Single-crystal film, laminated structure, semiconductor device, electronic apparatus, and system

Abstract

[Problem] To provide a single-crystal film and a layered structure useful for semiconductors. [Solution] A single-crystal film including a metal oxide containing germanium as a main component, in which the single-crystal film has, in part of or in the entirety of the film, a carbon concentration of 1×1018 cm-3 or less, the metal oxide has a rutile structure, and the single-crystal film has a thickness of 500 nm or more. Furthermore, the single-crystal film is used for applications such as semiconductor devices by using the single-crystal film including a dopant.

Description

Single-crystalline film, laminated structure, semiconductor device, electronic device, and system

[0001] The present invention relates to a single-crystalline film and a laminated structure useful for semiconductors.

[0002] In recent years, rutile-structured germanium dioxide (r-GeO ２ ) has attracted attention as a ultra-wide bandgap (UWBG) semiconductor promising for future power electronics devices. r-GeO ２ has a bandgap of 4.68 eV, and n-type and p-type semiconductors can be realized, and it can be produced at a low cost, so it is expected as a next-generation semiconductor device.

[0003] In Non-Patent Document 1, Patent Document 1, Patent Document 2, and Patent Document 3, a laminated structure in which a r-GeO ２ crystal film is laminated on a r-TiO ２ (001) substrate has been studied. However, in Non-Patent Document 1, Non-Patent Document 2 was submitted as an Erratum after the peer review of Non-Patent Document 1 (Non-Patent Document 2), and it was found that the crystal grains (abnormal grains) described in Non-Patent Document 1 and Patent Document 1 were rutile-type germanium dioxide crystals, and the other parts were amorphous phases. That is, only an amorphous phase was formed in most parts, and even when a crystal phase was formed, only crystal grains were formed in part. Therefore, a method for manufacturing a crystalline film with excellent crystallinity capable of performing electrical control has been awaited. Also, in Non-Patent Document 3, tin dioxide, which is easy to crystallize, is mixed with r-GeO ２ to produce an alloy thin film of r-(Ge,Sn)O ２ , and it is considered that n-type conductivity has been confirmed. However, since r-SnO ２ has a bandgap of 3.7 eV, which is smaller than that of r-GeO ２ , the characteristics of r-GeO ２ cannot be utilized in the r-(Ge,Sn)O ２ alloy thin film, and since it is difficult to control the composition of Ge and Sn, it has been difficult to control the electrical characteristics. Therefore, a method for obtaining conductivity in a single-phase r-GeO ２ thin film has been awaited.

[0004] H. Takane, K. Kaneko. , “Establishment of a growth route of crystallized rutile GeO2 thin film (≧ 1 mm / h) and its structural Applied Physics Letters Vol. 119, pp. 062104(1-6) (2021). H. Takane, K. Kaneko. , Erratum: “Establishment of a growth route of crystallized rutile GeO2 thin film (≧1 μm / h) and its structural Applied Physics Letters Vol. 120, 099903(1-3) (2022). H. Takane, et al. , “Band-gap engineering of rutile-structured SnO2-GeO2-SiO2 alloy system”, PHYSICAL REVIEW MATERIALS 6, 084604 (2022).

[0005] International Publication No. 2023 / 008452, International Publication No. 2023 / 008453, International Publication No. 2023 / 008454

[0006] The present invention aims to provide single-crystal films and multilayer structures useful for semiconductors.

[0007] As a result of diligent research to achieve the above objective, the inventors have newly developed a mist CVD apparatus using a guide partition, and have used the said mist CVD apparatus using a guide partition to produce a single crystal film mainly composed of a metal oxide containing germanium, wherein the carbon concentration in part or all of the film is 1 × 10⁻¹⁶. １８ cm －３We have successfully created the following single-crystal film, and have found that the obtained single-crystal film can be manufactured easily and at low cost, possesses excellent crystallinity and excellent electrical properties, and is useful for semiconductor devices, etc. We have found that such a single-crystal film can solve the above-mentioned conventional problems all at once. Furthermore, after obtaining the above findings, the inventors conducted further studies and completed the present invention.

