding layer; a second electrode formed on the contact layer and constituting a current path between the second electrode and the first electrode through the laminated structure; a passivation layer formed on the end face and having a bandgap larger than the window region; a dielectric reflective film covering a side of the passivation layer opposite to the end face; having The window region is a region in which voids are diffused and has a length of several tens of μm in the second direction, A semiconductor laser element, wherein the thickness of the passivation layer is set to be 10 nm or more and 150 nm or less.

2. a laminated structure in which a first conductive type cladding layer, an active layer, a second conductive type cladding layer, and a contact layer are laminated in a first direction, the laminated structure having an end face in a second direction intersecting the first direction and outputting laser light, a non-window region formed at least in a center portion in the second direction, and a window region formed between the non-window region and the end face and having a band gap larger than that of the non-window region; a first electrode electrically connected to the first conductivity type cladding layer; a second electrode formed on the contact layer and constituting a current path between the second electrode and the first electrode through the laminated structure; a passivation layer formed on the end face and having a bandgap larger than the window region; a dielectric reflective film covering a side of the passivation layer opposite to the end face; having The window region is a region in which impurities are diffused and has a length of several μm in the second direction, A semiconductor laser element, wherein the thickness of the passivation layer is set to be 10 nm or more and 150 nm or less.

3. 3. The semiconductor laser device according to claim 1, wherein the passivation layer is a layer that is substantially lattice-matched with the laminated structure.

4. 4. The semiconductor laser device according to claim 3, wherein the laminated structure is made of a GaAs-based semiconductor material, and the passivation layer contains a II-IV group compound semiconductor material as a layer material.

5. The semiconductor laser device according to claim 4 , wherein the passivation layer contains ZnSe as a layer material.

6. a laminated structure in which a first conductive type cladding layer, an active layer, a second conductive type cladding layer, and a contact layer are laminated in a first direction, the laminated structure having an end face in a second direction intersecting the first direction and outputting laser light, a non-window region formed at least in a center portion in the second direction, and a window region formed between the non-window region and the end face and having a band gap larger than that of the non-window region; a first electrode electrically connected to the first conductivity type cladding layer; a second electrode formed on the contact layer and constituting a current path between the second electrode and the first electrode through the laminated structure; a passivation layer formed on the end face and having a bandgap larger than the window region; a dielectric reflective film covering a side of the passivation layer opposite to the end face; having the passivation layer is a layer that is substantially lattice-matched to the laminated structure, The semiconductor laser element, wherein the laminated structure is made of a GaAs-based semiconductor material, and the passivation layer contains GaAs as a layer material.

7. 7. The semiconductor laser device according to claim 6, wherein the passivation layer has a thickness of 10 nm or more and 150 nm or less.

8. 8. The semiconductor laser device according to claim 1, wherein the passivation layer has a thickness of 10 nm or more and 50 nm or less.

9. forming a laminated structure in which a first conductive type cladding layer, an active layer, a second conductive type cladding layer, and a contact layer are laminated in a first direction, the laminated structure having a non-window region and a window region adjacent to the non-window region in a second direction intersecting the first direction and having a band gap larger than that of the non-window region; cleaving the laminated structure at the window region in air to form an end face in the second direction; cleaning the end face in an ultra-high vacuum; forming a passivation layer on the cleaned facet in an ultra-high vacuum, the passivation layer having a bandgap larger than that of the window region; forming a dielectric reflective film on the side of the passivation layer opposite the end face; Equipped with The window region is a region in which vacancies are diffused and has a length of several tens of micrometers in the second direction, or a region in which impurities are diffused and has a length of several micrometers in the second direction, A method for manufacturing a semiconductor laser element, wherein the thickness of the passivation layer is set to 10 nm or more and 150 nm or less.

10. forming a laminated structure in which a first conductive type cladding layer, an active layer, a second conductive type cladding layer, and a contact layer are laminated in a first direction, the laminated structure having a non-window region and a window region adjacent to the non-window region in a second direction intersecting the first direction and having a band gap larger than that of the non-window region; cleaving the laminated structure at the window region in air to form an end face in the second direction; cleaning the end face in an ultra-high vacuum; forming a passivation layer on the cleaned facet in an ultra-high vacuum, the passivation layer having a bandgap larger than that of the window region; forming a dielectric reflective film on the side of the passivation layer opposite the end face; Equipped with the passivation layer is a layer that is substantially lattice-matched to the laminated structure, The method for manufacturing a semiconductor laser element, wherein the laminated structure is made of a GaAs-based semiconductor material, and the passivation layer contains GaAs as a layer material.

11. 11. The method for manufacturing a semiconductor laser device according to claim 9, wherein in the step of cleaning the end face, the end face is cleaned by irradiating it with plasma.

12. forming a laminated structure on a semiconductor substrate in a first direction, the laminated structure including a first conductive type cladding layer, an active layer, a second conductive type cladding layer, and a contact layer doped with a second conductive type impurity, the laminated structure including a non-window region and a window region adjacent to the non-window region in a second direction intersecting the first direction and having a band gap larger than that of the non-window region; cleaving the laminated structure at the window region in an ultra-high vacuum to form an end face in the second direction; forming a passivation layer on the end surface in an ultra-high vacuum; forming a dielectric reflective film on the side of the passivation layer opposite the end face; Equipped with The window region is a region in which vacancies are diffused and has a length of several tens of micrometers in the second direction, or a region in which impurities are diffused and has a length of several micrometers in the second direction, A method for manufacturing a semiconductor laser element, wherein the thickness of the passivation layer is set to 10 nm or more and 150 nm or less.

13. forming a laminated structure on a semiconductor substrate in a first direction, the laminated structure including a first conductive type cladding layer, an active layer, a second conductive type cladding layer, and a contact layer doped with a second conductive type impurity, the laminated structure including a non-window region and a window region adjacent to the non-window region in a second direction intersecting the first direction and having a band gap larger than that of the non-window region; cleaving the laminated structure at the window region in an ultra-high vacuum to form an end face in the second direction; forming a passivation layer on the end surface in an ultra-high vacuum; forming a dielectric reflective film on the side of the passivation layer opposite the end face; Equipped with the passivation layer is a layer that is substantially lattice-matched to the laminated structure, The method for manufacturing a semiconductor laser element, wherein the laminated structure is made of a GaAs-based semiconductor material, and the passivation layer contains GaAs as a layer material.

14. 14. The method for manufacturing a semiconductor laser device according to claim 9, wherein in the step of forming the passivation layer, the passivation layer is formed by epitaxial growth.

15. 15. The method for manufacturing a semiconductor laser device according to claim 9, wherein the step of forming the passivation layer and the step of forming the dielectric reflective film are carried out in chambers connected to each other.

16. 16. The method for manufacturing a semiconductor laser device according to claim 9, wherein the step of forming the passivation layer and the step of forming the dielectric reflective film are carried out in separate chambers, respectively.

17. 17. The method for manufacturing a semiconductor laser device according to claim 9, wherein in the step of forming the laminated structure, the window region is formed by impurity diffusion or vacancy diffusion.

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