JP2006135269A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device in which a single crystal thin film composed of a GaN based compound having high crystal quality can be formed. <P>SOLUTION: The light emitting element 10 comprises a Ga<SB>2</SB>O<SB>3</SB>substrate 11 composed of β-Ga<SB>2</SB>O<SB>3</SB>single crystal having (100) face or (801) face as the major surface, and an n-GaN clad layer 13, an InGaN light emitting layer 14, a p-AlGaN clad layer 15, and a p-GaN contact layer 16 formed sequentially on the Ga<SB>2</SB>O<SB>3</SB>substrate 11 through a surface rearrangement layer 22. When the crystal orientation of β-Ga<SB>2</SB>O<SB>3</SB>single crystal of the Ga<SB>2</SB>O<SB>3</SB>substrate 11 is ä010}, the crystal orientation of a GaN system compound thin film consisting of the surface rearrangement layer 22, the n-GaN clad layer 13, the InGaN light emitting layer 14, and the p-AlGaN clad layer 15 is ä11-20} and they are substantially in parallel with each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a semiconductor device used for a light-emitting element such as a light-emitting diode (LED) or a laser diode (LD) in which a GaN-based compound thin film is formed on a β-Ga ₂ O ₃ single-crystal substrate. The present invention relates to a semiconductor device capable of forming a single crystal thin film made of a GaN-based compound.

FIG. 4 shows a conventional semiconductor device. The semiconductor device 30 includes an Al ₂ O ₃ substrate 31, a buffer layer 32 made of AlN formed on the surface of the Al ₂ O ₃ substrate 31 at a low temperature, and a MOCVD (Metal Organic Chemical Vapor Deposition) on the buffer layer 32. And a GaN growth layer 33 formed by epitaxial growth by the method (see, for example, Patent Document 1).

According to this semiconductor device 30, by forming the buffer layer 32 between the Al ₂ O ₃ substrate 31 and the GaN growth layer 33, the mismatch of lattice constants is alleviated and the deterioration of the crystal quality is suppressed.
Japanese Patent Publication No. 52-36117

  However, even if the conventional semiconductor device 30 is provided with the buffer layer 32, the lattice mismatch cannot be sufficiently relaxed, and it is difficult to obtain a high-quality GaN growth layer 33. Therefore, when applied to a light-emitting element, the crystallinity of the light-emitting layer is not sufficient, and there is a limit to improvement in light emission efficiency.

  Accordingly, an object of the present invention is to provide a semiconductor device capable of forming a single crystal thin film made of a GaN-based compound having a high crystal quality.

The present invention, in order to achieve the above object, a substrate made of β-Ga ₂ O ₃ system single crystal having a major surface, is formed on the primary surface, the β-Ga ₂ O ₃ constituting the substrate A semiconductor device comprising a surface rearrangement layer containing a wurtzite structure GaN-based compound in which part or all of oxygen atoms are substituted with nitrogen atoms and the c-axis is substantially perpendicular to the principal surface. provide.

According to this configuration, by providing the surface rearrangement layer on the substrate made of β-Ga ₂ O ₃ based single crystal, the wurtzite structure GaN based compound is formed on the β-Ga ₂ O ₃ based crystal structure. The single crystal thin film is grown with a reduced lattice mismatch. As a result, a decrease in crystal quality can be suppressed, and a single crystal thin film made of a high quality GaN compound can be obtained. At this time, the c-axis is preferably in an azimuth within a range of ± 15 ° with respect to the main surface.

  When the substrate has the (100) plane or the (801) plane as the principal plane, the crystal orientation <010> of the substrate and the crystal orientation <11-20> of the surface rearrangement layer are substantially parallel, The surface rearrangement layer preferably has N polarity.

The present invention, in order to achieve the above object, a substrate made of β-Ga ₂ O ₃ system single crystal having a major surface, is formed on the primary surface, the β-Ga ₂ O ₃ constituting the substrate A surface rearrangement layer including a wurtzite structure GaN-based compound in which part or all of oxygen atoms are replaced with nitrogen atoms and the c-axis is substantially perpendicular to the main surface, and is formed on the surface rearrangement layer. And a single crystal thin film made of a wurtzite structure GaN-based compound having a c-axis substantially perpendicular to the main surface.