[0008] In other words, the present invention relates to the following invention: [1] A single crystal film mainly composed of a metal oxide containing germanium, wherein the carbon concentration in part or all of the film is 1 × 10 １８ cm －３ A single crystal film characterized by the following: [2] The single crystal film according to [1] wherein the metal oxide has a rutile structure. [3] The single crystal film according to [1] wherein the film thickness is 500 nm or more. [4] The single crystal film according to [1] wherein the full width at half maximum of the rocking curve measured by X-ray diffraction in the oriented crystal axis direction is 600 arcsec or less. [5] The single crystal film according to [1] containing a dopant. [6] The carrier density is 1 × 10⁻¹⁶ ２２ cm －３ The single crystal film described in [1] above, which is as follows: [7] The single crystal film described in [1] above, which has an electrical resistivity of 0.03 Ωcm or less. [8] A mobility of 15 cm ２ A single crystal film according to [1] above, having a sheet resistance of 300 Ω / □ or less. [9] A single crystal film according to [1] above, having a sheet resistance of 300 Ω / □ or less.

[10] An area of ​​100 mm² ２ The single crystal film described in [1] above.

[11] The single crystal film described in [1] above, wherein the surface roughness is 25 nm or less.

[12] A laminated structure in which a single crystal film mainly composed of a metal oxide containing germanium is laminated on a crystal substrate directly or via another layer, wherein the carbon concentration in part or all of the single crystal film is 1 × 10 １８ cm －３ A laminated structure characterized by the following:

[13] The laminated structure according to

[12] wherein the crystal substrate has a rutile crystal structure.

[14] The laminated structure according to

[12] wherein the single crystal film has a rutile crystal structure.

[15] The area of ​​the single crystal film is 100 mm². ２

[12] The single crystal film described above.

[16] The laminated structure described above, wherein the thickness of the single crystal film is 500 nm or more.

[17] A semiconductor device comprising a single crystal film or a laminated structure, wherein the crystal film is the single crystal film described in claim 1, and the laminated structure is the laminated structure described above.

[18] The semiconductor device described above in

[17] , wherein the single crystal film of the single crystal film or the laminated structure is bonded to an ohmic electrode to form an ohmic contact.

[19] The semiconductor device described above in

[17] , wherein the ohmic electrode comprises one or more metal elements selected from the d-block metal elements and / or p-block metal elements of the periodic table.

[20] The semiconductor device described above in

[17] , which is a power device.

[21] The semiconductor device described in

[17] , which is a Schottky barrier diode (SBD), a junction barrier Schottky diode (JBS), a metal-semiconductor field-effect transistor (MESFET), an electrostatic induction transistor (SIT), a high electron-mobility transistor (HEMT), a metal-oxide-semiconductor field-effect transistor (MOSFET), a junction field-effect transistor (JFET), an insulated-gate bipolar transistor (IGBT), or a light-emitting diode (LED).

[22] An electronic device including a semiconductor device, characterized in that the semiconductor device is the semiconductor device described in

[17] .

[23] A system including an electronic device, characterized in that the electronic device is the electronic device described in

[22] .

[0009] The single-crystal film and multilayer structure of the present invention are useful for semiconductors.

