JP2008156141A - Semiconductor substrate and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor substrate made of a β-Ga<SB>2</SB>O<SB>3</SB>single crystal on which high-quality epitaxial crystal growth can be carried out with low dislocation density even when a GaN crystal is to be grown, and a semiconductor substrate made of a β-Ga<SB>2</SB>O<SB>3</SB>single crystal having an epitaxial layer by growing GaN on the (100) plane, and to provide a method for manufacturing a semiconductor substrate made of the above β-Ga<SB>2</SB>O<SB>3</SB>single crystal. <P>SOLUTION: The semiconductor substrate comprises a β-Ga<SB>2</SB>O<SB>3</SB>single crystal having the (100) plane as a given plane direction, in which oxygen is removed from the surface layer of the (100) plane. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a semiconductor substrate made of a β-Ga ₂ O ₃ single crystal used for semiconductor devices such as LEDs and lasers, and in particular, a high quality single crystal film even when GaN is epitaxially grown thereon. Relates to a semiconductor substrate made of a β-Ga ₂ O ₃ -based single crystal.

  Conventionally, a sapphire substrate has been used for a semiconductor substrate such as a semiconductor device such as an LED or a laser, but since the lattice mismatch with GaN grown thereon is as large as 16%, a good quality GaN single crystal film There is a problem that it cannot grow. As a solution to this problem, a sapphire substrate, a buffer layer made of AlN formed on the surface of the sapphire substrate at low temperature, and GaN formed by epitaxial growth on the buffer layer by MOCVD (Metal Organic Chemical Vapor Deposition) method There exists a semiconductor substrate provided with a growth layer (patent document 1).

According to this semiconductor substrate, by forming a buffer layer between the sapphire substrate and the GaN growth layer, the mismatch of lattice constants is alleviated and the deterioration of the quality of the epitaxial crystal laminated is suppressed.
Japanese Patent Publication No. 52-36117

  However, according to the semiconductor substrate of Patent Document 1, although the buffer layer is provided between the sapphire substrate and the GaN growth layer, the lattice mismatch cannot be sufficiently relaxed, and the high-quality GaN growth layer. Hard to get. And in the semiconductor device manufactured using this, for example, light emitting elements, such as LED and a laser, the crystallinity of the light emitting layer was not enough, and there existed a limit in the improvement of luminous efficiency. Therefore, conventionally, when GaN having different lattice constants is grown on a semiconductor substrate having a different crystal structure, high-quality epitaxial crystal growth has not been sufficient.

Accordingly, an object of the present invention is to provide a semiconductor substrate made of a β-Ga ₂ O ₃ single crystal capable of growing a high-quality epitaxial crystal having a low transition density even when GaN is crystal-grown. To provide a semiconductor substrate made of a β-Ga ₂ O ₃ single crystal having an epitaxial layer formed by growing silicon, and a method for manufacturing a semiconductor substrate made of these β-Ga ₂ O ₃ single crystals is there.

[1] In order to achieve the above object, the present invention has a (100) plane having a predetermined plane orientation, and the oxygen in the surface layer of the (100) plane is removed. Provided is a semiconductor substrate made of a Ga ₂ O ₃ based single crystal.

[2] According to the present invention, in order to achieve the above object, oxygen in the surface layer of the (100) plane having a predetermined plane orientation is removed, and the wurtzite type is formed on the (100) plane from which the oxygen is removed. Provided is a semiconductor substrate made of a β-Ga ₂ O ₃ based single crystal, characterized by having an epitaxial layer formed by growing GaN of the structure in the c-axis <0001> or <000-1> direction of the GaN To do.

[3] In order to achieve the above object, the present invention provides a substrate preparation step of preparing a substrate made of β-Ga ₂ O ₃ single crystal having a (100) plane having a predetermined plane orientation, And a method of producing a semiconductor substrate made of a β-Ga ₂ O ₃ single crystal, comprising: an oxygen removing step of removing oxygen from a surface layer having a (100) plane having a predetermined plane orientation. .

