JP2020073424A - α-Ga2O3 SINGLE CRYSTAL AND MANUFACTURING APPARATUS OF THE SAME AND SEMICONDUCTOR DEVICE USING THE SAME - Google Patents

Abstract

To provide a α-GaOsingle crystal applicable to a semiconductor device, a manufacturing apparatus of the α-GaOsingle crystal, and a semiconductor device using the α-GaOsingle crystal.SOLUTION: A α-GaOsingle crystal according to the present invention has a carbon concentration of 5×10cmor less and an absorption coefficient of 200 cmor less for a light of a wavelength of 300 nm or more.SELECTED DRAWING: Figure 6

Description

The present invention relates to an α-Ga ₂ O ₃ single crystal, a manufacturing apparatus for the same, and a semiconductor element using the same.

It is known that gallium oxide has five crystal structures of α, β, δ, ε and γ. Among them, β-Ga ₂ O ₃ has a large band gap of 4.9 eV, conductivity can be imparted by doping, it is thermodynamically most stable, and a single crystal substrate can be produced by melt growth. Has received great attention as a next-generation power semiconductor material with high breakdown voltage and low power consumption. Recently, it has been reported that a high-quality β-Ga ₂ O ₃ single crystal can be obtained at a high growth rate by a halide vapor phase epitaxy (HVPE) (for example, see Non-Patent Document 1).

On the other hand, the band gap of α-Ga ₂ O ₃ is about 5.3 eV, which is larger than that of β-Ga ₂ O ₃ , and α-Ga ₂ O ₃ is also a promising material. However, since α-Ga ₂ O ₃ is a metastable phase, a single crystal substrate cannot be manufactured by melt growth. Therefore, the α-Ga ₂ O ₃ single crystal film is manufactured by epitaxial growth (heteroepitaxial growth) on a heterogeneous substrate using a mist chemical vapor deposition (CVD) method (for example, Non-Patent Documents 2 to 4). See.).

However, according to Non-Patent Documents 2 to 4, since an organic compound is used as a raw material and the production temperature is low, the obtained α-Ga ₂ O ₃ is carbon (C), hydrogen (H). It is not suitable for practical use. Further, according to Non-Patent Documents 2 to 4, the in-plane rotational domain is mixed in the obtained α-Ga ₂ O ₃ and there is a problem in quality. Further, according to Non-Patent Documents 2 to 4, the mist CVD method has a very slow growth rate of α-Ga ₂ O ₃ of about 1 μm / hour, which is not only high in manufacturing cost but also a sapphire substrate during manufacturing. There is also a problem that Al diffuses from the.

Y. Oshima et al., Journal of Crystal Growth 410, 53-58, 2015. D. Shinohara et al., Jpn. J. Appl. Phys. 47, 2008, 7311-7313 T. Kawaharamura et al., Jpn. J. Appl. Phys. 51, 2012, 040207 K. Akaiwa et al., Jpn. J. Appl. Phys. 51, 2012, 070203

From the above, an object of the present invention is to provide an α-Ga ₂ O ₃ single crystal applicable to a semiconductor element, a manufacturing apparatus for the same, and a semiconductor element using the same.

The α-Ga ₂ O ₃ single crystal according to the present invention has a carbon concentration of 5 × 10 ¹⁸ cm ^-3 or less and an absorption coefficient of 200 cm ^-1 or less for light having a wavelength of 300 nm or more, which solves the above problems. ..
The chlorine concentration may be 1 × 10 ¹⁸ cm ⁻³ or less.
You may further contain the element which has a tetravalent valence.
A manufacturing apparatus for manufacturing α-Ga ₂ O ₃ by a halide vapor deposition method according to the present invention includes a reaction furnace and a heater for heating the reaction furnace, and in the reaction furnace, a gallium halide and an oxygen raw material are supplied. Are reacted to grow α-Ga ₂ O ₃ on the substrate, thereby solving the above problem.
The reaction furnace further includes a gallium raw material supply source, an oxygen raw material supply source, a gas discharge unit, and a substrate holder for mounting the substrate, and the gallium raw material supply source is provided with a gallium metal inside. The gallium raw material supply source is a halogen gas or a hydrogen halide gas is supplied to the gallium raw material supply source, to generate the gallium halide from the gallium metal in the gallium raw material supply source, The reaction is controlled to supply a gallium halide to the reaction furnace, and the oxygen raw material supply source uses the gas selected from at least one selected from the group consisting of O ₂ , H ₂ O, and N ₂ O as the oxygen raw material. It may be controlled to feed the furnace.
The heater may be controlled such that the inside of the reaction furnace has a temperature range of 250 ° C. or higher and lower than 650 ° C.
The gas discharge part may be controlled so that the partial pressure of the halide of gallium in the reaction furnace is 0.05 kPa or more and 10 kPa or less and the partial pressure of the oxygen raw material is 0.25 kPa or more and 50 kPa or less. ..
The gallium raw material supply source supplies the halogen gas or hydrogen halide gas to the gallium gas supply source only after the temperature in the reaction furnace reaches the film formation temperature, and only during film formation. The gallium halide may be controlled to be supplied to the reaction furnace, and the oxygen raw material supply source may be controlled to supply the oxygen raw material to the reaction furnace while the temperature of the reaction furnace is being raised. ..
A semiconductor device according to the present invention includes the above-mentioned α-Ga ₂ O ₃ single crystal, and thereby solves the above-mentioned problems.
The semiconductor element may be selected from the group consisting of a light emitting element, a diode, an ultraviolet ray detecting element, and a transistor.

Since the carbon concentration of the α-Ga ₂ O ₃ single crystal according to the present invention is controlled to 5 × 10 ¹⁸ cm ⁻³ or less, the impurity concentration is extremely low and the original characteristics of α-Ga ₂ O ₃ can be exhibited. Such an α-Ga ₂ O ₃ single crystal is suitable for a semiconductor device. According to the apparatus for producing α-Ga ₂ O ₃ according to the present invention, low α-Ga ₂ O ₃ impurity concentration can be obtained by using halide vapor phase epitaxy. Furthermore, since its growth rate is extremely fast, a thick film or substrate can be obtained.

The schematic diagram which shows the vapor phase growth apparatus which implements the halide vapor phase growth method (HVPE) of this invention. Shows a flowchart of manufacturing the α-Ga ₂ O ₃ single crystal of the present invention Schematic diagram showing a light emitting device provided with an α-Ga ₂ O ₃ single crystal of the present invention. Schematic diagram showing a transistor provided with an α-Ga ₂ O ₃ single crystal of the present invention Schematic diagram showing an ultraviolet detection element provided with the α-Ga ₂ O ₃ single crystal of the present invention The figure which shows the (omega) -2 (theta) scan X-ray-diffraction pattern of the film | membrane obtained in Example 1. The figure which shows the (omega) -2 (theta) scan X-ray-diffraction pattern of the film | membrane obtained in the comparative example 2. The figure which shows the result of the X-ray pole figure measurement of the film | membrane obtained in Example 1. The figure which shows the light absorption coefficient spectrum of the film | membrane obtained in Example 1.

