JP5862380B2 - Semiconductor laser element - Google Patents

Description

  The present invention relates to a semiconductor laser device.

  A conventional semiconductor laser element has an emission end face and a reflection end face provided on the opposite side to the emission end face. The light generated in the semiconductor laser element is resonated between both end faces, and laser light is emitted from the emission end face. (For example, see Patent Document 1)

Hei 08-330628

  However, when the size of the conventional semiconductor laser element is designed to be small, the distance from the reflection end face to the emission end face (hereinafter also referred to as “resonator length”) is necessarily shortened. For this reason, in a semiconductor laser element having a small element size, there is a problem in that it is difficult to sufficiently amplify even if light generated in the element is resonated, and it is difficult to obtain a high-power semiconductor laser element.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a semiconductor laser device having a high light output even though the device size is small.

  A semiconductor laser device according to one aspect includes a substrate and a semiconductor structure formed on the substrate and having three or more side surfaces. One side surface of the semiconductor structure is provided with a groove having a reflection surface that reflects light generated in the semiconductor structure to the other side surface and an emission surface that emits light generated in the semiconductor structure. The light generated in the semiconductor structure resonates in a region connecting the reflection surface, two or more side surfaces not provided with grooves, and the emission surface.

  A semiconductor laser device according to one aspect includes a substrate and a semiconductor structure formed on the substrate and having three or more side surfaces. One side surface of the semiconductor structure is provided with a reflection side groove having a reflection surface that reflects light generated in the semiconductor structure to the other side surface, and the other side surface of the semiconductor structure emits light generated in the semiconductor structure. An exit side groove having an exit surface is provided. The light generated in the semiconductor structure resonates in a region connecting the reflection surface, one or more side surfaces in which neither the reflection-side groove nor the emission-side groove is provided, and the emission surface.

  According to the present invention, it is possible to provide a semiconductor laser device having a high optical output even if the semiconductor laser device is downsized.

1 is a top view of a semiconductor laser device according to a first embodiment. 1 is a cross-sectional view of a semiconductor laser device according to a first embodiment. (A) is sectional drawing of AA of FIG. (B) is sectional drawing of BB of FIG. FIG. 6 is a top view of a semiconductor laser device according to a modification of the first embodiment. FIG. 6 is a top view of a semiconductor laser device according to a second embodiment. It is a top view of the semiconductor laser element which concerns on the modification of 2nd Embodiment. It is a top view which shows the cleavage direction for obtaining the semiconductor laser element of this invention.

Hereinafter, embodiments for implementing a semiconductor laser device according to the present invention will be described with reference to the drawings. However, the form shown below is the illustration for materializing the technical idea of this invention, Comprising: This invention is not limited to the following. In addition, the positions, sizes, and the like of members shown in each drawing may be exaggerated for clarity of explanation. About the same name and code | symbol, the same or the same member is shown in principle, and the duplicate description is abbreviate | omitted.
(First embodiment)

  FIG. 1 is a top view of the semiconductor laser device 100 according to the first embodiment. FIG. 2 shows a cross-sectional view of the semiconductor laser device 100. 2A is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 2B is a cross-sectional view taken along the line BB in FIG. FIG. 3 shows a top view of a modification of the first embodiment.

  As shown in FIG. 1, the semiconductor laser device 100 includes a substrate 10 and a semiconductor structure 20 formed on the substrate 10 and having three or more side surfaces 30 (30a to f). On one side surface 30 a of the semiconductor structure 20, there is a groove 40 having a reflection surface 50 that reflects light generated in the semiconductor structure 20 to the other side surface 30 b and an emission surface 60 that emits light generated in the semiconductor structure 20. Is provided. The light generated in the semiconductor structure 20 resonates in a region connecting the reflection surface 50, the two or more side surfaces 30 b to f in which the groove 40 is not provided, and the emission surface 60.

  Thereby, even if the element size is reduced, the high-power semiconductor laser element 100 can be obtained.