According to this configuration, by to the substrate made of Ga ₂ O ₃ single crystal providing the nitrided layer, a single crystal thin film made of a GaN-based compound of a wurtzite type structure on the Ga ₂ O ₃ system crystal structure The lattice mismatch is further reduced and grows. As a result, a decrease in crystal quality can be suppressed, and a single crystal thin film made of a high quality GaN compound can be obtained.

  The surface rearrangement layer and the single crystal thin film preferably have N polarity.

  The surface rearrangement layer and the single crystal thin film preferably include a gallium oxide layer and a gallium nitride layer.

  When the substrate has the (100) plane or the (801) plane as the principal plane, the crystal orientation <010> of the substrate and the crystal orientation <11-20> of the surface rearranged layer and the single crystal thin film are approximately It is preferable that they are parallel.

  The substrate preferably includes a buffer layer for inverting N polarity and Ga polarity between the surface rearrangement layer and the single crystal thin film.

In order to achieve the above object, the present invention prepares a substrate made of a β-Ga ₂ O ₃ -based single crystal having a main surface, and a predetermined source gas containing an element constituting a growth layer grown on the substrate In this atmosphere, by maintaining the substrate at a predetermined temperature, a surface rearrangement layer containing a wurtzite structure GaN-based compound having a c-axis substantially perpendicular to the main surface is formed on the main surface. A semiconductor device manufacturing method is provided.

According to this configuration, by to the substrate made of Ga ₂ O ₃ single crystal providing the nitrided layer, a single crystal thin film made of a GaN-based compound of a wurtzite type structure on the Ga ₂ O ₃ system crystal structure The lattice mismatch is further reduced and grows. As a result, a decrease in crystal quality can be suppressed, and a single crystal thin film made of a high quality GaN compound can be obtained.

In order to achieve the above object, the present invention prepares a substrate made of a β-Ga ₂ O ₃ -based single crystal having a main surface, and a predetermined source gas containing an element constituting a growth layer grown on the substrate In this atmosphere, by maintaining the substrate at a predetermined temperature, a surface rearrangement layer including a wurtzite structure GaN-based compound having a c-axis substantially perpendicular to the main surface is formed on the main surface, Provided is a method for manufacturing a semiconductor device, wherein a single crystal thin film made of a wurtzite structure GaN-based compound having a c-axis substantially perpendicular to the main surface is formed on a surface rearrangement layer.

  According to the present invention, a light emitting device including a single crystal thin film made of a GaN-based compound with high crystal quality can be obtained.

<First Embodiment>
<Configuration of light emitting element>
FIG. 1 is a schematic perspective view of a light emitting device according to a first embodiment of the present invention. The light emitting element 10 has a substrate 11 (hereinafter referred to as “Ga ₂ O ₃ substrate”) 11 made of β-Ga ₂ O ₃ exhibiting n-type conductivity, and has a surface on the Ga ₂ O ₃ substrate 11. Rearrangement layer 22, n-GaN cladding layer 13 exhibiting n-type conductivity, InGaN light-emitting layer 14 having a multiple quantum well structure (MQW), p-AlGaN cladding layer 15 exhibiting p-type conductivity, and p-type The p-GaN contact layer 16 exhibiting the above conductivity is sequentially laminated, the p-electrode 17 is formed on the upper surface of the p-GaN contact layer 16, and the n-electrode 18 is formed on the lower surface of the Ga ₂ O ₃ substrate 11. .

The Ga ₂ O ₃ substrate 11 is made of a β-Ga ₂ O ₃ single crystal and has transparency. The Ga ₂ O ₃ substrate 11 has a (100) plane as a main surface, and the main surfaces are a buffer layer 12, an n-GaN cladding layer 13, an InGaN light emitting layer 14, a p-AlGaN cladding layer 15, and a p-GaN contact layer 16. It becomes the growth surface of the semiconductor layer.

