JP5024637B2 - Semiconductor laser device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a semiconductor laser device having a plurality of waveguides and emitting laser beams having different wavelengths via each waveguide, and a method for manufacturing the same, and more particularly, to a laser beam emitted from the semiconductor laser device. The present invention relates to a semiconductor laser device having a plurality of waveguides having a configuration in which the wavelength can be freely set, and a manufacturing method thereof.

  In optical information equipment and optical communications such as optical disks, magneto-optical disk memories, laser beams and printers, the oscillation wavelength is visible in the 0.6 to 1.5 μm band in response to diversified recording formats and higher recording densities. A semiconductor laser element that emits a plurality of laser beams having different wavelengths in the optical region is demanded as a light source or the like.

  Conventionally, a semiconductor laser device having a plurality of wavelengths is manufactured by, for example, the following method using a selective growth technique of a compound semiconductor layer. For example, Patent Document 1 discloses the growth rate and composition of a compound semiconductor film that is scanned on an substrate with Ar laser light to generate a temperature distribution in the substrate, and then grown on the substrate by metalorganic molecular beam epitaxy. A method is disclosed in which a multi-wavelength semiconductor laser array or the like is integrated on a substrate controlled by distribution.

  Further, in Patent Document 2, a substrate is scanned with an Ar laser beam to generate a temperature distribution in the substrate, and then the surface configuration is changed by the temperature distribution, so that a compound semiconductor layer having a different orientation is formed on the substrate as a gas source MBE. A method of manufacturing a semiconductor laser device having a plurality of wavelengths by selectively growing by a (Molecular Beam Epitaxy) method is disclosed.

  Further, Patent Document 3 discloses a growth of a compound semiconductor layer in which a compound semiconductor layer having a different band gap is partially formed in advance on a substrate by MOCVD to generate a temperature distribution in the substrate, and then grown on the substrate. A method of integrating a multi-wavelength semiconductor laser array or the like on a substrate by controlling the speed and composition by temperature distribution is disclosed.

Japanese Patent Publication No. 5-343801 JP-A-6-236849 Japanese Patent Laid-Open No. 9-283858

  However, the methods of Patent Documents 1 to 3 described above have the following problems. In the methods of Patent Documents 1 and 2, when the temperature distribution is generated by irradiating Ar laser light, the substrate temperature in the region irradiated with Ar laser light changes according to the light intensity of the irradiated Ar laser light. There is no means for accurately adjusting the light intensity of the Ar laser light on the substrate, and a desired temperature distribution cannot be generated, which makes it difficult to accurately control the composition. Therefore, it is difficult to control the oscillation wavelength based on the composition, and it is technically difficult to manufacture a semiconductor laser element that emits a plurality of laser beams having desired wavelengths.

  In the method of Patent Document 3, when a compound semiconductor layer having a different band gap is partially formed on a substrate in advance to generate a temperature distribution, not only the applicable materials are limited, but also a semiconductor laser array is formed. There is also a problem that there is a restriction in arbitrarily setting the composition of the compound semiconductor layer of each semiconductor laser element to be configured. For this reason, it is difficult to put it to practical use as a manufacturing method of a semiconductor laser device that has a low degree of design freedom and emits laser beams having a plurality of desired wavelengths.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a semiconductor laser element having a plurality of waveguides capable of freely setting the wavelength of laser light emitted via each waveguide, and so on. An object of the present invention is to provide a method capable of manufacturing a simple semiconductor laser element by a small number of crystal growth steps.

  The semiconductor laser device of the present invention is a semiconductor laser device that has a plurality of waveguides and emits laser beams having different wavelengths via each waveguide, and includes a high region and a low region lower than the high region. A substrate provided with a step-like structure on the substrate surface to divide the region by a step, an active layer containing two types of group III elements including In and a group V element including N, respectively, and provided above and below the active layer, And a semiconductor laminate having a first conductivity type clad layer and a second conductivity type clad layer sandwiching an active layer and provided on a substrate. Here, the plurality of waveguides are provided in the high region of the step-like structure so that the distances from the steps are different from each other when viewed in plan from above the semiconductor stacked body.

  A method of manufacturing a semiconductor laser device of the present invention is a method of manufacturing a semiconductor laser device having a plurality of waveguides and emitting laser beams having different wavelengths from each other through each waveguide. A step-like structure is provided on the substrate surface that divides the low region lower than the high region by a step, an active layer containing two types of group III elements including In and a group V element including N, and upper and lower portions of the active layer. Forming a semiconductor laminate having a first conductivity type clad layer and a second conductivity type clad layer sandwiching the active layer on the substrate, respectively, and a plan view from above the semiconductor laminate. And a step of forming the plurality of waveguides in the high region of the step-like structure so that the distances from the steps are different from each other.

  In the semiconductor laser device of the present invention, the In concentration in the active layer provided in the high region of the step-like structure is higher as it is closer to the step and lower as it is farther from the step. The higher the In concentration in the active layer, the smaller the band gap energy of the active layer, and thus the longer the oscillation wavelength. In other words, in a semiconductor laser device having a plurality of waveguides provided in the high region of the step-like structure, the laser beam is emitted through the waveguides as the distance between the waveguide and the step-like structure increases. The wavelength of the laser light to be shortened. In other words, since the In concentration of the active layer in the waveguide closest to the step is the highest, the band gap of the active layer is the narrowest and the oscillation wavelength is the longest. As the waveguide is gradually moved away from the step, the In concentration in the active layer becomes lower, so that the band gap of the active layer becomes wider and the wavelength of the emitted laser light becomes longer. Accordingly, it is possible to realize a semiconductor laser element having a plurality of waveguides whose oscillation wavelengths are changed in the same substrate surface, for example, an AlGaInN-based semiconductor laser element.

  The semiconductor laser device of the present invention can be applied as long as it is a semiconductor laser device that emits laser light via a waveguide. For example, a pn junction isolation type current guide structure index guide type semiconductor laser device, gain guide type, pulse It can be applied to a semiconductor laser element of a session type or the like. Further, it is suitable as a semiconductor laser element used in a WDM light source or the like that requires a wide oscillation wavelength range.

  Note that the number of step-like structures is not limited, and it is sufficient that at least one step-like structure is formed on the substrate. The shape of the step-like structure is not limited, and the simplest step-like structure is a step-like structure in which there is one step and one high region and one low region are partitioned by the step. Further, a ridge that has a step on both sides, a low region on both sides and a high region in the center, or a concave groove that forms a high region on both sides and a low region in the center may be used. Moreover, there may be a plurality of ridges and concave grooves. The step height of the step-like structure may be 0.4 μm or more. There is no restriction on the inclination angle of the groove wall of the groove or the ridge side wall of the ridge, and the groove has an inclined surface with an inclination angle of 90 degrees or more so that the width of the groove bottom surface is wider than the opening width of the groove. A concave groove provided as a groove wall may be used. The ridge may be a ridge having an inclined surface with an inclination angle of 90 degrees or more as a ridge wall. Preferably, at least one of the waveguides is provided at a position where the distance between the waveguide and the stepped structure is 50 μm or less. By setting the distance between the waveguide and the step of the step-like structure to 50 μm or less, it is possible to form a waveguide in which the wavelength of the emitted laser light is clearly different from other waveguides.

  According to the semiconductor laser device of the present invention, a semiconductor stacked body is formed on a substrate having a stepped structure with a step, and the distance between the stepped structure and the waveguide is changed to change the In and N of the waveguide. By changing the In concentration in the active layer, it is possible to emit light having different wavelengths from the plurality of waveguides. In addition, according to the method for manufacturing a semiconductor laser device of the present invention, a semiconductor stacked body can be formed by a single crystal growth, the surface morphology is good, and the crystal growth rate in each waveguide is a step-like structure. Design and fabrication are facilitated because it hardly depends on the distance from the device.

1A and 1B are a top view and a side view showing a schematic configuration of a semiconductor laser element according to a first embodiment of the present invention. FIG. 6 is a top view and a side view illustrating a schematic configuration of a semiconductor laser element according to a second embodiment of the present invention. FIG. 6 is a top view and a side view illustrating a schematic configuration of a semiconductor laser element according to a third embodiment of the present invention. FIG. 6 is a top view and a side view showing a schematic configuration of a semiconductor laser element according to a fourth embodiment of the present invention. 1 is a perspective view showing a configuration of a semiconductor laser element of Example 1. FIG. FIG. 6 is a cross-sectional view taken along line II of FIG. 5 showing the configuration of the semiconductor laser device of Example 1. FIG. 3 is an enlarged cross-sectional view showing a laminated structure of compound semiconductor layers in the vicinity of a first waveguide of the semiconductor laser element of Example 1. 1 is a perspective view showing a configuration of a substrate for a semiconductor laser element of Example 1. FIG. 6 is a perspective view showing a configuration of a semiconductor laser element of Example 2. FIG. FIG. 10 is a cross-sectional view taken along line II-II in FIG. 9, showing the configuration of the semiconductor laser element of Example 2. FIG. 6 is a perspective view showing a configuration of a substrate for a semiconductor laser element of Example 2. 6 is a perspective view showing a configuration of a semiconductor laser element of Example 3. FIG. FIG. 13 is a cross-sectional view taken along the line III-III in FIG. 12, showing the configuration of the semiconductor laser element of Example 3. FIG. 6 is a perspective view showing a configuration of a substrate for a semiconductor laser element of Example 3. 6 is a cross-sectional view showing a configuration of a semiconductor laser device of Example 4. FIG. FIGS. 16A and 16B are schematic cross-sectional views showing the shape of a concave groove and the shape of a ridge, respectively, which are different from those of the embodiment. It is a graph which shows the relationship between the distance of the waveguide from the level | step difference of a step-like structure, and the wavelength of a laser beam. It is a graph which shows the relationship between a ridge width and the wavelength of a laser beam.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the composition of the compound semiconductor layer, the film thickness, the film forming method, and other dimensions shown in the following embodiment examples and examples are examples for facilitating understanding of the present invention, and the present invention It is not limited to these examples.