  In other words, in a conventional semiconductor laser device in which the reflecting surface and the emitting surface are provided on opposite sides, the distance connecting the reflecting surface and the emitting surface with a straight line is the resonator length, and the resonator length is reduced by the element size. Will be shorter. On the other hand, in the semiconductor laser element 100, the light resonating between the reflecting surface 50 and the emitting surface 60 passes through the two or more side surfaces 30b to f where the groove 40 is not provided. The resonator length can be increased as compared with the prior art that resonates on a straight line with the surface. Thereby, even if the element size is reduced, a sufficiently long resonator length can be formed, and a high-power laser beam can be emitted.

  The substrate 10 is for laminating semiconductor structures 20 to be described later. The substrate 10 is preferably a material having a cleavage plane so that the substrate 10 can be divided by cleavage. For example, a nitride semiconductor having a hexagonal crystal structure can be given.

  The upper surface of the substrate 10 (that is, the surface on which the semiconductor structure 20 is stacked) is preferably a c-plane. Thereby, the side surface 30 of the board | substrate 10 can be comprised by m surface. If the substrate 10 is cleaved along the m-plane, it is difficult for cleavage defects to occur. Therefore, by forming the side surface of the substrate 10 with the m-plane formed by cleaving, a semiconductor laser device having excellent mass productivity can be obtained.

As shown in FIGS. 2A and 2B, a semiconductor structure 20 is provided on the substrate 10. The semiconductor structure 20 is a stacked body in which a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23 are stacked in this order from the substrate side. The semiconductor structure 20 emits light when electrons and holes moved from the first semiconductor layer 21 which is a p-type semiconductor and the second semiconductor layer 23 which is an n-type semiconductor are recombined in the active layer 22. The light generated in the semiconductor structure 20 resonates in the plane, and is finally emitted to the outside from the emission surface 60 of the semiconductor structure 20. Examples of the material of the semiconductor structure 20 include a nitride semiconductor made of In _x Al _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). In the case of a nitride semiconductor, an m-plane can be formed on the side surface 30 of the semiconductor structure 20 as will be described later.

  The semiconductor structure 20 has three or more side surfaces 30 and in FIG. 1 has six side surfaces 30a-f. Side surfaces 30 a-f of the semiconductor structure 20 are formed along the stacking direction of the semiconductor structure 20. Also, the side surfaces 30a-f of the semiconductor structure 20 are preferably formed by etching. Thereby, the side surfaces 30a to f of the semiconductor structure 20 can be formed at the same time, and the productivity is improved as compared with the case where the side surfaces 30a to f of the semiconductor structure 20 are formed one by one by cleavage. Note that the etching for forming the side surfaces 30a to 30f of the semiconductor structure 20 may be either dry etching or wet etching.

  As shown in FIG. 2A or 2B, the side surface 30 of the semiconductor structure 20 is formed by continuously exposing the upper surface of the second semiconductor layer 23 to the lower surface of the first semiconductor layer 21. . However, for example, from the upper surface of the second semiconductor layer 23 to the middle of the first semiconductor layer 21 (between the upper surface and the lower surface of the first semiconductor layer 21) or from the upper surface of the second semiconductor layer 23 to the middle of the substrate 10 The side surface 30 may be exposed.

  Further, when a regular hexagon is formed on the side surfaces 30a to 30f of the semiconductor structure 20 as viewed from above as shown in FIG. 1, the side surfaces 30a to f of the semiconductor structure 20 are preferably m-planes. It is because flatter side surfaces 30a-f can be obtained by making the side surfaces 30a-f into stable m-planes.

  Further, when viewed from above, the outer edge of the semiconductor structure 20 can be provided inside the outer edge of the substrate 10 (see FIG. 1). Thereby, it is possible to prevent the side surface 30 of the semiconductor structure 20 from being damaged when the substrate 10 is cleaved.