  An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the same elements are denoted by the same reference numerals and the description thereof will be omitted.

(Embodiment 1)
In the first embodiment, the α-Ga ₂ O ₃ single crystal of the present invention and the manufacturing method thereof will be described in detail.

According to the α-Ga ₂ O ₃ single crystal of the present invention, the carbon concentration contained in the crystal is controlled to 5 × 10 ¹⁸ cm ⁻³ or less. Thereby, since the impurity concentration is extremely low, the original characteristics of α-Ga ₂ O ₃ , that is, the large band gap (5.3 eV) and the high light transmittance are exhibited, and therefore, the present invention can be applied to a semiconductor element, particularly a light emitting element.

Preferably, according to the α-Ga ₂ O ₃ single crystal of the present invention, the carbon concentration contained in the crystal is controlled to be less than 6 × 10 ¹⁷ cm ⁻³ . This ensures a large bandgap (5.3 eV) and high light transmittance, which is advantageous for semiconductor devices, particularly light-emitting devices.

The lower limit is not particularly limited, but may be 1 × 10 ¹⁵ cm ⁻³ or more. If the carbon concentration is within the above range, there is no problem in operation even if applied to a semiconductor element.

According to the α-Ga ₂ O ₃ single crystal of the present invention, the concentration of hydrogen contained in the crystal is controlled to be 5 × 10 ¹⁸ cm ⁻³ or less. With this, the impurity concentration is extremely low, and the original characteristics of α-Ga ₂ O ₃ are exhibited, so that it can be applied to a semiconductor element.

Preferably, according to the α-Ga ₂ O ₃ single crystal of the present invention, the hydrogen concentration contained in the crystal is controlled to be less than 5 × 10 ¹⁷ cm ⁻³ . This ensures a large bandgap (5.3 eV) and high light transmittance, which is advantageous for semiconductor devices, particularly light-emitting devices.

The lower limit is not particularly limited, but may be 1 × 10 ¹⁶ cm ⁻³ or more. If the hydrogen concentration is within the above range, the operation will not be affected even if it is applied to a semiconductor element.

According to the α-Ga ₂ O ₃ single crystal of the present invention, the concentration of aluminum contained in the crystal is controlled to 4 × 10 ¹⁶ cm ⁻³ or less. With this, the impurity concentration is extremely low, and the original characteristics of α-Ga ₂ O ₃ are exhibited, so that it can be applied to a semiconductor element.

Preferably, according to the α-Ga ₂ O ₃ single crystal of the present invention, the aluminum concentration contained in the crystal is controlled to be less than 4 × 10 ¹⁵ cm ⁻³ . This ensures a large bandgap (5.3 eV) and high light transmittance, which is advantageous for semiconductor devices, particularly light-emitting devices.

The lower limit is not particularly limited, but may be 1 × 10 ¹⁴ cm ⁻³ or more. If the aluminum concentration is within the above range, it will not affect the operation even if it is applied to a semiconductor element.

According to the α-Ga ₂ O ₃ single crystal of the present invention, the concentration of chlorine contained in the crystal is controlled to be 1 × 10 ¹⁸ cm ⁻³ or less. With this, the impurity concentration is extremely low, and the original characteristics of α-Ga ₂ O ₃ are exhibited, so that it can be applied to a semiconductor element.

Preferably, according to the α-Ga ₂ O ₃ single crystal of the present invention, the chlorine concentration contained in the crystal is controlled to 2 × 10 ¹⁷ cm ⁻³ or less. This ensures a large bandgap (5.3 eV) and high light transmittance, which is advantageous for semiconductor devices, particularly light-emitting devices.

The lower limit is not particularly limited, but may be 1 × 10 ¹⁵ cm ⁻³ or more. If the chlorine concentration is within the above range, it will not affect the operation even if it is applied to a semiconductor element.

As a matter of course, it is preferable that the α-Ga ₂ O ₃ single crystal satisfy all of these specific impurity concentrations, but in consideration of the semiconductor device application, at least the carbon concentration, further the carbon concentration and the hydrogen concentration, and Should satisfy carbon concentration, hydrogen concentration and aluminum concentration. If the manufacturing method of the present invention described below is adopted, for example, the carbon concentration is less than 6 × 10 ¹⁷ cm ⁻³ , the hydrogen concentration is less than 5 × 10 ¹⁷ cm ⁻³ , and the aluminum concentration is 4 × 10 ¹⁵ cm. ^An α-Ga ₂ O ₃ single crystal having a chlorine concentration of less than ⁻³ and a chlorine concentration of 1.5 × 10 ¹⁷ cm ⁻³ or less can be provided.

According to the α-Ga ₂ O ₃ single crystal of the present invention, at least the carbon concentration is controlled to 5 × 10 ¹⁸ cm ⁻³ or less, and thus the absorption coefficient for light such as ultraviolet light and visible light having a wavelength of 300 nm or more is 500 cm. It is ^-1 or less. Accordingly, when the α-Ga ₂ O ₃ single crystal of the present invention is applied to a light emitting element among semiconductor elements, light can be effectively transmitted, which is advantageous. More preferably, the α-Ga ₂ O ₃ single crystal of the present invention has an absorption coefficient of 200 cm ⁻¹ or less for light such as ultraviolet light and visible light having a wavelength of 300 nm or more. Accordingly, when the α-Ga ₂ O ₃ single crystal of the present invention is applied to a light emitting element, the emitted light from the light emitting element can be extracted more effectively.

The lower limit is not particularly limited, but may be 1 cm ⁻¹ or higher. When α-Ga ₂ O ₃ single crystal having an absorption coefficient in the above range is applied to a semiconductor element such as a light emitting element, high luminous efficiency can be maintained. Further, when such an α-Ga ₂ O ₃ single crystal is applied to a semiconductor element such as a transistor, a power device that enables high breakdown voltage and low loss based on a large band gap (5.3 eV) is provided. ..