<First Embodiment>
(Configuration of Semiconductor Laser Element 10)
FIG. 1A is a top view showing the layout of the semiconductor laser device (semiconductor laser device 10) of the first embodiment, and FIG. 1B is the shape of the step-like structure and the lead on the step-like structure. It is a typical side view which shows the position of a waveguide and a separation groove. The semiconductor laser element 10 is formed on an n-type GaAs substrate 12 having an inclined surface inclined at an inclination angle in a range of 2 ° to 15 ° in the [0-1-1] direction from the (100) plane, for example, [01-1 A step-like structure 14 extending in the direction.

  The step-like structure 14 is a step-like structure having the simplest configuration, and includes a single high region 16 and a single low region 20 that is lowered from the high region 16 by a step 18, for example, The height of the step 18 is 2.7 μm, the width of the high region 16 is 250 μm, the width of the low region 20 is 150 μm, and the length in the [01-1] direction is 600 μm. The semiconductor laser device 10 includes an active layer containing two types of group III elements including In and a group V element including P, a first conductivity type cladding layer disposed on and under the active layer, and a first conductivity type cladding layer sandwiching the active layer. A semiconductor laminate made of an AlGaInP-based compound semiconductor layer having a two-conductivity-type cladding layer is provided on the substrate 12.

  In the present embodiment, three waveguides 22 </ b> A to 22 </ b> C extending in the [01-1] direction are arranged in the high region 16 of the step-like structure 14. The first waveguide 22A is disposed in the high region 16 near the step 18 at a distance X from the step 18 of 50 μm or less, for example, about 4 μm. The second waveguide 22B is disposed in the high region 16 so that the distance Y from the step 18 is longer than the distance X and is 50 μm or less, for example, 34 μm. The third waveguide 22C has a distance Z from the step 18 longer than the distance Y, and is disposed in the high region 16 at a distance of about 104 μm, for example. When the width of each waveguide 22 is 3 μm, with the above arrangement, the distance between the first waveguide 22A and the second waveguide 22B is 27 μm, and the distance between the second waveguide 22B and the third waveguide 22C is 67 μm. . Each waveguide 22 is separated from each other by a separation groove 24 provided in the semiconductor stacked body.

  When an active layer having a multiple quantum well structure is grown on the substrate 12 having the step-like structure 14, the concentration of In in the active layer is higher as it is closer to the step 18 of the step-like structure 14, and becomes lower as the distance is further away. Therefore, according to the length of the distance between the waveguide 22 and the step 18, the In concentration of the active layer decreases in the order of the first waveguide 22A, the second waveguide 22B, and the third waveguide 22C, and the band gap is The first waveguide 22A, the second waveguide 22B, and the third waveguide 22C become wider in this order.

  In other words, the semiconductor laser element 10 has three waveguides whose oscillation wavelengths become shorter in the order of the first waveguide 22A, the second waveguide 22B, and the third waveguide 22C, and lasers having different wavelengths. Light is emitted via each waveguide 22A-C. That is, by changing the distance between the step and the waveguide, the oscillation wavelength of each waveguide of the semiconductor laser element can be changed. Further, since the compound semiconductor is formed on the inclined substrate, the surface morphology is good, abnormal growth is greatly suppressed, and there is almost no change in the growth rate due to the difference in the distance from the step of the step-like structure.

(Method for Manufacturing Semiconductor Laser Element 10)
A method for manufacturing the semiconductor laser device 10 will be described. First, on the n-type GaAs substrate 12 having an inclined surface inclined by 2 ° to 15 ° in the [0-1-1] direction from the (100) plane, the [01-1] direction is performed by a photolithography process and an etching process. A step-like structure 14 having a high region 16 and a low region 20 that are partitioned by a step 18 extending in the direction is formed.

  Next, an active layer containing two types of group III elements including In and a group V element including P is formed on the substrate 12 on which the stepped structure 14 is formed, for example, by MOCVD (metal organic chemical vapor deposition). An AlGaInP-based semiconductor stacked body is formed in a single crystal growth step, which is disposed above and below the active layer and has a first conductivity type cladding layer and a second conductivity type cladding layer sandwiching the active layer. Next, ridge stripes that respectively constitute the first waveguide 22A, the second waveguide 22B, and the third waveguide 22C of the semiconductor laser element are formed on the top of the semiconductor stacked body, and each waveguide 22 is separated by the separation groove 24. Then, by forming an electrode (not shown) and further cleaving, the semiconductor laser device 10 of this embodiment can be manufactured. According to the manufacturing method of the semiconductor laser device 10 in the present embodiment, the semiconductor stacked body of the semiconductor laser device 10 can be formed by a single crystal growth.

<Second Embodiment>
FIG. 2A is a top view showing the layout of the semiconductor laser device (semiconductor laser device 30) according to the second embodiment, and FIG. 2B is the shape of the concave groove, the waveguide for the concave groove, and It is a typical side view which shows the position of a separation groove. The semiconductor laser element 30 has the same configuration as the semiconductor laser element 10 of the first embodiment except that the shape of the step-like structure is different and the arrangement of the waveguides with respect to the step-like structure is different. .

  As shown in FIG. 2, the stepped structure of the semiconductor laser element 30 is provided on the same n-type GaAs substrate 12 as that of the semiconductor laser element 10 of the first embodiment, for example, in the [01-1] direction. It is formed as a groove 34 that extends. The concave groove 34 has steps 38A and B that divide the central low region 40 from the high regions 36A and B on both sides. For example, the height of the step 38, that is, the groove depth is 2.7 μm, the groove width is 62 μm, The length in the [01-1] direction is 600 μm. The semiconductor laser device 30 includes a semiconductor stacked body having the same configuration as that of the first embodiment on an n-type GaAs substrate 12.

  In the present embodiment, three waveguides 42 </ b> A to 42 </ b> C extending in the [01-1] direction are arranged in the high regions 36 on both sides of the groove 34. The first waveguide 42A is disposed in the high region 36B at a distance X of the concave groove 34 from the step 38B of 50 μm or less, for example, about 4 μm. The second waveguide 42B is arranged in the high region 38A with a distance Y from the step 38A longer than the distance X and 50 μm or less, for example, 34 μm. The third waveguide 42C is disposed in the high region 36B with a distance Z from the step 38B longer than the distance Y, for example, a distance of about 104 μm. With the above arrangement, the distance between the first waveguide 42A and the second waveguide 42B is 100 μm, and the distance between the second waveguide 42B and the third waveguide 42C is 200 μm. The waveguides 42 are separated from each other by a separation groove 44 provided in the semiconductor stacked body.

  In the semiconductor laser device 30 of the present embodiment, as in the semiconductor laser device 10 of the first embodiment, according to the length of the distance between the waveguide 42 and the step 38, the first waveguide 42A and the second waveguide 42B. In the order of the third waveguide 42C, the In concentration of the active layer decreases, and the band gap increases in the order of the first waveguide 42A, the second waveguide 42B, and the third waveguide 42C. . That is, the semiconductor laser device 30 of the present embodiment has three waveguides 42A to 42C, and the oscillation wavelength is in the order of the first waveguide 42A, the second waveguide 42B, and the third waveguide 42C. A short laser beam is emitted via each of the waveguides 42A to 42C.

  That is, in the present embodiment, the oscillation wavelength of each waveguide 42 can be freely changed by changing the distance between the step 38 and the waveguide 42. Further, by changing the groove width of the concave groove 34, the interval between the second waveguide 42B and the first waveguide 42A or the second waveguide 42B and the third waveguide can be obtained without changing the oscillation wavelength of each waveguide 42. Since the distance from 42C can be changed, the degree of freedom in design increases. Furthermore, since the semiconductor laminate is formed on the inclined substrate, the surface morphology is good, abnormal growth is greatly suppressed, and there is almost no change in growth rate due to the difference in distance from the concave groove 34.