  The resonance of light will be described with reference to FIG. The light generated in the semiconductor structure 20 is reflected by the reflecting surface 50 provided in the groove 40 of the side surface 30a toward the other side surface 30b adjacent to the side surface 30a. The light reaching the side surface 30b is reflected toward the side surface 30c adjacent to the side surface 30b. In this way, the light is sequentially reflected by the adjacent side surfaces, and finally reflected by the side surfaces 30b to f excluding the side surface 30a having the reflective surface 50, and then is reflected by the exit surface 60 provided in the groove 40 of the side surface 30a. Is reflected again in the opposite direction. By repeating this, the light is amplified and finally the laser light is emitted from the emission surface 60. That is, the light generated in the semiconductor structure 20 resonates on a regular hexagonal path inclined by 60 degrees from the regular hexagon formed on the side surface of the semiconductor structure 20 as indicated by an arrow in FIG. In order to resonate along such a path, it is preferable that the reflection surface 50 and the emission surface 60 are not parallel to the side surface 30a where the groove 40 is provided, but are arranged on different surfaces.

  For example, as shown in FIG. 1, the shape of the groove 40 viewed from above is a notch (V-shape) formed of two surfaces, and one side surface of the groove 40 is emitted from the reflecting surface 50 and the other side surface of the groove 40 is emitted. If the surface 60 is formed so as to be perpendicular to the light path, the light can be efficiently guided as described above.

  The groove 40 is preferably formed by etching. Thereby, the groove | channel 40 can be formed in arbitrary shapes. In order to reduce the number of steps, the trench 40 and the side surfaces 30a-f of the semiconductor structure 20 may be formed simultaneously.

As shown in FIG. 2B, the reflective surface 50 provided in the groove 40 is provided with a reflective film 80 in order to reflect the light generated in the semiconductor structure 20 toward the other side surface 30 b with certainty. Can be provided. Examples of the material of the reflective film 80 include oxides such as Al ₂ O ₃ , SiO ₂ , Nb ₂ O ₅ , TiO ₂ , and ZrO ₂ , and nitrides such as AlN, AlGaN, BN, and SiN. A dielectric multilayer film can be formed by combining two or more kinds.

A protective film having a predetermined reflectance lower than that of the reflective film 80 can be provided on the emission surface 60 provided in the groove 40. Examples of the protective film include oxides such as Al ₂ O ₃ , SiO ₂ , Nb ₂ O ₅ , TiO ₂ , and ZrO ₂ , or nitrides such as AlN, AlGaN, BN, and SiN. A dielectric multilayer film can also be formed by a combination of the above.

  As shown in FIGS. 1 and 2B, a ridge 70 may be provided on the upper portion of the semiconductor structure 20 (that is, a part of the upper side of the second semiconductor layer may be a ridge). The ridge 70 is provided corresponding to a region in which the light generated in the semiconductor structure 20 resonates from the reflection surface 50 to the emission surface 60, whereby light confinement and carrier confinement in the lateral direction (plane direction of the semiconductor structure 20). Can be improved. Specifically, as shown in FIG. 1, since the light generated in the semiconductor structure 20 resonates in a regular hexagonal path when viewed from above, the shape of the ridge 70 when viewed from above is a regular hexagon corresponding to the resonant path of this light. It can be.

  Further, as shown in FIG. 1, the corners on the outer peripheral side of the regular hexagonal ridge 70 can be formed so that the center of the width of the ridge serving as the main optical path coincides with the side surface 30. Thereby, the light reflected by the side surface 30 of the semiconductor structure 20 can be guided without deviating from the ridge 70 formation region.

  Although not shown, a p-electrode can be provided on the upper surface of the second semiconductor layer 23 and an n-electrode can be provided on the lower surface of the substrate 10. Thereby, compared with the case where the p electrode and the n electrode are arranged on the semiconductor structure, the size of the element can be reduced, and the number of semiconductor laser elements taken from the wafer 1000 is increased.

