Semiconductor film, composite film, and base substrate with semiconductor film

Abstract

Provided is an α-Cr2O3-based semiconductor film which has a corundum type crystal structure and has excellent semiconductor characteristics. The semiconductor film is composed of an α-Cr2O3 single crystal and / or an α-Cr2O3-based solid solution single crystal each having a corundum type crystal structure, and has a crystal defect density of 1.0 × 107 / cm2 or less.

Description

Semiconductor film, composite film, and semiconductor film-attached base substrate

[0001] The present disclosure relates to a semiconductor film, a composite film, and a semiconductor film-attached base substrate, and in particular to an α-Cr film having a corundum-type crystal structure. ２ O ３ and / or α-Cr ２ O ３ This relates to a semiconductor film composed of a solid solution of the system.

[0002] Materials with a corundum structure are considered promising as wide bandgap semiconductors. ２ O ３ Most of the reports on corundum structure materials such as these have been about n-type semiconductors, which has been a major obstacle to using corundum structure materials in devices (see Non-Patent Document 1 (Alexandros Kyrtsos et al., "On the feasibility of p-type GaO", Appl. Phys. Lett. 112, 032108 (2018))).

[0003] In recent years, α-Rh has been used as a semiconductor material with a corundum structure. ２ O ３ and α-Ir ２ O ３ It has been reported that the α-(Ir,Ga)O exhibits p-type conductivity (Kentaro Kaneko et al., "Ultra-wide bandgap corundum-structured p-type α-(Ir,Ga)O" in Non-Patent Document 2). 3 However, these materials have low crystal quality, insufficient semiconductor properties, and no reports of n-type conductivity have been published. Furthermore, these materials use rare metals such as Ir and Rh, which makes them very expensive.

[0004] Cr ２ O ３is also known as a material with semiconductor properties. For example, Non-Patent Document 3 (Jarnail Singh et al., "Structural and optoelectronic properties of epitaxial Ni-substituted Cr2O3 thin films for p-type TCO applications", Materials Science in Semiconductor Processing 123 (2021) 105483) describes the formation of Ni-doped p-type Cr2O3 films on a sapphire substrate by PLD (pulsed laser deposition). ２ O ３ This document discloses a film having a thickness of 1.93×10 １８ ~7.24 x 10 １８ / cm ３ The carrier concentration is disclosed, but the carrier mobility is 0.1 to 2 cm ２ / V·s, and therefore the semiconductor properties were poor.

[0005] Non-Patent Document 4 (Giang T. Dang et al., "Growth of α-Cr2O3 single crystals by mist CVD using ammonium dichromate", Appl. Phys. Express 11, 111101 (2018)) describes the growth of α-Cr2O3 single crystals by mist CVD on a sapphire substrate. ２ O ３ However, the α-Cr film disclosed in this document ２ O ３ The film had a large half-width of the X-ray rocking curve of the (006) plane of 150 arcsec or more, and also had many crystal defects, so its properties as a semiconductor film were poor.

[0006] Non-patent document 5 (Sahadeb Ghosh et. al., "Epitaxial growth and interface band alignment studies of all oxide α-Cr2O3 / β-Ga2O3 p-nheterojunction", Appl. Phys. Lett. 115, 061602 (2019)) describes n-type β-Ga. ２ O ３ and p-type α-Cr ２ O ３ However, there have been reports of the fabrication of pn heterojunctions consisting of β-Ga ２ O ３ is a crystalline form different from the corundum structure, and α-Cr ２ O ３ These semiconductor materials do not exhibit good semiconductor properties because of the high level of crystal defects in them.

[0007] By the way, α-Ga ２ O ３ As a base substrate used for crystal growth of a semiconductor film, α-Cr ２ O ３ For example, Patent Document 1 (WO2021 / 064816) proposes a method for manufacturing a semiconductor device having an alignment layer containing α-Ga ２ O ３ , or α-Ga ２ O ３ A substrate having an orientation layer used for crystal growth of a semiconductor film composed of an α-Cr-based solid solution, ２ O ３ , or α-Cr ２ O ３ In addition, Patent Document 2 (WO2021 / 064817) discloses a solid solution of α-Ga containing material. ２ O ３ A base substrate having an orientation layer used for crystal growth of a semiconductor film containing α-Cr. ２ O ３ However, the α-Cr alloys disclosed in Patent Documents 1 and 2 are made of a material containing Ti and / or Fe in a predetermined molar ratio. ２ O ３Although the orientation layer containing the above is good in terms of crystallinity, it does not have semiconductor properties.

[0008] WO2021 / 064816WO2021 / 064817

[0009] Alexandros Kyrtsos et al., "On the feasibility of p-type Ga2O3", Appl. Phys. Lett. 112, 032108 (2018)Kentaro Kaneko et al., "Ultra-wide bandgap corundum-structured p-type α-(Ir,Ga)2O3 alloys for α-Ga2O3 electronics", Appl. Phys. Lett. 118, 102104 (2021)Jarnail Singh et al., "Structural and optoelectronic properties of epitaxial Ni-substituted Cr2O3 thin films for p-type TCO applications", Materials Science in Semiconductor Processing 123 (2021) 105483Giang T. Dang et. al., "Growth of α-Cr2O3 single crystals by mist CVD using ammonium dichromate", Appl. Phys. Express 11, 111101 (2018)Sahadeb Ghosh et. al., "Epitaxial growth and interface band alignment studies of all oxide α-Cr2O3 / β-Ga2O3 p-nheterojunction", Appl. Phys. Lett. 115, 061602 (2019)

[0010] As mentioned above, α-Cr exhibits good semiconductor properties. ２ O ３ Such materials have not been reported so far.

[0011] The present inventors have now discovered that the semiconductor film is made of α-Cr ２ O ３ Single crystal and / or α-Cr ２ O ３ The system is composed of a solid solution single crystal, and the crystal defect density is 1.0 × 10 ７ / cm ２ By reducing the thickness to below 0.1 mm, it is possible to obtain α-Cr with a corundum-type crystal structure that has excellent semiconductor properties. ２ O ３ It has been found that a semiconductor film based on the above-mentioned compound can be provided.

[0012] Therefore, an object of the present invention is to provide an α-Cr alloy having a corundum-type crystal structure with excellent semiconductor properties. ２ O ３ Another object of the present invention is to provide such an α-Cr-based semiconductor film. ２ O ３ A composite film containing a semiconductor film of α-Cr or such a semiconductor film ２ O ３ The present invention aims to provide a base substrate with a semiconductor film formed thereon.