Although α-Ga ₂ O ₃ is not limited to the size of the single crystal (the area of the thickness and the main surface) of the present invention, for example, those of the α-Ga ₂ O ₃ single crystal of the present invention formed on a heterogeneous substrate When used as a substrate of a semiconductor element without removing a different type substrate, the main surface preferably has a size of 10 cm ² or more. Further, when the α-Ga ₂ O ₃ single crystal of the present invention is separated from a different type of substrate and used as a free-standing substrate, the thickness is preferably 200 μm or more and 30 mm or less. When the thickness is in this range, the α-Ga ₂ O ₃ single crystal of the present invention can be used as a free-standing substrate, and a plurality of free-standing substrates can be manufactured at once by slicing, so that the handling is easy. Yes, it is practical. When the α-Ga ₂ O ₃ single crystal of the present invention is a free-standing substrate having the above-mentioned size, a film made of the α-Ga ₂ O ₃ single crystal of the present invention (for example, a thickness of 100 nm to 50 μm) thereon. May be formed.

The α-Ga ₂ O ₃ single crystal of the present invention may further contain an element having a tetravalent valence. This makes it possible to control the resistivity of the α-Ga ₂ O ₃ single crystal. Specifically, an element having a valence of 4 can substitute Ga in the α-Ga ₂ O ₃ single crystal and can function as an n-type dopant. Such an element having a tetravalent valence is at least one element selected from the group consisting of Si, Hf, Ge, Sn, Ti and Zr. Since these elements can be easily replaced with Ga, the conductivity can be easily controlled. Among them, Si is preferable because it can be easily replaced with Ga.

More preferably, the concentration of the element having a tetravalent valence in the α-Ga ₂ O ₃ single crystal of the present invention is controlled to 1 × 10 ¹⁵ cm ⁻³ or more and 1 × 10 ¹⁹ cm ⁻³ or less. Within this range, the electrical resistivity of the α-Ga ₂ O ₃ single crystal of the present invention may be low, and thus it can function as an n-type substrate of a semiconductor element.

As described above, according to the α-Ga ₂ O ₃ single crystal of the present invention, since the concentration of impurities such as carbon contained being controlled very low, the α-Ga ₂ O ₃ single crystal original characteristics It can exert an advantage. Further, by containing an element having a tetravalent valence, the resistivity is controlled so as to show n-type conductivity, so that it functions as a semiconductor substrate of a semiconductor element such as a light emitting element, a diode, an ultraviolet ray detecting element and a transistor. You can Such an α-Ga ₂ O ₃ single crystal of the present invention can be manufactured by employing, for example, a halide vapor phase epitaxy method (HVPE).

Next, a method for producing the α-Ga ₂ O ₃ single crystal of the present invention using the halide vapor phase epitaxy (HVPE) will be described with reference to FIGS. 1 and 2.

FIG. 1 is a schematic diagram showing a vapor phase growth apparatus for carrying out the halide vapor phase growth method (HVPE) of the present invention.
FIG. 2 is a diagram showing a flowchart for producing the α-Ga ₂ O ₃ single crystal of the present invention.

  The vapor phase growth apparatus 100 of the present invention includes at least a sealed reaction furnace 110 and a heater 120 that heats the reaction furnace 110. As the reaction furnace 110, any reaction furnace that does not react with the raw material is applied, but it may be, for example, a quartz tube. As the heater 120, any heater capable of heating up to at least 700 ° C. is applied, but by way of example, it may be a resistance heating type heater.

The reaction furnace 110 includes at least a gallium raw material supply source 130, an oxygen raw material supply source 140, a gas discharge part 150, and a substrate holder 160 on which a substrate for growing α-Ga ₂ O ₃ is placed. A gallium metal 170 is placed inside the gallium raw material supply source 130, and a halogen gas or a hydrogen halide gas is supplied. On the other hand, from the oxygen source supply source 140, an oxygen source selected from the group consisting of O ₂ , H ₂ O and N ₂ O is supplied. In addition, these may be supplied together with a carrier gas which is an inert gas. The inert gas is nitrogen (N ₂ ) gas, helium (He) gas, neon (Ne) gas, argon (Ar) gas, or the like.

  The gas exhaust unit 150 may be connected to a vacuum pump such as a diffusion pump or a rotary pump, and controls not only the unreacted gas in the reaction furnace 110 but also the reaction furnace 110 under reduced pressure. May be. This can suppress the gas phase reaction and improve the growth rate distribution.

Step S210: Using the vapor deposition apparatus 100 of FIG. 1, the α-Ga ₂ O ₃ of the present invention is grown on the substrate by the halide vapor deposition method (HVPE).

In step S210, at least a gallium raw material and an oxygen raw material are used as raw materials. The gallium raw material includes a halide of gallium (Ga), and the oxygen raw material is at least one selected from the group consisting of O ₂ , H ₂ O and N ₂ O. The gallium halide and these oxygen raw materials can easily react to form gallium oxide. The Ga halide is easily formed by the reaction between the gallium metal 170 and the halogen gas or the hydrogen halide gas.

Preferably, the Ga halide comprises GaCl and / or GaCl ₃ . These halides have excellent reactivity and can promote the growth of gallium oxide.

Preferably, the oxygen source is O ₂ and / or H ₂ O. These oxygen sources have good reactivity with, for example, GaCl and / or GaCl _3, and can promote the growth of gallium oxide according to any of the following equations.
2GaCl (g) + (3/2) O ₂ (g) → Ga ₂ O ₃ (s) + Cl ₂ (g)
2GaCl (g) + 3H ₂ O (g) → Ga ₂ O ₃ (s) + 2HCl (g) + 2H ₂ (g)
2GaCl ₃ (g) + (3/2) O ₂ (g) → Ga ₂ O ₃ (s) + 3Cl ₂ (g)
2GaCl ₃ (g) + 3H ₂ O (g) → Ga ₂ O ₃ (s) + 6HCl (g)

In step S210, α-Ga ₂ O ₃ is grown at a growth temperature in a temperature range higher than 250 ° C. and lower than 650 ° C. At a growth temperature of 250 ° C. or lower, the growth rate may be significantly reduced, and the crystallinity may be significantly reduced due to the reduction of the surface migration of the raw material. At a growth temperature of 650 ° C. or higher, stable β-Ga ₂ O ₃ may be generated and α-Ga ₂ O ₃ may not be obtained.

In step S210, α-Ga ₂ O ₃ is preferably grown at a growth temperature in a temperature range of 350 ° C. or higher and 600 ° C. or lower. Within this temperature range, α-Ga ₂ O ₃ can be obtained without β-Ga ₂ O ₃ growing.

Note that when α-Ga ₂ O ₃ containing an element having a tetravalent valence is obtained as a dopant, a raw material containing an element having a tetravalent valence may be supplied. When the raw material containing the element having a tetravalent valence is a gas, it may be mixed and flowed from the gallium raw material supply source, or a separate raw material supply source may be provided. When the raw material containing the element having a valence of 4 is solid or liquid, it may be placed like the gallium metal 170.

  As described above, the element having such a tetravalent valence is at least one element selected from the group consisting of Si, Hf, Ge, Sn, Ti and Zr. Since these elements can be easily replaced with Ga, the conductivity can be easily controlled.