  A reflective film (not shown) can be provided on the side surfaces 30b to 30f in order to reflect light generated in the semiconductor structure 20. Thereby, light generated in the semiconductor structure 20 is reflected from the side surfaces 30b to 30f of the semiconductor structure 20 into the semiconductor structure 20 without leaking to the outside, so that light loss can be suppressed. The material of the reflective film is preferably the same as that of the reflective film 80 provided on the reflective surface 50. Thereby, a reflective film can be simultaneously formed on the side surfaces 30b to 30f and the reflective surface 50 of the semiconductor structure 20, and productivity can be improved.

  As shown in FIG. 6, a regular hexagonal semiconductor laser device 100 can be obtained by cleaving a wafer 1000 in which a plurality of semiconductor structures 20 are arranged on a substrate 10 in three directions (dotted lines shown in FIG. 6). The cleavage in these three directions is preferably performed along the m plane. Thereby, the yield at the time of cleavage can be improved. Further, by cleaving only two of the three directions indicated by the dotted lines in FIG. 6, it is possible to obtain a semiconductor laser device in which the semiconductor structure 20 is a regular hexagon and the outermost edge of the substrate is a parallelogram. Thereby, an element can be formed by a small number of cleavages, and productivity can be improved. In FIG. 6, the groove 40, the ridge 70, and the reflective film 80 are omitted for simplicity of explanation.

The semiconductor laser device 100 according to the first embodiment can be modified as shown in FIG. That is, as shown in FIG. 3A, the semiconductor structure 20 has a regular hexagonal shape in a top view, which is the same as the semiconductor laser device 100 shown in FIG. 1, but the reflection surface 50 and the emission surface 60 of the groove 40 are predetermined. When the light resonates between the reflecting surface 50 and the emitting surface 60, the entire surface may be skipped from the side surface a where the groove 40 is provided and passed through the side surface c and the side surface e. Further, as shown in FIG. 3B, when the top view of the semiconductor structure 20 is an equilateral triangle, when the light resonates between the reflecting surface 50 and the emitting surface 60 provided on the side surface 30g, the side surface 30g. And 30i. The shape of the semiconductor structure 20 in a top view may be a regular n-gon (n ≧ 3), but in particular, if it is a regular hexagon or a regular triangle, all side surfaces can be m-planes, and flat side surfaces can be formed. Can be formed.
(Second Embodiment)

  Hereinafter, a semiconductor laser device 200 according to the second embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a top view of the semiconductor laser element 200. FIG. 5 is a top view of the modification.

  4 is different from the semiconductor laser device 100 in which the reflection surface 50 and the emission surface 60 are provided on the same side surface 30a, the side surfaces 30a and 30e (specifically, the reflection surface 50 and the emission surface 60 are different). Specifically, it is provided in the reflection side groove 41 on the side surface 30a and the emission side groove 42 on the side surface 30e. Other configurations are substantially the same as those of the semiconductor laser device 100 described above.

  As shown in FIG. 4, the semiconductor laser element 200 includes a substrate 10 and a semiconductor structure 20 formed on the substrate 10 and having three or more side surfaces 30 (30a to f). The one side surface 30a of the semiconductor structure 20 is provided with a reflection side groove 41 having a reflection surface 50 for reflecting the light generated in the semiconductor structure 20 to the other side surface 30b. An emission side groove 42 having an emission surface 60 for emitting light generated in the semiconductor structure 20 is provided. The light generated in the semiconductor structure 20 resonates in a region connecting the reflection surface 50, the one or more side surfaces 30 b to 30 d in which neither the reflection-side groove 41 nor the emission-side groove 42 is provided, and the emission surface 60.

  Thereby, in addition to being able to lengthen the resonator length, the resonator length can be adjusted to a desired length. As a result, it is possible to obtain an arbitrary light output while having a high output.