[0013] According to the present disclosure, the following aspects are provided: [Aspect 1] An α-Cr alloy having a corundum-type crystal structure. ２ O ３ Single crystal and / or α-Cr ２ O ３ A semiconductor film made of a single crystal of a solid solution of 1.0×10 ７ / cm ２ A semiconductor film having a crystal defect density of 3 to 1000 cm. [Aspect 2] The semiconductor film according to Aspect 1, wherein the X-ray rocking curve half width of the (006) plane on the surface of the semiconductor film is 100 arcsec or less. [Aspect 3] The semiconductor film according to Aspect 1 or 2, wherein the X-ray rocking curve half width of the (104) plane on the surface of the semiconductor film is 500 arcsec or less. [Aspect 4] The semiconductor film has a crystal defect density of 3 to 1000 cm. ２ The semiconductor film according to any one of aspects 1 to 3, wherein the semiconductor film exhibits a carrier mobility of 1×10 / V·s. １２ / cm ３ ~1 x 10 ２１ / cm ３The semiconductor film according to any one of Aspects 1 to 4, having a carrier concentration of 1×10. [Aspect 6] The semiconductor film according to any one of Aspects 1 to 5, having a thickness of 0.1 to 15 μm. [Aspect 7] The semiconductor film according to any one of Aspects 1 to 6, having p-type conductivity or n-type conductivity. [Aspect 8] The semiconductor film contains Ni as a dopant, and the Ni atomic concentration in the semiconductor film is 1×10 １４ ~1 x 10 ２２ / cm ３ The semiconductor film according to any one of aspects 1 to 7, wherein the semiconductor film contains Ni as a dopant, and the Ni atomic concentration C Ｎｉ The carrier concentration C in the semiconductor film Ｃ Ratio C to Ｎｉ / C Ｃ The semiconductor film according to any one of aspects 1 to 8, wherein is 1 to 100. [Aspect 10] A composite film comprising a plurality of semiconductor films having a corundum-type crystal structure, wherein each of the plurality of semiconductor films is α-Cr ２ O ３ Single crystal and / or α-Cr ２ O ３ at least one of the plurality of semiconductor films is a p-type conductive film and at least one other of the plurality of semiconductor films is an n-type conductive film, and the p-type conductive film and / or the n-type conductive film is 1.0×10 ７ / cm ２ A composite film having the following crystal defect density (or the semiconductor film according to any one of Aspects 1 to 9): [Aspect 11] The composite film according to Aspect 10, wherein the plurality of semiconductor films are epitaxially grown films. [Aspect 12] A composite film comprising: a base substrate having an orientation layer; and an α-Cr semiconductor film having a corundum-type crystal structure provided on the orientation layer. ２ O ３ Single crystal and / or α-Cr ２ O ３ and a semiconductor film formed of a single crystal of a Zn-based solid solution, wherein the semiconductor film has a surface area of ​​1.0×10 ７ / cm ２The present invention relates to a semiconductor film having a low defect density (or the semiconductor film according to any one of aspects 1 to 9), wherein the surface of the orientation layer close to the semiconductor film is made of a material having a corundum-type crystal structure with an a-axis length and / or a c-axis length greater than those of sapphire, and the orientation layer is made of α-Cr ２ O ３ , or α-Cr ２ O ３ A base substrate with a semiconductor film, the base substrate being composed of a solid solution containing: [Aspect 13] The base substrate with a semiconductor film according to Aspect 12, wherein each of the alignment layer and the semiconductor film is an epitaxially grown film.

[0014] Fig. 4 is a schematic cross-sectional view showing an example of a base substrate with a semiconductor film. Fig. 5 is a schematic cross-sectional view showing another example of a base substrate with a semiconductor film. Fig. 6 is a schematic cross-sectional view showing the configuration of an aerosol deposition (AD) apparatus. Fig. 7 is a schematic cross-sectional view showing the configuration of a pulsed laser deposition (PLD) apparatus. Fig. 8 is a schematic plan view for explaining a scanning step of irradiating a target with a laser beam in the PLD apparatus shown in Fig. 4.

[0015] Semiconductor film In this document, a semiconductor film refers to a film that has semiconductor properties. Therefore, whether a film is a semiconductor film or not can be determined by examining whether it has semiconductor properties. An example of a method for examining whether a film has semiconductor properties is Hall measurement at room temperature, which can measure carrier concentration and mobility. In addition, whether a film has semiconductor properties can also be determined by measuring the Seebeck coefficient at room temperature or SCM (scanning capacitance microscope) measurement.

[0016] The semiconductor film according to the present invention is an α-Cr semiconductor having a corundum-type crystal structure. ２ O ３ Single crystal and / or α-Cr ２ O ３ Therefore, the semiconductor film according to the present invention is composed of α-Cr-based solid solution single crystals. ２ O ３ and α-Cr ２ O ３ In order to include both α-Cr and α-Cr-based solid solutions, ２ O ３This semiconductor film can be collectively called a 1.0×10 ７ / cm ２ The crystal defect density is 1.0×10 ７ / cm ２ By reducing the thickness to below 0.1 mm, it is possible to obtain α-Cr with a corundum-type crystal structure that has excellent semiconductor properties. ２ O ３ That is, as described above, it is possible to provide an α-Cr-based semiconductor film that exhibits good semiconductor properties. ２ O ３ Although no such material has been reported so far, the inventors have ２ O ３ As a result of extensive research into the semiconducting properties of α-Cr based materials, we have found that α-Cr, which has a corundum-type crystal structure and excellent semiconducting properties, ２ O ３ This has resulted in the provision of a semiconductor film based on this compound.

[0017] α-Cr of the present invention ２ O ３ The crystal defect density of the semiconductor film is 1.0×10 ７ / cm ２ is preferably 1.0×10 ６ / cm ２ or less, more preferably 1.0 × 10 ３ / cm ２ or less. There is no particular restriction on the lower limit of the crystal defect density, and the lower the limit, the better. In this specification, crystal defects refer to threading edge dislocations, threading screw dislocations, threading mixed dislocations, and basal plane dislocations, and the crystal defect density refers to the total density of each dislocation. Basal plane dislocations become a problem when the semiconductor film has an off-angle, but do not become a problem when there is no off-angle, since they are not exposed to the surface of the semiconductor film. For example, if threading edge dislocations are 3×10 ４ / cm ２ , threading screw dislocations 6 × 10 ４ / cm ２ , threading mixed dislocations 4 × 10 ４ / cm ２ If it is included, the crystal defect density is 1.3 × 10 ５ / cm ２The method for measuring the crystal defects or the crystal defect density is not particularly limited, and known techniques such as transmission electron microscopy, X-ray topography, and etching of the film surface can be used. The crystal defect density of the semiconductor film is measured for at least one surface of the semiconductor film, and, for example, when an underlying substrate is present, it is preferably measured for the surface opposite to the underlying substrate (the surface on which the film is formed).

[0018] α-Cr of the present invention ２ O ３ The α-Cr based semiconductor film has a corundum type crystal structure. ２ O ３ Single crystal and / or α-Cr ２ O ３ system solid solution (i.e., α-Cr ２ O ３ It is composed of a single crystal of α-Cr (a solid solution of α-Cr and a different material). ２ O ３ The α-Cr solid solution may contain a dopant, as described below. ２ O ３ The α-Cr based semiconductor film is composed of a single crystal having a corundum type crystal structure, and therefore can be said to be an oriented film. ２ O ３ Single crystal and / or α-Cr ２ O ３ These α-Cr films are composed of single crystals of a solid solution of α-Cr. ２ O ３ Single crystal and α-Cr ２ O ３ The solid solution single crystal of α-Cr-based alloy refers to a crystal oriented in both the c-axis and a-axis directions, and may include biaxially oriented films and mosaic crystals. Mosaic crystals are crystals that do not have clear grain boundaries, but are a collection of crystals whose orientation is slightly different from either or both of the c-axis and a-axis. Such oriented films have a structure in which the crystal orientation is roughly aligned in the approximately normal direction (c-axis direction) and the in-plane direction (a-axis direction). This structure contributes to excellent semiconductor properties and also makes it possible to further form an additional semiconductor layer with excellent quality, particularly excellent orientation, on the semiconductor film. That is, α-Cr ２ O ３When an additional semiconductor layer is further formed on the α-Cr semiconductor film, the crystal orientation of the additional semiconductor layer is also α-Cr. ２ O ３ Therefore, the crystal orientation of the α-Cr semiconductor film is roughly the same as that of the α-Cr semiconductor film. ２ O ３ It is also possible to use an additional semiconductor film formed on the organic semiconductor film as an alignment film.