[0010] This is an example of a schematic configuration diagram of a film deposition apparatus preferably used in the present invention. This is a schematic diagram showing an atomization apparatus preferably used in the present invention. This is a diagram showing the 2θ / ω result in the XRD diffraction results in Example 1. This is a diagram showing the ω scan result in the XRD diffraction results in Example 1. This is a diagram showing the AFM image in Example 1. This is a diagram showing the SEM image in Example 1. This is a diagram showing the EDS image in Example 1. This is a diagram showing the 2θ / ω result in the XRD diffraction results in Example 2. This is a diagram showing the ω scan result in the XRD diffraction results in Example 2. This is a diagram showing the 2θ / ω result in the XRD diffraction results in Example 3. This is a diagram showing the ω scan result in the XRD diffraction results in Example 3. This is a schematic diagram showing a preferred example of a Schottky barrier diode (SBD) of the present invention. This is a schematic diagram showing a preferred example of a high electron mobility transistor (HEMT) of the present invention. This is a schematic diagram showing a preferred example of a metal-oxide-semiconductor field-effect transistor (MOSFET) of the present invention. This is a schematic diagram showing a preferred example of a junction field-effect transistor (JFET) of the present invention. This figure schematically shows a preferred example of an insulated-gate bipolar transistor (IGBT) of the present invention. This figure schematically shows a preferred example of a light-emitting element (LED) of the present invention. This figure schematically shows a preferred example of a junction barrier Schottky diode (JBS) of the present invention. This figure schematically shows a preferred example of a metal-semiconductor field-effect transistor (MESFET) of the present invention. This figure schematically shows a preferred example of an electrostatic induction transistor (SIT) of the present invention. This figure schematic illustrates a part of the manufacturing process of the SIT in Figure 20. This figure schematically shows a sample in which an ohmic electrode was formed on a crystal film in Example 2. This figure shows the results of ohmic measurement using Figure 22. This figure schematically shows a cross-sectional view of an atomizing device preferably used in the present invention, viewed from the side. This figure shows the results of SIMS measurement in a test example. This figure schematically shows a sample in which an ohmic electrode was formed on a crystal film in Example 3. This figure shows the results of ohmic measurement using Figure 26.

[0011] The single crystal film of the present invention is a single crystal film mainly composed of a metal oxide containing germanium, wherein the carbon concentration in part or all of the film is 1 × 10⁻¹⁶ １８ cm －３ The present invention is characterized by the following: Furthermore, the laminated structure in the present invention is a laminated structure in which a single crystal film mainly composed of a metal oxide containing germanium is laminated on a crystal substrate directly or via another layer, wherein the carbon concentration in part or all of the single crystal film is 1 × 10 １８ cm －３ The following features are present. In this specification, "film" can be read as "layer." A "laminated structure" is a structure that includes one or more crystalline layers, and may also include layers other than crystalline layers (e.g., amorphous layers). Furthermore, the crystalline film is preferably a single-crystal layer, but may also be a polycrystalline layer. Such a single-crystal film with a low carbon concentration can be made into a single-crystal film with excellent electrical properties.

[0012] In the present invention, the area of ​​the single crystal film is 100 mm². ２ It is more preferable that the area is as described above. The thickness of the single crystal film is preferably 500 nm or more. Within this preferred range, the crystalline film can have better breakdown voltage and superior electrical properties. The metal oxide is not particularly limited as long as it does not hinder the objectives of the present invention, and may have a tetragonal rutile crystal structure, a trigonal α-quartz structure, or an orthorhombic CaCl ２ It may also be a type crystal structure, α-PbO ２ The crystal structure may be a pyrite-type crystal structure which is tetragonal, but in the present invention, it is preferable to have a rutile-type structure which is tetragonal. Within this preferred range, semiconductor properties can be improved.

[0013] The single crystal film in the present invention preferably contains a dopant. The dopant is not particularly limited as long as it does not hinder the objective of the present invention, but it preferably contains an element from Group 13 or Group 15 of the periodic table. Examples of the Group 15 elements of the periodic table include nitrogen, phosphorus, arsenic, antimony, and bismuth, and examples of the Group 13 elements of the periodic table include boron, aluminum, gallium, and indium. With such a preferred range, better electrical properties can be obtained and the film can be manufactured more easily.

[0014] In this invention, the electrical resistivity is preferably 0.03 Ωcm or less. Furthermore, the sheet resistance is preferably 300 Ω / □ or less, and more preferably 200 Ω / □ or less. The mobility is 15 cm. ２ It is preferable that the carrier density is 1 × 10⁻¹⁰ or higher. In the present invention, the carrier density is not particularly limited as long as it does not hinder the objective of the present invention, but the carrier density is 1 × 10⁻¹⁰ ２２ cm －３ The following is preferable. According to this preferred range, semiconductor properties can be improved and better electrical properties can be obtained.