  That is, as shown in FIG. 4, when the reflection-side groove 41 is provided on the side surface 30a and the emission-side groove 42 is provided on the side surface 30e, the resonator length is a length that passes through three points of the side surfaces 30b to 30d. On the other hand, when the exit side groove 42 is provided on the side surface 30d as shown in FIG. 5A, the resonator length becomes a length passing through two points of the side surfaces 30b and 30c. be able to. On the other hand, when the exit side groove 42 is provided on the side surface 30f as shown in FIG. 5 (b), the resonator length becomes a length passing through the four points of the side surfaces 30b to 30e, so that the resonator length can be increased. . In this way, by changing the arrangement of the emission side grooves 42 and changing the number of times of passing through the side surface on which neither the reflection side grooves 41 nor the emission side grooves 42 are provided, even if the semiconductor laser elements are small and the same size, the resonator length Can be adjusted arbitrarily. Thereby, a laser beam can be made into a desired output.

  If the shape of the semiconductor structure 20 in the semiconductor laser element 200 in a top view is a regular hexagon as shown in FIG. 4, the side surface 30 of the semiconductor structure 20 can be configured as an m-plane, so that a flat side surface 30 is obtained. be able to. In addition, even when the regular triangle is formed, the side surface 30 of the semiconductor structure 20 can be configured as an m-plane, and the same effect as in the case of the regular hexagon can be obtained, but the regular hexagon (that is, more polygonal) resonates. The instrument length can be adjusted more finely. The semiconductor laser element 200 is not limited to the above-described shape, and the shape of the top view can be a regular n-gon (n ≧ 3).

  Further, in the semiconductor laser device 200 shown in FIG. 4, the shape of the semiconductor structure 20 in a top view is a regular hexagon, and light that resonates between the reflecting surface 50 and the emitting surface 60 passes through the side surfaces 30b to 30d. As a modification, only the side surface 30c can be passed by setting the reflection surface 50 of the reflection side groove 41 and the emission surface 60 of the emission side groove 42 to a predetermined inclination angle.

DESCRIPTION OF SYMBOLS 100, 200 ... Semiconductor laser element 10 ... Substrate 20 ... Semiconductor structure 21 ... 1st semiconductor layer 22 ... Active layer 23 ... 2nd semiconductor layer 30, 30ai ... Side surface 40 ... groove 41 ... reflection side groove 42 ... emission side groove 50 ... reflection surface 60 ... emission surface 70 ... ridge 80 ... reflection film 1000 ... wafer

Claims (5)

In a semiconductor laser device comprising a substrate and a semiconductor structure formed on the substrate and having three or more side surfaces,
One side surface of the semiconductor structure is provided with a groove having a reflection surface that reflects light generated in the semiconductor structure to another side surface, and an emission surface that emits light generated in the semiconductor structure,
The light generated in the semiconductor structure resonates in a region connecting the reflecting surface, two or more side surfaces not provided with the groove, and the emitting surface. In a semiconductor laser device comprising a substrate and a semiconductor structure formed on the substrate and having three or more side surfaces,
One side surface of the semiconductor structure is provided with a reflection side groove having a reflection surface that reflects light generated in the semiconductor structure to the other side surface.
The other side surface of the semiconductor structure is provided with an emission side groove having an emission surface for emitting light generated in the semiconductor structure,
The light generated in the semiconductor structure resonates in a region connecting the reflection surface, one or more side surfaces in which neither the reflection-side groove nor the emission-side groove is provided, and the emission surface. element. A ridge is provided on top of the semiconductor structure,
3. The semiconductor laser device according to claim 1, wherein the ridge is provided corresponding to a region where light generated in the semiconductor structure resonates from the reflection surface to the emission surface. 4. The semiconductor structure is made of a nitride semiconductor,
Three or more side surfaces of the semiconductor structure are m-planes;
4. The semiconductor laser device according to claim 1, wherein when viewed from above, a regular triangle or a regular hexagon is formed on three or more side surfaces of the semiconductor structure. The substrate is made of a nitride semiconductor,
The semiconductor laser device according to claim 1, wherein the side surface of the substrate is an m-plane formed by cleavage.

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