[0019] α-Cr of the present invention ２ O ３ The X-ray rocking curve half-width (hereinafter referred to as XRC half-width) of the (006) plane of the corundum-type crystal structure on the surface of the semiconductor film is preferably 100 arcsec or less, more preferably 80 arcsec or less, even more preferably 50 arcsec or less, and particularly preferably 30 arcsec or less. Furthermore, the XRC half-width of the (104) plane on the surface of the semiconductor film of the present invention is preferably 500 arcsec or less, more preferably 100 arcsec or less, even more preferably 50 arcsec or less, and particularly preferably 30 arcsec or less. Thus, the XRC half-width of both the (006) plane and the (104) plane is preferably small. Therefore, although there are no lower limits for the XRC half-width of both the (006) plane and the (104) plane, it is typically 20 arcsec or more. When the XRC half width falls within the above range, the properties as a semiconductor film can be improved.

[0020] That is, as a method for evaluating the crystallinity of a material, a method is known in which XRC measurements are carried out on the (006) plane or (104) plane of a corundum-type crystal structure and the half-width is used for evaluation. The XRC half-width also reflects crystal defects, mosaicing, and the amount of warpage of the material. In particular, the XRC half-width of the (104) plane of a corundum-type crystal structure is suitable as a method for evaluating the quality of an oriented layer because it reflects all of the various defects such as threading edge dislocations and threading screw dislocations, the mosaicing of regions (domains) with different tilts (inclination of the crystal axis in the growth orientation) and twists (rotation of the crystal axis within the surface), and the state of warpage. Therefore, when the XRC range width is within the above range, the oriented layer has few crystal defects, small mosaicing (few domains), and small warpage. As a result, it is possible to form α-Cr on such an oriented layer. ２ O３ , α-Ga ２ O ３ When forming a semiconductor layer such as a crystalline layer, crystal defects and mosaic patterns do not propagate inside the semiconductor layer, and a high-quality semiconductor layer with little warpage can be obtained. As described above, the smaller the XRC half-width of the (104) plane of the corundum-type crystal structure in the oriented layer, the better. There is no problem even if it is a value equivalent to the half-width specific to the X-ray source used for measurement, but in practice, a value of 30 arcsec or more is preferable.

[0021] α-Cr ２ O ３ The carrier concentration of a semiconductor film having good characteristics is 1×10 １２ ~1 x 10 ２２ / cm ３ When the carrier mobility is 3 cm ２ / V·s or more. High carrier mobility is desirable. Therefore, the semiconductor film ２ / V·s or more, and more preferably 10 cm ２ / V·s or more, more preferably 50 cm ２ / V·s or more, particularly preferably 100 cm ２ / V·s or more, most preferably 500 cm ２ The upper limit of the carrier mobility is not particularly limited, but is typically 3000 cm ２ / V s or less, more typically 1000 cm ２ When the semiconductor film is used as a contact layer with an electrode, the １６ / cm ３ It is preferable that the carrier concentration is 1×10 or more, and more preferably 1×10 １７ / cm ３ More preferably, 1×10 １８ / cm ３ More preferably, 1×10 １９ / cm ３ The upper limit of the carrier concentration is not particularly limited, but if it is too high, the crystallinity of the semiconductor film may be impaired. ２２ / cm ３On the other hand, when the semiconductor film is used as a drift layer of a field effect transistor, a Schottky barrier diode, or the like, the １４ / cm ３ ~1 x 10 １８ / cm ３ Preferably, the carrier concentration is 1×10 １５ / cm ３ ~1 x 10 １７ / cm ３ , particularly preferably 1 × 10 １５ / cm ３ ~1 x 10 １６ / cm ３ The carrier concentration and carrier mobility can be determined by Hall measurements, as described later in the Examples.

[0022] α-Cr of the present invention ２ O ３ The thickness of the semiconductor film can be adjusted appropriately from the viewpoint of cost and the required properties. That is, if the film is too thick, it takes a long time to form, so from the viewpoint of cost, it is preferable not to make it extremely thick. On the other hand, to improve the crystal quality, it is preferable to make the film relatively thick. In this way, the film thickness can be adjusted appropriately to match the desired properties. Therefore, the thickness of the semiconductor film is not particularly limited, but from the viewpoint of forming a semiconductor device, it is preferably 0.1 to 15 μm, more preferably 0.5 to 14 μm, even more preferably 1.0 to 12 μm, and particularly preferably 1.5 to 10 μm.

[0023] α-Cr of the present invention ２ O ３ The α-Cr based semiconductor film preferably has p-type conductivity or n-type conductivity, in other words, is a p-type film or an n-type film. ２ O ３ The p-type conductivity or n-type conductivity can be imparted to the α-Cr semiconductor film by adding a predetermined dopant. ２ O ３ When the α-Cr-based semiconductor film has p-type conductivity, the semiconductor film preferably contains, as a dopant, one or more elements selected from the group consisting of alkaline earth metal elements such as Be, Ca, and Mg, and Ni, Zn, Cu, Sm, and Ce.２ O ３ When the Si-based semiconductor film has n-type conductivity, the semiconductor film preferably contains at least one dopant selected from the group consisting of Si, Sn, Ge, and Ti.

[0024] α-Cr of the present invention ２ O ３ The dopant concentration in the silicon-based semiconductor film is 1×10 １２ ~10 ２３ / cm ３ The dopant concentration may be adjusted appropriately so that the carrier concentration of the semiconductor film falls within the above-mentioned range. ２ O ３ The method for measuring the amount of dopant contained in the semiconductor film is not particularly limited and any known method may be used, but SIMS (secondary ion mass spectrometry), particularly D-SIMS (dynamic SIMS), is preferred. Measurement of the amount of dopant by D-SIMS will be described later in the Examples.

[0025] α-Cr of the present invention ２ O ３ The dopant concentration in the semiconductor film is C Ｄ The carrier concentration C in the semiconductor film measured by Hall measurement at room temperature ｃ Ratio C to Ｄ / C ｃ is preferably 10,000 or less, more preferably 1,000 or less, and even more preferably 100 or less. Ｄ / C ｃ Since it is preferable that is small, the ratio C Ｄ / C ｃ Although there is no lower limit for , it is typically 1 or more.

[0026] In a preferred embodiment of the present invention, α-Cr ２ O ３ The α-Cr-based semiconductor film contains Ni as a dopant. ２ O ３ The Ni atom concentration in the semiconductor film is 1×10 １７ ~1 x 10 ２２ / cm ３ is preferable, and more preferably 1×10 １８ / cm ３ ~1 x 10 ２２ / cm ３ , more preferably 1 × 10 １９ / cm ３ ~1 x 10 ２２ / cm ３ , particularly preferably 1 × 10 ２０ / cm ３ ~1 x 10 ２２ / cm ３ In the above embodiment, α-Cr ２ O ３ Ni atomic concentration C in the Ni-based semiconductor film Ｎｉ The carrier concentration C in the semiconductor film Ｃ Ratio C to Ｎｉ / C Ｃ is preferably 1 to 100, more preferably 1 to 80, even more preferably 1 to 60, and particularly preferably 1 to 20.