[4] The method for producing a semiconductor substrate made of a β-Ga ₂ O ₃ single crystal according to the above [3], wherein the oxygen removing step is heat-treated in an atmosphere of 1 atm or less. Good.

[5] The method for producing a semiconductor substrate made of a β-Ga ₂ O ₃ single crystal as described in [4] above, wherein the oxygen removing step is heat-treated in a low temperature H ₂ atmosphere. Good.

According to the present invention, even when GaN is crystal-grown, GaN grows on a (100) plane of a semiconductor substrate made of a β-Ga ₂ O ₃ single crystal capable of high-quality epitaxial crystal growth with a low transition density. a semiconductor substrate made of β-Ga ₂ O ₃ single crystal having an epitaxial layer formed Te, and can provide a method for manufacturing a semiconductor substrate consisting of β-Ga ₂ O ₃ system single crystal.

(First embodiment)
FIG. 1A is an external perspective view of a semiconductor substrate that defines a plane orientation according to the first embodiment of the present invention. FIG. 1B is a diagram showing a crystal structure by enlarging the portion of the (100) plane of the semiconductor substrate of FIG.

The semiconductor substrate according to the first embodiment of the present invention has a (100) plane having a predetermined plane orientation, and the oxygen is removed from the surface layer of the (100) plane. A semiconductor substrate 1 made of a Ga ₂ O ₃ single crystal.

The semiconductor substrate 1 is a semiconductor substrate 1 made of a β-Ga ₂ O ₃ based single crystal, and is formed in a plate shape having a predetermined plane orientation. The azimuth axis of the crystal structure of β-Ga ₂ O ₃ is composed of an a-axis <100>, a b-axis <010>, and a c-axis <001>, and the semiconductor substrate 1 has a predetermined plane defined by these three axes It is formed in a plate shape with an orientation, that is, a (100) plane, a (010) plane, and a (001) plane. As shown in FIG. 1A, the (100) plane has a large area because epitaxial crystal growth of GaN or a GaN-based compound is performed on the surface when a semiconductor device is manufactured. It is plate-shaped.

When a part of the semiconductor substrate 1 is enlarged to show a crystal structure as shown in FIG. 1B, the crystal structure of β-Ga ₂ O ₃ is a-axis <100>, b-axis <010>, c-axis <001> has Ga (gallium) atoms 30 and O (oxygen) atoms 40 arranged in a predetermined crystal structure. The enlarged view of part A shown in FIG. 1B shows a part of the surface layer of the (100) plane of the semiconductor substrate 1, and in this surface layer, a part of the O atoms 40 is removed by an oxygen removing method described later. Has been. The O atom 40 to be removed is preferably one O atom layer on the (100) surface of the crystal structure of β-Ga ₂ O ₃ , but is not limited to this, and the transition density becomes low in the epitaxial crystal growth of GaN. It suffices if the O atom is removed.

(Method for Producing Semiconductor Substrate 1 Consisting of β-Ga ₂ O ₃ System Single Crystal According to First Embodiment)
The method of manufacturing a semiconductor substrate 1 made of β-Ga ₂ O ₃ single crystal according to the first embodiment is comprised of a β-Ga ₂ O ₃ single crystal having a predetermined surface orientation (100) surface A substrate preparing step for preparing a substrate and an oxygen removing step for removing oxygen on the surface of the (100) plane which is the predetermined plane orientation of the substrate are configured.

(Board preparation process)
The substrate preparation step of preparing a substrate made of a β-Ga ₂ O ₃ based single crystal having a (100) plane having a predetermined plane orientation is performed by manufacturing the predetermined semiconductor substrate 1 shown above or a semiconductor substrate manufactured in advance. This is a step of preparing the oxygen removal step of the next step by purchasing 1 or the like.

  As for the semiconductor substrate 1, first, a bulk crystal is produced by the EFG method or the FZ method, and the plate-like semiconductor substrate 1 is produced by cutting or cleaving this.