For example, when the element having a tetravalent valence is Si, as a raw material containing Si, silane (SiH ₄ ), silicon tetrachloride (SiCl ₄ ), trichlorosilane (TCS), dichlorosilane (DCS), etc. It can be used and these may be flowed together with a nitrogen carrier gas. Alternatively, when a quartz tube is used as the reaction furnace 110, Si may be diffused from quartz.

In step S210, the partial pressure of the gallium raw material is in the range of 0.05 kPa or more and 10 kPa or less, and the partial pressure of the oxygen raw material is in the range of 0.25 kPa or more and 50 kPa or less. Within this range, the reaction proceeds and an α-Ga ₂ O ₃ single crystal can be obtained. Specifically, when the partial pressure of the gallium raw material is less than 0.05 kPa and the partial pressure of the oxygen raw material is less than 0.25 kPa, the reaction does not proceed and α-Ga ₂ O ₃ may not grow. When the partial pressure of the gallium raw material exceeds 10 kPa and the partial pressure of the oxygen raw material exceeds 50 kPa, the growth rate is too high, so that α-Ga ₂ O ₃ is polycrystallized, particles are generated, or the crystallinity is lowered. Can happen.

In step S210, the partial pressure of the gallium raw material is preferably in the range of 0.1 kPa or more and 2.0 kPa or less, and the partial pressure of the oxygen raw material is preferably in the range of 0.5 kPa or more and 10 kPa or less. Within this range, the reaction proceeds and an α-Ga ₂ O ₃ single crystal can be reliably obtained.

In step S210, the growth rate of α-Ga ₂ O ₃ is controlled within the range of 5 μm / hour or more and 1 mm / hour. If the growth rate of the _α-Ga 2 _{O 3} is less than 5 [mu] m / time, since the growth rate is low, the reaction may not be obtained _α-Ga 2 _{O 3} does not proceed. When the growth rate of α-Ga ₂ O ₃ exceeds 1 mm / hour, the growth rate is too high, and thus α-Ga ₂ O ₃ may be polycrystallized.

In step S210, the substrate may be a sapphire substrate. The crystal structure of the sapphire substrate, alpha-Ga Since ₂ is the same corundum as that of O _3, it is possible to obtain the alpha-Ga ₂ O ₃ in any plane orientation. Specifically, the sapphire substrate is a substrate selected from the group consisting of (0001), M (10-10), A (11-20), R (10-12), and these inclined substrates. .. On these substrates, α-Ga ₂ O ₃ having the same plane orientation as that of the substrate can be reliably grown. The α-Ga ₂ O ₃ on the sapphire substrate obtained in step S210 can be directly used as it is for manufacturing devices such as semiconductor elements without removing the foreign substrate. Furthermore, in the case of manufacturing the α-Ga ₂ O ₃ free-standing substrate, it can be performed by the process of step S220 and later described later.

Continuing to refer to FIG.
Step S220: Subsequent to the growing step of step S210, the substrate is removed.

In step S210, for example, when the thickness of α-Ga ₂ O ₃ is grown to 200 μm or more, the substrate is removed in step S220 to obtain an α-Ga ₂ O ₃ free-standing film or substrate. .. The above-mentioned film thickness is an example film thickness that can remove the substrate without damaging the α-Ga ₂ O _{3 and} is not limited to this.

The step S210 may be performed again using the α-Ga ₂ O ₃ free-standing film or the substrate obtained in step S220 as the substrate in step S210. Thereby, an α-Ga ₂ O ₃ bulk single crystal is obtained.

Step S230: Following step S220, the α-Ga ₂ O ₃ removed from the substrate is sliced.

For example, if the self-supporting film or substrate of _α-Ga 2 _{O 3} obtained is sufficiently thick at the step S220 (e.g., more than 3 mm), which by slicing the multi-wire saw or the like, a plurality of _α-Ga 2 _{O 3} A free standing film or substrate can be obtained. Note that step S230 may be performed subsequent to step S210.

As described above, according to the manufacturing method of α-Ga ₂ O ₃ according to the present invention, a low α-Ga ₂ O ₃ impurity concentration by using a halide vapor phase epitaxy obtained. Furthermore, since its growth rate is extremely fast, a thick film or substrate can be obtained. In addition, single-crystal or polycrystalline α-Ga ₂ O ₃ can be obtained by appropriately selecting the conditions of step S210 described above.

(Embodiment 2)
In the second embodiment, a semiconductor element using the α-Ga ₂ O ₃ single crystal of the present invention will be described in detail.

As described above, the α-Ga ₂ O ₃ single crystal of the present invention is applied to a semiconductor element selected from the group consisting of a light emitting element, a diode, an ultraviolet detection element and a transistor.

FIG. 3 is a schematic diagram showing a light emitting device including the α-Ga ₂ O ₃ single crystal of the present invention.

The light emitting device 300 includes at least the α-Ga ₂ O ₃ single crystal 310 of the present invention, a light emitting layer 320 formed on one main surface of the α-Ga ₂ O ₃ single crystal 310, and α-Ga ₂ O. An n-electrode 330 formed on the other main surface of the ₃ single crystal 310 and a p-electrode 340 formed on the light emitting layer 320 are provided.

The α-Ga ₂ O ₃ single crystal 310 is the α-Ga ₂ O ₃ single crystal of the present invention described in the first embodiment, but preferably further contains an element having a valence of 4 and n Shows the conductivity of the mold. For example, the α-Ga ₂ O ₃ single crystal 310 contains at least one element selected from the group consisting of Si, Hf, Ge, Sn, Ti and Zr. The thickness of the α-Ga ₂ O ₃ single crystal 310 is, for example, 100 μm or more and 1000 μm or less.

  The light emitting layer 320 includes, for example, an n-type clad layer, an active layer, a p-type clad layer, and a p-type contact layer, and a semiconductor material having a desired wavelength for emitting light is appropriately selected. For example, in the case of blue light emission, n-type GaN (4 μm) is selected as the n-type cladding layer, InGaN / GaN multiple well structure is selected as the active layer, and p-type AlGaN (100 nm) is selected as the p-type cladding layer. , P-type GaN (200 nm) may be selected as the p-type contact layer, and the composition and structure of the active layer may be appropriately selected.

  Further, in the light emitting element 300, the lead 380 is connected to the p electrode 340 by the wire bonding 370, and the current is supplied from the outside.