  The semiconductor laser element 30 can be manufactured in the same manner as the semiconductor laser element 10 of the first embodiment. That is, the concave groove 34 extending in the [01-1] direction is formed as a step-like structure on the same n-type GaAs substrate 12 as the semiconductor laser element 10 by a photolithography process and an etching process. Thereafter, the semiconductor laser element 30 can be manufactured by a single crystal growth in the same manner as the semiconductor laser element 10 of the first embodiment.

<Third Embodiment>
FIG. 3A is a top view showing the layout of the semiconductor laser device (semiconductor laser device 50) according to the third embodiment, and FIG. 3B is the shape of the ridge, and the waveguide and separation groove for the ridge. It is a typical side view which shows the position. The semiconductor laser device 50 has the same configuration as the semiconductor laser device 10 of the first embodiment except that the shape of the step-like structure is different and the arrangement of the waveguide with respect to the step-like structure is different.

  The step-like structure of the semiconductor laser element 50 has a plurality of ridge widths that are provided on the same n-type GaAs substrate 12 as that of the semiconductor laser element 10 of the first embodiment and extend in the [01-1] direction, for example. The convex ridges 54A to 54C (three ridges are shown in FIG. 3) are formed. The ridge 54 divides a high region 56 on the ridge 54 and a low region 60 on both sides from the high region 56 by a step 58. For example, the ridge height is 2.7 μm, the ridge width is 100 μm, the period is 150 μm, and [01− 1] The length in the direction is 600 μm. The semiconductor laser device 50 includes a semiconductor stacked body having the same configuration as that of the semiconductor laser device 10 of the first embodiment on an n-type GaAs substrate 12.

  In the present embodiment, one waveguide 62A-C extending in the [01-1] direction is provided on each ridge 54A-C. The first waveguide 62A is provided on the first ridge 54A so that the distance X from the step 58 closer to the first ridge 54A is 50 μm or less, for example, about 4 μm. The second waveguide 62B is provided on the second ridge 54B so that the distance Y from the step 58 closer to the second ridge 62B is longer than the distance X and is 50 μm or less, for example, about 24 μm. The third waveguide 62C is provided on the third ridge 54C so that the distance Z from the step 58 closer to the third ridge 62C is longer than the distance Y, for example, a distance of about 44 μm. When the width of each waveguide is 3 μm, the distance between the first waveguide 62A and the second waveguide 62B and the distance between the second waveguide 62B and the third waveguide 62C are the same distance due to the above arrangement. And 167 μm respectively. Each waveguide 62 is separated from each other by a separation groove 64.

  In the semiconductor laser device 50 of the present embodiment, similarly to the semiconductor laser device 10 of the first embodiment, according to the distance between the step 58 and the waveguide 62, the first waveguide 62A and the second waveguide 62B. In the order of the third waveguide 62C, the In concentration of the active layer decreases, and the band gap increases in the order of the first waveguide 62A, the second waveguide 62B, and the third waveguide 62C. That is, the semiconductor laser device 50 of the present embodiment has three waveguides 62A to 62C, and the oscillation wavelength is in the order of the first waveguide 62A, the second waveguide 62B, and the third waveguide 62C. A short laser beam is emitted via each waveguide 62A-C.

  In the semiconductor laser device 50 of the present embodiment, the oscillation wavelength of each waveguide can be freely changed by changing the distance between the step 58 and the waveguide 62. Further, by changing the interval between the ridges 54, without changing the oscillation wavelength of each waveguide 62, the interval between the first waveguide 62A and the second waveguide 62B, the second waveguide 62B and the third waveguide 62C. Since the interval between and can be changed, the degree of freedom in design increases. Further, since the semiconductor laminate is formed on the inclined substrate, the surface morphology is good, abnormal growth is greatly suppressed, and there is almost no growth rate change due to the difference in distance from the step 58.

  The manufacturing method of the semiconductor laser device 50 can also be manufactured in the same manner as the semiconductor laser device 10 of the first embodiment. That is, ridges 54A to 54C extending in the [01-1] direction are formed on the same n-type GaAs substrate 12 as the semiconductor laser device 10 by a photolithography process and an etching process. Thereafter, in the same manner as the semiconductor laser device 10 of the first embodiment, the semiconductor laser device 50 of the present embodiment example can be manufactured by a single crystal growth.

<Fourth embodiment>
4A is a top view showing the layout of the semiconductor laser device (semiconductor laser device 70) according to the present embodiment, and FIG. 4B is the shape of the ridge, and the position of the waveguide and the separation groove with respect to the ridge. It is a typical side view which shows. 4 that are the same as those shown in FIG. 3 are marked with the same symbols and descriptions of them will be omitted. The semiconductor laser element 70 has the same configuration as that of the semiconductor laser element 50 of the third embodiment except that the ridge widths of the three ridges 72A to 72C (only three are simply shown in FIG. 4) are different from each other. I have.

  The ridges 72A to 72C have, for example, a ridge height of 2.7 μm, a period P of 150 μm, a length in the [01-1] direction of 600 μm, and a ridge width of the first ridge 72A of 100 μm or less, for example, about 25 μm. The second ridge 72B is wider than the first ridge 72A and 100 μm or less, for example, about 35 μm, and the third ridge 72C is 100 μm wider than the second ridge 72B. Here, the period P means from the center of the first ridge 74A to the center of the second ridge 74B and from the center of the second ridge 74B to the center of the third ridge 74C, as shown in FIG. The semiconductor laser element 70 includes a semiconductor stacked body having the same configuration as that of the first embodiment on an n-type GaAs substrate 72.

  In the present embodiment, three waveguides 74 </ b> A to 74 </ b> C extending in the [01-1] direction are arranged one by one near the center of each ridge 72. Accordingly, the distance X from the step 58 on both sides of the first ridge 72A is about 12.5 μm in the first waveguide 74A, and the distance Y from the step 58 on both sides of the second ridge 72B is in the second waveguide 72B. The third waveguide 72C has a distance Z from the step 58 on both sides of the third ridge 72C of about 50 μm. When the width of each waveguide is 3 μm, the distance between the first waveguide 74A and the second waveguide 74B and the distance between the second waveguide 74B and the third waveguide 74C are the same due to the above arrangement. Respectively, which is 147 μm.

  In the semiconductor laser device 70 of the present embodiment, as in the semiconductor laser device 10 of the first embodiment, according to the distance between the step 58 and the waveguide 74, the first waveguide 74A and the second waveguide 74B. In the order of the third waveguide 74C, the In concentration of the active layer decreases, and the band gap increases in the order of the first waveguide 74A, the second waveguide 74B, and the third waveguide 74C. That is, the semiconductor laser device 70 of the present embodiment has three waveguides, and laser light having a short oscillation wavelength in the order of the first waveguide 74A, the second waveguide 74B, and the third waveguide 74C. Is emitted via each of the waveguides 74A to 74C.

  In the present embodiment, by changing the distance between the step 58 and the waveguide 74 by changing the ridge width of the ridge 72, the oscillation wavelength of each waveguide can be freely changed. Furthermore, since the ridges 72 having different ridge widths are used, the In concentration of the active layer of each waveguide 74 is affected by the step 58 on both sides of the waveguide 74, and therefore the In layer of the active layer is changed by a small change in the ridge width. The concentration can be changed greatly, that is, the band gap can be changed greatly. Further, by changing the interval between the ridges 72, without changing the oscillation wavelength of each waveguide 74, the interval between the first waveguide 74A and the second waveguide 74B, and the second waveguide 74B and the third waveguide 74C. Since it is possible to change the interval, the degree of freedom in design can be increased. Further, since the semiconductor laminate is formed on the inclined substrate, the surface morphology is good, abnormal growth is greatly suppressed, and there is almost no growth rate change due to the difference in distance from the step 58.

  The manufacturing method of the semiconductor laser device 50 can also be manufactured in the same manner as the semiconductor laser device 10 of the first embodiment. That is, ridges 72A to 72C extending in the [01-1] direction are formed on the same n-type GaAs substrate 12 as the semiconductor laser element 10 by a photolithography process and an etching process. Thereafter, in the same manner as the semiconductor laser device 10 of the first embodiment, the semiconductor laser device 70 of the present embodiment example can be manufactured by a single crystal growth.

<Fifth embodiment>
(Configuration of semiconductor laser element)
The semiconductor laser device according to the present embodiment is different from the semiconductor laser device 10 of the first embodiment in the following items (1) and (2), and other configurations are the same as those of the first embodiment. This is the same as the semiconductor laser device 10 of the embodiment.
(1) The semiconductor laser device according to the present embodiment has an n-type GaAs substrate 10 having an inclined surface inclined at an inclination angle in the range of 2 ° to 15 ° in the [0-1-1] direction from the (100) plane. Instead, a step-like structure is provided on an n-type GaN substrate having a flat substrate surface that is not an inclined surface, that is, a (0001) plane as the substrate surface.
(2) The semiconductor laser device according to the present embodiment is replaced with a semiconductor stacked body composed of an AlGaInP-based compound semiconductor layer having an active layer containing two types of group III elements including In and a group V element including P. And a semiconductor laminate comprising an AlGaInN-based compound semiconductor layer having an active layer containing two types of Group III elements including In and Group V elements including N on a substrate.

