JP2021141293A - Semiconductor light-emitting element - Google Patents

Abstract

To provide a semiconductor light-emitting element capable of easily and highly accurately forming a waveguide with an increased equivalent index of refraction in the center.SOLUTION: A semiconductor light-emitting element 1 includes: an optical guide layer 30 and a second semiconductor layer 40 located above the optical guide layer 30 (on the positive side of the Z-axis). A ridge 50 is formed in the second semiconductor layer 40. Multiple grooves 51 extending in the vertical direction are formed on the ridge 50. In the width direction (Y-axis direction) of the ridge 50, the spacing between multiple grooves 51 is narrower on the outside than in the center.SELECTED DRAWING: Figure 1

Description

The present invention relates to a semiconductor light emitting device and is suitable for use in, for example, processing of a product.

In recent years, semiconductor light emitting devices have been used for processing various products. In this case, in order to improve the processing quality, it is preferable that the light emitted from the semiconductor light emitting device has a high output and is a basic mode in which the higher-order mode is cut. The following Patent Documents 1 and 2 describe a configuration in which the refractive index of the central portion of the waveguide is increased and the refractive index of the peripheral portion of the waveguide is decreased in order to cut light in a higher-order mode. ..

In Patent Document 1, the refractive index of the waveguide is adjusted by forming a plurality of ridge stripes having different heights on the waveguide. In this configuration, the height of the ridge stripe arranged in the central portion of the waveguide is set higher than that of the ridge stripe arranged in the peripheral portion of the waveguide, so that the central portion of the waveguide composed of a plurality of ridge stripes is set. Refractive index is increased.

In Patent Document 2, the refractive index of the waveguide is adjusted by adjusting the shape of the bottom surface of the groove connecting the plurality of ridge stripes. In this configuration, the bottom surface of each groove is formed so as to follow a lens shape in which the central portion of the waveguide is high and the peripheral portion is low, so that the refractive index of the central portion of the waveguide composed of a plurality of ridge stripes is increased. ..

Japanese Unexamined Patent Publication No. 1-175281 International Publication No. 2011/012100

In the configuration described in Patent Document 1, in order to form a plurality of ridge stripes having different heights, it is necessary to repeat etching, which complicates the manufacturing process. Further, in the configuration described in Patent Document 2, in order to form the bottom surface of each groove along the lens shape, etching is performed using the heat-shrinked resist as a sacrificial layer by utilizing the thermal effect of the resist. .. Therefore, the shrinkage rate of the resist tends to vary in the surface of the semiconductor wafer, and it becomes difficult to form the bottom surface of the lens shape with high accuracy.

In view of such a problem, an object of the present invention is to provide a semiconductor light emitting device capable of forming a waveguide having an increased equivalent refractive index at the center easily and with high accuracy.

The first aspect of the present invention relates to a semiconductor light emitting device. The semiconductor light emitting device according to this embodiment includes an optical guide layer and a semiconductor layer arranged above the optical guide layer and having a ridge portion formed therein. A plurality of grooves extending in the vertical direction are formed in the ridge portion, and in the width direction of the ridge portion, the distance between the plurality of grooves is narrower on the outside than in the center.

According to the semiconductor light emitting device according to this aspect, a waveguide for propagating the light generated in the optical guide layer is formed corresponding to the ridge portion, and a plurality of groove portions formed in the ridge portion in the width direction of the ridge portion. The distance between the two is narrower on the outside than in the center. As a result, the equivalent refractive index at the center is increased in the waveguide corresponding to the ridge portion. Therefore, it is possible to obtain high beam quality laser light by cutting the high-order mode laser light in the semiconductor light emitting device. Further, the plurality of grooves arranged at different intervals can be formed relatively easily by the etching process. Therefore, a waveguide with an increased equivalent refractive index at the center can be formed easily and with high accuracy.

A second aspect of the present invention relates to a semiconductor light emitting device. The semiconductor light emitting device according to this embodiment includes an optical guide layer and a semiconductor layer arranged above the optical guide layer and having a ridge portion formed therein. A plurality of groove portions extending in the vertical direction are formed in the ridge portion, and the width of the plurality of groove portions is wider on the outside than in the center in the width direction of the ridge portion.