A method of manufacturing such a light emitting device 300 will be described. The light-emitting element 300 is formed on the α-Ga ₂ O ₃ single crystal 310 obtained in Embodiment 1 by a vapor phase epitaxial growth method, a liquid phase epitaxial growth method, a halide vapor phase growth method, a metal organic chemical vapor deposition method (MOCVD). And the like. Then, the light emitting layer 320 is formed by using the existing growth technique such as, and then the n electrode 330 and the p electrode 340 are formed by the existing electrode forming technique such as vacuum deposition and sputtering.

According to the light emitting device 300 of the present invention, as described in detail in Embodiment 1, since the α-Ga ₂ O ₃ single crystal 310 that is transparent to ultraviolet and visible light is used, the emitted light of ultraviolet and visible light is used. Can be taken out to the outside with high efficiency through the α-Ga ₂ O ₃ single crystal 310. Further, according to the light emitting element 300 of the present invention, the conductivity of the α-Ga ₂ O ₃ single crystal 310 can be controlled by controlling the addition amount of the element having a tetravalent valence, and thus the light emitting element 300 A current can be passed in the vertical direction. As a result, the layer structure and the manufacturing process of the light emitting device 300 can be simplified, which is preferable.

The light emitting device of the present invention is not limited to the structure shown in FIG. As the light emitting layer 320, an existing light emitting layer such as another double hetero structure or a quantum well structure can be adopted. Further, an interface control layer may be provided between the α-Ga ₂ O ₃ single crystal 310 of the present invention and the light emitting layer 320. For example, when the light emitting layer 320 is AlGaN, an AlGaN buffer layer is formed as an interface control layer on the α-Ga ₂ O ₃ single crystal 310 to form AlGaN having high crystallinity and few defects, thereby improving the light emission efficiency. Can be improved.

FIG. 4 is a schematic diagram showing a transistor provided with the α-Ga ₂ O ₃ single crystal of the present invention.

The transistor 400 at least faces the α-Ga ₂ O ₃ single crystal 410 of the present invention, the source 420 formed on a part of one main surface of the α-Ga ₂ O ₃ single crystal 410, and the source 420. A drain 430 formed as described above, a channel 440 formed between the source 420 and the drain 430, an insulating film 450 formed on the channel 440, and a gate electrode 460 formed on the insulating film 450. ..

The α-Ga ₂ O ₃ single crystal 410 is the α-Ga ₂ O ₃ single crystal of the present invention described in the first embodiment, but preferably further contains an element having a tetravalent valence, and n Shows the conductivity of the mold. For example, the α-Ga ₂ O ₃ single crystal 410 contains at least one element selected from the group consisting of Si, Hf, Ge, Sn, Ti and Zr. The thickness of the α-Ga ₂ O ₃ single crystal 410 is, for example, 0.1 μm or more and 10 μm or less.

Incidentally, _α-Ga 2 _{O 3} single crystal 410 is comprised of a single may be made of a single crystal, doped _α-Ga 2 _{O 3} single crystal film on a non-doped _α-Ga 2 _{O 3} single crystal plurality May be made of a single crystal. As shown in FIG. 4, the α-Ga ₂ O ₃ single crystal 410 may be a single crystal film on the sapphire substrate 401.

The source 420 includes an n + region 470a in which a part of the α-Ga ₂ O ₃ single crystal 410 is highly-implanted with an element having a valence of 4 and an electrode 480a formed on the n + region 470a. .. The element having a tetravalent valence is at least one element selected from the group consisting of Si, Hf, Ge, Sn, Ti and Zr, and the implantation concentration thereof is 1 × 10 ¹⁵ cm ⁻³ or more 1. × may be ¹⁰ 19 ^{cm -3} or less. The electrode 480a is a metal material selected from the group consisting of Al, Ti, Pt, Ru, Au, and alloys thereof.

The drain 430 includes an n + region 470b in which a part of the α-Ga ₂ O ₃ single crystal 410 is highly-implanted with an element having a valence of 4 and an electrode 480b formed on the n + region 470b. .. Like the n + region 470a, the element having a tetravalent valence is at least one element selected from the group consisting of Si, Hf, Ge, Sn, Ti, and Zr, and the implantation concentration thereof is 1 ×. It may be in the range of 10 ¹⁵ cm ⁻³ or more and 1 × 10 ¹⁹ cm ⁻³ or less. The electrode 480b is a metal material selected from the group consisting of Al, Ti, Pt, Ru, Au, and alloys thereof.

The insulating film 450 is an insulating material selected from the group consisting of Al ₂ O ₃ , SiO ₂ , HfO ₂ , SiN, and SiON. The gate electrode 406 is a metal material selected from the group consisting of Al, Ti, Pt, Ru, Au, and alloys thereof. The thickness of the insulating film 450 is, for example, 1 nm or more and 100 nm or less.

A method for manufacturing such a transistor 400 will be described. The transistor 400 is manufactured by an existing LSI manufacturing process. For example, in the transistor 400, n + regions 470a and 470b are formed by ion implantation on the α-Ga ₂ O ₃ single crystal 410 obtained in Embodiment 1 by photolithography and then vapor phase epitaxial growth method is performed. , An insulating film 450 is formed by using an existing growth technique such as a liquid phase epitaxial growth method, a halide vapor phase growth method, a metal organic chemical vapor deposition method (MOCVD), and then an existing electrode such as a vacuum vapor deposition and a sputtering method is formed. It is manufactured by forming the electrodes 480a and 480b and the gate electrode 460 by a forming technique.

Although not shown, the α-Ga ₂ O ₃ single crystal of the present invention is used as an n-type semiconductor to form a pn junction (may be a heterojunction) to manufacture a diode.

Figure 5 is a schematic view showing an ultraviolet detector element having a α-Ga ₂ O ₃ single crystal of the present invention.

As shown in FIGS. 5 (A) and 5 (B), the ultraviolet ray detecting elements 500 and 500 ′ have at least the α-Ga ₂ O ₃ single crystal 510 of the present invention and the α-Ga ₂ O ₃ single crystal 510. A Schottky electrode 520 formed on the substrate and an ohmic electrode 530 formed on the α-Ga ₂ O ₃ single crystal 510. Specifically, according to the ultraviolet detection element 500 of FIG. 5A, the Schottky electrode 520 is formed on one main surface of the α-Ga ₂ O ₃ single crystal 510, and the ohmic electrode 530 is the α-. It is formed on the other main surface (back surface in FIG. 5) of the Ga ₂ O ₃ single crystal 510. On the other hand, according to the ultraviolet ray detection element 500 ′ of FIG. 5B, since the α-Ga ₂ O ₃ single crystal 510 is located on the sapphire substrate 540, the Schottky electrode 520 and the ohmic electrode 530 are , Both are formed on the same main surface of the α-Ga ₂ O ₃ single crystal 510.