[0015] In the present invention, "main component" means that the content of a germanium-containing metal oxide in the single crystal film or the crystalline film is 50 at% or more in terms of the composition ratio of the single crystal film or the crystalline film. In embodiments of the present invention, it is preferable that the content of a germanium-containing metal oxide in the single crystal film or the crystalline film is 70 at% or more in terms of the composition ratio of the single crystal film or the crystalline film, and more preferably 90 at% or more. Furthermore, it is preferable that the single crystal film or the crystalline film contains a germanium-containing metal oxide as its main component. According to such preferred ranges, the interface becomes better, the electrical properties can be improved, and the semiconductor properties can also be improved. Furthermore, the single crystal film or the crystalline film may also contain other metals other than germanium-containing metal oxides. Examples of such other metals include one or more metals selected from Group 14 metals of the periodic table other than germanium (such as tin or silicon) or Group 4 metals of the periodic table (such as titanium, zirconia, or hafnium). It is preferable that the atomic ratio of the germanium-containing metal oxide in the single crystal film or in the crystal film is 0.5 or higher. Furthermore, the crystal structure of the metal oxide is not particularly limited and may be a tetragonal rutile-type crystal structure, a trigonal α-quartz-type structure, or an orthorhombic CaCl ２ It may also be a type crystal structure, α-PbO ２ The crystal structure may be a pyrite-type crystal structure, which is tetragonal, but in the present invention, a rutile-type structure which is tetragonal is preferred. By specifying such a preferred range, a crystal film with better semiconductor properties can be realized.

[0016] The preferred single crystal film or the laminated structure described above can be obtained more easily, for example, by using the film-forming apparatus shown in Figure 1. The thickness of the single crystal film is not particularly limited as long as it does not hinder the objective of the present invention, but in the present invention, it is preferably 500 nm or more. The surface roughness (RMS) of the crystal film is preferably 25 nm or less. Furthermore, the full width at half maximum of the rocking curve measured by X-ray diffraction in the direction of the oriented crystal axis is preferably 600 arcsec or less. By using such preferred film thickness, surface roughness, or full width at half maximum of the rocking curve, when the laminated structure is applied to a semiconductor device, it is possible to impart superior electrical properties such as breakdown voltage to the semiconductor device. The surface roughness (RMS) refers to the value obtained by calculating it in accordance with JIS B0601 using the surface shape measurement results for a 10 μm square region by atomic force microscopy (AFM).

[0017] Furthermore, the crystalline substrate is not particularly limited as long as it does not hinder the objectives of the present invention, and may be a known substrate, an insulating substrate, a conductive substrate, or a semiconductor substrate. It may be a single-crystal substrate or a polycrystalline substrate. The crystalline substrate may also be a substrate having a metal film on its surface. In the case of a conductive substrate, a vertical device can be manufactured without removing the substrate. The crystalline substrate is not particularly limited as long as it does not hinder the objectives of the present invention, but it is preferable that it has a rutile-type crystalline structure. Examples of substrates having a rutile-type crystalline structure include rutile-type GeO ２ Substrate, magnesium fluoride substrate, or rutile-type structure TiO ２ Examples include substrates. The crystalline substrate may have an off-angle. The metal oxide is not particularly limited as long as it does not hinder the objectives of the present invention, and may have a tetragonal rutile-type crystal structure, a trigonal α-quartz-type structure, or an orthorhombic CaCl ２ It may also be a type crystal structure, α-PbO ２The crystal structure may be a tetragonal pyrite-type crystal structure, but in the present invention, a tetragonal rutile-type structure is preferred. Within this preferred range, electrical properties can be further improved, better crystallinity can be achieved, and it can be easily applied to semiconductor devices and the like.

[0018] In the present invention, the film may be formed directly on the crystal substrate, but on the crystal substrate, a single crystal layer mainly composed of a metal oxide containing germanium is formed, and the carbon concentration in part or all of the film is 1 × 10 １８ cm －３ The following are layers different from the crystalline layer (for example, n-type semiconductor layer, n ＋ type semiconductor layer, n － A film may be formed on the substrate via other layers, such as a semiconductor layer, an insulating layer (including a semi-insulating layer), or a buffer layer, after lamination. In particular, a buffer layer can be suitably used to mitigate the lattice constant difference between the crystal substrate and the single crystal layer. Examples of materials used for the buffer layer include SnO ２ , TiO ２ , VO ２ , MnO ２ RuO ２ , CsO ２ IrO ２ , GeO ２ CuO ２ , PbO ２ AgO ２ ,CrO ２ SiO ２ Examples include SiC, GaN, Pt, and mixed crystals thereof.