In the EFG method, a predetermined amount of β-Ga ₂ O ₃ as a raw material is put in a crucible and heated to be dissolved to obtain a β-Ga ₂ O ₃ melt. The β-Ga ₂ O ₃ melt is raised to the upper surface of the slit die by a capillary phenomenon by a slit formed in the slit die arranged in the crucible, and cooled by bringing the β-Ga ₂ O ₃ melt into contact with the seed crystal, A bulk crystal having a cross section of an arbitrary shape is prepared.

  The FZ method is manufactured by an infrared heating single crystal manufacturing apparatus. One end of the seed crystal is held on the seed chuck, and the upper end of the rod-like polycrystalline material is held on the material chuck. The upper and lower positions of the upper rotating shaft are adjusted to bring the upper end of the seed crystal into contact with the lower end of the polycrystalline material. The upper and lower positions of the upper and lower rotary shafts are adjusted so that the light from the halogen lamp is condensed at the upper end of the seed crystal and the lower end of the polycrystalline material. By making these adjustments, the upper end portion of the seed crystal and the lower end portion of the polycrystalline material are heated, and the heated portion is dissolved to form dissolution droplets. At this time, only the seed crystal is rotated. Next, the polycrystalline material and the seed crystal are melted while rotating in the opposite direction so that the polycrystalline material and the seed crystal are sufficiently blended, and the polycrystalline material and the seed crystal are pulled in the opposite directions to obtain a single unit of appropriate length and thickness. Bulk crystals are formed by forming crystals.

A plate-like semiconductor substrate 1 having a predetermined plane orientation is produced from the β-Ga ₂ O ₃ bulk crystal produced as described above as follows. When the β-Ga ₂ O ₃ bulk crystal is grown in the b-axis <010> orientation, the cleaving property of the (100) plane becomes strong, so that it is a plane perpendicular to the plane parallel to the (100) plane. The semiconductor substrate 1 having a predetermined plane orientation is produced by cutting. When the crystal is grown in the a-axis <100> orientation and the c-axis <001> orientation, the cleaving properties of the (100) plane and the (001) plane are weakened. There is no restriction on the cut surface.

(Oxygen removal process)
The oxygen removing step is a step of removing oxygen from the surface layer of the (100) plane of the semiconductor substrate 1 made of β-Ga ₂ O ₃ based single crystal, and the following oxygen removing method can be used. is there.
(1) Heat treatment in a pressure (vacuum) lower than 1 atm (1 × 10 ⁵ Pa) (2) Low temperature (below 400 to 1000 ° C.), H ₂ , He + H ₂ , Ar + H ₂ , inert gas + H ₂ atmosphere (3) Treatment in H ₂ , He + H ₂ , Ar + H ₂ , inert gas + H ₂ plasma

The amount of oxygen removed from the surface layer of the (100) surface of the semiconductor substrate 1 is appropriately changed by, for example, the set atmospheric pressure, the heat treatment temperature, or the H ₂ flow rate, plasma intensity, and flow rate when heat treatment is performed in an H ₂ atmosphere. Is set by

Note that the method is applicable to the semiconductor substrate according to the first embodiment of the present invention as long as it is a method of removing oxygen from the surface layer of the (100) surface of the semiconductor substrate 1 without being limited to the above-described oxygen removing method. it can.
(Second Embodiment)

FIG. 2A is a diagram showing a semiconductor substrate 10 according to the second embodiment of the present invention. In the case where GaN is epitaxially grown on the semiconductor substrate 1 according to the first embodiment, FIG. is a diagram showing the crystal growth orientation, as viewed from the b-axis direction of the Ga ₂ O _3. Similarly, FIG. 2B is a view of GaN as seen from the c-axis <0001> or <000-1> direction (viewed from the upper side of FIG. 2A).

In the semiconductor substrate 10 according to the second embodiment of the present invention, the oxygen in the surface layer of the (100) plane having a predetermined plane orientation is removed, and the wurtzite is formed on the (100) plane from which the oxygen is removed. This is a semiconductor substrate made of a β-Ga ₂ O ₃ based single crystal having an epitaxial layer formed by growing GaN having a mold structure in the c-axis <0001> or <000-1> direction of the GaN.