According to the semiconductor light emitting device according to this aspect, a waveguide for propagating the light generated in the optical guide layer is formed corresponding to the ridge portion, and the width of the plurality of grooves formed in the ridge portion is centered on the outside. Is wider than. As a result, the equivalent refractive index at the center is increased in the waveguide corresponding to the ridge portion. Therefore, it is possible to obtain high beam quality laser light by cutting the high-order mode laser light in the semiconductor light emitting device. Further, the plurality of grooves arranged in different widths can be formed relatively easily by the etching process. Therefore, a waveguide with an increased equivalent refractive index at the center can be formed easily and with high accuracy.

As described above, according to the present invention, it is possible to provide a semiconductor light emitting device capable of forming a waveguide having an increased equivalent refractive index at the center easily and with high accuracy.

The effects or significance of the present invention will be further clarified by the description of the embodiments shown below. However, the embodiments shown below are merely examples when the present invention is put into practice, and the present invention is not limited to those described in the following embodiments.

FIG. 1A is a top view schematically showing the configuration of the semiconductor light emitting device according to the first embodiment. FIG. 1B is a cross-sectional view schematically showing the configuration of the semiconductor light emitting device according to the first embodiment. 2A and 2B are cross-sectional views for explaining a method for manufacturing a semiconductor light emitting device according to the first embodiment. 3A and 3B are cross-sectional views for explaining a method for manufacturing a semiconductor light emitting device according to the first embodiment. 4 (a) and 4 (b) are cross-sectional views for explaining a method for manufacturing a semiconductor light emitting device according to the first embodiment. 5 (a) and 5 (b) are cross-sectional views for explaining a method for manufacturing a semiconductor light emitting device according to the first embodiment. 6 (a) and 6 (b) are cross-sectional views for explaining a method for manufacturing a semiconductor light emitting device according to the first embodiment. FIG. 7 is a diagram showing the distribution of the equivalent refractive index in the Y-axis direction in the semiconductor light emitting device according to the first embodiment. FIG. 8 is a cross-sectional view schematically showing the configuration of the semiconductor light emitting device according to the first embodiment. 9 (a) and 9 (b) are diagrams showing the distribution of the equivalent refractive index in the Y-axis direction in the semiconductor light emitting device according to the modified example. FIG. 10 is a simulation result showing the relationship between the number of regions of the ridge portion and the number of excitation modes when the distribution of the equivalent refractive index is an isosceles triangle shape and a Gaussian shape according to the modified example. FIG. 11 is a cross-sectional view schematically showing the configuration of the semiconductor light emitting device according to the second embodiment. FIG. 12 is a diagram showing the distribution of the equivalent refractive index in the Y-axis direction in the semiconductor light emitting device according to the second embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, the X, Y, and Z axes that are orthogonal to each other are added to each figure. The X-axis direction is the light propagation direction in the waveguide, and the Y-axis direction is the width direction of the waveguide. The Z-axis direction is the stacking direction of each layer constituting the semiconductor light emitting device.

<Embodiment 1>
FIG. 1A is a top view schematically showing the configuration of the semiconductor light emitting device 1, and FIG. 1B is a cross-sectional view schematically showing the configuration of the semiconductor light emitting device 1. In FIG. 1A, the pad electrode 72 is not shown for convenience. FIG. 1B is a cross-sectional view of the semiconductor light emitting device 1 cut at AA'in FIG. 1A as viewed in the positive direction of the X-axis.

As shown in FIG. 1A, the semiconductor light emitting device 1 is provided with a waveguide WG. The waveguide WG extends linearly in the X-axis direction. The waveguide WG has an action of limiting the progress of light to the outside of the waveguide WG in the Y-axis direction.

The end face 1a is an end face of the waveguide WG located on the positive side of the X-axis, and is also an end face on the emission side of the semiconductor light emitting element 1. The end face 1b is an end face of the waveguide WG located on the negative side of the X-axis, and is also an end face on the reflection side of the semiconductor light emitting element 1. Hereinafter, the light heading from the end face 1b side to the end face 1a is referred to as a "forward wave", and the light heading from the end face 1a side to the end face 1b is referred to as a "backward wave".

When the forward wave reaches the end face 1a, a part of the forward wave is emitted from the end face 1a in the positive direction of the X axis as emitted light, and a part of the forward wave is reflected by the end face 1a to become a backward wave. The receding wave travels in the negative direction of the X-axis through the waveguide WG, and when it reaches the end face 1b, most of the receding wave is reflected by the end face 1b and becomes a forward wave. In this way, the light generated in the semiconductor light emitting device 1 is amplified between the end face 1a and the end face 1b and emitted from the end face 1a.