[0027] α-Cr of the present invention ２ O ３ The α-Cr-based semiconductor film preferably has a size of 5 mm square or more. ２ O ３ The silicon-based semiconductor film is typically circular, preferably with a diameter of 2.54 cm (1 inch) or more, more preferably 5.08 cm (2 inches) or more. There is no particular upper limit to the size of the semiconductor film, but it is typically 30 cm (12 inches) or less in diameter. In this specification, the term "circular shape" does not necessarily mean a perfect circle, but may also mean a roughly circular shape that can be recognized as a circle overall. For example, the shape may be a shape in which a portion of the circle is cut out for identifying the crystal orientation or for other purposes.

[0028] According to a preferred embodiment of the present invention, there is provided a composite film comprising a plurality of semiconductor films having a corundum-type crystal structure. ２ O ３ Single crystal and / or α-Cr ２ O ３At least one of the plurality of semiconductor films is a p-type conductive film, and at least another of the plurality of semiconductor films is an n-type conductive film. The p-type conductive film and / or the n-type conductive film are each 1.0×10 ７ / cm ２ Therefore, the p-type conductive film and / or the n-type conductive film among the plurality of semiconductor films has the crystal defect density of the above-mentioned α-Cr of the present invention. ２ O ３ The α-Cr-based semiconductor film of the present invention can be a p-type conductive film and / or an n-type conductive film, in particular. Therefore, among the multiple semiconductor films in this embodiment, the configuration of at least the p-type conductive film and / or the n-type conductive film is as described above, including the preferred embodiments. ２ O ３ The composite film containing the Cr-based semiconductor film allows the formation of a high-quality device having a complex structure. ２ O ３ α-Cr epitaxially grown on the template ２ O ３ It is preferable that the film is epitaxially grown from a silicon-based semiconductor film, that is, an epitaxially grown film.

[0029] 1 and 2, the semiconductor film-attached base substrate 10 includes a base substrate 14 having an alignment layer 16 and an α-Cr film formed on the alignment layer 16. ２ O ３ 2, a plurality of semiconductor films 12 may be provided on the alignment layer 16 to form the composite film 13 as described above. Therefore, at least one of the plurality of semiconductor films 12 may be a p-type conductive film, and at least another of the plurality of semiconductor films 12 may be an n-type conductive film. ２ O ３ The α-Cr based semiconductor film 12 has a corundum type crystal structure. ２ O ３ Single crystal and / or α-Cr ２ O ３ It is composed of a single crystal of a solid solution of 1.0 × 10７ / cm ２ The low defect semiconductor film has the following crystal defect density: ２ O ３ Therefore, the α-Cr semiconductor film in this embodiment ２ O ３ The structure of the α-Cr based semiconductor film 12 is as described above, including the preferred embodiment. The surface of the orientation layer 16 that is closer to the semiconductor film 12 is made of a material having a corundum-type crystal structure with a longer a-axis length and / or a c-axis length than sapphire, and the orientation layer 16 is made of α-Cr based semiconductor film 12. ２ O ３ , or α-Cr ２ O ３ That is, the orientation layer 16 is made of a solid solution containing Cr for epitaxial growth of the semiconductor film 12. ２ O ３ Therefore, the orientation layer 16 is preferably a film epitaxially grown from the sapphire substrate 18, i.e., an epitaxially grown film. ２ O ３ It is preferable that the Cr film is an epitaxially grown film from a template or a semiconductor film epitaxially grown thereon. ２ O ３ α-Cr with a corundum-type crystal structure that can function as a template ２ O ３ As the base substrate 14 having the alignment layer 16, the base substrates disclosed in Patent Documents 1 and 2 can be used.

[0030] Manufacturing method of the α-Cr of the present invention ２ O ３ The semiconductor film, composite film, and semiconductor film-attached base substrate are made of the above-mentioned α-Cr (as disclosed in, for example, Patent Documents 1 and 2). ２ O ３ , or α-Cr ２ O ３ A substrate having an orientation layer formed of a solid solution containing ２ O ３template) and α-Cr ２ O ３ based material, α-Ga ２ O ３ The semiconductor layer can be manufactured by forming a film of a semiconductor material such as a silicon-based material. The method for forming the semiconductor layer can be any known method and is not particularly limited, but preferred examples include various CVD (chemical vapor deposition) methods such as mist CVD (mist chemical vapor deposition), HVPE (halide vapor phase epitaxy), and MBE (molecular beam epitaxy), as well as various PVD (physical vapor deposition) methods such as PLD (pulsed laser deposition) and sputtering. The method for introducing a dopant into the semiconductor film can also be any known method and is not particularly limited, and may include a method of doping during film formation or a method of doping into the film by ion implantation after film formation.

[0031] The semiconductor film thus obtained can be used as is or divided into semiconductor elements. Alternatively, the semiconductor film may be peeled off from the base substrate to form a single film. In this case, a release layer may be provided in advance on the surface (film formation surface) of the base substrate to facilitate peeling from the base substrate. Examples of such release layers include a C-implanted layer or an H-implanted layer provided on the surface of the base substrate. Alternatively, C or H may be implanted into the semiconductor film at the initial stage of film formation, and a release layer may be provided on the semiconductor film side. Furthermore, it is also possible to bond and adhere a support substrate (mounting substrate) different from the base substrate to the surface of the semiconductor film formed on the base substrate (i.e., the surface opposite the base substrate), and then peel and remove the base substrate from the semiconductor film. Such a support substrate (mounting substrate) can be one having a thermal expansion coefficient of 6 to 13 ppm / K at 25 to 400°C, such as a substrate composed of a Cu-Mo composite metal. Examples of methods for bonding and adhering the semiconductor film to the support substrate (mounting substrate) include known methods such as brazing, soldering, and solid-state bonding. Furthermore, an electrode such as an ohmic electrode or a Schottky electrode, or another layer such as an adhesive layer may be provided between the semiconductor film and the support substrate.

[0032] In the manufacture of semiconductor elements such as power devices, functional layers such as drift layers are formed on semiconductor films. Known methods can be used to form functional layers such as drift layers, and preferred examples include mist CVD, HVPE, MBE, MOCVD, and hydrothermal synthesis, with mist CVD or HVPE being particularly preferred.

[0033] The present invention will be explained in more detail by the following examples, but the present invention is not limited to the following examples.

[0034] Example 1: p-Cr ２ O ３ / Cr ２ O ３ Template In this example, a sapphire substrate is used as a base substrate for film formation. ２ O ３ Cr with orientation layer ２ O ３ A template (diameter 50.8 mm (2 inches), thickness 0.48 mm, c-plane, no off-angle) was prepared. ２ O ３ Ni-doped α-Cr using a template ２ O ３ The specific procedure is as follows:

[0035] (1) Cr ２ O ３ Underlying substrate (Cr ２ O ３ (1a) Preparation of Oriented Precursor Layer Commercially available Cr was used as raw material powder. ２ O ３ Using powder and a sapphire substrate (diameter 50.8 mm (2 inches), thickness 0.43 mm, c-plane, off-angle 0.2°), Cr was deposited on the seed substrate (sapphire substrate) by the AD apparatus shown in FIG. ２ O ３An AD film (orientation precursor layer) consisting of the above was formed. The AD film was formed using an aerosol deposition (AD) apparatus 20 shown in FIG. 3. The AD apparatus 20 shown in FIG. 3 is configured as an apparatus used in the AD method, in which raw material powder is sprayed onto a substrate under a subatmospheric pressure. This AD apparatus 20 includes an aerosol generation unit 22 that generates an aerosol of raw material powder containing raw material components, and a film formation unit 30 that sprays the raw material powder onto a sapphire substrate 21 to form a film containing the raw material components. The aerosol generation unit 22 includes an aerosol generation chamber 23 that contains the raw material powder and generates an aerosol by receiving a carrier gas supplied from a gas cylinder (not shown), a raw material supply pipe 24 that supplies the generated aerosol to the film formation unit 30, and a vibrator 25 that applies vibrations at a frequency of 10 to 100 Hz to the aerosol generation chamber 23 and the aerosol therein. The film forming unit 30 includes a film forming chamber 32 that sprays an aerosol onto the sapphire substrate 21, a substrate holder 34 that is disposed inside the film forming chamber 32 and fixes the sapphire substrate 21, and an XY stage 33 that moves the substrate holder 34 in the X-axis and Y-axis directions. The film forming unit 30 also includes an injection nozzle 36 that has a slit 37 formed at its tip and sprays the aerosol onto the sapphire substrate 21, and a vacuum pump 38 that reduces the pressure in the film forming chamber 32.