[0019] The aforementioned single crystal layer is a single crystal film mainly composed of a metal oxide containing germanium, obtained, for example, by using the film deposition apparatus shown in Figure 1, wherein the carbon concentration in part or all of the film is 1 × 10⁻¹⁶ １８ cm －３The following can be more easily obtained by forming a single crystal film. Furthermore, doping can be appropriately performed using the aforementioned film-forming apparatus. The doped crystal can be suitably used as a semiconductor film or semiconductor layer, and n-type dopants or p-type dopants can be applied to conventional doping methods in oxide semiconductors. Examples of the n-type dopants include antimony (Sb), arsenic (As), bismuth (Bi), phosphorus (P), fluorine (F), niobium (Nb), vanadium (V), tantalum (Ta), or tungsten (W). Examples of the p-type dopants include aluminum (Al), gallium (Ga), or indium (In). In this invention, the laminated structure obtained in this manner is also included.

[0020] In the present invention, it is preferable that the single crystal film or the single crystal film of the laminated structure is bonded to the ohmic electrode to form an ohmic contact. The ohmic electrode is not particularly limited as long as it does not hinder the objective of the present invention, but it is preferable that it contains one or more metal elements selected from the d-block metal elements and / or p-block metal elements of the periodic table. Examples of the d-block metal elements include Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Pt, Ni, Au, Ag, Hg, Zn, Cd, and Pd. Examples of the p-block metal elements include Al, Ga, In, Sn, Pb, Tl, Bi, and Po. Furthermore, in the present invention, it is preferable that the metal layer contains In. Such a preferred range can result in better ohmic properties.

[0021] The laminated structure can be used, for example, in a semiconductor device, either as is or after being subjected to known processing methods such as substrate peeling, using known means. Examples of the semiconductor device include Schottky barrier diodes (SBDs), junction barrier Schottky diodes (JBSs), metal-semiconductor field-effect transistors (MESFETs), electrostatic induction transistors (SITs), high electron-mobility transistors (HEMTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), junction field-effect transistors (JFETs), insulated-gate bipolar transistors (IGBTs), or light-emitting diodes (LEDs). Furthermore, it may be a module on which these semiconductor devices are mounted, or an electronic device and its components equipped with these semiconductor devices, and is useful for a variety of applications, and is particularly preferably applied to power devices. The semiconductor device can be classified into a horizontal device, where electrodes are formed on one side of the semiconductor layer, and a vertical device, where electrodes are formed on both the front and back sides of the semiconductor layer. In the present invention, the semiconductor device can be suitably used as both a horizontal and a vertical device.

[0022] The following describes, in more detail, examples of semiconductor devices preferably used in the present invention with reference to the drawings, but the present invention is not limited to these examples. A preferred example of using a single crystal film as a semiconductor layer in the present invention is shown below.

[0023] Figure 12 shows n － Semiconductor layer 101a, n ＋ A preferred example of a Schottky barrier diode (SBD) comprising a p-type semiconductor layer 101b, a p-type semiconductor layer 102, a metal layer 103, an insulating layer 104, a Schottky electrode 105a, and an ohmic electrode 105b is shown. The metal layer 103 is made of a metal such as Al and covers the Schottky electrode 105a.

[0024] Figure 13 shows the n-type semiconductor layer 121a with a wide bandgap, the n-type semiconductor layer 121b with a narrow bandgap, and n ＋A preferred example of a high electron mobility transistor (HEMT) comprising a p-type semiconductor layer 121c, a p-type semiconductor layer 123, a gate electrode 125a, a source electrode 125b, a drain electrode 125c, and a substrate 129 is shown.