The α-Ga ₂ O ₃ single crystal 510 is the α-Ga ₂ O ₃ single crystal of the present invention described in the first embodiment, but preferably further contains an element having a tetravalent valence, n Shows the conductivity of the mold. For example, the α-Ga ₂ O ₃ single crystal 510 contains at least one element selected from the group consisting of Si, Hf, Ge, Sn, Ti and Zr. The thickness of the α-Ga ₂ O ₃ single crystal 510 is, for example, 100 μm or more and 1000 μm or less.

Note that the α-Ga ₂ O ₃ single crystal 510 may be formed of a single single crystal body as illustrated in FIG. 5A or may be a single crystal on a sapphire substrate 540 as illustrated in FIG. 5B. It may be a crystal film. However, in the case of a single crystal film on the sapphire substrate 540, the ohmic electrode 530 is formed near the Schottky electrode 520 on the main surface of the α-Ga ₂ O ₃ single crystal 510, not on the back surface of the sapphire substrate 540.

  The Schottky electrode 520 may be a metal material selected from the group consisting of Ni, Pt, Au, and alloys thereof.

  The ohmic electrode 530 can be a metal material selected from the group consisting of Ti, In, and alloys thereof.

A method of manufacturing such an ultraviolet ray detection element 500 will be described. The ultraviolet ray detection element 500 is manufactured by an existing large-scale integrated circuit (LSI) manufacturing process. For example, the ultraviolet ray detection element 500 includes the Schottky electrode 520 and the ohmic electrode 530 on the main surface and the back surface of the α-Ga ₂ O ₃ single crystal 510 obtained in the first embodiment, and the existing metal such as vacuum vapor deposition and sputtering. It is manufactured by forming the film by a film forming technique and photolithography. Similarly, in the ultraviolet ray detecting element 500 ′, the Schottky electrode 520 and the ohmic electrode 530 are formed on the main surface of the α-Ga ₂ O ₃ single crystal 510 formed on the sapphire substrate 540 by the above-described metal film forming technique and photolithography. It may be formed by lithography.

  The present invention will now be described in detail with reference to specific examples, but it should be noted that the present invention is not limited to these examples.

[Example 1]
In Example 1, an α-Ga ₂ O ₃ single crystal was formed on a (0001) plane (c-plane) sapphire substrate by the halide vapor phase epitaxy method (HVPE) according to the present invention using the vapor phase growth apparatus 100 shown in FIG. 1. It was manufactured (step S210 in FIG. 2).

The specific manufacturing conditions are as follows. In the vapor phase growth apparatus 100, the reaction furnace 110 was a quartz tube, and the inside was maintained at atmospheric pressure. A c-plane sapphire substrate (area of 10 cm ² or more) was installed on the substrate holder 160 in the reaction furnace 110. The inside of the reaction furnace 110 was maintained at 550 ° C. by the heater 120.

A gallium (Ga) metal 170 (purity of 99.99999% or more) was placed inside the gallium raw material supply source 130, and hydrogen chloride (HCl) gas (purity of 99.999% or more) was supplied as a hydrogen halide gas. As a result, Ga metal and HCl were reacted to generate Ga halide of GaCl and / or GaCl ₃ as a gallium raw material. O ₂ gas (purity 99.99995% or more) was supplied as an oxygen source from the oxygen source supply source 140. The Ga halide and O ₂ gas were flown as N ₂ gas (purity of 99.9999% or more) as a carrier gas. The Ga halide (GaCl / GaCl ₃ ) partial pressure and O ₂ partial pressure were maintained at 0.25 kPa and 1.0 kPa, respectively. The HCl gas was introduced only during the film formation after the temperature inside the reaction furnace 110 reached 550 ° C., but the O ₂ gas was continuously introduced from the temperature increase to the temperature decrease. The film formation time was 7 minutes.

The film thickness of the film thus obtained on the c-plane sapphire substrate was measured, and the growth rate was calculated. Further, ω-2θ scan X-ray diffraction measurement was performed, and it was identified that the obtained film was α-Ga ₂ O ₃ . Results are shown in FIG. Furthermore, it was confirmed that the obtained film was a single crystal by performing an X-ray pole figure (Pole Figure) measurement using (10-12) diffraction of α-Ga ₂ O ₃ . The results are shown in Fig. 8 (A). The impurity concentration of the obtained film was measured using secondary ion mass spectrometry (SIMS). The results are shown in Table 2. The light absorption spectrum of the obtained film was measured. The results are shown in Fig. 9.

[Comparative example 2]
Comparative Example 2 was the same as Example 1 except that the growth temperature was 650 ° C. In the same manner as in Example 1, the film thickness was measured and the growth rate was calculated. The film thus obtained was identified by ω-2θ scan X-ray diffraction measurement. The results are shown in Fig. 7.

[Comparative Example 3]
Comparative Example 2 was the same as Example 1 except that the growth temperature was 250 ° C. In the same manner as in Example 1, the film thickness was measured and the growth rate was calculated.

[Example 4]
Example 4 was the same as Example 1 except that an R (10-12) plane sapphire substrate was used as the substrate. In the same manner as in Example 1, the film thickness was measured and the growth rate was calculated. ω-2θ scan X-ray diffraction measurement and X-ray pole figure measurement were performed to identify the film.

[Example 5]
Example 5 was the same as Example 1 except that an M (10-10) plane sapphire substrate was used as the substrate. In the same manner as in Example 1, the film thickness was measured and the growth rate was calculated. ω-2θ scan X-ray diffraction measurement and X-ray pole figure measurement were performed to identify the film.

[Example 6]
Example 6 was the same as Example 1 except that an A (11-20) plane sapphire substrate was used as the substrate. In the same manner as in Example 1, the film thickness was measured and the growth rate was calculated. ω-2θ scan X-ray diffraction measurement and X-ray pole figure measurement were performed to identify the film.

[Example 7]
Example 7 was the same as Example 1 except that a c-plane 10 ° off-sapphire substrate was used as the substrate. In the same manner as in Example 1, the film thickness was measured and the growth rate was calculated. ω-2θ scan X-ray diffraction measurement and X-ray pole figure measurement were performed to identify the film.

  The experimental conditions of the above Examples / Comparative Examples 1 to 7, the film thickness and the growth rate are summarized in Table 1 for simplicity, and the results are described in detail.

FIG. 6 is a view showing an ω-2θ scan X-ray diffraction pattern of the film obtained in Example 1.
FIG. 7 is a view showing an ω-2θ scan X-ray diffraction pattern of the film obtained in Comparative Example 2.

According to FIG. 6, the diffraction pattern of the film obtained in Example 1 showed only the diffraction peak of (0006) of α-Ga ₂ O ₃ and its higher-order diffraction peaks. From this, it was found that the film obtained in Example 1 was c-plane oriented α-Ga ₂ O ₃ with no β-Ga ₂ O ₃ mixed therein. In addition, it was confirmed that the films obtained in Examples 4 to 7 also exhibited only diffraction peaks from α-Ga ₂ O ₃ having the same plane orientation as that of each sapphire substrate.