As shown in FIG. 1B, the semiconductor light emitting device 1 includes a substrate 10, a first semiconductor layer 20, an optical guide layer 30, a second semiconductor layer 40, an insulating film 60, and a p-side electrode 71. The pad electrode 72 and the n-side electrode 80 are provided.

The first semiconductor layer 20 is arranged above the substrate 10. The first semiconductor layer 20 is an n-side clad layer.

The optical guide layer 30 is arranged above the first semiconductor layer 20. The optical guide layer 30 has a laminated structure in which the n-side optical guide layer 31, the active layer 32, and the p-side optical guide layer 33 are laminated in this order from the bottom. The light emitting region 30a is arranged at a position corresponding to the waveguide WG, and is a region in which most of the light emitted from the semiconductor light emitting device 1 is generated and propagated.

The second semiconductor layer 40 is arranged above the p-side optical guide layer 33. The second semiconductor layer 40 has a laminated structure in which the electron barrier layer 41, the p-side clad layer 42, and the p-side contact layer 43 are laminated in this order from the bottom.

The ridge portion 50 is formed on the upper portion of the second semiconductor layer 40 and has a ridge shape (protrusion shape). As shown in FIG. 1A, the ridge portion 50 has a shape extending in the X-axis direction, and has a shape protruding in the Z-axis positive direction as shown in FIG. 1B. There is. Further, on the upper surface of the ridge portion 50, six grooves 50a extending in the X-axis direction and having a depth in the Z-axis direction are formed. By forming the six grooves 50a in the ridge portion 50, seven ridge stripe portions 52 are formed between the end portion of the ridge portion 50 and the groove 50a and between the two adjacent grooves 50a. ..

The insulating film 60 is arranged above the p-side clad layer 42 on the outside in the Y-axis direction of the waveguide WG in order to confine the light in the light emitting region 30a. Further, the insulating film 60 is also arranged in the groove 50a of the ridge portion 50, and the groove portion 51 is formed by arranging the insulating film 60 in the groove 50a.

The p-side electrode 71 is arranged above the p-side contact layer 43 at a position corresponding to the waveguide WG. The p-side electrode 71 is an ohmic electrode that makes ohmic contact with the p-side contact layer 43. The pad electrode 72 has a shape longer in the Y-axis direction than the waveguide WG, and is in contact with the p-side electrode 71 and the insulating film 60.

The n-side electrode 80 is an ohmic electrode that is arranged below the substrate 10 and makes ohmic contact with the substrate 10.

Next, a method of manufacturing the semiconductor light emitting device 1 will be described with reference to FIGS. 2 (a) to 6 (b). 2 (a) to 6 (b) are cross-sectional views similar to those in FIG. 1 (b).

As shown in FIG. 2A, a metalorganic chemical vapor deposition (MOCVD method) is performed on a substrate 10 which is an n-type hexagonal GaN substrate whose main surface is the (0001) plane. 1 The semiconductor layer 20, the optical guide layer 30, and the second semiconductor layer 40 are sequentially formed.

Specifically, an n-type Al0.03GaN clad layer is grown by 2 μm as the first semiconductor layer 20 on the substrate 10 having a thickness of 400 μm. Subsequently, an i-GaN layer of 0.1 μm is grown on the first semiconductor layer 20 as the n-side optical guide layer 31. Further, an active layer 32 composed of two cycles of an In0.02GaN barrier layer and an In0.07GaN quantum well layer is grown. The film thickness of the barrier layer may be set to, for example, 20 nm, and the film thickness of the quantum well layer may be set to, for example, 7 nm. The barrier layer may be grown not only between the quantum well layers but also above and below the quantum well layers. Subsequently, the i-GaN layer is grown by 0.1 μm as the p-side optical guide layer 33.

Subsequently, Al0.35GaN is grown by 5 nm as the electron barrier layer 41. Subsequently, from a strained superlattice of 0.48 μm formed on the electron barrier layer 41 as a p-side clad layer 42 by repeating p-Al 0.0.06 GaN layer 1.5 nm and GaN layer 1.5 nm for 160 cycles. Grow the layer. Subsequently, a 0.05 μm-thick p-GaN layer is grown as the p-side contact layer 43.

