JPH09166796A - Optical semiconductor element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to form a diagonal end face structure inclined in the stripe direction of active layers from the normal direction of the element end face by using a selective MOVPE method. SOLUTION: An off angle substrate 11 inclined in the surface bearing by >=5 deg. from a (100) to <011> direction is adopted in place of a (100) surface substrate usually used in the manufacture of the optical semiconductor element. A mask having striped gap parts of about 0.5 to 2.0μm width is patterned on the substrate 11 and the striped active layers 15 are formed only in these gap parts by the selective MOVPE method. At this time, the stripe direction of the gap parts is set in the direction of the intersection lines of the substrate 11 surface and the (011) face. Further, clad layers, etc., are formed to cover these active layers. The substrate is cloven by exposing the (011) face when the cleavage of the substrate in the direction perpendicular to the stripes of the active layers is attempted at the time of cutting out the element from the wafer.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a selective MOVPE for forming a semiconductor crystal on only a part of a substrate by crystal growth.
Semiconductor device in which an active layer or an optical guide layer is formed by using a method and a method of manufacturing the same, particularly, for an element such as a semiconductor optical amplifier element which needs to reduce the light reflectance at an end of the element. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Among optical semiconductor devices used for optical communication and optical switching, it is very important to reduce the light reflectance at the end face of a semiconductor optical amplifier device (hereinafter abbreviated as LD amplifier). is there. For example, as a practical LD amplifier, 2
A gain of 0 dB or more is often required, but this requires that the reflectivity of the end face of the element be about 5 × 10 ⁻⁴ or less. Simply covering the element end face with a non-reflective coating such as a dielectric film
It is difficult to achieve such a small reflectance.
As a structure used together with an anti-reflection coating to realize a small reflectance, a structure with a window region in which an active layer is interrupted at an element end is adopted. FIG. 6 is a perspective view of an LD amplifier with a window region, and partially shows a cross section. A part of the light emitted from the optical waveguide including the striped active layer 32 and the clad layer 33 filling the active layer 32 is reflected by the end face of the element and returns. However, with this structure, the rate at which the reflected light couples back into the optical waveguide can be reduced to about 1/100. That is, the effective reflectance becomes 1/100 times.
There is the following report as an example of an optical semiconductor device provided with such a window region 34. In both cases, the AR coating (non-reflection coating) on the window region and the element end surface realizes an effective reflectance of 10 ⁻⁴ .

(1) P.I. Doussie, et a
l. , J. et al. Photonics Technology. Le
tt. , PTL-6, pp 170-172 (1991). Cha, et. al. Electr. Le
tt. , Vol. 25, pp1241-1242 (19
89) (3) S.M. Kitamura, et al. , J. et al. Ph
otonics Technology. Lett. , PTL
-6, pp 173-175 (1994) Another method of lowering the effective reflectivity is to tilt the element end face from the stripe direction of the active layer. It is possible that the effective reflectance can be reduced by about one digit by tilting to 7 degrees or more. Wang, et. al. Electr. L
ett. , Vol. 25, pp1139-1141 (1
989) (5) D.I. R. Scifres, J.M. Quantum
Electr. Vol. 14, pp223-227 (1
978), and based on this fact, LD
Examples of the realization of the amplifier include (6) C.I. E. FIG. Zah, et. al. Electr.
Lett. , Vol. 23, pp990-991 (19
87) (7) Solder and others JP-A-3-136388, a report on a semiconductor optical amplifier and the like can be mentioned.

FIG. 7 is a top view of the substrate surface viewed from above, and shows the features of the invention described in Reference (6). In the invention described in Document (6), the stripe-shaped active layer 41 is formed on the (100) surface InP substrate in a direction having an angle of about 7 degrees with the <011> direction. Thereby, the stripe direction of the active layer is exposed by cleavage (011).
The element is inclined from the normal direction of the end face. FIG. 8 shows <001>.
FIG. 4 is a side view of the element viewed from the side of the substrate in the direction, and shows the features of the invention described in Document (7). In the invention described in Document (7), an off-angle substrate whose surface orientation is inclined from (100) to the <010> direction is used, and the stripe direction of the active layer 52 is set to the intersecting line direction between the substrate surface and the (001) plane. . Since the device end face of the (010) plane is formed by cleavage, the normal line of the device end face is inclined from the stripe direction of the active layer.