  In addition, although there is no restriction | limiting in the extending | stretching direction of a step-like structure, in this example of embodiment, it is supposed that the step-like structure is extended | stretched in the [01-1] direction similarly to 1st Embodiment. Except for the above, FIG. 1A is a top view showing the layout of the semiconductor laser device of this embodiment, and FIG. 1B is the shape of the step-like structure of the semiconductor laser device of this embodiment. Moreover, it can be a schematic side view showing the position of the waveguide and the separation groove on the step-like structure.

  In the following description of the semiconductor laser device according to the present embodiment, the description of the semiconductor laser device 10 according to the first embodiment has been corrected in consideration of the above items (1) and (2). Is. As shown in FIG. 1, the semiconductor laser device 11 according to the present embodiment has a step-like structure extending, for example, in the [01-1] direction on an n-type GaN substrate 12 having a (0001) plane substrate surface. 14 is provided.

  The step-like structure 14 is a step-like structure having the simplest configuration, and includes a single high region 16 and a single low region 20 that is lowered from the high region 16 by a step 18, for example, The height of the step 18 is 2.7 μm, the width of the high region 16 is 250 μm, the width of the low region 20 is 150 μm, and the length in the [01-1] direction is 600 μm. The semiconductor laser element 11 includes an active layer containing two types of group III elements including In and a group V element including N, a first conductivity type cladding layer disposed on and under the active layer, and a first conductivity type cladding layer sandwiching the active layer. A semiconductor laminate made of an AlGaInN-based compound semiconductor layer having a two-conductivity-type cladding layer is provided on the substrate 12.

  In the present embodiment, three waveguides 22 </ b> A to 22 </ b> C extending in the [01-1] direction are arranged in the high region 16 of the step-like structure 14. The first waveguide 22A is disposed in the high region 16 near the step 18 at a distance X from the step 18 of 50 μm or less, for example, about 4 μm. The second waveguide 22B is disposed in the high region 16 so that the distance Y from the step 18 is longer than the distance X and is 50 μm or less, for example, 34 μm. The third waveguide 22C has a distance Z from the step 18 longer than the distance Y, and is disposed in the high region 16 at a distance of about 104 μm, for example. When the width of each waveguide 22 is 3 μm, with the above arrangement, the distance between the first waveguide 22A and the second waveguide 22B is 27 μm, and the distance between the second waveguide 22B and the third waveguide 22C is 67 μm. . Each waveguide 22 is separated from each other by a separation groove 24 provided in the semiconductor stacked body.

  When an active layer having a multiple quantum well structure is grown on the substrate 12 having the step-like structure 14, the concentration of In in the active layer is higher as it is closer to the step 18 of the step-like structure 14, and becomes lower as the distance is further away. Therefore, according to the length of the distance between the waveguide 22 and the step 18, the In concentration of the active layer decreases in the order of the first waveguide 22A, the second waveguide 22B, and the third waveguide 22C, and the band gap is The first waveguide 22A, the second waveguide 22B, and the third waveguide 22C become wider in this order.

  That is, the semiconductor laser device 11 according to the present embodiment has three waveguides whose oscillation wavelengths become shorter in the order of the first waveguide 22A, the second waveguide 22B, and the third waveguide 22C. In addition, laser beams having different wavelengths are emitted via the respective waveguides 22A to 22C. That is, in this embodiment, the oscillation wavelength of each waveguide of the semiconductor laser element can be changed by changing the distance between the step and the waveguide. Further, since the compound semiconductor is formed on the inclined substrate, the surface morphology is good, abnormal growth is greatly suppressed, and there is almost no change in the growth rate due to the difference in the distance from the step of the step-like structure.

(Method for manufacturing semiconductor laser device)
The manufacturing method of the semiconductor laser device according to the present embodiment is the same as that of the semiconductor laser device 10 according to the first embodiment except that the manufacturing method is different from the manufacturing method of the semiconductor laser device 10 according to the first embodiment in the following items (1) and (2). The same steps as those of the semiconductor laser element 10 are provided.
(1) In the manufacturing method of the semiconductor laser device of the present embodiment, the substrate has an inclined surface inclined at an inclination angle in the range of 2 ° to 15 ° in the [0-1-1] direction from the (100) plane. Instead of the n-type GaAs substrate 10, an n-type GaN substrate having a flat substrate surface that is not an inclined surface, that is, a (0001) surface as the substrate surface is used.
(2) In the method of manufacturing a semiconductor laser device according to the present embodiment, a semiconductor stacked body composed of an AlGaInN-based compound semiconductor layer having an active layer containing two types of group III elements including In and a group V element including N is used. Instead, a semiconductor stacked body made of an AlGaInN-based compound semiconductor layer having an active layer containing two types of group III elements including In and a group V element including N is formed on a substrate.

  In the following description of the method for manufacturing the semiconductor laser device according to the present embodiment, the above-described items (1) and (2) are taken into consideration, and the method for manufacturing the semiconductor laser device 10 according to the first embodiment is described below. The explanation about is corrected. First, a high region 16 and a low region defined by a step 18 extending in the [01-1] direction are formed on an n-type GaN substrate 12 having a (0001) plane substrate surface by a photolithography process and an etching process. 20 is formed.

  Next, an active layer containing two kinds of group III elements including In and a group V element including N is formed on the substrate 12 on which the step-like structure 14 is formed, for example, by MOCVD (metal organic chemical vapor deposition). An AlGaInN-based semiconductor stacked body is formed in one crystal growth step, which is disposed above and below the active layer and has a first conductivity type cladding layer and a second conductivity type cladding layer sandwiching the active layer. Next, ridge stripes that respectively constitute the first waveguide 22A, the second waveguide 22B, and the third waveguide 22C of the semiconductor laser element are formed on the top of the semiconductor stacked body, and each waveguide 22 is separated by the separation groove 24. Then, by forming an electrode (not shown) and further cleaving, the semiconductor laser device 11 of this embodiment can be manufactured. According to the manufacturing method of the semiconductor laser device of the present embodiment, the semiconductor stacked body of the semiconductor laser device 11 can be formed by one crystal growth.

  In the fifth embodiment, the step-like structure or the ridge structure according to the second to fourth embodiments can be employed. In this case, FIGS. Reference can be made to the drawings in the form.

Example 1
This example is a specific example of the semiconductor laser device of the first embodiment, and FIGS. 5, 6, and 7 are perspective views showing the configuration of the semiconductor laser device 80 of Example 1, respectively. FIG. 6 is a cross-sectional view taken along a line II in FIG. 5 and an enlarged cross-sectional view showing a laminated structure of compound semiconductor layers in the vicinity of a first waveguide. Of the parts shown in FIGS. 5 to 7, the same parts as those in FIG. As shown in FIG. 5, the semiconductor laser device 80 of the present example has the same step-like structure 14 as that of the first embodiment on an inclined surface inclined by 10 ° in the [0-1-1] direction from the (100) plane. On an n-type GaAs substrate 81 provided with a semiconductor laminated body 82 made of an AlGaInP-based compound semiconductor layer.

  As shown in FIG. 7, the semiconductor stacked body 82 is formed on an n-type GaAs substrate 81, an n-type cladding layer 84 having a thickness of 1.1 μm made of (Al0.7Ga0.3) 0.5In0.5P, and (Al0 .5Ga0.5) 0.5In0.5P guide layer 86, Ga0.5In0.5P / (Al0.5Ga0.5) 0.5In0.5P multi-quantum well structure active layer 88, (Al0.5Ga0. 5) Guide layer 90 made of 0.5In0.5P, p-type cladding layer 92 having a thickness of 0.3 μm made of (Al0.7Ga0.3) 0.5In0.5P, and p-type etching stop made of Ga0.5In0.5P A layer 94, a p-type cladding layer 96 made of (Al0.7Ga0.3) 0.5In0.5P with a thickness of 1.1 μm, and a p-type carrier made of GaAs with a thickness of 0.35 μm. It is configured as a laminated structure of up layer 98. The active layer 88 is a three-cycle multiple quantum composed of a Ga0.5In0.5P layer having a thickness of 3.5 nm and an (Al0.5Ga0.5) 0.5In0.5P layer having a thickness of 4.0 nm. It is formed as a well structure. FIG. 7 shows a stacked structure of compound semiconductor layers in the vicinity of the first ridge stripe 23A, but the semiconductor stacked body 82 has the same stacked structure in other regions.

  As shown in FIG. 6, the p-type cap layer 98 and the p-type cladding layer 96 are etched using the etching stop layer 94 as an etching stop layer in the semiconductor stacked body 82, and the first to third waveguides 22 </ b> A to 22 </ b> C are formed. First to third ridge stripes 23A to 23C each having a width of 3 μm are formed on the high region 16 of the step-like structure 14 in the [01-1] direction. The distance between the first ridge stripe 23A and the step 18 is 4 μm, the distance between the second ridge stripe 23B and the step 18 is 34 μm, and the distance between the third ridge stripe 23C and the step 18 is 104 μm.