Next, as shown in FIG. 2B, an insulating film made _{of SiO 2} having a film thickness of 0.3 μm is formed as a protective film 91 on the p-side contact layer 43 by, for example, a thermal CVD method.

Next, as shown in FIG. 3A, the protective film 91 located in the region other than the ridge portion 50 and the region of the groove 50a is etched by, for example, a photolithography method and an etching method using hydrofluoric acid. That is, the region other than the groove 50a of the ridge portion 50 is left in a striped shape, and the other region is etched. As a result, the protective film 91 is formed into a shape extending in the X-axis direction by etching, and is divided into a plurality of (7 in the case of FIG. 3A) with a gap in the Y-axis direction. Further, considering that the end faces 1a and 1b (see FIG. 1A) are formed by utilizing the natural cleavage plane (m plane) of the hexagonal nitride semiconductor, the orientation of the stripes is parallel to the m-axis direction. do.

Next, as shown in FIG. 3B, the upper part of the laminated structure is etched to a depth of 0.4 μm using the protective film 91 as a mask by, for example, an inductively coupled plasma (ICP) etching method, and etching is performed. The lower end of the range is defined as the range of the p-side clad layer 42. As a result, a ridge portion 50 and a groove 50a provided in the ridge portion 50 are formed on the upper part of the p-side contact layer 43 and the p-side clad layer 42.

At this time, etching is performed so that the depth of each groove 50a in the Z-axis direction (depth from the upper surface of the p-side contact layer 43) is equal to the depth dp. Further, etching is performed so that the position of the bottom surface of the groove 50a in the Z-axis direction is equal to the position of the top surface of the p-side clad layer 42 located outside the ridge portion 50. As a result, the upper surface of the p-side clad layer 42 is also positioned at a depth dp from the upper surface of the p-side contact layer 43. When the ridge portion 50 and the groove 50a are etched in this way, the process of forming the ridge portion 50 and the process of forming the groove 50a can be simplified.

Next, as shown in FIG. 4A, the strip-shaped protective film 91 is removed using, for example, hydrofluoric acid. The width of the groove 50a formed in the ridge portion 50 and the width of the ridge stripe portion 52 separated by the groove 50a are determined by the width of the protective film 91 described with reference to FIG. 3A. In the first embodiment, the widths of the six grooves 50a in the Y-axis direction are all d10. Further, in the Y-axis direction, the intervals of the grooves 50a (width of the ridge stripe portion 52) are d21, d22, d23, and d24 from the center to the outside, and the relationship between the widths of the grooves 50a is d21> d22> d23. > D24.

For example, each size of the ridge portion 50 in the Y-axis direction is set as follows. The width of the ridge portion 50 (the length from the left end to the right end of the ridge portion 50) is set to 16 μm. The width d10 of the groove 50a is set to about 0.05 to 0.5 μm, and is preferably set to 0.3 μm or less. The widths d21, d22, d23, and d24 of the ridge stripe portion 52 are set to 3.5 μm, 1.8 μm, 1.3 μm, and 0.5 μm, respectively.

Next, as shown in FIG. 4 (b), for example, by the thermal CVD method, the laminated structure shown in FIG. 4 (a) is insulated from _{SiO 2 having a film thickness of 200 nm over the entire surface including the ridge portion 50.} The film 60 is formed. At this time, the groove portion 51 is formed by filling the six grooves 50a with the insulating material of the insulating film 60. That is, the groove 51 is composed of the groove 50a and the insulating material of the insulating film 60 housed in the groove 50a. Therefore, in the Y-axis direction, the width of the groove portion 51 is the same as the width d10 of the groove 50a shown in FIG. 4A, and the distance between the groove portions 51 (width of the ridge stripe portion 52) is shown in FIG. The intervals d21, d22, d23, and d24 of the grooves 50a shown in the above are the same.

Next, as shown in FIG. 5A, only the insulating film 60 located on the p-side contact layer 43 is removed by, for example, a photolithography method and an etching method using hydrofluoric acid, and the p-side contact layer is removed. The upper surface of 43 is exposed. As a result, the insulating film 60 arranged in the groove 50a projects upward from the upper surface of the p-side contact layer 43.