[0036] The AD film formation conditions were as follows. Specifically, Ar was used as the carrier gas, and a ceramic nozzle with a 5 mm long x 0.3 mm short slit was used. The nozzle scanning conditions were a scan speed of 0.5 mm / s, with the nozzle moving 55 mm in a direction perpendicular to the long side of the slit and advancing, then 5 mm in the direction of the long side of the slit, then 55 mm in a direction perpendicular to the long side of the slit and returning, and then 5 mm in the direction of the long side of the slit and in the opposite direction from the initial position. After moving 55 mm from the initial position in the direction of the long side of the slit, the nozzle repeated the following scans in the opposite direction and returned to the initial position. This cycle was repeated 500 times. In one film formation cycle at room temperature, the carrier gas pressure was set to 0.07 MPa, the flow rate was 8 L / min, and the chamber pressure was adjusted to 100 Pa or less. The thickness of the AD film (orientation precursor layer) formed in this manner was 120 μm.

[0037] (1b) Heat Treatment of Orientation Precursor Layer The sapphire substrate on which the AD film was formed was taken out of the AD apparatus and annealed at 1700° C. for 4 hours in a nitrogen atmosphere.

[0038] (1c) Grinding and polishing The obtained substrate is fixed on a ceramic surface plate, and the surface originating from the AD film is ground using a grindstone with a grit size up to #2000 until the orientation layer is exposed, and then the plate surface is smoothed by lapping using diamond abrasive grains.At this time, the size of the diamond abrasive grains is gradually reduced from 3 μm to 0.5 μm while lapping, thereby improving the flatness of the plate surface.After that, a mirror finish is performed by chemical mechanical polishing (CMP) using colloidal silica, and Cr is applied to the sapphire substrate. ２ O ３ Cr with orientation layer ２ O ３ The base substrate is Cr ２ O ３ The arithmetic mean roughness Ra of the surface of the orientation layer after processing was 0.1 nm, the amount of grinding and polishing was 70 μm, and the Cr after polishing ２ O ３ The thickness of the base substrate was 0.48 mm. The surface on which the AD film was formed is referred to as the "front surface."

[0039] (2) PLD film formation Ni-doped Cr by pulsed laser deposition (PLD) method ２ O ３ The film was made of the Cr obtained in (1c) above. ２ O ３ A film was formed on the surface of the base substrate. Specifically, the following procedure was carried out.

[0040] (2a) Ni-doped Cr ２ O ３ Preparation of target Cr for use in PLD ２ O ３ The target was prepared as follows: Cr as raw material powder ２ O ３The NiO powder and the NiO powder were weighed and mixed so that the atomic ratio of Ni to Cr was 0.15 to obtain a mixed powder. The obtained mixed powder was molded into a disk shape with a diameter of 100 mm and a thickness of 4 mm, and the obtained molded body was sintered in an air atmosphere at 1100°C for 48 hours. A disk with a diameter of 50.8 mm and a thickness of 1.5 mm was cut from the obtained sintered body and subjected to surface polishing. In this way, Ni-doped Cr for PLD was obtained. ２ O ３ Got the target.

[0041] (2b) Ni-doped Cr ２ O ３ Film formation The obtained Ni-doped Cr ２ O ３ Target (hereinafter referred to as target) and Cr ２ O ３ The substrate (hereinafter referred to as the base substrate) was placed in a pulsed laser deposition (PLD) apparatus. The configuration of the PLD apparatus 40 is shown in FIG. 4. The PLD apparatus 40 is comprised of a chamber 42, a target 46 attached to a target rotation shaft 44 in the chamber 42, and a Cr substrate attached to a substrate rotation shaft 48 in the chamber 42 so that the surface on which the AD film was formed faces the target 46. ２ O ３ The PLD apparatus 40 includes a base substrate 50, a vacuum means 52 consisting of a rotary pump 52a and a turbo molecular pump 52b for evacuating the chamber 42, a laser scanning device 54 for irradiating the target 46 with pulsed laser light, and a gas inlet 56 for introducing gas into the chamber 42. ２ O ３ The distance from the base substrate 50 was set to 8 cm. The chamber 42 was evacuated to a vacuum by the vacuum means 52. －４ After confirming that the vacuum level reached 100 Pa, high purity O ２ The gas was introduced into the chamber 42 so as to reach a pressure of 50 Pa. ２ O ３ The base substrate 50 was heated with a heater (not shown) while being rotated at about 10 rpm to a temperature of 600° C. Thereafter, a repetition frequency of 10 Hz and a fluence of 3 J / cm were applied. ２The target 46 is irradiated with a KrF excimer laser while being scanned linearly between the end and center thereof to cause ablation, and the constituent material of the target 46 is turned into Cr. ２ O ３ The deposition was performed on the base substrate 50. The deposition time was 1 hour. The steps of scanning the laser on the target 46 were as follows: First, as shown in FIG. 5, a Ni-doped Cr film having a diameter of 50.8 mm was deposited on the base substrate 50. ２ O ３ The target 46 was divided into three segments S1, S2, and S3 by dividing a virtual line segment along its radius into thirds (length of each segment: approximately 16.9 mm). Each of the segments S1, S2, and S3 was further divided into 2,000 steps to determine each step for scanning. During the PLD growth process, the laser beam was advanced from the target center (point 0 in FIG. 1b) to the edge of the target (point 3 in FIG. 5), and then from the edge of the target (point 3 in FIG. 5) to the target center (point 0 in FIG. 5). During this PLD growth, the target 46 was rotated via the target rotation axis 44. The scan rates for the three segments S1, S2, and S3 were 100 steps / s, 60 steps / s, and 20 steps / s, respectively. Thus, Cr ２ O ３ A 1.5 μm thick Ni-doped Cr film was applied to the surface of the base substrate. ２ O ３ By forming a film, Ni-doped Cr ２ O ３ Cr with film ２ O ３ The base substrate was obtained.

[0042] (3) Ni-doped Cr ２ O ３ Evaluation of semiconductor film (3a) Surface EDS The surface of the obtained film (i.e., Cr ２ O ３ EDS measurements were performed on the surface of the substrate (the surface opposite to the base substrate). As a result, only Cr, Ni, and O were detected, and it was found that the film formed on the surface was composed of Cr oxide containing Ni. ２ O ３The film is made of Cr with a diameter of 50.8 mm. ２ O ３ This was observed over the entire surface of the base substrate.