The Ga ₂ O ₃ substrate 11 is basically made of β-Ga ₂ O ₃ single crystal as described above, but is made of Cu, Ag, Zn, Cd, Al, In, Si, Ge, and Sn. You may comprise with the oxide which has as a main component Ga which added 1 or more types chosen from the group which consists of. By adding these elements, the lattice constant or band gap energy can be controlled. For example, by adding elements of Al and In, (Ga _x Al _y In _(1-xy) ) ₂ O ₃ (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) The Ga ₂ O ₃ substrate 11 represented by

The surface rearrangement layer 22 heats the Ga ₂ O ₃ substrate 11 in a predetermined NH ₃ atmosphere in a MOCVD apparatus for a predetermined time to form β-Ga ₂ O ₃ constituting the surface of the Ga ₂ O ₃ substrate 11. A part or all of oxygen atoms are replaced with nitrogen atoms. On the surface of the Ga ₂ O ₃ substrate 11, a mixed layer of β-Ga ₂ O ₃ and GaN or a layer made of GaN is formed. . The surface rearrangement layer 22 does not need to be thick, and has a thickness of 1000 nm or less, preferably 200 nm or less. With this thickness, the GaN layer formed on the surface rearrangement layer 22 can take over the influence of the crystal lattice of the substrate. As long as the surface rearrangement layer 22 is the same as or approximates to the lattice constant of β-Ga ₂ O ₃ constituting the Ga ₂ O ₃ substrate 11, the surface rearrangement layer 22 may be formed on another surface.

A GaN-based compound thin film composed of the n-GaN cladding layer 13, the InGaN light emitting layer 14, the p-AlGaN cladding layer 15, the p-GaN contact layer 16, and the like is formed by MOCVD. This GaN-based compound thin film may contain an additive such as a group III element such as B, Al, In, or Tl. For example, by adding elements of Al and In, the general formula Ga _x Al _y In _(1-xy) N (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) The represented GaN-based compound thin film can be used.

  Further, instead of the n-GaN cladding layer 13 described above, a thin film made of InGaN, AlGaN or InGaAlN may be grown. Since these are almost the same as the lattice constant of GaN, lattice mismatch is unlikely to occur and the crystal quality is not easily lowered.

  The InGaN light emitting layer 14 is formed of, for example, a semiconductor made of non-doped InGaN to which no impurity is added, and has a single quantum well structure or a multiple quantum well structure (MQW). The emission wavelength can be changed by changing the band gap of the InGaN light-emitting layer 14 by adjusting the composition ratio of In and Ga or by using p-type or n-type conductivity.

  The p electrode 17 is formed on the p-GaN contact layer 16 with a material that can provide ohmic contact by vapor deposition, sputtering, or the like. As a material of the p-electrode 17, a simple metal such as Au, Al, Be, Ni, Pt, In, Sn, Cr, Ti, Zn, or at least two kinds of alloys thereof (for example, Au—Zn alloy, Au—Be) Alloys), those forming these in a two-layer structure (for example, Ni / Au), ITO, or the like can be used.

The n-electrode 18 is formed on the lower surface of the Ga ₂ O ₃ substrate 11 with a material that can provide ohmic contact by vapor deposition, sputtering, or the like. As a material for the n-electrode 18, a simple metal such as Au, Al, Co, Ge, Ti, Sn, In, Ni, Pt, W, Mo, Cr, Cu, Pb, or at least two kinds of these alloys (for example, (Au—Ge alloy), those formed in a two-layer structure (for example, Al / Ti, Au / Ni, Au / Co), ITO, or the like can be used.

<Substrate formation method>
Next, a method for forming the Ga ₂ O ₃ substrate 11 will be described. That is, a β-Ga ₂ O ₃ single crystal as a material of the Ga ₂ O ₃ substrate 11 is produced by an FZ (floating zone) method, and the β-Ga ₂ O ₃ single crystal is cut into a predetermined size to obtain a substrate. Make it.