Next, as shown in FIG. 5 (b), a metal laminated film composed of palladium and platinum is formed at least on the exposed p-side contact layer 43 by, for example, an electron beam (EB) vapor deposition method. Then, by a lift-off method for removing the resist pattern, the metal laminated film other than the position corresponding to the p-side contact layer 43 is removed to form the p-side electrode 71.

Next, as shown in FIG. 6 (a), by the lithography method and the lift-off method, for example, the length in the X-axis direction is 900 μm and the Y-axis is covered so as to cover the laminated structure shown in FIG. 5 (b). A pad electrode 72 made of Ti / Pt / Au having a length of 150 μm in the direction is selectively formed. Subsequently, the lower surface of the substrate 10 is polished with a diamond slurry to thin the substrate 10 until the thickness of the substrate 10 is about 100 μm.

Next, as shown in FIG. 6B, the n-side electrode 80 is formed by forming a metal laminated film made of, for example, Ti, platinum, and gold on the lower surface of the substrate 10 by, for example, an EB vapor deposition method.

Next, the semiconductor light emitting device that has completed the manufacturing process up to FIG. 6B is cleaved (primary cleaved) along the m-plane so that the length in the m-axis direction is, for example, 2000 μm. Subsequently, for example, using an electron cyclotron resonance (ECR) sputtering method, a front coat film is formed on the cleavage surface that emits laser light to form an end surface 1a, and a rear coat film is formed on the cleavage surface on the opposite side. It is formed to form the end face 1b. The reflectance of the end faces 1a and 1b is set by adjusting the material, composition, film thickness and the like of the coating film. Here, in order to obtain high efficiency of the laser characteristics, the reflectance of the end face 1a on the front side is set to 0.6%, and the reflectance of the end face 1b on the rear side is set to 95.3%. The reflectance of the end face 1a is preferably set to about 0.1% to 18%, and the reflectance of the end face 1b is preferably set to 90% or more.

Subsequently, the primary cleaved semiconductor light emitting device is cleaved (secondary cleaved) so that the length in the Y-axis direction has a pitch of 400 μm, for example. In this way, the semiconductor light emitting device 1 shown in FIGS. 1A and 1B is completed.

FIG. 7 is a diagram showing the distribution of the equivalent refractive index in the Y-axis direction in the semiconductor light emitting device 1. The equivalent refractive index is a refractive index that substantially acts on light, and is a refractive index defined for light propagating inside the semiconductor light emitting device 1.

The distribution of the equivalent refractive index shown in FIG. 7 is obtained by dividing the semiconductor light emitting element 1 by a line parallel to the Z axis passing through the center of the groove 51 in the Y axis direction, and equivalent refraction in each region of the divided semiconductor light emitting element 1. It is obtained by calculating the refractive index using the rate method. According to the first embodiment, the widths of the six groove portions 51 are set to be equal in the Y-axis direction, and the intervals between the groove portions 51 are set to be narrower on the outside than on the center. As a result, as shown in the distribution of the equivalent refractive index, the refractive index gradually decreases from the center to the outside in the waveguide WG corresponding to the ridge portion 50. As described above, when the refractive index gradually decreases from the center to the outside, the number of oscillation modes in the Y-axis direction (slow-axis direction) can be reduced.

FIG. 8 is a cross-sectional view schematically showing the configuration of the semiconductor light emitting device 3.

The semiconductor light emitting device 3 includes a semiconductor light emitting element 1 and a submount 2. The p-side electrode 71 side of the semiconductor light emitting device 1 is fused to, for example, a submount 2 made of SiC and AuSn solder whose surface is Au metal coated. As a result, the semiconductor light emitting device 3 is completed. The semiconductor light emitting device 3 is used, for example, for processing a product.

The semiconductor light emitting device 3 shown in FIG. 8 has a form in which the p-side electrode 71 side of the semiconductor light emitting element 1 is connected to the submount 2 (junction down mounting), but the present invention is not limited to this, and the n of the semiconductor light emitting element 1 is n. The side electrode 80 may be connected to the submount 2 (junction up mounting). Further, the semiconductor light emitting device 3 may have a form in which separate submounts are connected to both the p-side electrode 71 and the n-side electrode 80.

<Effect of Embodiment 1>
According to the first embodiment, the following effects are achieved.