[0043] (3b) EBSD: Ni-doped Cr was observed using an SEM (SU-5000, manufactured by Hitachi High-Technologies Corporation) equipped with an electron backscatter diffraction (EBSD) device (Nordlys Nano, manufactured by Oxford Instruments). ２ O ３ The deposition side of the film (i.e., Cr ２ O ３ The surface inverse pole figure orientation mapping of the surface (opposite side to the base substrate) was carried out in a field of view of 500 μm×500 μm. The conditions for this EBSD measurement were as follows:

[0044] <EBSD measurement conditions> Acceleration voltage: 15 kV Spot intensity: 70 Working distance: 22.5 mm Step size: 0.5 μm Sample tilt angle: 70° Measurement program: Aztec (version 3.3)

[0045] From the obtained inverse pole figure orientation mapping, Ni-doped Cr ２ O ３ It was found that the film had a biaxially oriented corundum-type crystal structure in which the c-axis was oriented in the normal direction to the substrate and also in the in-plane direction.

[0046] (3c) D-SIMS Measurement Using D-SIMS (CAMECA, IMS-7f), Ni-doped Cr ２ O ３ Cr with film ２ O ３ The Ni concentration was measured in a region about 5 μm deep from the surface of the substrate on which the film was formed. The primary ion species used in the measurement was Cs ＋ Measurements were performed using PLD ions at a primary ion acceleration voltage of 14.5 kV. As a result, Ni was detected in high concentrations in the region from the surface to a depth of approximately 0.7 μm, but the amount of Ni detected decreased in deeper regions, and was below the detection limit in regions with a depth of 1.5 μm or more. ２ O ３ Since no Ni was detected in the D-SIMS measurement of the base substrate, Cr ２ O ３α-Cr having a corundum-type crystal structure containing Ni on the surface of the base substrate ２ O ３ film (hereinafter, Ni-doped α-Cr ２ O ３ The average concentration of Ni atoms in the region from the surface to a depth of 0.7 μm was approximately 1×10 ２０ / cm ３ It was.

[0047] (3d) Planar TEM of the deposition surface Ni-doped α-Cr ２ O ３ Planar TEM observation (plan view) was performed to evaluate the crystal defect density of the film. A sample was cut out so as to include the surface on the deposition side, and processed by ion milling so that the sample thickness (T) around the measurement field of view was 150 nm. The obtained slice was subjected to TEM observation at an accelerating voltage of 300 kV using a transmission electron microscope (Hitachi, H-90001UHR-I) to evaluate the crystal defect density. In practice, eight TEM images with a measurement field of view of 4.1 μm × 3.1 μm were observed, and the number of defects observed within each was calculated. As a result, no crystal defects were observed in the obtained TEM image, and the crystal defect density was 9.9 × 10 ５ / cm ２ It was found to be less than

[0048] (3e) XRC of the surface of the film-forming side. Using an XRD device (manufactured by Bruker-AXS, D8-DISCOVER), Ni-doped α-Cr ２ O ３ XRC measurement was carried out on the (104) plane of the film-forming surface. ２ O ３After the axis was set so that the peak of the (104) plane of Ni-doped α-Cr was obtained, the conditions were as follows: tube voltage 40 kV, tube current 40 mA, collimator diameter 0.5 mm, anti-scattering slit 3 mm, ω range 13 to 20°, ω step width 0.005°, and counting time 0.5 seconds. The X-ray source used was a Ge (022) asymmetric reflection monochromator that converted CuKα radiation into parallel monochromatic light. The full width at half maximum (FWHM) of the obtained XRC profile of the (104) plane was determined by smoothing the profile and then searching for a peak using XRD analysis software (LEPTOS Ver. 4.03, manufactured by Bruker-AXS). As a result, Ni-doped α-Cr ２ O ３ The full width at half maximum of the (104) plane XRC profile on the surface of the film on the deposition side was 55 arcsec.

[0049] In addition, Ni-doped α-Cr ２ O ３ XRC measurement of the (006) plane of the film-forming surface was also carried out. ２ O ３ After the axis was adjusted so that the peak of the (006) plane was obtained, the measurement was performed at ω = 10.0 to 15.0°. The other conditions and analysis method were the same as those for the XRC measurement of the (104) plane described above. As a result, Ni-doped α-Cr ２ O ３ The full width at half maximum of the (006) plane XRC profile on the surface of the film on the deposition side was 40 arcsec.

[0050] Cr film not formed by PLD using the same method as above ２ O ３ Cr of the base substrate ２ O ３ XRC measurements were carried out on the (104) and (006) planes on the orientation layer side. As a result, the half-width of the (104) plane XRC profile was 39 arcsec., and the half-width of the (006) plane XRC profile was 33 arcsec. ２ O ３ The XRC profile of the film shows Ni-doped α-Cr ２ O ３ Not only the film but also Cr２ O ３ Underlying substrate (especially Cr ２ O ３ The above results indicate that the Ni-doped α-Cr ２ O ３ The XRC half-width of the film was estimated to be 100 arcsec or less for both the (104) and (006) planes.

[0051] (3f) Hall effect measurement Ni-doped α-Cr ２ O ３ Hall measurements were carried out on the Ni-doped α-Cr films. ２ O ３ Cr with film ２ O ３ A 10 mm square test piece was cut out from the base substrate and coated with Ni-doped α-Cr ２ O ３ Metallic indium (In) with a diameter of approximately 2 mm was soldered to the four corners of the film to prepare a sample for Hall effect measurement. The sample for Hall effect measurement was set in a Hall effect / resistivity measurement device (ResiTest 8400, manufactured by Toyo Corporation), and Hall measurement was performed at room temperature to determine the carrier concentration and mobility. The mobility range measurable with this device is 10 －３ ~10 ６ cm ２ As a result, the Hall coefficient of Ni-doped α-Cr ２ O ３ The film is p-type, and the hole concentration is 6.87×10 １９ cm －３ , Hall mobility is 29.6 cm ２ / Vs.

[0052] The Ni atom concentration obtained in (3c) above was about 1×10 ２０ / cm ３ , and the hole concentration is 6.87×10 １９ cm －３ From Ni-doped α-Cr ２ O ３ Ni atomic concentration in the film, C Ｎｉ Carrier concentration C Ｃ Ratio C to Ｎｉ / C ＣThe calculated value was approximately 1.46.

[0053] Ni-doped α-Cr ２ O ３ Cr without a film ２ O ３ Cr of the base substrate ２ O ３ The alignment layer was also subjected to Hall measurement using the same method as above, and the results showed that both the carrier concentration and mobility were below the detection limit.

[0054] Example 2: p-Cr ２ O ３ / Cr ２ O ３ Template: Cr was prepared in the same manner as in Example 1 except that the PLD film formation temperature was set to 400°C in (2b) above. ２ O ３ The substrate was prepared, PLD film was formed, and various evaluations were carried out. As a result, α-Cr containing biaxially oriented Ni was obtained. ２ O ３ The membrane is made of Cr with a diameter of 50.8 mm. ２ O ３ The Ni-doped α-Cr alloy was also found to have a high Cr content. ２ O ３ The crystal defect density of the film is 9.9 × 10 ５ cm ２ The concentration was less than the detection limit. ２ O ３ The XRC half-widths of the (006) and (104) planes of the film were 60 arcsec and 560 arcsec, respectively. ２ O ３ The film is p-type, and the hole concentration is 4.52×10 １９ cm －３ , Hall mobility is 15.4 cm ２ / Vs. Ni-doped α-Cr ２ O ３ The Ni atom concentration in the film and the film thickness were similar to those in Example 1. ２ O ３ Ni atomic concentration in the film, C Ｎｉ Carrier concentration C Ｃ Ratio C toＮｉ / C Ｃ The calculated value was approximately 2.21.