[0025] Figure 14 shows n － Type semiconductor layer 131a, first n ＋ Type semiconductor layer 131b, second n ＋ p-type semiconductor layer 131c, p-type semiconductor layer 132, p ＋ A preferred example of a metal-oxide-semiconductor field-effect transistor (MOSFET) comprising a type semiconductor layer 132a, a gate insulating film 134, a gate electrode 135a, a source electrode 135b, and a drain electrode 135c is shown. ＋ The type semiconductor layer 132a may be a p-type semiconductor layer, or it may be the same as the p-type semiconductor layer 132.

[0026] Figure 15 shows n － Type semiconductor layer 141a, first n ＋ A preferred example of a junction field-effect transistor (JFET) comprising a type semiconductor layer 141b, a second n+ type semiconductor layer 141c, a p-type semiconductor layer 142, a gate electrode 145a, a source electrode 145b, and a drain electrode 145c is shown.

[0027] Figure 16 shows n-type semiconductor layer 151, n － Semiconductor layer 151a, n ＋ A preferred example of an insulated-gate bipolar transistor (IGBT) comprising a p-type semiconductor layer 151b, a p-type semiconductor layer 152, a gate insulating film 154, a gate electrode 155a, an emitter electrode 155b, and a collector electrode 155c is shown.

[0028] (LED) Figure 17 shows an example of a semiconductor device of the present invention when the semiconductor device is a light-emitting diode (LED). The semiconductor light-emitting device in Figure 17 has an n-type semiconductor layer 161 on a second electrode 165b, and a light-emitting layer 163 is laminated on the n-type semiconductor layer 161. A p-type semiconductor layer 162 is laminated on the light-emitting layer 163. A translucent electrode 167 that transmits light generated by the light-emitting layer 163 is provided on the p-type semiconductor layer 162, and a first electrode 165a is laminated on the translucent electrode 167. Note that the semiconductor light-emitting device in Figure 17 may be covered with a protective layer except for the electrode portion.

[0029] Examples of materials for translucent electrodes include conductive materials such as oxides containing indium (In) or titanium (Ti). More specifically, for example, In ２ O ３ ZnO, SnO ２ Ga ２ O ３ , TiO ２ , CEO ２ Alternatively, these may include mixed crystals of two or more of these materials, or materials doped therewith. Translucent electrodes can be formed by providing these materials by known means such as sputtering. Furthermore, after forming the translucent electrodes, thermal annealing may be performed to make the translucent electrodes transparent.

[0030] In the semiconductor light-emitting element shown in Figure 17, the first electrode 165a is the positive electrode and the second electrode 165b is the negative electrode. By passing current through the p-type semiconductor layer 162, the light-emitting layer 163, and the n-type semiconductor layer 161 via these electrodes, the light-emitting layer 163 emits light.

[0031] Examples of materials for the first electrode 165a and the second electrode 165b include metals such as Al, Mo, Co, Zr, Sn, Nb, Fe, Cr, Ta, Ti, Au, Pt, V, Mn, Ni, Cu, Hf, W, Ir, Zn, In, Pd, Nd, or Ag, or alloys thereof; metal oxide conductive films such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and zinc indium oxide (IZO); organic conductive compounds such as polyaniline, polythiophene, or polypyrrole; or mixtures thereof. The electrode deposition method is not particularly limited and can be formed on the substrate according to a method appropriately selected from wet methods such as printing, spraying, and coating; physical methods such as vacuum deposition, sputtering, and ion plating; and chemical methods such as CVD and plasma CVD, taking into consideration the suitability with the material.

[0032] Figure 18 shows the main part of a junction barrier Schottky diode (JBS), which is one of the preferred embodiments of the present invention. The JBS in Figure 18 has an ohmic electrode 1020, n － Semiconductor layer 1010a, n ＋ The semiconductor device in Figure 18 comprises a p-type semiconductor layer 1010b, a Schottky electrode 1030, and an electric field relaxation region 1060. The Schottky electrode 1030 is composed of a metal layer 1030a, a metal layer 1030b, and a metal layer 1030c. In the semiconductor device in Figure 18, the outer ends of the metal layer 1030a and / or metal layer 1030b, which serve as the second electrode layer, are located outside the outer end of the metal layer 1030c, which serves as the first electrode layer. In addition, in the semiconductor device in Figure 18, the electric field relaxation region 1060 comprises at least a portion of the second electrode layer located outside the outer end of the first electrode layer, and the outer end of the second electrode, with at least two electric field relaxation regions 1060 arranged in a planar manner. In addition, in the semiconductor device in Figure 18, the electric field relaxation region 1060 is composed of a p-type semiconductor, and n － A PN junction is formed between the semiconductor layer 1010a and the PG layer.