A waveguide WG for propagating the light generated in the optical guide layer 30 is formed corresponding to the ridge portion 50, and a plurality of groove portions 51 formed in the ridge portion 50 in the width direction (Y-axis direction) of the ridge portion 50. The distance between the two is narrower on the outside than in the center. That is, as shown in FIG. 4A, the intervals d21, d22, d23, and d24 of the groove 51 are set to d21> d22> d23> d24. As a result, as shown in FIG. 7, the equivalent refractive index at the center is increased in the waveguide WG corresponding to the ridge portion 50. Therefore, the high-order mode laser beam can be cut by the semiconductor light emitting device 1 to obtain a high beam quality laser beam. Further, the plurality of groove portions 51 arranged at different intervals can be formed relatively easily by the etching process. Therefore, the waveguide WG having an increased equivalent refractive index at the center can be formed easily and with high accuracy.

A configuration (comparative example) in which the width of the waveguide WG in the Y-axis direction is narrowed in order to cut the laser beam in the higher-order mode is also conceivable. However, in such a comparative example, when the laser beam is amplified in the waveguide WG, the temperature tends to rise in the waveguide WG, and the semiconductor light emitting device 1 tends to deteriorate. On the other hand, according to the first embodiment, since the laser beam in the higher-order mode can be cut by forming the plurality of groove portions 51 in the ridge portion 50, it is not necessary to narrow the width of the waveguide WG in the Y-axis direction. .. Therefore, it is possible to suppress the temperature rise in the waveguide WG and suppress the deterioration of the semiconductor light emitting element 1 while cutting the laser beam in the higher-order mode.

In the width direction (Y-axis direction) of the ridge portion 50, the widths of the plurality of groove portions 51 are equal to each other. That is, as shown in FIG. 4A, the widths of the plurality of groove portions 51 are all set to d10. As a result, the width of the groove 51 formed in the ridge 50 can be minimized, and the second semiconductor layer 40 (p-side contact layer 43) can be sufficiently left in the ridge 50. Therefore, the current applied to the semiconductor light emitting element 1 in order to emit a predetermined level of laser light can be suppressed to a low level, and damage to the semiconductor light emitting element 1 can be suppressed.

The depths of the plurality of grooves 51 in the vertical direction are equal to each other. As a result, the plurality of groove portions 51 can be formed more easily by the etching process.

The equivalent refractive index of the plurality of groove portions 51 is lower than the equivalent refractive index of the ridge portion 50 (ridge stripe portion 52) other than the plurality of groove portions 51. As a result, the equivalent refractive index on the outside of the waveguide WG can be set low by the grooves provided at narrow intervals on the outside of the ridge portion 50 in the width direction (Y-axis direction).

The plurality of groove portions 51 are formed by filling the grooves 50a formed in the second semiconductor layer 40 by the etching process with the insulating material of the insulating film 60. Thereby, the equivalent refractive index of the plurality of groove portions 51 can be easily set lower than the equivalent refractive index of the ridge portion 50 (ridge stripe portion 52) other than the plurality of groove portions 51.

<Example of changing the distribution shape of the number of regions in the ridge and the equivalent refractive index>
In the first embodiment, the ridge portion 50 is formed with six groove portions 51, so that the ridge portion 50 is divided into seven and seven ridge stripe portions 52 are formed. However, the number of regions (divisions) of the ridge portion 50 is not limited to 7, and may be 3 or more. Further, the distribution shape of the equivalent refractive index may be higher at the center than at the outside. Hereinafter, a specific example of changing the distribution shape of the number of regions of the ridge portion 50 and the equivalent refractive index will be described.

9 (a) and 9 (b) are diagrams showing the distribution of the equivalent refractive index in the Y-axis direction in the semiconductor light emitting device 1 according to this modified example. 9 (a) and 9 (b) are both modified examples in which the number of groove portions 51 formed in the ridge portion 50 is 10, and the number of regions of the ridge portion 50 is 11. In the modified examples shown in FIGS. 9A and 9B, the width of each groove 51 is the same at d10 as compared with the first embodiment, and only the spacing between the grooves 51 is different.