Further, in recent years, a low reflectance of about 1 × 10 ⁻⁴ or less has been realized by employing a method using the above-mentioned window structure and the oblique end face in combination. Thereby, a high gain LD amplifier of 25 dB or more is realized. Examples of this are: F. Timeeijer, OAA '94 T
technical Digest 34 / WD1-1
(1994). In this report, the reflectivity was sufficiently suppressed,
An element gain of dB or more is realized.

Incidentally, an LD amplifier is required to be of a polarization-independent type whose gain characteristic does not depend on the polarization state of an input signal. In order to satisfy this requirement, it is effective to adopt a structure in which the width of the stripe-shaped active layer is about 0.5 μm, which is about 1/3 smaller than that of a normal optical semiconductor element. As a method of manufacturing such a narrow stripe-shaped active layer, the selective MOVPE method is effective. Select MOV
In the PE method, as shown in FIG. 9A, two stripe-shaped SiO ₂ masks 61 are formed on a substrate in a thickness of 0.5 to 2.0 μm.
The stripe-shaped active layer 62 is selectively grown only at this interval, and the crystal is grown only at this interval. With this method, a narrow stripe-shaped active layer having a width of about 0.5 μm can be uniformly formed with good reproducibility. In the invention described in Document (3) using this method, a uniform 4-ch LD amplifier array having an element gain of 20 dB is realized.

[0007]

As described above, L
In a D amplifier or the like, a structure is provided in which a window region is provided or an end surface is inclined obliquely in order to suppress the reflectance at the element end. Further, in order to realize a high gain characteristic of 30 dB or more, it is necessary to adopt both the window structure and the oblique end face structure. Also,
It is effective to use a structure having a submicron-width active layer in order to obtain a polarization independent type.
A manufacturing method based on the E method is employed. However,
When the selective MOVPE method is used, there are the following problems in forming an oblique end face structure.

In forming the active layer by the selective MOVPE method, it is necessary to form the stripe direction of the active layer in the <011> direction. When formed in the <011> direction, the side surfaces of the stripe-shaped active layer are formed smoothly (FIG. 9A). However, when a direction having an angle with respect to the <011> direction is formed as in the invention described in Document (6) in order to obtain an oblique end surface structure, as shown in FIG. Irregularities due to steps occur at a pitch of 1000 °. In the LD amplifier, unevenness on the side surface of the active layer becomes a reflection or scattering portion for light guided through the active layer. Therefore, in the selective MOVPE method, there is a problem in forming the stripe-shaped active layer obliquely to the (011) end face.

In manufacturing an oblique end face structure using an off-angle substrate, which is also disclosed in the literature (7),
It is also a problem whether a good cleavage plane can be exposed. The cleavage that exposes the (010) plane shown in the literature (7) is actually difficult. In particular, when cleaving a ridge type structure, as shown in FIG. 10, there was a problem that the ridge portion 72 was easily collapsed.

[0010]

According to the first aspect of the present invention, a mask having stripe-shaped voids is formed on a flat semiconductor substrate, and a semiconductor crystal is formed in the voids by a crystal growth method. In a method for manufacturing an optical semiconductor device including at least a step, there is provided a method for manufacturing an optical semiconductor device, wherein an off-angle substrate whose surface orientation is inclined at least 5 degrees from a (100) direction to a <011> direction is used as the semiconductor substrate. can get.

According to a second aspect of the present invention, in the method of manufacturing an optical semiconductor device according to the first aspect, the stripe direction of the void portion is set to a direction of an intersection line between the substrate surface and the (0-11) plane. Thus, a method for manufacturing an optical semiconductor device is obtained.

According to a third aspect of the present invention, in the method for manufacturing an optical semiconductor device according to the first or second aspect, the semiconductor crystal formed in the gap portion includes a photoactive layer and a light guide layer. A method for manufacturing an optical semiconductor device, characterized in that at least one of them is formed.

According to a fourth aspect of the present invention, in the method of manufacturing an optical semiconductor device according to the third aspect, the stripe-shaped voids are partially filled, and the semiconductor crystals are partially cut off. Thus, a method for manufacturing an optical semiconductor device is obtained.