[0033] The means for forming each layer in Figure 18 are not particularly limited and may be known means, as long as they do not hinder the objective of the present invention. Examples include means of forming a film by vacuum deposition, CVD, sputtering, or various coating techniques, followed by patterning by photolithography, or means of directly patterning using printing technology.

[0034] (MESFET) Figure 19 shows an example of a metal-semiconductor field-effect transistor (MESFET) according to the present invention. The MESFET in Figure 19 is n － Semiconductor layer 111a, n ＋ The device comprises a semiconductor layer 111b, a buffer layer 118, a semi-insulating layer 114, a gate electrode 115a, a source electrode 115b, and a drain electrode 115c.

[0035] The materials for the gate electrode, drain electrode, and source electrode may be known electrode materials, and examples of such electrode materials include metals or alloys thereof such as Al, Mo, Co, Zr, Sn, Nb, Fe, Cr, Ta, Ti, Au, Pt, V, Mn, Ni, Cu, Hf, W, Ir, Zn, In, Pd, Nd, or Ag; metal oxide conductive films such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and zinc indium oxide (IZO); organic conductive compounds such as polyaniline, polythiophene, or polypyrrol; or mixtures thereof. The gate electrode, drain electrode, and source electrode can be formed by known means such as vacuum deposition or sputtering.

[0036] The semi-insulating layer 114 only needs to be composed of a semi-insulating material. Examples of such semi-insulating materials include those containing semi-insulating dopants such as magnesium (Mg), ruthenium (Ru), iron (Fe), beryllium (Be), cesium (Cs), strontium (Sr), and barium (Ba), as well as those that have not undergone doping treatment.

[0037] In the MESFET shown in Figure 19, a good depletion layer is formed beneath the gate electrode, allowing for efficient control of the current flowing from the drain electrode to the source electrode.

[0038] (SIT) FIG. 20 shows an example when the semiconductor device of the present invention is a SIT. The SIT in FIG. 20 includes an n － -type semiconductor layer 241a, n ＋ -type semiconductor layers 241b and 141c, a gate electrode 245a, a source electrode 245b, and a drain electrode 245c.

[0039] On the drain electrode 245c, for example, an n ＋ -type semiconductor layer 241b with a thickness of 100 nm to 100 μm is formed. On the n ＋ -type semiconductor layer 241b, for example, an n － -type semiconductor layer 241a with a thickness of 100 nm to 100 μm is formed. And further, on the n － -type semiconductor layer 241a, an n ＋ -type semiconductor layer 241c is formed. On the n ＋ -type semiconductor layer 241c, a source electrode 145b is formed.

[0040] Also, in the n － -type semiconductor layer 241a, a plurality of trench grooves with a depth that penetrates the n ＋ -type semiconductor layer 241c and reaches a depth in the middle of the n － -type semiconductor layer 241a are formed. On the n － -type semiconductor layer 241a in the trench grooves, a gate electrode 245a is formed.

[0041] In the on state of the SIT in FIG. 20, when a voltage is applied between the source electrode 245b and the drain electrode 245c and a positive voltage is applied to the gate electrode 245a with respect to the source electrode 245b, a channel layer is formed in the n － -type semiconductor layer 241a, and electrons are injected into the n － -type semiconductor layer 241a, and it turns on. The off state is achieved by setting the voltage of the gate electrode to 0 V, so that the channel layer cannot be formed, and the n － -type semiconductor layer is filled with a depletion layer and turns off.