  Each ridge stripe 23 </ b> A to 23 </ b> C is buried with an n-type buried layer 100 made of a GaAs layer on the side of the ridge except for the p-type cap layer 98 on each ridge stripe 23. A current confinement structure is formed by the pn junction isolation between the p-type cap layer 98 and the p-type cladding layer 96 and the n-type buried layer 100. Further, mutually independent p-side electrodes 102 are formed on the p-type cap layer 98 and the n-type buried layer 100 so as to be connected to the p-type cap layer 98 of each ridge stripe 23. Further, since the p-side electrode 102 on the second ridge stripe 23B is connected via the extraction electrode 104 extending across the third ridge stripe 23C, the p-side electrode 102 of the third ridge stripe 23C is connected to the p-side electrode 102. An insulating film 106 is provided between the extraction electrode 104. Further, a common n-side electrode 108 is formed on the back surface of the n-type GaAs substrate 81 as shown in FIG. An element isolation groove 24 is formed between the ridge stripes 23A to 23C, and the isolation groove 24 between the second ridge stripe 23B and the third ridge stripe 23C is a buried insulating layer embedded with an insulator such as polyimide. 110. In FIG. 5, the lead-out electrode 104 of the p-side electrode 102 of the second ridge stripe 23B extends across the first ridge stripe 23A, unlike FIG. 6, for convenience.

  The semiconductor laser device 80 of this example is formed as an index guide structure in each of the first to third ridge stripes 23A to 23C, and as described in the first embodiment, the first waveguide 22A. The second waveguide 22B and the third waveguide 22C have three waveguides whose oscillation wavelengths are shortened in this order, and emit laser beams having mutually different wavelengths via the respective waveguides 22A to 22C. . With the above configuration, the semiconductor laser device 80 of this example has the same effects as those of the first embodiment.

  With reference to FIG. 8, the manufacturing method of the semiconductor laser device 80 of the present embodiment will be described. FIG. 8 is a perspective view showing the configuration of the substrate for the semiconductor laser element 80 of the present embodiment. As shown in FIG. 8, n-type GaAs having an inclined surface inclined by 10 ° in the [0-1-1] direction from the (100) plane by photolithography and a wet etching method using a mixed etchant of H 2 SO 4, H 2 O 2, and H 2 O. The substrate 81 is etched to form a concave groove 112 having a depth of 2.7 μm, a width of 200 μm, extending in the [01-1] direction and having a step 18 on both sides as a groove wall in the [0-1-1] direction. Formed at a period of 800 μm. In FIG. 8, the substrate region that finally constitutes one semiconductor laser element 80 is indicated by Z.

  Next, on the substrate 81 in which the concave groove 112 is formed, the film thickness made of (Al0.7Ga0.3) 0.5In0.5P is 1.1 μm by MOCVD with a substrate temperature of 690 ° C. as shown in FIG. N-type cladding layer 84, guide layer 86 made of (Al0.5Ga0.5) 0.5In0.5P, and multiple quantum well structure made of Ga0.5In0.5P / (Al0.5Ga0.5) 0.5In0.5P Active layer 88, guide layer 90 made of (Al0.5Ga0.5) 0.5In0.5P, p-type cladding layer 92 made of (Al0.7Ga0.3) 0.5In0.5P and having a thickness of 0.3 μm, Ga0. A p-type etching stop layer 94 made of 5In0.5P, a p-type cladding layer 96 made of (Al0.7Ga0.3) 0.5In0.5P with a thickness of 1.1 μm, and Ga Thickness made of s is a 0.35μm p-type cap layer 98 are sequentially stacked to form a semiconductor laminate 82.

  Next, by using the etching stop layer 94 as an etching stop layer, the first to third ridge stripes 23A to 23C having a width of 3 μm extending in the [01-1] direction are formed by photolithography and wet etching as shown in FIG. They were formed 4 μm, 34 μm, and 104 μm apart from the step 18 of the groove 112. Next, an n-type GaAs buried layer 100 is formed in a region excluding the p-type cap layer 98 on the first to third ridge stripes 23A to 23C by masking with an insulating film and MOCVD, and the first to third ridges are formed. The ridge side of stripes 23A-C was embedded. Subsequently, etching is performed by photolithography and a wet etching method using a mixed etchant of H 2 SO 4, H 2 O 2, and H 2 O, and between the first ridge stripe 23 A and the second ridge stripe 23 B, and between the second ridge stripe 23 B and the third ridge stripe 23 C. The element isolation trenches 24 having a width of 10 μm and reaching the n-type GaAs substrate 81 are formed. In forming the separation groove 24, wet etching using a mixed solution of HCl and H 2 O as an etchant, RIE, or the like may be used.

Next, the p-side electrode 102 was formed on the p-type cap layer 98 and the n-type buried layer 100 so as to be connected to the p-type cap layer 10 of the first to third ridge stripes 23A to 23C. Next, an insulating layer 106 made of SiO 2, SiN or the like is partially formed on the p-side electrode 102 of the third ridge stripe 23C by masking, and then the buried insulating layer 110 is formed by filling the isolation trench 24 with polyimide or the like. did. Further, the extraction electrode 104 was formed to form a two-layer wiring for the p-side electrode 102 of the second ridge stripe 23B.
Further, after the back surface of the n-type GaAs substrate 81 was polished and adjusted to a predetermined substrate thickness, the n-side electrode 108 was formed. Finally, cleavage was performed on the (01-1) plane, and element isolation was performed on the (0-1-1) plane, thereby manufacturing the semiconductor laser element 80 shown in FIG. As described above, the AlGaInP semiconductor laser device 80 including the three waveguides 22A to 22C having different oscillation wavelengths can be formed on the same substrate 81 by one crystal growth.

(Example 2)
This example is a specific example of the semiconductor laser device of the second embodiment, and FIGS. 9 and 10 are a perspective view and a perspective view showing a configuration of the semiconductor laser device 120 of Example 2, respectively. It is sectional drawing in line II-II. Of the parts shown in FIG. 9 and FIG. 10, the same parts as those in FIG. 2 and FIG. 5 to FIG. As shown in FIG. 9, the semiconductor laser device 120 of this example has the same structure as that of Example 1 on the inclined surface of an n-type GaAs substrate 81 having the same concave groove 34 as that of the second embodiment as a step-like structure. A semiconductor stacked body 82 (see FIG. 7) made of the same AlGaInP-based compound semiconductor layer is provided. In this example, as described in the second embodiment, the groove 34 has a depth of 2.7 μm, a width of 62 μm, and a period of 500 μm on the inclined surface of the n-type GaAs substrate 81 [ [01-1] direction.

  As shown in FIG. 10, the first to third ridge stripes 43A to 43C each having a width of 3 μm constituting the first to third waveguides 42A to 42C are formed on the etching stop layer 94 as in the first embodiment. The p-type cap layer 98 and the p-type cladding layer 96 are formed in the [01-1] direction by etching. The first ridge stripe 43A is 4 μm away from one step 38B of the groove 34, the second ridge stripe 43B is 34 μm away from the other step 38A of the groove 34, and the third ridge stripe 43C is The groove 34 is provided at a position 104 μm away from one step 38 </ b> B of the concave groove 34. The first to third ridge stripes 43 </ b> A to 43 </ b> C are buried with the n-type GaAs buried layer 100 as in the first embodiment. Further, as in the first embodiment, element isolation grooves 44 are formed between the ridge stripes 43, and the isolation grooves 44 between the first ridge stripe 43A and the third ridge stripe 43C are made of an insulator such as polyimide. This is a buried insulating layer 110 buried in (1).

  With the above configuration, the semiconductor laser device 120 of this example is formed as an index guide structure in each of the first to third ridge stripes 43A to 43C. As described in the second embodiment, The first waveguide 42A, the second waveguide 42B, and the third waveguide 42C have three waveguides 42A to 42C whose oscillation wavelengths are shortened in this order, and laser beams having mutually different wavelengths are supplied to the respective waveguides. It emits via 42A-C. With the configuration described above, the semiconductor laser device 120 of this example has the same effects as those of the second embodiment.

  With reference to FIG. 11, the manufacturing method of the semiconductor laser device 120 of the present embodiment will be described. FIG. 11 is a perspective view showing the configuration of the substrate for the semiconductor laser device 120 of the present embodiment. As shown in FIG. 11, the n-type GaAs substrate 81 is etched in the same manner as in Example 1, and the concave groove 34 having a depth of 2.7 μm and a width of 62 μm and extending in the [01-1] direction is formed as [0− 1-1] was formed with a period of 500 μm in the direction. In FIG. 11, a region that finally constitutes one semiconductor laser element 120 is indicated by Z.