[0055] Example 3: n-Cr ２ O ３ / Cr ２ O ３ Template: Ni-doped Cr in (2a) and (2b) above ２ O ３ Ti-doped Cr instead of target ２ O ３ Cr was produced in the same manner as in Example 1, except that the target was prepared as follows. ２ O ３ Preparation of base substrate, Ti-doped Cr by PLD ２ O ３ The semiconductor film was formed and various evaluations were carried out.

[0056] (2') Ti-doped Cr ２ O ３ Target preparation: Cr as raw material powder ２ O ３ and TiO ２ Cr so that the atomic ratio of Ti to Cr was 0.15. ２ O ３ and TiO ２ The mixed powder was weighed and mixed to obtain a mixed powder. The mixed powder was molded into a disk shape with a diameter of 100 mm and a thickness of 4 mm, and the obtained molded body was sintered in an air atmosphere at 1100°C for 48 hours. A disk with a diameter of 50.8 mm and a thickness of 1.5 mm was cut out from the obtained sintered body and subjected to surface polishing. In this way, Ti-doped Cr for PLD was obtained. ２ O ３ Got the target.

[0057] (3') Ti-doped Cr ２ O ３ Evaluation of the semiconductor film (3a') Surface EDS The surface of the obtained film (i.e., Cr ２ O ３ EDS measurements were performed on the surface opposite to the base substrate. As a result, only Cr, Ti, and O were detected, and it was found that the film formed on the surface was composed of Cr oxide containing Ti.２ O ３ The film is made of Cr with a diameter of 50.8 mm. ２ O ３ This was observed over the entire surface of the base substrate.

[0058] (3b') EBSD: The Ti-doped Cr was observed using an SEM (SU-5000, manufactured by Hitachi High-Technologies Corporation) equipped with an electron backscatter diffraction (EBSD) device (Nordlys Nano, manufactured by Oxford Instruments). ２ O ３ Inverse pole figure orientation mapping of the surface of the film on the deposition side was carried out in a field of view of 500 μm×500 μm under the same conditions as in Example 1. From the obtained inverse pole figure orientation mapping, it was found that Ti-doped Cr ２ O ３ It was found that the film had a biaxially oriented corundum-type crystal structure in which the c-axis was oriented in the normal direction to the substrate and also in the in-plane direction.

[0059] (3c') D-SIMS Measurement Using D-SIMS (CAMECA, IMS-7f), Ti-doped Cr ２ O ３ Cr with film ２ O ３ The Ti concentration was measured in a range of about 5 μm deep from the surface of the base substrate on which the film was formed. The primary ion species used in the measurement was Cs ＋ Measurements were performed using PLD ions at a primary ion acceleration voltage of 14.5 kV. As a result, Ti was detected at a high concentration in the region from the surface to a depth of approximately 0.7 μm, but the amount of Ti detected decreased in deeper regions, and was below the detection limit in regions with a depth of 1.5 μm or more. ２ O ３ Since Ti was not detected in the D-SIMS measurement of the base substrate, Cr ２ O ３ α-Cr having a corundum-type crystal structure containing Ti on the surface of the base substrate ２ O ３ film (hereinafter referred to as Ti-doped α-Cr) ２ O ３ The average concentration of Ti atoms in the region from the surface to a depth of 0.7 μm was approximately 2×10 ２０ / cm ３ It was.

[0060] (3d') Planar TEM image of the deposition side surface Ti-doped α-Cr ２ O ３ To evaluate the crystal defect density of the film, planar TEM observation (plan view) was carried out in the same manner as in Example 1. As a result, no crystal defects were observed in the obtained TEM image, and the crystal defect density was 9.9 × 10 ５ / cm ２ It was found to be less than

[0061] (3e') XRC of the deposition side surface Ti-doped α-Cr ２ O ３ XRC measurements of the (104) and (006) planes of the film-forming surface were carried out in the same manner as in Example 1. As a result, Ti-doped α-Cr ２ O ３ The full width at half maximum of the (104) plane XRC profile of the film was 74 arcsec., and the full width at half maximum of the (006) plane XRC profile was 46 arcsec. ２ O ３ Cr of the base substrate ２ O ３ XRC measurements were carried out on the (104) and (006) planes on the orientation layer side. As a result, the half-width of the XRC profile of the (104) plane was 41 arcsec., and that of the (006) plane was 34 arcsec. From the above results, it was found that Ti-doped α-Cr ２ O ３ The XRC half-width of the film was estimated to be 100 arcsec or less for both the (104) and (006) planes.

[0062] (3f') Hall effect measurement Ti-doped α-Cr was used in the same manner as in Example 1. ２ O ３ Hall measurements were carried out on the films. The Hall coefficients indicated that the Ti-doped α-Cr ２ O ３ The film is n-type and has a carrier concentration of 8.07 × 10 １９ cm －３ , carrier mobility is 21.4 cm ２ / Vs. Ti-doped α-Cr ２ O ３Ti atomic concentration in the film, C Ｔｉ Carrier concentration C Ｃ Ratio C to Ｔｊ / C Ｃ The calculated value was approximately 2.48.

[0063] Example 4: p-Cr ２ O ３ / Cr ２ O ３ Template: Ni-doped Cr in (2a) and (2b) above ２ O ３ Instead of the target, Mg-doped Cr ２ O ３ Cr was produced in the same manner as in Example 1, except that the target was prepared as follows. ２ O ３ Preparation of base substrate, Mg-doped Cr by PLD ２ O ３ The semiconductor film was formed and various evaluations were carried out.

[0064] (2'') Mg-doped Cr ２ O ３ Target preparation: Cr as raw material powder ２ O ３ and MgO were mixed with Cr so that the atomic ratio of Mg to Cr was 0.15. ２ O ３ and MgO were weighed and mixed to obtain a mixed powder. The obtained mixed powder was molded into a disk shape with a diameter of 100 mm and a thickness of 4 mm, and the obtained molded body was sintered in an air atmosphere at 1100°C for 48 hours. A disk with a diameter of 50.8 mm and a thickness of 1.5 mm was cut out from the obtained sintered body and subjected to surface polishing. In this way, Mg-doped Cr for PLD was obtained. ２ O ３ Got the target.

[0065] (3'') Mg-doped Cr ２ O ３ Evaluation of semiconductor film (3a'') Surface EDS The surface of the obtained film (i.e., Cr ２ O ３EDS measurements were performed on the surface opposite to the base substrate. As a result, only Cr, Mg, and O were detected, and it was found that the film formed on the surface was composed of Cr oxide containing Mg. ２ O ３ The film is made of Cr with a diameter of 50.8 mm. ２ O ３ This was observed over the entire surface of the base substrate.

[0066] (3b'') EBSD The Mg-doped Cr was observed using a SEM (SU-5000, manufactured by Hitachi High-Technologies Corporation) equipped with an electron backscatter diffraction (EBSD) spectrometer (Nordlys Nano, manufactured by Oxford Instruments). ２ O ３ Inverse pole figure orientation mapping of the surface of the film on the deposition side was carried out in a field of view of 500 μm×500 μm under the same conditions as in Example 1. From the obtained inverse pole figure orientation mapping, it was found that the Mg-doped Cr ２ O ３ It was found that the film had a biaxially oriented corundum-type crystal structure in which the c-axis was oriented in the normal direction to the substrate and also in the in-plane direction.