In the modified example shown in FIG. 9A, the plurality of groove portions 51 are provided so that the distribution of the equivalent refractive index decreases substantially linearly from the center to the outside in the width direction (Y-axis direction) of the ridge portion 50. It is set. That is, as shown by the broken line in FIG. 9A, the distribution of the equivalent refractive index has a shape similar to an isosceles triangle with the center of the ridge portion 50 as the apex and the outer end as the base. In the modified example shown in FIG. 9 (b), as shown by the broken line in FIG. 9 (b), the distribution of the equivalent refractive index is substantially Gauss from the center to the outside in the width direction (Y-axis direction) of the ridge portion 50. A plurality of groove portions 51 are set so as to be low in shape. In any of the modified examples shown in FIGS. 9 (a) and 9 (b), the distance between the plurality of groove portions 51 is set so that the outer side is narrower than the center, so that the outer side is shown in FIGS. 9 (a) and 9 (b). The distribution of the equivalent refractive index can be formed as described above.

FIG. 10 shows the relationship between the number of regions of the ridge portion 50 (the number of ridge stripe portions 52) and the number of modes in the Y-axis direction (number of excitation modes) when the distribution of the equivalent refractive index is an isosceles triangle shape and a Gaussian shape. It is a simulation result showing.

As can be seen with reference to FIG. 10, regardless of whether the equivalent refractive index distribution is an isosceles triangle shape or a Gaussian shape, the number of excitation modes decreases as the number of regions of the ridge portion 50 increases, and the semiconductor light emitting element 1 starts from. The beam quality of the obtained laser beam is improved.

Further, when the distribution of the equivalent refractive index has a Gaussian shape, the number of excitation modes can be suppressed with a smaller number of regions of the ridge portion 50 as compared with the case where the distribution of the equivalent refractive index has an isosceles right triangle shape.

Further, when the distribution of the equivalent refractive index is an isosceles triangle shape, when the number of regions of the ridge portion 50 divided by the plurality of groove portions 51 is 25 or more, the number of excitation modes is 5 or less, and the semiconductor light emitting element 1 The beam quality of the obtained laser beam can be improved. Further, when the distribution of the equivalent refractive index is Gaussian, if the number of regions of the ridge portion 50 divided by the plurality of groove portions 51 is 5 or more, the excitation mode becomes 5 or less, and the laser obtained from the semiconductor light emitting element 1 The beam quality of light can be improved. Further, when the distribution of the equivalent refractive index is Gaussian, the number of excitation modes is set to 5 or less with a smaller number of regions of the ridge portion 50 as compared with the case where the distribution of the equivalent refractive index is an isosceles triangle. can.

<Embodiment 2>
In the first embodiment, the widths of the plurality of groove portions 51 are all set to d10 in the Y-axis direction, and the plurality of groove portions 51 are set so that the distance between the groove portions 51 is narrower than the center on the outside. On the other hand, in the second embodiment, the plurality of groove portions 51 are set so that the intervals between the groove portions 51 are equal and the width of the plurality of groove portions 51 is wider than the center in the Y-axis direction.

FIG. 11 is a cross-sectional view schematically showing the configuration of the semiconductor light emitting device 1 according to the second embodiment.

In the second embodiment, the intervals of the groove portions 51 are all set to d20 in the Y-axis direction, and the widths of the plurality of groove portions 51 are d11, d12, and d13 from the center to the outside, and each groove portion 51 has a width of d11, d12, and d13. The width relationship is d11 <d12 <d13.

FIG. 12 is a diagram showing the distribution of the equivalent refractive index in the Y-axis direction in the semiconductor light emitting device 1 according to the second embodiment.

Similar to the case of FIG. 7, the distribution of the equivalent refractive index shown in FIG. 12 is obtained by dividing the semiconductor light emitting element 1 by a line parallel to the Z axis passing through the center of the groove 51 in the Y axis direction and dividing the semiconductor light emitting element 1. It is obtained by calculating the refractive index using the equivalent refractive index method in each region of. In the second embodiment, the intervals of the groove portions 51 are set to be equal in the Y-axis direction, and the widths of the six groove portions 51 are set to be wider on the outside than on the center. As a result, as shown in the distribution of the equivalent refractive index, the refractive index gradually decreases from the center to the outside in the waveguide WG corresponding to the ridge portion 50.

Therefore, according to the second embodiment, the equivalent refractive index at the center is increased in the waveguide WG corresponding to the ridge portion 50, so that the semiconductor light emitting element 1 cuts the laser beam in the higher-order mode as in the first embodiment. Therefore, high beam quality laser light can be obtained. Further, the plurality of groove portions 51 arranged in different widths can be formed relatively easily by the etching process. Therefore, the waveguide WG having an increased equivalent refractive index at the center can be formed easily and with high accuracy.