  Next, the same semiconductor stacked body 82 as that of Example 1 was formed on the substrate 81 having the concave grooves 34 by MOCVD at a substrate temperature of 690 ° C. in the same manner as in Example 1. Thereafter, the first to third ridge stripes 43A to 43C are formed in the same manner as in the first embodiment, and the ridge sides of the first to third ridge stripes 43A to C are embedded by the n-type GaAs buried layer 100. A p-side electrode 102, an insulating layer 106, a buried insulating layer 110, and an extraction electrode 104 were formed. Next, the semiconductor laser device 120 shown in FIG. 9 was fabricated by cleaving on the (01-1) plane and isolating the device on the (0-1-1) plane. As described above, the semiconductor laser device 120 including the three waveguides 42A to 42C having different oscillation wavelengths can be formed on the same substrate 81 by a single crystal growth.

(Example 3)
This example is a specific example of the semiconductor laser device of the third embodiment, and FIGS. 12 and 13 are a perspective view and a perspective view showing the configuration of the semiconductor laser device 122 of Example 3, respectively. It is sectional drawing in arrow III-III. Of the parts shown in FIG. 12 and FIG. 13, the same parts as those in FIG. 3 and FIG. 5 to FIG. As shown in FIG. 12, the semiconductor laser device 122 of this example includes an n-type GaAs substrate 81 having the same three ridges 54A to 54C as the semiconductor laser device 50 of the third embodiment as a step-like structure. The semiconductor laminated body 82 (refer FIG. 7) which consists of the same AlGaInP type compound semiconductor layer as Example 1 is provided on this inclined surface. In this example, as described in the third embodiment, the three first to third ridges 54A to 54C have a height of 2.7 μm and a width of 100 μm on the n-type GaAs substrate 81. The period is 150 μm and is formed in the [01-1] direction.

  As shown in FIG. 13, the first to third ridge stripes 63A to 63C each having a width of 3 μm constituting the first to third waveguides 62A to 62C are formed on the etching stop layer 94 as in the first embodiment. The p-type cap layer 98 and the p-type cladding layer 96 are formed in the [01-1] direction by etching. The first ridge stripe 63A is located 4 μm away from one step 58A of the first ridge 54A, and the second ridge stripe 63B is located 24 μm away from one step 58A of the second ridge 54B. Are formed on the first to third ridges 54A-C, respectively, at a position 44 μm away from one step 58A of the third ridge 54C.

  The first to third ridge stripes 63A to 63C are buried with the n-type GaAs buried layer 100 as in the first embodiment. Further, as in the first embodiment, an element isolation groove 44 is formed between the ridge stripes 63A to 63C, and the isolation groove 44 between the first ridge stripe 63A and the second ridge stripe 63B is made of polyimide or the like. The buried insulating layer 110 is filled with an insulator.

  With the above configuration, the semiconductor laser element 122 of this example is formed as an index guide structure in each of the first to third ridge stripes 63A to 63C, and as described in the third embodiment, In this order, the first waveguide 62A, the second waveguide 62B, and the third waveguide 62C have three waveguides 62A to 62C whose oscillation wavelengths become shorter. It emits via 62A-C. With the above configuration, the semiconductor laser element 122 of this example has the same effects as those of the third embodiment.

  With reference to FIG. 14, the manufacturing method of the semiconductor laser device of the present embodiment will be described. FIG. 14 is a perspective view showing a configuration of a substrate for producing the semiconductor laser element 122 of the present embodiment. As shown in FIG. 14, the n-type GaAs substrate 81 is etched in the same manner as in Example 1, and the ridges 54A to C extending in the [01-1] direction having a depth of 2.7 μm and a width of 100 μm are set to [0]. -1-1] in the direction of 150 μm. In FIG. 14, a region that finally constitutes one semiconductor laser element 122 is indicated by Z.

  Next, the same semiconductor stacked body 82 as that of Example 1 was formed on the substrate 81 on which the ridge 54 was formed by MOCVD at a substrate temperature of 690 ° C. in the same manner as in Example 1. Thereafter, in the same manner as in Example 1, the first to third ridge stripes 63A to 63C are formed, and the ridge sides of the first to third ridge stripes 63A to C are embedded with the n-type GaAs buried layer 100, and then A p-side electrode 102, an insulating layer 106, a buried insulating layer 110, and an extraction electrode 104 were formed. Next, the semiconductor laser element 122 shown in FIG. 12 was produced by cleaving on the (01-1) plane and isolating the elements on the (0-1-1) plane. As described above, the semiconductor laser element 122 including the three waveguides 62A to 62C having different oscillation wavelengths can be formed on the same substrate 81 by one crystal growth.

Example 4
This example is a specific example of the semiconductor laser device of the fourth embodiment, and FIG. 15 is a cross-sectional view showing the configuration of the semiconductor laser device 124 of Example 4 corresponding to FIG. 13 of Example 3. is there. 15 that are the same as those shown in FIGS. 4 and 5 to 7 are marked with the same symbols and descriptions of them will be omitted. As shown in FIG. 15, the semiconductor laser device 124 of the present example has a step-like structure on an inclined surface of an n-type GaAs substrate 81 having the same three ridges 74A to C as in the fourth embodiment. The semiconductor laminated body 82 (refer FIG. 7) which consists of the same AlGaInP type compound semiconductor layer as Example 1 is provided. In the present example, as described in the fourth embodiment, the three first to third ridges 74A to 74C having different ridge widths on the n-type GaAs substrate 81 have a height of 2 0.7 [mu] m and a period of 150 [mu] m, formed in the [01-1] direction. The ridge width is 25 μm for the first ridge 74A, 35 μm for the second ridge 74B, and 100 μm for the third ridge 74C.

  The first to third ridge stripes 73A to 73C each having a width of 3 μm and constituting the first to third waveguides 72A to 72C are formed in the p-type cap layer 98 and p on the etching stop layer 94 as in the first embodiment. The mold cladding layer 96 is formed in the [01-1] direction by etching. As shown in FIG. 15, the first to third ridge stripes 73A to 73C are located substantially at the center on the first ridge 74A, the second ridge 74B, and the third ridge 74C, respectively. Accordingly, the distance from the step 58 on both sides of the first ridge 74A is about 12.5 μm in the first waveguide 72A, and the distance from the step 58 on both sides in the second ridge 74B is 17.5 μm in the second waveguide 72B. Thus, the distance from the step 58 on both sides of the third ridge 74C of the third waveguide 74C is about 50 μm.

  Further, the first to third ridge stripes 73A to 73C are buried with the n-type GaAs buried layer 100 as in the first embodiment. Further, as in the first embodiment, element isolation grooves 64 are formed between the ridge stripes 73, and the isolation grooves 64 between the first ridge stripe 63A and the second ridge stripe 63B are made of an insulator such as polyimide. This is a buried insulating layer 110 buried in (1).

  With the above configuration, the semiconductor laser element 124 of the present example is formed as an index guide structure in each of the first to third ridge stripes 73A to 73C, and as described in the fourth embodiment, There are three waveguides 72A to 72C whose oscillation wavelengths are shortened in the order of the first waveguide 72A, the second waveguide 72B, and the third waveguide 72C. The light is emitted through ~ C. With the above configuration, the semiconductor laser element 124 of this example has the same effects as those of the fourth embodiment.

  The semiconductor laser device 124 of the present embodiment is the same as that of the third embodiment except that three first to third ridges 74A to 74C having different ridge widths are formed on the n-type GaAs substrate 81. It can be manufactured in the same manner as 122.

  In Examples 1 to 4, the height of the ridge or the depth of the groove was 2.7 μm. However, the present invention is not limited to this, and the same effect can be obtained if the height is 0.4 μm or more. The same effect can be obtained even when the height of the ridge or the depth of the groove is 4 μm, for example. In the first to fourth embodiments, the semiconductor laser device having an index guide structure in which the ridge side of the p-type ridge is buried with the n-type GaAs buried layer has been described as an example, but the first invention is applied. The laser structure that can be used is not limited to this, and can be applied to, for example, a gain guide type semiconductor laser element, a balsation type semiconductor laser element, or the like.

  The formation of the groove or ridge structure is not limited to the wet etching method, and there is no limitation on the formation method as long as the groove or ridge structure can be formed. For example, RIE (reactive ion etching) may be used. Also, the type of etchant used in the wet etching method is not limited as long as a concave groove or ridge structure can be formed. Further, when forming the groove or ridge structure, the inclination angle of the groove side wall of the groove or the side wall of the ridge is not limited to the inclination shown in the drawings of the first to fourth embodiments. For example, as shown in FIG. 16A, the groove may be a groove having an inclined surface with an inclination angle of 90 degrees or more as a groove wall so that the width of the groove bottom surface is wider than the opening width of the groove. Similarly, as shown in FIG. 16B, the ridge structure may be a ridge structure having an inclined surface with an inclination angle of 90 degrees or more as a ridge wall.

  In Examples 1 to 4, the active layer 88 is a multiple quantum well layer. However, the active layer 88 may be a bulk active layer, and the multiple quantum well layer may be a strained superlattice layer. The strain may be a compressive strain, a tensile strain, or a strain compensated strain superlattice layer. Further, although the growth temperature of the semiconductor stacked body 82 is 690 ° C., it may be a low temperature lower than 690 ° C. or a high temperature higher than 690 ° C. Obtainable.