According to the fifth aspect of the present invention, in an optical semiconductor device including a flat semiconductor substrate and a semiconductor crystal formed on the surface of the semiconductor substrate, the semiconductor substrate has a surface orientation of (100) to <011. An off-angle substrate inclined at least 5 degrees in the direction is used, and the semiconductor crystal extends in a direction of an intersection line between the substrate surface and the (0-11) plane. can get.

According to a sixth aspect of the present invention, there is provided the optical semiconductor device according to the fifth aspect, wherein the semiconductor crystal has a stripe shape that is partially interrupted. Can be

According to a seventh aspect of the present invention, in the optical semiconductor device according to the fifth or sixth aspect, the semiconductor crystal includes at least one of a photoactive layer and a light guide layer. An optical semiconductor device is obtained.

[0017]

According to the present invention, instead of the (100) surface substrate usually used in the semiconductor process, the surface orientation is (100).
An off-angle substrate inclined several degrees in the <011> direction is used. A stripe-shaped active layer is formed in the direction of the line of intersection of the substrate surface and the (0-11) plane. When using an InP substrate,
When an attempt is made to cleave the substrate in a direction perpendicular to the stripe, the substrate is cleaved exposing the (011) plane. Therefore, the stripe direction of the active layer and the normal line of the cleavage plane have an angle. That is, an oblique end face structure in which the reflectance at the element end face is reduced is formed. By the way, select MOVP on off board
When the stripe-shaped active layer is formed by the method E, it is a problem whether or not the side and top surfaces of the stripe-shaped active layer are formed smoothly without unevenness. Therefore, an attempt was made to actually form an off-substrate of up to 10 degrees. The stripe direction is an intersecting line direction between the substrate surface and the (0-11) plane. As a result, the upper surface of the striped active layer could be formed smoothly as in the case of using a normal (100) surface substrate. Regarding the side surface, irregularities were generated, but the irregularities are shown in FIG.
It was confirmed that it was smaller than the conventional example shown in (b).
Note that, also in the invention described in Document (7), an off-substrate having a surface orientation inclined from (100) is used as in the present invention. However, unlike the present invention, the invention described in the document (7) uses a substrate inclined in the <010> direction. The present invention is characterized by using an off-substrate inclined in the <011> direction. An object of the present invention is to make it possible to form an oblique end face structure by the selective MOVPE method, and claim the structural features of the oblique end face structure formed using an off-substrate (7). This is different from the described invention. Further, when an off-substrate is used, as shown in FIG. 10, in a structure having a lip portion, there is a concern about collapse due to cleavage. However, if the stripe direction is <011>
As a result, it was confirmed that a good cleavage plane including the lip portion was formed.

[0018]

FIG. 1A is a schematic view of an LD amplifier manufactured by using the present invention. FIG. 1B is a perspective view, partially showing a cross section to show the active layer.
The following is a detailed procedure of the first embodiment for realizing this. FIG. 3A used for description is a diagram viewed from above the off-angle substrate 11, and FIGS. 3B to 3E are cross-sectional views taken along the line aa 'in FIG. 3A.

As shown in FIG. 2, an off-angle substrate 11 made of n-type InP and having an off-orientation plane 21 whose surface orientation is inclined by 10 degrees from the (100) direction to the <011> direction is used.

On the off-angle substrate 11, a stripe-shaped mask 13 made of SiO ₂ having a stripe-shaped void portion 12 in the direction of the intersection of the substrate surface (off-orientation plane 21) and the (0-11) plane was formed. . The mask 13 has a width of 30 μm, and the gap has a stripe shape with a width of 0.8 μm (FIG. 3A).

The buffer layer 14 (an n-type InP layer having a thickness of 1000
Å), active layer 15 (undoped InGaAsP layer having λ = 1.34 μm composition, thickness 3000 Å), cover layer 16
A semiconductor stripe 17 made of (p-type InP layer) was formed. The thickness of the active layer 15 is 5000 at the center between the upper side and the lower side.
Å (FIG. 3B).

The mask 13 beside the semiconductor stripe 17 was removed, and the gap 12 was widened to 7 μm (FIG. 3C).

The cladding layer 18 (p-type InP layer, 5 μm in thickness) and the cap layer 19 (p ⁺ -type InGaAs) cover the semiconductor stripe 17 by selective MOVPE.
A layer having a thickness of 3000 °) was formed (FIG. 3D).