Hereinafter, the manufacturing method of a board | substrate is demonstrated in detail. First, a β-Ga ₂ O ₃ seed crystal and a β-Ga ₂ O ₃ polycrystalline material are prepared. As the β-Ga ₂ O ₃ seed crystal, a β-Ga ₂ O ₃ single crystal is cut out along the heel interface and formed into a predetermined size. The β-Ga ₂ O ₃ polycrystalline material is prepared by, for example, filling a rubber tube with β-Ga ₂ O ₃ powder having a purity of 4N, cold-compressing it at 500 MPa, and sintering at 1500 ° C. for 10 hours. can get.

Next, in an atmosphere of a mixed gas of nitrogen and oxygen (changed between 100% nitrogen and 100% oxygen) having a total pressure of 1 to 2 atm in a quartz tube, β-Ga ₂ O ₃ seed crystal and β The tips of the —Ga ₂ O ₃ polycrystalline material are brought into contact with each other, and the contact portions are heated and melted. When the melted β-Ga ₂ O ₃ polycrystalline material is cooled, the β-Ga ₂ O ₃ single crystal is in the same direction as the axial direction of the β-Ga ₂ O ₃ seed crystal (a-axis, b-axis, or c direction). Furthermore, we intend to dissolve the _β-Ga 2 _{O 3} polycrystalline away from the seed crystal, dissolved _β-Ga 2 _{O 3} polycrystal gradually cooled to obtain a _β-Ga 2 _{O 3} single crystal. The β-Ga ₂ O ₃ single crystal is cleaved along, for example, the (100) plane, and cut into a predetermined size to produce the Ga ₂ O ₃ substrate 11. As a result of measuring the specific resistance of the Ga ₂ O ₃ substrate 11 thus produced, a value of 0.1 Ω · cm or less was obtained at room temperature.

<Method for forming surface rearrangement layer>
Next, a method for forming the surface rearrangement layer 22 will be described. First, the Ga ₂ O ₃ substrate 11 is held in the reaction container so that the main surface on which the surface rearrangement layer 22 is to be formed appears. Then, the temperature in the reaction vessel is adjusted so that the temperature of the surface of the Ga ₂ O ₃ substrate 11 is 500 ° C. or higher, preferably 800 ° C. ± 50 ° C. The reaction vessel is heated to a nitrogen source with 760 torr of NH ₃ as an atmosphere and heated for a predetermined time, so that part or all of β-Ga ₂ O ₃ oxygen atoms constituting the surface of the Ga ₂ O ₃ substrate 11 are nitrogen atoms. As a result of the replacement, a layer in which β-Ga ₂ O ₃ and GaN are mixed or a layer made of GaN is formed on the surface of the Ga ₂ O ₃ substrate 11. The plane orientation of the Ga ₂ O ₃ substrate 11 on which the surface rearrangement layer 22 is grown is the (100) plane, and an error of ± 15 ° is allowed for each plane.

<Method for forming GaN-based compound thin film>
The GaN-based compound thin films of the n-GaN cladding layer 13, the InGaN light emitting layer 14, the p-AlGaN cladding layer 15, and the p-GaN contact layer 16 are formed by MOCVD. In order to form the n-GaN cladding layer 13 and the p-GaN cladding layer 15, TMG and NH ₃ are used as source gases, and in order to form the InGaN light-emitting layer 14, TMI (trimethylindium), TMG are used as source gases. In order to form the p-AlGaN cladding layer 15 using (trimethylgallium) and NH ₃ , TMA, TMG, and NH ₃ are used as source gases. The carrier gas is an inert gas such as He for the reasons described above. In this case, the growth of the GaN-based compound thin film is promoted by a predetermined temperature range. At this time, the GaN-based compound thin film has N polarity. Note that in the case of a surface having Ga polarity, a buffer layer for converting the polarity may be formed.

<Formation of thin films with different carrier concentrations>
In order to change the carrier concentration of GaN as in the case of the n-GaN cladding layer 13 and the p-GaN contact layer 16 by the MOCVD apparatus, the amount of n-type dopant or p-type dopant added to GaN is changed.