  FIG. 3 is a view showing a crystal structure of GaN having a wurtzite structure, (a) a Ga plane, and (b) a nitrogen plane, and is composed of Ga (gallium) atoms 30 and N (nitrogen) atoms 50. FIG. Note that a GaN-based compound such as AlGaN or InGaN has a crystal structure in which part of the Ga atom 30 is substituted with Al, In, or the like.

The semiconductor substrate 10 according to the second embodiment is formed from the semiconductor substrate 1 according to the first embodiment, that is, a β-Ga ₂ O ₃ -based single crystal from which oxygen is removed from the (100) plane surface layer. It is obtained by growing GaN in the c-axis <0001> or <000-1> direction on the (100) plane of the resulting semiconductor substrate 1.

(Method of forming GaN epitaxial layer by MOCVD method)
A method for manufacturing the semiconductor substrate 10 according to the second embodiment described above by MOCVD will be described.

First, the semiconductor substrate 1 from which oxygen in the (100) plane surface layer has been removed is held in a reaction vessel. The temperature in the reaction vessel is adjusted so that the surface temperature of the semiconductor substrate 1 becomes a predetermined temperature, for example, 400 ° C. to 700 ° C. The inside of the reaction vessel is depressurized to 100 torr, and TMG (trimethylgallium) as a Ga feed material and NH ₃ as a nitrogen source are supplied into the reaction vessel together with helium gas or hydrogen gas as a carrier gas, to a predetermined thickness. The GaN layer is epitaxially grown. Thereafter, it is preferable to perform a so-called high temperature annealing treatment. Thereby, the (11-20) plane of GaN and the (010) plane of β-Ga ₂ O ₃ become substantially parallel.

FIG. 4 shows the GaN c-axis <0001> or <000-1> direction when GaN is epitaxially grown on the surface of the β-Ga ₂ O ₃ substrate of the semiconductor substrate 1 according to the first embodiment. As seen, the crystal lattice is visualized by connecting Ga atoms 30 and N atoms 50 of GaN with lines, and the crystal lattice by connecting Ga atoms 30 and O atoms 50 of β-Ga ₂ O ₃ with lines. This is an illustration of a visual representation of the above. FIG. 5 is a visual representation of the arrangement state of Ga atoms 30 and O atoms 50 viewed from the (001) plane of the β-Ga ₂ O ₃ substrate.

According to the semiconductor substrate 10 according to the second embodiment, there is no deviation between the crystals of β-Ga ₂ O ₃ and GaN. This is because, in the semiconductor substrate 1 according to the first embodiment, the oxygen of the surface layer of the (100) plane of β-Ga ₂ O ₃ is removed, so that the lattice constant of GaN is β-Ga ₂ O _3. This is because the GaN layer is epitaxially grown so as to match the lattice constant of That is, when viewed from a two-unit lattice of GaN, translational properties are satisfied in the b-axis and c-axis directions of β-Ga ₂ O ₃ , and the translational movement distance is laterally the c-axis of β-Ga ₂ O ₃ The vertical axis is three times the b-axis of β-Ga ₂ O ₃ .

(Operations and effects of the first and second embodiments)
The operation and effect of the semiconductor substrate 1 according to the first embodiment of the present invention and the semiconductor substrate 10 according to the second embodiment of the present invention configured using the semiconductor substrate 1 will be described.

FIG. 6 is a diagram showing lattice constants of GaN and β-Ga ₂ O ₃ . Although the crystal structures of GaN and β-Ga ₂ O ₃ are completely different, the vertical and horizontal numerical values are approximated. For example, in the vertical direction, as shown in the figure, 3.189 of GaN and 3.04 of β-Ga ₂ O ₃ are approximated, but the mismatch is 4.7%. In the lateral direction, 5.52 of GaN and 5.80 of β-Ga ₂ O ₃ are close to each other, but the mismatch is 5.1%. When compared in terms of area, the mismatch is 0.16% between 3.189 × 5.52 and 3.04 × 5.80.