<Other changes>
Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various other modifications can be made.

For example, in the above embodiment and the modified example, the groove 51 is formed by filling the groove 50a with the insulating material of the insulating film 60, but the material filled in the groove 50a is not limited to the insulating material of the insulating film 60. It may be lower than the equivalent refractive index of the ridge portion 50 (ridge stripe portion 52) other than the plurality of groove portions 51.

Further, in the above embodiment and the modified example, the depth of the plurality of grooves 50a (grooves 51) in the vertical direction may be larger on the outside than in the center in the Y-axis direction. However, in order to easily form the groove 51, it is preferable that the depths of the plurality of grooves 51 in the vertical direction are the same as in the above embodiment.

Further, in the above embodiment and the modified example, the position of the bottom surface of the groove 50a (groove portion 51) in the Z-axis direction may be different from the position of the upper surface of the p-side clad layer 42 located outside the ridge portion 50. .. However, in order to easily form the groove portion 51 and the ridge portion 50, it is preferable that the position of the bottom surface of the groove 50a and the position of the top surface of the p-side clad layer 42 are equal to each other, as in the above embodiment.

Further, in the first embodiment and the modified example, the groove portion 51 is set so that the distance (gap) between the plurality of groove portions 51 is narrower than the center on the outside, and the pitch of the groove portions 51 (Y of the two adjacent groove portions 51). It is substantially equivalent to setting the groove 51 so that the outer side is narrower than the center (the distance between the centers in the axial direction). That is, even when the groove portion 51 is configured so that the pitch of the groove portion 51 is narrower on the outside than on the center, it is possible to form a waveguide WG in which the equivalent refractive index in the center is increased, as in the first embodiment and the modified example.

The semiconductor light emitting device 3 is not limited to the processing of products, and may be used for other purposes.

In addition, various modifications of the embodiment of the present invention can be made as appropriate within the scope of the technical idea shown in the claims.

1 Semiconductor light emitting element 30 Optical guide layer 40 Second semiconductor layer (semiconductor layer)
50 Ridge part 50a Groove 51 Groove part

Claims (10)

Light guide layer and
A semiconductor layer arranged above the optical guide layer and having a ridge portion formed therein is provided.
A plurality of grooves extending in the vertical direction are formed in the ridge portion.
In the width direction of the ridge portion, the distance between the plurality of grooves portions is narrower on the outside than on the center.
A semiconductor light emitting device characterized by this. In the semiconductor light emitting device according to claim 1,
In the width direction of the ridge portion, the widths of the plurality of groove portions are equal to each other.
A semiconductor light emitting device characterized by this. In the semiconductor light emitting device according to claim 1 or 2.
The depths of the plurality of grooves in the vertical direction are equal to each other.
A semiconductor light emitting device characterized by this. The semiconductor light emitting device according to any one of claims 1 to 3.
The plurality of groove portions are set so that the distribution of the equivalent refractive index decreases substantially linearly from the center to the outside in the width direction of the ridge portion.
A semiconductor light emitting device characterized by this. In the semiconductor light emitting device according to claim 4,
The number of regions of the ridge portion divided by the plurality of grooves is 25 or more.
A semiconductor light emitting device characterized by this. The semiconductor light emitting device according to any one of claims 1 to 3.
The plurality of grooves are set so that the distribution of the equivalent refractive index decreases in a substantially Gaussian shape from the center to the outside in the width direction of the ridge.
A semiconductor light emitting device characterized by this. In the semiconductor light emitting device according to claim 6,
The number of regions of the ridge portion divided by the plurality of grooves is 5 or more.
A semiconductor light emitting device characterized by this. In the semiconductor light emitting device according to any one of claims 1 to 7.
The equivalent refractive index of the plurality of grooves is lower than the equivalent refractive index of the ridges other than the plurality of grooves.
A semiconductor light emitting device characterized by this. In the semiconductor light emitting device according to claim 8,
The plurality of grooves are formed by filling the grooves formed in the semiconductor layer by an etching process with an insulating material.
A semiconductor light emitting device characterized by this. Light guide layer and
A semiconductor layer arranged above the optical guide layer and having a ridge portion formed therein is provided.
A plurality of grooves extending in the vertical direction are formed in the ridge portion.
In the width direction of the ridge portion, the width of the plurality of groove portions is wider on the outside than on the center.
A semiconductor light emitting device characterized by this.

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