The entire surface is made of SiO ₂ insulating film 1A (thickness 30).
00Å), the insulating film 1A is removed only on the horizontal plane of the cap layer 19, and the electrode 1B (Au (thickness 4000Å) / T
i (thickness: 500 mm)) was attached to the entire surface of the substrate (FIG. 3).
(E)).

After alloying, back-surface polishing, and back-surface electrode attachment, cleavage is performed on a cross section (same as aa 'cross section) crossing the stripe direction in FIG.
It was cut out to 0 μm, and about 10 ⁻² non-reflective coating was applied to both end faces 1C.

Thus, the LD amplifier shown in FIG. 1B was manufactured. As is apparent from the above description, this LD amplifier uses an off-angle substrate 11 whose surface orientation is tilted by 10 degrees from the (100) direction to the <011> direction as a semiconductor substrate, and the semiconductor stripe 17 is formed between the substrate surface and ( 0-1
1) It is characterized by extending in the direction of the line of intersection with the plane. When the LD amplifier shown in FIG. 1B was evaluated, an internal gain of 20 dB or more was obtained at an injection current of 70 mA. Further, gain ripple (gain variation depending on wavelength) caused by residual reflectance at the element end face was hardly noticeable.

A second embodiment will be described. FIG. 4A shows the second
3 is a schematic diagram of an LD amplifier manufactured according to the embodiment of FIG.
FIG. 4A is a perspective view, partially showing a cross section to show the active layer. The detailed procedure of this embodiment will be described below. FIG. 4B used in the description is a diagram viewed from above the off-angle substrate 11.

On the off-angle substrate 11 having the same configuration as the off-angle substrate 11 used in the first embodiment, a SiO having a stripe-shaped void portion 91 in the direction of the intersection of the substrate surface and the (0-11) plane is used. Striped mask 9 consisting of ₂
2 was formed. The mask 92 has a width of 30 μm, and the stripe-shaped void portion 91 is partially filled and has a length of 650 μm.
m, width 0.8 μm. The partially filled portion, that is, the space between the ends of each void 91 is 50 μm, and after the manufacturing process, becomes a window region 93 without an active layer (FIG. 4B).

As in the first embodiment, the selected MOVP
A semiconductor stripe including the active layer 94 was formed in the cavity 91 by the E method. However, no semiconductor stripe is formed in the window region 93 at this time. The active layer 91 is the same as that of the first embodiment, and is undoped with 1.34 μm composition InGa.
It is made of AsP crystal and has a thickness of 3000 mm and a width of 5000 mm.

As in the case of the first embodiment, the voids 91 are
After spreading the semiconductor stripe, the cladding layer 95
Embedded in At this time, the cladding layer 95 is also formed on the window region 93.

Thereafter, the same process as that of the first embodiment is performed to form the cap layer 96, the insulating film 97, and the electrode 98, and the cleavage is performed at the center of the window region 93 to form the window region shown in FIG. An LD amplifier with a diagonal end face structure was manufactured. A non-reflective coating of about 10 ^-2 was applied to both end faces 1C.

As is apparent from the above description, this LD amplifier is characterized in that the semiconductor stripe has a partially interrupted stripe shape, that is, a semiconductor device having a window region 93. The LD shown in FIG.
When the amplifier was evaluated, an internal gain of 25 dB or more was obtained at an injection current of 100 mA, and the gain ripple was hardly noticeable.

A third embodiment will be described. FIG. 5A is a schematic diagram of a semiconductor structure of an LD amplifier integrated gate device manufactured according to the third embodiment. FIG. 5A is a perspective view, partially showing a cross section to show the active layer. The following is the detailed procedure for making this. FIG. 5B used for description is a view of the off-angle substrate 11 as viewed from above, and FIG. 5C is bb ′ or c− in FIG. 5B.
It is c 'sectional drawing.

On the off-angle substrate 11, a SiO ₂ mask 1 having a gap portion 101 composed of a branch portion and a stripe portion
02 was formed. The mask 102 was formed such that the stripe portion of the void portion 101 was in the direction of the intersection line between the substrate surface and the (0-11) plane. The width of the mask 102 is shown in FIG.
As shown in (b), the thickness was partially 50 μm, and the other portions were formed to be 30 μm. The width of the gap 101 is uniform at 0.8 μm (FIG. 5B).