  That is, in order to form thin films having different carrier concentrations, for example, the n-GaN clad layer 13 and the p-GaN contact layer 16 by the MOCVD apparatus, the following process is performed.

First, the n-GaN cladding layer 13 will be described. In the reaction vessel, the Ga ₂ O ₃ substrate 11 is held such that the surface on which the thin film is formed faces up. Then, the temperature in the reaction vessel for example, as 1080 ° C., TMG and 54 × ^{10 -6} mol / min, TMA (trimethyl aluminum) and 6 × ^{10 -6} mol / min, monosilane (SiH ₄₎ and 22 × 10 ^{- A} flow rate of ¹¹ mol / min is applied for 60 minutes to grow Si-doped Ga _0.9 Al _0.1 N (n-GaN cladding layer 13) with a thickness of 3 μm. Note that the temperature, the TMA concentration, and the like can be increased or decreased within a range that does not affect the film growth.

Next, the p-GaN contact layer 16 will be described. The temperature in the reaction vessel is, for example, 1080 ° C., TMG is flowed at 54 × 10 ⁻⁶ mol / min together with bisdiclopentadienylmagnesium (Cp ₂ Mg), and Mg-doped GaN (p-GaN contact layer 16) is flown. Growing with a film thickness of 1 μm. Note that the temperature, the TMA concentration, and the like can be increased or decreased within a range that does not affect the film growth.

  Instead of the n-GaN cladding layer 13, InGaN, AlGaN, or InGaAlN may be grown. In the case of InGaN and AlGaN, the lattice constant with the surface rearrangement layer 22 can be made to substantially match, and in the case of InAlGaN, the lattice constant with the surface rearrangement layer 22 can be made to match.

<Effect of Embodiment>
The light emitting element 10 according to this embodiment has the following effects.
(A) In the (100) plane of the β-Ga ₂ O ₃ single crystal of the Ga ₂ O ₃ substrate 11, the unit cell is hexagonal and approximates to a wurtzite structure that is a crystal structure of GaN. A single crystal thin film of GaN is grown so that the crystal orientation <11-20> of the wurtzite structure and the crystal orientation <010> of the Ga ₂ O ₃ substrate 11 are substantially parallel. At this time, a GaN-based compound thin film having a close lattice constant and good crystallinity can be obtained. Therefore, deterioration of crystal quality can be suppressed, and a light-emitting element with improved light emission efficiency can be obtained.
(B) By exposing the N surface, various growth methods for growing a thin film on the N surface can be used, so that a semiconductor device suitable for the application can be obtained.
(C) Since the Ga ₂ O ₃ substrate 11 and the surface rearrangement layer 22 have translucency and conductivity, a light-emitting diode having a vertical electrode structure can be formed. As a result, the light-emitting element 10 Therefore, the current density can be lowered, and the lifetime of the light emitting element 10 can be extended.
(D) Since the light-emitting element 10 has a multiple quantum well structure, the probability that the electrons and holes serving as carriers are confined in the InGaN light-emitting layer 14 and recombined increases, so that the light emission rate is greatly increased. To improve.
(E) By exposing the N surface, a good single crystal film is formed without being eroded by the hydrogen carrier gas.

2A and 2B show a light-emitting element according to Example 1, where FIG. 2A is a schematic view seen from the top surface of the light-emitting element, and FIG. 2B is a side view.
The Ga ₂ O ₃ substrate 11 is obtained by growing a β-Ga ₂ O ₃ single crystal in the planar direction along the b-axis and the c-axis and growing in the thickness direction along the a-axis direction.

The GaN-based compound thin film layer 23 is formed of GaN such as an n-GaN cladding layer 13, an InGaN light emitting layer 14, a p-AlGaN cladding layer 15, and a p-GaN contact layer 16 on the (100) plane of the Ga ₂ O ₃ substrate 11. A system compound thin film is grown in the planar direction along the a-axis and the b-axis, and is grown in the thickness direction along the c-axis direction.
According to Example 1, when the crystal orientation of β-Ga ₂ O _{3 on} the crystal surface in the (100) plane of the Ga ₂ O ₃ substrate 11 is <010>, the crystal orientation on the crystal surface of GaN is <11-20>.