(Experimental example 1)
The semiconductor laser devices 80, 120, and 122 of Examples 1 to 3 having waveguides with various distances between the stepped step and the waveguide are prepared as samples, and a photoluminescence spectrum corresponding to the band gap of the waveguide. The measurement results are shown in FIG. FIG. 17 is a graph showing the relationship between the distance of the waveguide from the step of the step-like structure and the wavelength of the laser beam. The horizontal axis represents the distance of the waveguide from the step of the step-like structure, and the distance The wavelength of the laser beam emitted from the waveguide is plotted on the vertical axis. As can be seen from FIG. 17, the emission wavelength becomes longer as the distance between the waveguide and the stepped structure becomes shorter, and the wavelength becomes shorter as the distance increases. In addition, as shown in FIG. 17, since the emission wavelength hardly changes in a region 50 μm away from the stepped structure, in order to realize a semiconductor laser device that oscillates light of different wavelengths on the same substrate. Preferably, at least one waveguide is arranged within a range of 50 μm from the step-like structure.

(Experimental example 2)
The semiconductor laser device 124 of Example 4 having ridges having different ridge widths and having various ridge widths was manufactured, and a photoluminescence spectrum corresponding to the band gap of the waveguide on each ridge was measured. 18 shows the measurement results. Measurements were taken at the center of the ridge. FIG. 18 is a graph showing the relationship between the ridge width and the wavelength of the laser beam. The horizontal axis represents the ridge width, and the vertical axis represents the wavelength of the laser beam emitted from the waveguide on the ridge having the ridge width. taking it. As can be seen from FIG. 18, it was confirmed that the emission wavelength was shortened as the ridge width was increased. As shown in FIG. 18, since the emission wavelength hardly changes when the ridge width exceeds 100 μm, in order to realize lasers that oscillate laser beams having different wavelengths on the same substrate, at least one waveguide is provided. Is preferably disposed on a ridge having a width of 100 μm or less.

(Example 5)
This example is a specific example of the semiconductor laser device of the fifth embodiment, and is formed on an n-type GaN substrate provided with the same step-like structure 14 as the semiconductor laser device of the first embodiment. A semiconductor stacked body made of an AlGaInN-based compound semiconductor layer is provided. The configuration of the semiconductor laser device of this example is described in paragraphs [0039] to [0043] in which the configuration of the semiconductor laser device of example 1 is described. By reading in this way, the configuration of the semiconductor laser device of this example can be described. 5 is a perspective view showing the configuration of the semiconductor laser device of the fifth embodiment, FIG. 6 is a cross-sectional view of the semiconductor laser device of the fifth embodiment taken along line II in FIG. 5, and FIG. It can be set as the cross-sectional enlarged view which shows the laminated structure of the compound semiconductor layer of the 1st waveguide vicinity of Example 5. FIG.

In the following replacement, the left side of → is the element of the first embodiment, and the right side of → is the corresponding element of the fifth embodiment. Basically, GaAs is replaced with GaN, and P of AlGaInP is replaced with N to obtain AlGaInN.
Semiconductor laser device 80 of Example 1 → Semiconductor laser device 80 of Example 5
An n-type GaAs substrate 81 provided with the same step-like structure 14 as in the first embodiment on a tilted surface inclined by 10 ° in the [0-1-1] direction from the (100) plane → a substrate surface consisting of a (0001) plane An n-type GaN substrate 81 provided with the same step-like structure 14 as in the first embodiment.
AlGaInP-based → AlGaInN-based (Al0.7Ga0.3) n-type cladding layer 84 having a thickness of 1.1 μm and a thickness of 1.1 μm → (A10.7Ga0.3) 0.5In0.5N having a thickness of 1 .1 μm n-type cladding layer 84

Guide layer 86 made of (Al0.5Ga0.5) 0.5In0.5P → guide layer 86 made of (A10.5Ga0.5) 0.5In0.5N
Active layer 88 having a multiple quantum well structure composed of Ga0.5In0.5P / (Al0.5Ga0.5) 0.5In0.5P → Multilayer composed of Ga0.5In0.5N / (A10.5Ga0.5) 0.5In0.5N Quantum well structure active layer 88
Guide layer 90 made of (Al0.5Ga0.5) 0.5In0.5P → Guide layer 90 made of (A10.5Ga0.5) 0.5In0.5N
A p-type cladding layer 92 having a thickness of 0.3 μm made of (Al0.7Ga0.3) 0.5In0.5P → a p-type cladding layer having a thickness of 0.3 μm made of (A10.7Ga0.3) 0.5In0.5N 92
P-type etching stop layer 94 made of Ga0.5In0.5P → p-type etching stop layer 94 made of Ga0.5In0.5N
A p-type cladding layer 96 with a thickness of 1.1 μm made of (Al0.7Ga0.3) 0.5In0.5P → p-type with a thickness of 1.1 μm made of (A10.7Ga0.3) 0.5In0.5N Clad layer 96
P-type cap layer 98 made of GaAs with a thickness of 0.35 μm → p-type cap layer 98 made of GaN with a thickness of 0.35 μm

  The active layer 88 of Example 5 was composed of a Ga0.5In0.5P layer having a thickness of 3.5 nm and an (Al0.5Ga0.5) 0.5In0.5P layer having a thickness of 4.0 nm. Instead of the three-period multi-quantum well structure of Example 1, it is composed of Ga0.5In0.5N with a thickness of 3.5 nm and (A10.5Ga0.5) 0.5In0.5N with a thickness of 4.0 nm. It is formed as a multi-quantum well structure having three periods.

  Further, in the description of paragraphs [0045] to [0048] describing the manufacturing method of the semiconductor laser device of the first embodiment, the semiconductor laser device of the present embodiment can be read in the same manner as described above with reference to FIG. The manufacturing method can be explained.

  In the following description of the fifth embodiment, the above-described replacement is performed. As shown in FIG. 5, the semiconductor laser device 80 of this example is formed on an n-type GaN substrate 81 having the same step-like structure 14 as that of the first embodiment on a (0001) plane substrate surface. A semiconductor stacked body 82 made of an AlGaInN-based compound semiconductor layer is provided.

  As shown in FIG. 7, the semiconductor stacked body 82 is formed on an n-type GaN substrate 81 and an n-type cladding layer 84 having a thickness of 1.1 μm made of (Al0.7Ga0.3) 0.5In0.5N, (Al0 .5Ga0.5) 0.5In0.5N guide layer 86, Ga0.5In0.5N / (Al0.5Ga0.5) 0.5In0.5N multi-quantum well structure active layer 88, (Al0.5Ga0. 5) Guide layer 90 made of 0.5In0.5N, p-type cladding layer 92 having a thickness of 0.3 μm made of (Al0.7Ga0.3) 0.5In0.5N, and p-type etching stop made of Ga0.5In0.5N Layer 94, a p-type cladding layer 96 made of (Al0.7Ga0.3) 0.5In0.5N with a thickness of 1.1 μm, and a p-type cladding made of GaAs with a thickness of 0.35 μm. It is configured as a laminated structure of the layer 98. The active layer 88 is a three-cycle multiple quantum composed of a Ga0.5In0.5N layer having a thickness of 3.5 nm and an (Al0.5Ga0.5) 0.5In0.5N layer having a thickness of 4.0 nm. It is formed as a well structure. FIG. 7 shows a stacked structure of compound semiconductor layers in the vicinity of the first ridge stripe 23A, but the semiconductor stacked body 82 has the same stacked structure in other regions.

As shown in FIG. 6, the p-type cap layer 98 and the p-type cladding layer 96 are etched using the etching stop layer 94 as an etching stop layer in the semiconductor stacked body 82, and the first to third waveguides 22 </ b> A to C are formed. First to third ridge stripes 23A to 23C each having a width of 3 μm are formed on the high region 16 of the step-like structure 14 in the [01-1] direction.
The distance between the first ridge stripe 23A and the step 18 is 4 μm, the distance between the second ridge stripe 23B and the step 18 is 34 μm, and the distance between the third ridge stripe 23C and the step 18 is 104 μm.

  Each ridge stripe 23 </ b> A to 23 </ b> C is buried with an n-type buried layer 100 made of a GaAs layer on the side of the ridge except for the p-type cap layer 98 on each ridge stripe 23. A current confinement structure is formed by the pn junction isolation between the p-type cap layer 98 and the p-type cladding layer 96 and the n-type buried layer 100. Further, mutually independent p-side electrodes 102 are formed on the p-type cap layer 98 and the n-type buried layer 100 so as to be connected to the p-type cap layer 98 of each ridge stripe 23. Further, since the p-side electrode 102 on the second ridge stripe 23B is connected via the extraction electrode 104 extending across the third ridge stripe 23C, the p-side electrode 102 of the third ridge stripe 23C is connected to the p-side electrode 102. An insulating film 106 is provided between the extraction electrode 104. Further, a common n-side electrode 108 is formed on the back surface of the n-type GaAs substrate 81 as shown in FIG. An element isolation groove 24 is formed between the ridge stripes 23A to 23C, and the isolation groove 24 between the second ridge stripe 23B and the third ridge stripe 23C is a buried insulating layer embedded with an insulator such as polyimide. 110. In FIG. 5, the lead-out electrode 104 of the p-side electrode 102 of the second ridge stripe 23B extends across the first ridge stripe 23A, unlike FIG. 6, for convenience.