FIG. 7 is a diagram visualizing a state where a lattice of GaN and a lattice image of β-Ga ₂ O ₃ are combined.

The lattice dimension of the β-Ga ₂ O ₃ substrate is 3.04 × 5.80. On the other hand, the hexagonal vertical and horizontal dimensions of the crystal lattice visualized by connecting Ga atoms 30 of GaN growing on the β-Ga ₂ O ₃ substrate with lines are 3.189 × 5.52. Therefore, as described above, although the lattice constants are approximated, lattice mismatch occurs when crystals are grown, and high-quality epitaxial crystal growth is difficult.

FIG. 8 shows GaN Ga atoms 30 and GaN as viewed from the c-axis <0001> or <000-1> direction of GaN when GaN is epitaxially grown on the conventional β-Ga ₂ O ₃ substrate. The crystal lattice is visualized by connecting the N atoms 50 with lines, and the crystal lattice is visualized by connecting the Ga atoms 30 and O atoms 50 of β-Ga ₂ O ₃ with lines. It is shown in the figure. FIG. 9 is a visual representation of the arrangement state of Ga atoms 30 and O atoms 50 viewed from the (001) plane of the β-Ga ₂ O ₃ substrate.

8 and 9, since there are O atoms 50 in the surface layer of the β-Ga ₂ O ₃ substrate, heteroepitaxial growth occurs, and lattice mismatch is likely to occur at the substrate interface.

The O atoms 50 in the surface layer of the β-Ga ₂ O ₃ substrate are removed as shown in FIG. 5, and as shown in FIG. 4 when viewed from the c-axis <0001> or <000-1> direction of GaN. In addition, a hexagon obtained by linking the Ga atoms 30 with lines to visualize the crystal lattice becomes clear. That is, it can be seen that one layer of Ga atoms 30 is arranged at the apex and center of the hexagon. Therefore, when GaN is epitaxially grown on the surface of the β-Ga ₂ O ₃ substrate in such a state, growth close to homoepitaxial is obtained near the interface of the β-Ga ₂ O ₃ substrate, and high-quality epitaxial crystal growth is achieved. It becomes possible.

From the above, according to the first and second embodiments, the following effects are obtained.
(1) Even when GaN is grown on a semiconductor substrate made of a β-Ga ₂ O ₃ single crystal, high-quality epitaxial crystal growth with a low transition density is possible.
(2) When heteroepitaxial crystal growth of GaN is performed on a semiconductor substrate made of a β-Ga ₂ O ₃ system single crystal, the dislocation density can be lowered by optimizing the growth conditions. As a result, we have great expectations as a laser substrate.
(3) The semiconductor substrate according to the embodiment of the present invention can be used as a general-purpose semiconductor substrate for manufacturing semiconductor devices, for example, light emitting elements such as LEDs and lasers, and has an advantage that it can be used for a wide range of applications. .

(Application Example of Semiconductor Substrate According to Second Embodiment to Laser Light-Emitting Element)
FIG. 10 is a schematic perspective view of a semiconductor laser 101 when the semiconductor substrate 10 according to the second embodiment is applied to a semiconductor laser. The semiconductor laser 101 includes a substrate 10 made of a β-Ga ₂ O ₃ single crystal, an epitaxial layer 111 formed by growing a (0001) plane of a GaN-based compound having a wurtzite structure on the substrate 10, And a laser resonator in which a resonator end face 113 which is a cleavage plane of the epitaxial layer 111 is formed at both ends of the active region 112.

The substrate 10 made of _β-Ga 2 _{O 3} system single crystal, although basically in that it consists in _β-Ga 2 _{O 3} single crystal as described above, Cu, Ag, Zn, Cd , Al, In, You may comprise with the oxide which made Ga the main component which added 1 or more types chosen from the group which consists of Si, Ge, and Sn. By adding these elements, the lattice constant or band gap energy can be controlled. For example, by adding Al and In elements, (GaxAlyIn (1-xy)) ₂ O ₃ (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) A semiconductor substrate can be obtained.