The surface rearrangement was performed by heating the Ga ₂ O ₃ substrate to 500 ° C. or higher in a 1 Torr NH ₃ atmosphere. XPS (X-ray photoelectron spectroscopic analysis) was performed by using a JPS-9010TR system and irradiating the Mg target with X-rays generated by flowing a current of 10 mA at 10 kV at a right angle to the (100) plane. .

FIG. 3 is a diagram showing the state of the surface of the Ga ₂ O ₃ substrate 11 before and after the surface rearrangement. This figure shows X-ray photoelectron emission spectra before and after nitriding in the (100) plane of the Ga ₂ O ₃ substrate 11. This confirms the acceptance of nitrogen atoms on the surface of the Ga ₂ O ₃ substrate 11 by XPS. The solid line shows the X-ray photoelectron emission spectrum before nitriding, and the broken line shows the X-ray photoelectron emission spectrum after nitriding. According to this figure, the following can be understood.

(1) The peak due to the 1s electron of the oxygen atom decreases.
(2) The peak due to the 1s electron of the nitrogen atom increases.
(3) The peak attributed to the 3d electrons of Ga does not change much.

The concentration ratio of oxygen atoms to Ga atoms on the surface of the Ga ₂ O ₃ substrate 11 before nitriding is 53:47, which is calculated from the ratio of the emission intensity of 3d electrons of Ga atoms and 1s electrons of oxygen atoms. The concentration ratio is approximately in agreement with the stoichiometric value. The concentration ratio of oxygen atoms and nitrogen atoms on the surface of the Ga ₂ O ₃ substrate after the surface rearrangement is 56:44, and the peak based on the emission of 1s electrons of oxygen atoms decreases, and the emission of 1s electrons of nitrogen atoms decreases. Based peak appeared. This indicates that the oxygen atoms on the surface of the Ga ₂ O ₃ substrate 11 are replaced by nitrogen atoms. According to XPS, it can be seen that nitrogen atoms are only incorporated into the surface.

Moreover, the electrical conductivity, the carrier concentration, and the carrier mobility of the surface rearrangement layer 22 are 50Ω ⁻¹ cm ⁻¹ , 1 × 10 ¹⁸ cm, and 100 cm ² V ⁻¹ S ⁻¹ , respectively. There is no impact on

In the surface rearrangement, the Ga ₂ O ₃ substrate 11 was heated to 800 ° C. in an NH ₃ atmosphere of 760 Torr (1 atm). Even under these conditions, a surface rearrangement layer could be formed in the same manner as in Example 1.

In Example 5, when the crystal orientation of β-Ga ₂ O _{3 on} the (100) plane of the Ga ₂ O ₃ substrate 11 is <010>, the crystal orientation of GaN is <11-20>, which is substantially parallel. is doing. In this case, although the shape of the unit cell on the (100) plane is not hexagonal, GaN having good crystallinity was epitaxially grown in the same orientation as the (801) plane.

<Other embodiments>
Although the FZ method has been described as the growth method of the Ga ₂ O ₃ substrate 11, β-Ga manufactured by the FZ method can be applied even if another growth method such as an EFG (Edge-defined Film-fed Growth method) method is applied. ₂ O ₃ can be produced similar _beta-Ga 2 _{O 3} single crystal and the single crystal can be produced _Ga 2 _{O 3} substrate 11 by cutting it.

  Also, the MOCVD method has been described as a method for growing a GaN-based compound thin film. However, even if another growth method such as a PLD (Pulsed Laser Deposition) method or MBE (Molecular Beam Epitaxy) method is applied, it is the same as that by the MOCVD method. Can be epitaxially grown.

Although the case where the Ga ₂ O ₃ substrate 11 on which the nitriding layer 22 is grown is the (100) plane has been described, the same effect can be obtained even when the (801) plane is inclined 13.52 ° with respect to the (100) plane. Can play.