According to FIG. 7, although the diffraction pattern of the film obtained in Comparative Example 2 is different from that of Example 1 in FIG. 6, a slight diffraction peak of (0006) of α-Ga ₂ O ₃ is observed. , Β-Ga ₂ O ₃ was observed. From this, it was found that the film obtained in Comparative Example 2 was a β-Ga ₂ O ₃ polycrystal containing a small amount of α-Ga ₂ O ₃ .

  In Comparative Example 3, since the growth rate was remarkably reduced, a film whose crystallinity could be evaluated could not be obtained. The decrease in the growth rate is due to the decrease in the reaction efficiency between HCl and Ga and the decrease in the rate of the crystal precipitation reaction (reaction rate limiting rate) with the decrease in the growth temperature.

Referring to the growth rates of Example 1 and Examples 4 to 7 in Table 1, the growth rate was 10 μm / hour or more and 1 mm / hour or less (specifically, 17 μm / hour or more and 40 μm / hour or less). Compared with the growth rate (for example, 1 μm / hour) of α-Ga ₂ O ₃ by the mist CVD method according to Non-Patent Documents 2 to 4, if the halide vapor phase growth method according to the present invention is adopted, it is at least several ten times or more. It was found that α-Ga ₂ O ₃ can be produced at a high growth rate.

From the above, when the halide vapor phase epitaxy method (HVPE) of the present invention is used, an α-Ga ₂ O ₃ film is formed on a sapphire substrate having an arbitrary surface at a growth temperature in a temperature range higher than 250 ° C. and lower than 650 ° C. It was found that it can be manufactured at a large growth rate.

  FIG. 8 is a diagram showing the result of X-ray pole figure measurement of the film obtained in Example 1.

FIG. 8A is a diagram showing the result of X-ray pole figure measurement using (10-12) diffraction of the film (α-Ga ₂ O ₃ film) obtained in Example 1. For reference, FIG. 8B also shows the result of the X-ray pole figure measurement using (10-12) diffraction of the c-plane sapphire substrate.

According to FIG. 8A, three spots are shown at positions rotated by 120 degrees. This result is consistent with the crystal structure of α-Ga ₂ O ₃ having three-fold rotational symmetry around the normal to the c-plane, and the α-Ga ₂ O ₃ film obtained in Example 1 was It shows that the single crystal does not include regions of different orientations such as in-plane rotational domains.

Further, the locations of the three spots shown in FIG. 8 (A) were the same as the locations of the three spots in FIG. 8 (B). This indicates that the α-Ga ₂ O ₃ film obtained in Example 1 grew according to the plane orientation of the c-plane sapphire substrate.

  Although not shown, it was confirmed that the films obtained in Examples 4 to 7 also showed the pole figure similar to that of the sapphire substrate expected for the single crystal film.

As described above, when the halide vapor phase epitaxy method (HVPE) of the present invention is used, the α-Ga ₂ O ₃ single crystal is grown on a sapphire substrate having an arbitrary surface at a growth temperature in a temperature range higher than 250 ° C. and lower than 650 ° C. It has been found that the film can be produced at high growth rates.

Table 2 shows the result of the impurity concentration of the α-Ga ₂ O ₃ film obtained in Example 1.

From Table 2, it was found that the concentrations of Al, C and H were below the detection limit for each element. The concentration of Cl was 1.5 × 10 ¹⁷ cm ⁻³ , and the concentration of Si was 3.0 × 10 ¹⁶ cm ⁻³ . Compared to non-patent each impurity concentration of the alpha-Ga ₂ O ₃ film produced by the mist CVD method disclosed in Reference 3 shown as a reference example, according to the alpha-Ga ₂ O ₃ film of the present invention, among others, It was found that the amounts of impurities of Al, C and H were dramatically reduced. This is because, according to the halide vapor phase epitaxy method (HVPE) of the present invention, an organic compound which causes contamination by C and H is not used as a starting material, and the growth rate is very high, so that This is due to the small diffusion of Al.

On the other hand, Si is due to the diffusion of Si from the quartz tube used as the reaction furnace 110 (FIG. 1), but according to the present invention, α-Ga containing Si as an element having a tetravalent valence. It is suggested that if one wants to obtain a ₂ O ₃ film, it suffices to manipulate the growth conditions without using a raw material containing Si.

  FIG. 9 is a diagram showing a light absorption coefficient spectrum of the film obtained in Example 1.

As shown in FIG. 9, it was found that the α-Ga ₂ O ₃ film (single crystal film) obtained in Example 1 had an absorption coefficient of 500 cm ⁻¹ or less for light having a wavelength of 300 nm or more. Specifically, the absorption coefficient for light with a wavelength of 300 nm was 200 cm ⁻¹ . This result is consistent with the extremely low impurity concentration of the α-Ga ₂ O ₃ film obtained by the halide vapor phase epitaxy (HVPE) of the present invention, as described with reference to Table 2.

  Although not shown, the films obtained in Examples 4 to 7 also showed similar light absorption coefficient spectra, and it was confirmed that the impurity concentration was low.

From the above, when the halide vapor phase epitaxy method (HVPE) of the present invention is used, the carbon concentration is 5 × 10 ¹⁸ cm ⁻³ or less, the hydrogen concentration is 5 × 10 ¹⁸ cm ⁻³ or less, and the aluminum concentration is 4 or less. It was found that an α-Ga ₂ O ₃ single crystal having a chlorine concentration of 1 × 10 ¹⁶ cm ⁻³ or less and a chlorine concentration of 1 × 10 ¹⁸ cm ⁻³ or less was obtained. Since the α-Ga ₂ O ₃ single crystal according to the present invention has a small absorption coefficient for a wavelength of 300 nm, if such an α-Ga ₂ O ₃ single crystal is used as a substrate of a light emitting device, emitted light can be efficiently extracted. You can

[Example 8]
In Example 8, an α-Ga ₂ O ₃ single crystal free-standing substrate was manufactured by the halide vapor phase epitaxy method (HVPE) according to the present invention using the vapor phase growth apparatus 100 shown in FIG. 1. In Example 8, the partial pressure of Ga halide (GaCl / GaCl ₃ ) and the partial pressure of O ₂ were maintained at 0.5 kPa and 2.0 kPa, respectively, and the growth time was 5 hours (300 minutes). Other than that was the same as that of Example 1.