[0067] (3c'') D-SIMS Measurement Using D-SIMS (CAMECA, IMS-7f), Mg-doped Cr ２ O ３ Cr with film ２ O ３ The Mg concentration was measured in a range of about 5 μm deep from the surface of the base substrate on which the film was formed. The primary ion species used in the measurement was Cs ＋ Measurements were performed using PLD ions at a primary ion acceleration voltage of 14.5 kV. As a result, high concentrations of Mg were detected in the region from the surface to a depth of approximately 0.7 μm, but the amount of Mg detected decreased in deeper regions, and was below the detection limit in regions with a depth of 1.5 μm or more. ２ O ３ Since no Mg was detected in the D-SIMS measurement of the base substrate, Cr ２ O ３ α-Cr having a corundum-type crystal structure containing Mg on the surface of the base substrate ２ O ３ film (hereinafter referred to as Mg-doped α-Cr２ O ３ The average Mg atom concentration in the region from the surface to a depth of 0.7 μm was approximately 2×10 ２０ / cm ３ It was.

[0068] (3d'') Planar TEM image of the deposition side of Mg-doped α-Cr ２ O ３ To evaluate the crystal defect density of the film, planar TEM observation (plan view) was carried out in the same manner as in Example 1. As a result, no crystal defects were observed in the obtained TEM image, and the crystal defect density was 9.9 × 10 ５ / cm ２ It was found to be less than

[0069] (3e'') XRC of the deposition side surface of Mg-doped α-Cr ２ O ３ XRC measurements of the (104) and (006) planes of the film-forming surface were carried out in the same manner as in Example 1. As a result, Mg-doped α-Cr ２ O ３ The full width at half maximum of the (104) plane XRC profile of the film was 69 arcsec., and the full width at half maximum of the (006) plane XRC profile was 51 arcsec. ２ O ３ Cr of the base substrate ２ O ３ XRC measurements were carried out on the (104) and (006) planes on the orientation layer side. As a result, the half-width of the XRC profile of the (104) plane was 39 arcsec., and that of the (006) plane was 33 arcsec. From the above results, it was found that the Mg-doped α-Cr ２ O ３ The XRC half-width of the film was estimated to be 100 arcsec or less for both the (104) and (006) planes.

[0070] (3f'') Hall effect measurement Mg-doped α-Cr was measured in the same manner as in Example 1. ２ O ３ Hall measurements were carried out on the films. As a result, the Hall coefficients indicated that the Mg-doped α-Cr ２ O ３The film is p-type and the carrier concentration is 4.03 × 10 １９ cm －３ , carrier mobility is 14.9 cm ２ / Vs. Mg-doped α-Cr ２ O ３ Mg atomic concentration in the film, C Ｍｇ Carrier concentration C Ｃ Ratio C to Ｍｇ / C Ｃ was calculated to be approximately 4.96.

[0071] Example 5 (comparison): p-Cr ２ O ３ PLD film formation and various evaluations were carried out in the same manner as in Example 1, except that a sapphire substrate (diameter 50.8 mm (2 inches), thickness 0.43 mm, c-plane, off-angle 0.2°) was used for the PLD film formation in (2) above without undergoing AD film formation, heat treatment, grinding, or polishing. As a result, biaxially oriented Ni-containing α-Cr ２ O ３ The membrane is made of Cr with a diameter of 50.8 mm. ２ O ３ The crystal defect density was 1.5 × 10 １０ / cm ２ Ni-doped α-Cr ２ O ３ The XRC half-widths of the (006) and (104) planes of the film were 153 arcsec and 3850 arcsec, respectively. ２ O ３ The film is p-type, and the hole concentration is 1.20×10 １８ cm －３ , Hall mobility is 0.6 cm ２ / Vs.

[0072] Example 6: n-Cr ２ O ３ / p-Cr ２ O ３ / Cr ２ O ３ Template: p-type Cr prepared in Example 1 ２ O ３ Film (Ni-doped α-Cr２ O ３ The n-type Cr film was formed on the film in the same manner as in Example 3. ２ O ３ Film (Mg-doped α-Cr ２ O ３ The composite film obtained was evaluated in the same manner as in the previous example. ２ O ３ The full widths at half maximum of the XRC profiles of the (104) and (006) planes of the film were 64 arcsec. and 61 arcsec., respectively. ２ O ３ The crystal defect density of the film was below the measurement limit. ２ O ３ film and n-type Cr ２ O ３ were confirmed to be p-type and n-type, respectively.

Claims

1. α-Cr with a corundum-type crystal structure ２ O ３ Single crystal and / or α-Cr ２ O ３ A semiconductor film made of a single crystal of a solid solution of 1.0×10 ７ / cm ２ A semiconductor film having a crystal defect density of:

2. The semiconductor film according to claim 1, wherein the X-ray rocking curve half-width of the (006) plane on the surface of said semiconductor film is 100 arcsec or less.

3. The semiconductor film according to claim 1 or 2, wherein the X-ray rocking curve half-width of the (104) plane on the surface of said semiconductor film is 500 arcsec or less.

4. The semiconductor film has a conductivity of 3 to 1000 cm ２ 3. The semiconductor film of claim 1, wherein the semiconductor film exhibits a carrier mobility of 0.1 V. / V·s.

5. The semiconductor film is 1×10 １２ / cm ３ ~1 x 10 ２１ / cm ３ 3. The semiconductor film according to claim 1, wherein the semiconductor film has a carrier concentration of 6. The semiconductor film according to claim 1 or 2, wherein the semiconductor film has a thickness of 0.1 to 15 μm.

7. The semiconductor film according to claim 1 or 2, wherein the semiconductor film has p-type conductivity or n-type conductivity.

8. The semiconductor film contains Ni as a dopant, and the Ni atomic concentration in the semiconductor film is 1×10 １４ ~1 x 10 ２２ / cm ３ The semiconductor film according to claim 1 or 2, wherein 9. The semiconductor film contains Ni as a dopant, and the Ni atomic concentration C in the semiconductor film Ｎｉ The carrier concentration C in the semiconductor film Ｃ Ratio C to Ｎｉ / C Ｃ 3. The semiconductor film according to claim 1, wherein is 1 to 100.

10. A composite film composed of a plurality of semiconductor films having a corundum-type crystal structure, wherein each of the plurality of semiconductor films is an α-Cr ２ O ３ Single crystal and / or α-Cr ２ O ３ at least one of the plurality of semiconductor films is a p-type conductive film and at least one other of the plurality of semiconductor films is an n-type conductive film, and the p-type conductive film and / or the n-type conductive film is 1.0×10 ７ / cm ２ A composite film having a crystal defect density of:

11. The composite film of claim 10, wherein said plurality of semiconductor films are epitaxially grown films.

12. A substrate having an orientation layer, and an α-Cr layer having a corundum-type crystal structure provided on the orientation layer. ２ O ３ Single crystal and / or α-Cr ２ O ３ and a semiconductor film formed of a single crystal of a Zn-based solid solution, wherein the semiconductor film has a surface area of ​​1.0×10 ７ / cm ２ The surface of the orientation layer close to the semiconductor film is made of a material having a corundum-type crystal structure with an a-axis length and / or a c-axis length greater than those of sapphire, and the orientation layer is made of α-Cr ２ O ３ , or α-Cr ２ O ３ A semiconductor film-bearing base substrate is formed from a solid solution containing 13. The base substrate with a semiconductor film according to claim 12, wherein the alignment layer and the semiconductor film are each an epitaxially grown film.

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