The buffer layer 103 (an n-type InP layer having a thickness of 10
00Å), an undoped InGaAsP layer 104 and a cover layer 105 (p-type InP layer) 1
06 was formed. Selective MOVPE is performed in a region where the InGaAsP layer 104 is sandwiched between portions having a mask width of 50 μm.
The test was performed under the condition of a composition of 34 μm. InGa in this region
The AsP layer 104 becomes the active layer 107 that controls light amplification and gate operation. The layer thickness of the active layer 107 was 5000 ° at the center between the upper side and the lower side. Due to the characteristics of the selected MOVPE,
In a region where the mask width is smaller than 30 μm, InG
The wavelength composition of the aAsP layer 104 is shorter than that of the active layer 107. In this embodiment, the composition is set to λ = 1.25. The InGaAsP layer 104 in this region becomes the light guide layer 108 (FIG. 5C).

A semiconductor stripe was buried in the cladding layer 109 by the same process as in the first and second embodiments, and the same insulating film coating and electrode process were performed. The electrode was formed so as to be in contact only with the upper part of the active layer 107 so that current could be independently injected into the two active layer portions 10A shown in FIG.

After alloying, back surface polishing, and back surface electrode attachment, cleavage is performed along the bb 'and dd' sections in FIG. 5 (b), and both end surfaces 1C are coated with a non-reflective coating of about 10 ^-2. gave.

As is clear from the above description, this LD amplifier is characterized in that the semiconductor stripe 106 includes the active layer 107 and the light guide layer 108. The LD amplifier integrated gate device shown in FIG. 5A was evaluated. The active layer portion 10A into which the current is injected operates as a gate amplifier. In each of the two gate amplifiers, an internal gain of 20 dB or more was obtained at an injection current of 70 mA, and the gain ripple was hardly noticeable. The light loss passing through the gate amplifier when there is no current injection is 30 dB or more, and the on / off ratio between when current is injected and when no current is injected is 50
A gate operation of dB or more was obtained.

In the above-described first, second, and third embodiments, an off angle of 10 degrees is used.
Even with smaller or larger off-angle substrates,
Similarly, an LD amplifier having an oblique end face element structure can be formed. However, when the off angle is 15 degrees or more, the emission direction approaches the in-plane direction of the element end face, and optical coupling with the optical fiber becomes difficult. When the angle increases, it becomes difficult to cleave the (011) plane. Further, as the active layer, λ = 1.
An InGaAsP layer having a composition of about 6 μm may be used.
In this case, the optical amplifier amplifies the input light of λ = 1.55 μm, and the gain ripple is suppressed as in the embodiment described above. Furthermore, even when a multi-layer structure including a quantum well layer and amplifying light of λ = 1.31 or 1.55 μm is used as an active layer, light amplification is performed and the same effect is obtained on gain ripple. Can be.

[0040]

According to the present invention, in order to obtain a high gain of 25 dB or more by suppressing the ripple on the gain in the LD amplifier, it is necessary to make the reflectance of the guided light in the element at the element end 10 ^-4 or less.
For this purpose, it is important to adopt an oblique end face structure in which the stripe direction of the active layer is inclined from the normal direction of the element end face, in addition to the window region where the active layer is interrupted at the element end. On the other hand, a method using the selective MOVPE method is effective for forming a stripe-shaped active layer having a submicron width required for an LD amplifier. However, when the selective MOVPE method is used, it is difficult to form an oblique end face structure. However, according to the present invention, it is possible to form a submicron-width stripe-shaped active layer having good uniformity at an angle from the normal direction of the element end face, utilizing the features of the selective MOVPE method. Further, when cleaving the off-angle substrate, it has been a problem to expose a good cleavage plane. However, according to the present invention, the substrate can be exposed without any problem. In particular, in the case of having a lip-type structure, there was a problem that the lip was easily collapsed during cleavage,
The present invention does not cause collapse.

[Brief description of the drawings]

FIG. 1A is a perspective view showing characteristics when a stripe-shaped active layer is formed according to the first embodiment of the present invention, and FIG. 1B is an LD having an oblique end surface structure manufactured based on the active layer. It is a perspective view showing an amplifier, and shows a partial section in order to show an active layer.

FIG. 2 is a diagram illustrating an off-angle azimuth of a semiconductor substrate used in the first embodiment.