  The semiconductor laser device 80 of this example is formed as an index guide structure in each of the first to third ridge stripes 23A to 23C. As described in the first embodiment, the first waveguide 22A, It has three waveguides whose oscillation wavelengths become shorter in the order of the second waveguide 22B and the third waveguide 22C, and emits laser beams having mutually different wavelengths via the respective waveguides 22A to 22C. With the above configuration, the semiconductor laser device 80 of this example has the same effects as those of the first embodiment.

With reference to FIG. 8, the manufacturing method of the semiconductor laser device 80 of the present embodiment will be described. FIG. 8 is a perspective view showing the configuration of the substrate for the semiconductor laser element 80 of the present embodiment. As shown in FIG. 8, an n-type GaN substrate 81 having a (0001) plane as a substrate surface is etched by photolithography and a wet etching method using a mixed etchant composed of H ₂ SO ₄ , H ₂ O ₂ and H ₂ O. Then, the groove 112 having a depth of 2.7 μm, a width of 200 μm, extending in the [01-1] direction, and having a step 18 on both sides as a groove wall, has a period of 800 μm in the [0-1-1] direction. Formed. In FIG. 8, the substrate region that finally constitutes one semiconductor laser element 80 is indicated by Z.

  Next, on the substrate 81 in which the concave groove 112 is formed, the film thickness made of (Al0.7Ga0.3) 0.5In0.5N is 1.1 μm by MOCVD with a substrate temperature of 690 ° C. as shown in FIG. N-type cladding layer 84, guide layer 86 made of (Al0.5Ga0.5) 0.5In0.5N, and multiple quantum well structure made of Ga0.5In0.5N / (Al0.5Ga0.5) 0.5In0.5N Active layer 88, guide layer 90 made of (Al0.5Ga0.5) 0.5In0.5N, p-type cladding layer 92 made of (Al0.7Ga0.3) 0.5In0.5N and having a thickness of 0.3 μm, Ga0. P-type etching stop layer 94 made of 5In0.5N, p-type cladding layer 96 having a thickness of 1.1 μm made of (Al0.7Ga0.3) 0.5In0.5N, and Ga Thickness made of s is a 0.35μm p-type cap layer 98 are sequentially stacked to form a semiconductor laminate 82.

Next, by using the etching stop layer 94 as an etching stop layer, the first to third ridge stripes 23A to 23C having a width of 3 μm extending in the [01-1] direction are formed by photolithography and wet etching as shown in FIG. They were formed 4 μm, 34 μm, and 104 μm apart from the step 18 of the groove 112. Next, an n-type GaAs buried layer 100 is formed in a region excluding the p-type cap layer 98 on the first to third ridge stripes 23A to 23C by masking with an insulating film and MOCVD, and the first to third ridges are formed. The ridge side of stripes 23A-C was embedded. Subsequently, etching is performed by photolithography and a wet etching method using a mixed etchant of H ₂ SO ₄ , H ₂ O _2, and H ₂ O, and between the first ridge stripe 23A and the second ridge stripe 23B, and the second ridge. Element isolation grooves 24 each having a width of 10 μm and reaching the n-type GaAs substrate 81 were formed between the stripes 23B and the third ridge stripes 23C. In forming the separation groove 24, wet etching using HCl and H ₂ O as an etchant, RIE, or the like may be used.

Next, the p-side electrode 102 was formed on the p-type cap layer 98 and the n-type buried layer 100 so as to be connected to the p-type cap layer 10 of the first to third ridge stripes 23A to 23C. Next, an insulating layer 106 made of SiO ₂ , SiN or the like is partially formed on the p-side electrode 102 of the third ridge stripe 23C by masking, and then the isolation trench 24 is filled with polyimide or the like to form a buried insulating layer 110. Formed. Further, the extraction electrode 104 was formed to form a two-layer wiring for the p-side electrode 102 of the second ridge stripe 23B. Further, after the back surface of the n-type GaAs substrate 81 was polished and adjusted to a predetermined substrate thickness, the n-side electrode 108 was formed. Finally, cleavage was performed on the (01-1) plane, and element isolation was performed on the (0-1-1) plane, thereby manufacturing the semiconductor laser element 80 shown in FIG. As described above, the AlGaInN semiconductor laser device 80 including the three waveguides 22A to 22C having different oscillation wavelengths can be formed on the same substrate 81 by one crystal growth.

(Examples 6 to 8)
For the second to fourth embodiments, the same replacement as the replacement for the first embodiment described in the fifth embodiment can be performed. Further, by replacing the readings, FIGS. 9 to 15 referred to in the second to fourth embodiments can be directly referred to as the drawings of the sixth to eighth embodiments.

  In Examples 5 to 8, an n-type GaN substrate is used as the substrate. However, the substrate is not limited to an n-type GaN substrate. For example, a sapphire substrate or a substrate obtained by laminating a GaN layer on a sapphire substrate can be used. . In Examples 5 to 8 using a GaN substrate, the n-side electrode 108 is provided on the back surface of the n-side GaN substrate 81, but a sapphire substrate or a substrate formed by laminating a GaN layer on the sapphire substrate is used as the substrate. In some cases, since the sapphire substrate has no conductivity, a contact layer made of an n-type AlGaInN layer is provided between the substrate and the n-type cladding layer 84, and a part of the contact layer is exposed, and the exposed surface is n-side. An electrode is provided. The n-side electrode of each waveguide is connected to the outside by a common extraction electrode.

  DESCRIPTION OF SYMBOLS 10 ... Semiconductor laser element of 1st Embodiment, 12 ... n-type GaAs substrate, 14 ... Step-like structure, 16 ... High region 18 ... Step, 20 ... Low region, 22 ... Waveguide , 24... Separation groove, 30... Semiconductor laser device of the second embodiment, 34... Groove, 36... High region, 38. 44... Separation groove, 50... Semiconductor laser device of embodiment example, 54... Ridge, 56... High region, 58. , 70... Semiconductor laser device of the fourth embodiment, 72... Ridge, 74... Waveguide, 80... Semiconductor laser device of Example 1, 81. 84, n-type cladding layer, 86, guide layer, 88, active layer, 90, gas. Layer ... 92 ... p-type cladding layer, 94 ... p-type etching stop layer, 96 ... p-type cladding layer, 98 ... p-type cap layer, 100 ... n-type buried layer, 23A-C ... 1st to 3rd ridge stripe, 102... P-side electrode, 104... Extraction electrode, 106... Insulating film, 108... N-side electrode, 110. Semiconductor laser device of Example 2, 43A to C... First to third ridge stripes, 122... Semiconductor laser device of Example 3, 63A to C... First to third ridge stripes, 124. Semiconductor laser elements 73A to C... First to third ridge stripes.

Claims (7)

A semiconductor laser element having a plurality of waveguides and emitting laser beams having different wavelengths from each other through each waveguide,
A substrate provided with a step-like structure on the substrate surface for separating a high region and a low region lower than the high region by a step;
An active layer containing two types of group III elements including In and a group V element including N, and a first conductivity type cladding layer and a second conductivity type provided above and below the active layer and sandwiching the active layer, respectively. A semiconductor laminate having a cladding layer and provided on the substrate,
The semiconductor laser device, wherein the plurality of waveguides are provided in a high region of the step-like structure so that the distances from the steps are different from each other when viewed from above the semiconductor stacked body. 2. The semiconductor laser device according to claim 1, wherein the step-like structure has a concave groove on the substrate, and the plurality of waveguides are respectively provided in a high region delimited by a step of the concave groove. The semiconductor laser device according to claim 1, wherein the step-like structure has a ridge on the substrate, and the plurality of waveguides are provided on the ridge. The semiconductor laser device according to claim 1, wherein the substrate is any one of a GaN substrate, a sapphire substrate, and a substrate in which a GaN-based semiconductor layer is stacked on the sapphire substrate. 2. The semiconductor laser device according to claim 1, wherein at least one of the waveguides is provided at a position where a distance between the waveguide and a step of the step-like structure is 50 μm or less. The semiconductor laser device according to claim 2, wherein at least one of the waveguides is provided at a position where a distance between the waveguide and the step of the concave groove is 50 μm or less. A method of manufacturing a semiconductor laser device having a plurality of waveguides and emitting laser beams having mutually different wavelengths via each waveguide,
Providing a step-like structure on the substrate surface that divides a high region and a low region lower than the high region by a step; and
An active layer containing two types of group III elements including In and a group V element including N, and a first conductivity type cladding layer and a second conductivity type disposed above and below the active layer and sandwiching the active layer Forming a semiconductor laminate having a clad layer on a substrate;
A step of forming each of the plurality of waveguides in a high region of the step-like structure so that the distances from the steps are different from each other when viewed in plan from above the semiconductor laminate. Production method.

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