As shown in FIG. 10, the semiconductor laser 101 includes an n-GaN layer 122, an n-InGaN layer 123, and an n-AlGaN layer 124 on the (100) plane of the substrate 10 made of a β-Ga ₂ O ₃ single crystal. , An n-GaN layer 125, an InGaN MQW 126, a p-AlGaN layer 127, a p-GaN layer 128, a p-AlGaN layer 129, and a p-GaN layer 130 are formed as the epitaxial layer 111. An n-electrode 131 is formed on the surface of the substrate 10 where the epitaxial layer 111 is not formed, and a p-electrode 132 is formed on the opposite surface. The epitaxial layer 111 is configured to include all or a part of each of the above layers.

  In the above, mainly, the n-GaN layer 122 is a contact layer, the n-InGaN layer 123 is a cladding layer, the n-AlGaN layer 124 is a base layer, the n-GaN layer 125 is a guide layer, the InGaN MQW 126 is a light emitting layer, p- The AlGaN layer 127 functions as a cap layer, the p-GaN layer 128 functions as a guide layer, the p-AlGaN layer 129 functions as a cladding layer, and the p-GaN layer 130 functions as a contact layer.

  As shown in FIG. 10, the p-electrode 132 is a stripe-type electrode, and the range of the active region 112 is set by defining the range of current confinement by the stripe width.

Here, as shown in FIG. 10, the epitaxial layer 111 is formed in parallel to the (100) plane of the substrate 10 made of β-Ga ₂ O ₃ based single crystal, but the (001) plane of the substrate 10 is (100). ) With the surface at an angle of 103.7 °. Therefore, the (001) plane that is the cleavage plane of the substrate 10 and the (1-100) plane that is the cleavage plane of the epitaxial layer 111 have an angle corresponding to the above 103.7 °. Does not occur.

  The laser resonator of the semiconductor laser 101 is formed with the (1-100) plane of the epitaxial layer 111 including the active region 112, that is, the cleavage planes at both ends of the epitaxial layer 111 as the resonator end surface 113.

Although not shown, in the semiconductor laser 101, wiring for supplying current is applied to the n electrode 131 and the p electrode 132 by wire bonding or the like, and packaging for mounting is performed.
(Effect of application to laser light emitting device)

When the semiconductor substrate according to the second embodiment is applied to a laser light emitting element, the following effects are obtained.
(1) Since the (0001) plane of the GaN-based compound is grown on the (100) plane of the substrate 10 made of β-Ga ₂ O ₃ single crystal, the cleavage plane is a plane in substantially the same direction. Therefore, a high-quality resonator end face 113 can be easily obtained using cleavage.
(2) Since the substrate 10 made of β-Ga ₂ O ₃ based single crystal has conductivity, it is possible to have a vertical structure in which electrodes are provided on the epitaxial layer 111 side and the substrate 10 on the opposite side. The semiconductor laser can be manufactured by a simple manufacturing process.
(3) Since the substrate 10 made of β-Ga ₂ O ₃ based single crystal has a thermal expansion coefficient very close to that of GaN, it is less affected by the warpage of the substrate 10 during the process, and is uniform over the entire substrate 10. The epitaxial layer 111 is obtained and the yield is improved.

  From the above, for example, there is no need to remove a sapphire substrate by a laser lift method and replace it with a Si substrate or the like, and a laser resonator with high accuracy by a simple manufacturing process using cleavage. A semiconductor laser in which is formed becomes possible.