  Note that the light-emitting element 10 according to the present invention is not limited to a light-emitting diode or a laser diode, but can also be applied to a semiconductor such as a transistor, a thyristor, or a diode. Specifically, a field effect transistor, a photodiode, a solar cell, etc. are mentioned, for example.

1 is a schematic perspective view of a light emitting element according to a first embodiment of the present invention. The light emitting element which concerns on Example 1 is shown, (a) is the schematic seen from the upper surface of the light emitting element, (b) is a side view. It is a diagram showing a state before and after the Ga ₂ O ₃ substrate of the surface of the surface reconstruction. It is sectional drawing which shows the conventional semiconductor layer.

Explanation of symbols

10 light-emitting element 11 _Ga 2 _{O 3} substrate 13 n-GaN cladding layer 14 InGaN light-emitting layer 15 p-AlGaN cladding layer 16 p-GaN contact layer seventeen n electrode 18 p electrode 22 surface reconstruction layer 23 GaN-based compound thin film layer 30 semiconductor Layer 31 Al ₂ O ₃ substrate 32 buffer layer 33 GaN growth layer

Claims (9)

A substrate made of a β-Ga ₂ O ₃ single crystal having a main surface;
A wurtzite structure formed on the main surface, wherein some or all of the oxygen atoms of β-Ga ₂ O ₃ constituting the substrate are replaced with nitrogen atoms, and the c-axis is substantially perpendicular to the main surface A semiconductor device comprising a surface rearrangement layer containing a GaN-based compound. When the substrate has a (100) plane or (801) plane as the principal plane, the crystal orientation <010> of the substrate and the crystal orientation <11-20> of the surface rearrangement layer are substantially parallel,
The semiconductor device according to claim 1, wherein the surface rearrangement layer has N polarity. A substrate made of a β-Ga ₂ O ₃ single crystal having a main surface;
A wurtzite structure formed on the main surface, wherein some or all of the oxygen atoms of β-Ga ₂ O ₃ constituting the substrate are replaced with nitrogen atoms, and the c-axis is substantially perpendicular to the main surface A surface rearrangement layer containing a GaN-based compound;
A semiconductor device comprising: a single crystal thin film made of a wurtzite structure GaN-based compound formed on the surface rearrangement layer and having a c-axis substantially perpendicular to the main surface.   4. The semiconductor device according to claim 3, wherein the surface rearrangement layer and the single crystal thin film have N polarity.   The semiconductor device according to claim 3, wherein the surface rearrangement layer and the single crystal thin film include a gallium oxide layer and a gallium nitride layer.   When the substrate has the (100) plane or the (801) plane as the principal plane, the crystal orientation <010> of the substrate and the crystal orientation <11-20> of the surface rearranged layer and the single crystal thin film are approximately The semiconductor device according to claim 3, wherein the semiconductor device is parallel.   4. The semiconductor device according to claim 3, wherein the substrate includes a buffer layer for inverting N polarity and Ga polarity between the surface rearrangement layer and the single crystal thin film. A substrate made of a β-Ga ₂ O ₃ single crystal having a main surface is prepared,
By maintaining the substrate at a predetermined temperature in an atmosphere of a predetermined source gas containing an element constituting a growth layer grown on the substrate, the c-axis is substantially perpendicular to the main surface on the main surface. A method of manufacturing a semiconductor device, comprising forming a surface rearrangement layer containing a wurtzite structure GaN-based compound. A substrate made of a β-Ga ₂ O ₃ single crystal having a main surface is prepared,
By maintaining the substrate at a predetermined temperature in an atmosphere of a predetermined source gas containing an element constituting a growth layer grown on the substrate, the c-axis is substantially perpendicular to the main surface on the main surface. Forming a surface rearrangement layer containing a wurtzite structure GaN-based compound;
A method of manufacturing a semiconductor device, comprising: forming a single crystal thin film made of a wurtzite structure GaN-based compound having a c-axis substantially perpendicular to the main surface on the surface rearrangement layer.