FIGS. 3 (a) to 3 (e) are diagrams for explaining the procedure of the first embodiment in which the LD amplifier shown in FIG. 1 (b) is manufactured, and FIG. It is the top view which looked down, and (b)-(e) is sectional drawing which crosses the stripe direction of an active layer.

FIG. 4A is a diagram illustrating an LD amplifier with a window structure manufactured according to a second embodiment, and FIG. 4B is a diagram illustrating a procedure for manufacturing the LD amplifier of FIG. Yes,
FIG. 3 is a top view looking down from above the substrate.

FIG. 5A shows an LD manufactured according to a third embodiment.
It is a diagram showing a semiconductor structure of the amplifier integrated gate element,
(B), (c) is a diagram for explaining the procedure of manufacturing the LD amplifier integrated gate element of (a), (b) is a top view looking down from above the substrate, (c) is It is sectional drawing which crosses the stripe direction of an active layer.

FIG. 6 is a perspective view showing a first example of a conventional LD amplifier, and showing a structure of the LD amplifier having a window region used for effectively reducing the reflectance at an element end.

FIG. 7 is a diagram illustrating a second example of a conventional LD amplifier, illustrating a structure of the LD amplifier having an oblique end surface, and is a top view of the element as viewed from above a substrate.

FIG. 8 is a side view of the LD amplifier shown in FIG. 7, viewed from the side of the substrate.

FIGS. 9A and 9B are perspective views showing a striped active layer formed by a conventional selective MOVPE.

FIG. 10 is a view showing a collapse of a lip portion that may occur at the time of cleavage when a lip structure is formed on an off-angle substrate in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Off-angle board | substrate 12 Void part 13 Stripe mask 14 Buffer layer 15 Active layer 16 Cover layer 17 Semiconductor stripe 18 Cladding layer 19 Cap layer 1A Insulating film 1B Electrode 1C End face 21 Off orientation plane 31 (100) substrate 32 Active layer 33 Cladding Layer 34 Window area 35 Electrode 36 Insulating film 41 Embedded active layer 51 Off-angle substrate 52 Active layer 61 Mask 62 Active layer 63 Mask 64 Active layer 71 Off-angle substrate 72 Semiconductor ridge 91 Void 92 Stripe mask 93 Window Region 94 Active layer 95 Cladding layer 96 Cap layer 97 Insulating film 98 Electrode 101 Void 102 Mask 103 Buffer layer 104 InGaAsP layer 105 Cover layer 107 Active layer 108 Light guide layer 109 Cladding layer 10A Active layer section 10B Half Conductor light guide

Claims (7)

[Claims] 1. A method for manufacturing an optical semiconductor element, which comprises at least a step of forming a mask having stripe-shaped voids on a flat semiconductor substrate and forming a semiconductor crystal in the voids by a crystal growth method. A method for manufacturing an optical semiconductor element, characterized in that an off-angle substrate having a surface orientation inclined from a (100) direction to a <011> direction by 5 degrees or more is used as the substrate. 2. The method of manufacturing an optical semiconductor device according to claim 1, wherein the direction of the stripe of the gap is a direction of an intersection line between the surface of the substrate and a surface indicated by (1) below. A method for manufacturing an optical semiconductor device. [Outside 1] 3. The method of manufacturing an optical semiconductor device according to claim 1, wherein the semiconductor crystal formed in the gap includes at least one of a photoactive layer and a light guide layer. A method of manufacturing an optical semiconductor device. 4. The method of manufacturing an optical semiconductor device according to claim 3, wherein a part of the stripe-shaped void is buried, and the semiconductor crystal is formed as a partially broken stripe. A method for manufacturing an optical semiconductor device, characterized by: 5. An optical semiconductor device comprising a flat semiconductor substrate and a semiconductor crystal formed on the surface of the semiconductor substrate, wherein the semiconductor substrate has a surface orientation of (100) to <100.
An optical semiconductor element, wherein an off-angle substrate inclined at least 5 degrees in the <011> direction is used, and the semiconductor crystal extends in a direction of an intersection line between the substrate surface and the (0-11) plane. . 6. The optical semiconductor device according to claim 5, wherein said semiconductor crystal has a stripe shape with a partial break. 7. The optical semiconductor device according to claim 5, wherein the semiconductor crystal includes at least one of a photoactive layer and a light guide layer.