FIG. 1A is an external perspective view of a semiconductor substrate that defines a plane orientation according to the first embodiment of the present invention. FIG. 1B is a diagram showing a crystal structure by enlarging the portion of the (100) plane of the semiconductor substrate of FIG. FIG. 2A is a diagram showing a semiconductor substrate 10 according to the second embodiment of the present invention. In the case where GaN is epitaxially grown on the semiconductor substrate 1 according to the first embodiment, FIG. is a diagram showing the crystal growth orientation, as viewed from the b-axis direction of the Ga ₂ O _3. Similarly, FIG. 2B is a view of GaN as seen from the c-axis <0001> or <000-1> direction (viewed from the upper side of FIG. 2A). FIG. 3 is a view showing a crystal structure of GaN having a wurtzite structure, (a) a Ga plane, and (b) a nitrogen plane, and is composed of Ga (gallium) atoms 30 and N (nitrogen) atoms 50. FIG. FIG. 4 shows the GaN c-axis <0001> or <000-1> direction when GaN is epitaxially grown on the surface of the β-Ga ₂ O ₃ substrate of the semiconductor substrate 1 according to the first embodiment. As seen, the crystal lattice is visualized by connecting Ga atoms 30 and N atoms 50 of GaN with lines, and the crystal lattice by connecting Ga atoms 30 and O atoms 50 of β-Ga ₂ O ₃ with lines. This is an illustration of a visual representation of the above. FIG. 5 is a visual representation of the arrangement state of Ga atoms 30 and O atoms 50 viewed from the (001) plane of the β-Ga ₂ O ₃ substrate. FIG. 6 is a diagram showing lattice constants of GaN and β-Ga ₂ O ₃ . FIG. 7 is a diagram visualizing a state where a lattice of GaN and a lattice image of β-Ga ₂ O ₃ are combined. FIG. 8 shows GaN Ga atoms 30 and GaN as viewed from the c-axis <0001> or <000-1> direction of GaN when GaN is epitaxially grown on the conventional β-Ga ₂ O ₃ substrate. The crystal lattice is visualized by connecting the N atoms 50 with lines, and the crystal lattice is visualized by connecting the Ga atoms 30 and O atoms 50 of β-Ga ₂ O ₃ with lines. It is shown in the figure. FIG. 9 is a diagram visualizing the arrangement state of Ga atoms 30 and O atoms 50 viewed from the (001) plane of the β-Ga ₂ O ₃ substrate. FIG. 10 is a schematic perspective view of a semiconductor laser 101 when the semiconductor substrate 10 according to the second embodiment is applied to a semiconductor laser.

Explanation of symbols

1, 10 Semiconductor substrate 30 Ga (gallium) atom 40 O (oxygen) atom 50 N (nitrogen) atom 101 Semiconductor laser 111 Epitaxial layer 112 Active region 113 Resonator end face 122 n-GaN layer 123 n-InGaN layer 124 n-AlGaN Layer 125 n-GaN layer 126 InGaN MQW
127 p-AlGaN layer 128 p-GaN layer 129 p-AlGaN layer 130 p-GaN layer 131 n-electrode 132 p-electrode

Claims (5)

A semiconductor substrate comprising a β-Ga ₂ O ₃ -based single crystal having a (100) plane having a predetermined plane orientation, wherein oxygen in a surface layer of the (100) plane is removed. Oxygen in the surface layer of the (100) plane having a predetermined plane orientation is removed, and the wurtzite-type GaN is formed on the (100) plane from which the oxygen is removed, and the c-axis <0001> or <000 of the GaN. A semiconductor substrate made of a β-Ga ₂ O ₃ single crystal, characterized by having an epitaxial layer formed by growing in the -1> direction. A substrate preparation step of preparing a substrate made of a β-Ga ₂ O ₃ -based single crystal having a (100) plane having a predetermined plane orientation;
An oxygen removing step of removing oxygen from the surface layer of the (100) plane which is the predetermined plane orientation of the substrate;
A method for producing a semiconductor substrate comprising a β-Ga ₂ O ₃ -based single crystal, comprising: The method for manufacturing a semiconductor substrate comprising a β-Ga ₂ O ₃ single crystal according to claim 3, wherein the oxygen removing step is heat-treated in an atmosphere of 1 atm or less. The method for manufacturing a semiconductor substrate comprising a β-Ga ₂ O ₃ single crystal according to claim 3, wherein the oxygen removing step is heat-treated in a low temperature and H ₂ atmosphere.

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