After growth for 5 hours, a film having a thickness of 600 μm and an area of 10 cm ² or more was obtained on the c-plane sapphire substrate (step S210 in FIG. 2). ω-2θ scan X-ray diffraction measurement and X-ray pole figure measurement were performed, and it was confirmed that the obtained film was an α-Ga ₂ O ₃ single crystal. The film growth rate was 120 μm / hour.

Then, the c-plane sapphire substrate was removed (step S220 in FIG. 2). The substrate was easily removed manually without the use of special equipment. Both surfaces of the α-Ga ₂ O ₃ single crystal from which the substrate was removed were polished to obtain an α-Ga ₂ O ₃ single crystal free-standing substrate having a thickness of 400 μm and an area of 10 cm ² or more.

From the above, it was found that a free-standing substrate made of α-Ga ₂ O ₃ single crystal can be manufactured by using the halide vapor phase epitaxy method (HVPE) of the present invention.

[Example 9]
In Example 9, a plurality of α-Ga ₂ O ₃ single crystal free-standing substrates were manufactured by the halide vapor phase epitaxy method (HVPE) according to the present invention using the vapor phase growth apparatus 100 of FIG. 1. In Example 9, an α-Ga ₂ O ₃ single crystal free-standing substrate having a thickness of 400 μm and an area of 10 cm ² or more obtained in Example 8 was used as the substrate, and the growth time was 30 hours (1800 minutes). The same as in Example 8.

After growing for 30 hours, a film having a thickness of 3 mm was obtained on the α-Ga ₂ O ₃ single crystal free-standing substrate (step S210 in FIG. 2). ω-2θ scan X-ray diffraction measurement and X-ray pole figure measurement were performed, and it was confirmed that the obtained film was also an α-Ga ₂ O ₃ single crystal. The film growth rate was 100 μm / hour.

Then, the obtained α-Ga ₂ O ₃ single crystal was sliced into four pieces with a multi-wire saw (step S220 in FIG. 2). Both sides of each sliced α-Ga ₂ O ₃ single crystal were polished to obtain four α-Ga ₂ O ₃ single crystal free-standing substrates having a thickness of 400 μm.

From the above, according to the halide vapor phase epitaxy method (HVPE) of the present invention, a free-standing substrate made of α-Ga ₂ O ₃ single crystal is used as a growth substrate, and α-Ga ₂ O ₃ single crystal (bulk) is used. It has been found that a single crystal) can be produced. Further, it was found that a plurality of α-Ga ₂ O ₃ single crystal free-standing substrates can be obtained from the α-Ga ₂ O ₃ bulk single crystal.

By adopting the manufacturing method of the present invention, a high-quality α-Ga ₂ O ₃ single crystal film with controlled impurity concentration and a high growth rate can be obtained, and thus an α-Ga ₂ O ₃ single crystal substrate can be obtained. Since the α-Ga ₂ O ₃ single crystal of the present invention has an extremely low impurity concentration, it can exhibit the original properties of α-Ga ₂ O ₃ . Such an α-Ga ₂ O ₃ single crystal can be applied to various semiconductor elements such as a light emitting element, a diode, a transistor, and an ultraviolet ray detecting element. Further, α-Ga ₂ O ₃ single crystal is effective for light emitting devices and power applications among semiconductor devices because of its large bandgap and excellent light-transmitting property. Since the α-Ga ₂ O ₃ single crystal of the present invention has a corundum structure, band gap engineering by a mixed crystal with α-Al ₂ O ₃ or α-In ₂ O ₃ having the same corundum structure, or α-Al. Heterostructures with ₂ O ₃ or α-In ₂ O ₃ are also possible.

100 vapor phase growth apparatus 110 reaction furnace 120 heater 130 gallium raw material supply source 140 oxygen raw material supply source 150 gas discharge part 160 substrate holder 170 gallium metal 300 light emitting device 310, 410, 510 α-Ga ₂ O ₃ single crystal 320 light emitting layer 330 n electrode 340 p electrode 370 wire bonding 380 lead 401, 540 sapphire substrate 400 transistor 420 source 430 drain 440 channel 450 insulating film 460 gate electrode 470a, 470b n + region 480a, 480b electrode 500, 500 'UV detector 520 Schottky electrode 530 Ohmic electrode

Claims (10)

An α-Ga ₂ O ₃ single crystal having a carbon concentration of 5 × 10 ¹⁸ cm ⁻³ or less and an absorption coefficient of 200 cm ⁻¹ or less for light having a wavelength of 300 nm or more. The α-Ga ₂ O ₃ single crystal according to claim 1, wherein the chlorine concentration is 1 × 10 ¹⁸ cm ⁻³ or less. The α-Ga ₂ O ₃ single crystal according to claim 1 or 2, further containing an element having a tetravalent valence. A manufacturing apparatus for manufacturing α-Ga ₂ O ₃ by a halide vapor phase growth method,
A reactor,
A heater for heating the reaction furnace,
A manufacturing apparatus in which a halide of gallium and an oxygen source are reacted in the reaction furnace to grow α-Ga ₂ O ₃ on a substrate. The reaction furnace further includes a gallium raw material supply source, an oxygen raw material supply source, a gas discharge unit, and a substrate holder for mounting the substrate,
The gallium raw material supply source, gallium metal is installed inside,
The gallium raw material supply source, halogen gas or hydrogen halide gas is supplied to the gallium raw material supply source, to generate the gallium halide from the gallium metal in the gallium raw material supply source, the gallium halide Controlled to supply to the reactor,
The oxygen source according to claim 4, wherein the oxygen source is controlled to supply a gas selected from at least one of O ₂ , H ₂ O and N ₂ O to the reactor as the oxygen source. Manufacturing equipment.   The manufacturing apparatus according to claim 5, wherein the heater is controlled such that the inside of the reaction furnace is in a temperature range of 250 ° C or higher and lower than 650 ° C.   The gas discharge part is controlled so that the partial pressure of the halide of gallium in the reaction furnace is 0.05 kPa or more and 10 kPa or less and the partial pressure of the oxygen raw material is 0.25 kPa or more and 50 kPa or less. Item 5. The manufacturing apparatus according to Item 5 or 6. The gallium raw material supply source supplies the halogen gas or hydrogen halide gas to the gallium gas supply source only after the temperature in the reaction furnace reaches the film formation temperature, and only during film formation. Controlled to supply gallium halide to the reactor,
The said oxygen raw material supply source is a manufacturing apparatus in any one of Claims 5-7 controlled so that the said oxygen raw material may be supplied to the said reaction furnace from the temperature rising of the said reaction furnace to the temperature fall. A semiconductor device comprising the α-Ga ₂ O ₃ single crystal according to claim 1.   10. The semiconductor element according to claim 9, wherein the semiconductor element is selected from the group consisting of a light emitting element, a diode, an ultraviolet ray detecting element, and a transistor.