[0042] FIG. 21 shows a part of the manufacturing process of the SIT in FIG. 20. For example, using a laminate as shown in FIG. 21(a), n －Semiconductor layer 241a and n ＋ An etching mask is provided in a predetermined region of the semiconductor layer 241c, and anisotropic etching is performed using the etching mask as a mask, for example by reactive ion etching, so that as shown in Figure 21(b), the n ＋ From the surface of the type semiconductor layer 241c, the n － A trench groove is formed to a depth that reaches partway through the semiconductor layer 241a. Then, a gate electrode material such as polysilicon is deposited into the trench groove using a method such as CVD, vacuum deposition, or sputtering. － It is formed to be less than or equal to the thickness of the type semiconductor layer 241a. Furthermore, using known means such as vacuum deposition, sputtering, and CVD, n ＋ A source electrode 245b is placed on the type semiconductor layer 241c, n ＋ A SIT can be manufactured by forming a drain electrode 245c on the semiconductor layer 241b. The electrode materials for the source electrode and the drain electrode may be known electrode materials, and examples of such electrode materials include metals or alloys thereof such as Al, Mo, Co, Zr, Sn, Nb, Fe, Cr, Ta, Ti, Au, Pt, V, Mn, Ni, Cu, Hf, W, Ir, Zn, In, Pd, Nd, or Ag; metal oxide conductive films such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and zinc indium oxide (IZO); organic conductive compounds such as polyaniline, polythiophene, or polypyrrol; or mixtures thereof.

[0043] The above example shows an example in which a p-type semiconductor is not used, but the present invention is not limited to this and may use a p-type semiconductor. The p-type semiconductor may be the same material as the n-type semiconductor and contain a p-type dopant, or it may be a different p-type semiconductor.

[0044] (Example 1) Figure 1 is a diagram showing an example of a preferred embodiment of the film-forming apparatus according to the present invention. The film-forming apparatus 19 consists of a film-forming sample 20, a sample stage 21, a carrier gas source 22a, a carrier gas source 22b, a flow rate control valve 23a, a flow rate control valve 23b, a film-forming chamber 27, a heater 28, and an atomizing device 30. The atomizing device 30 consists of a raw material partition 24, a raw material solution for atomization 24a, an ultrasonically transparent substrate 24b, a stage 24c, an ultrasonic transducer 26, a guide partition 31, an ultrasonic transmission liquid tank 35, and an ultrasonic transmission liquid 36. Figure 2 is a diagram showing an example of another preferred embodiment of the film-forming apparatus when the atomizing device according to the present invention is used as an atomizing stage for film formation. The atomizing device 30 consists of a raw material partition 24, a raw material solution for atomization 24a, an ultrasonically transparent substrate 24b, a stage 24c, an ultrasonic transducer 26, a guide partition 31, an ultrasonic transmission liquid tank 35, and an ultrasonic transmission liquid 36. The sample stage 21 is made of quartz, and the surface on which the film-forming sample 20 is placed is inclined from the horizontal plane. By making both the film-forming chamber 27 and the sample stage 21 out of quartz, the contamination of the crystalline film formed on the film-forming sample 20 with impurities originating from the apparatus is suppressed. The atomizing raw material solution 24a is contained within the raw material partition wall 24. The guide partition wall 31 is in contact with the ultrasonically transparent substrate 24b. Figure 24 is a schematic cross-sectional view of the atomizing apparatus used in the present invention, viewed from the side. The atomizing apparatus 30 in Figure 24 consists of a raw material partition wall 24, an ultrasonically transparent substrate 24b, a stage 24c, an ultrasonic transducer 26, a guide partition wall 31, and an ultrasonically transmitted liquid tank 35. Here, the ultrasonic transducer is surrounded by the guide partition wall up to the ultrasonically transparent substrate, and the guide partition wall 31 is in contact with the ultrasonically transmitted liquid tank 35. The ultrasonic waves emitted from the ultrasonic transducer 26 are transmitted more efficiently to the raw material partition 24 by using the guide partition 31.

[0045] The ultrasonic transducer is not particularly limited as long as it is an element capable of generating ultrasonic vibrations and can irradiate the bottom surface of the raw material partition with ultrasonic waves; it may be a known ultrasonic transducer. The frequency of the ultrasonic transducer is not particularly limited as long as it does not hinder the objectives of the present invention, but is preferably 2.4 MHz or higher, and more preferably 3.0 MHz or higher. For example, an ultrasonic transducer can be provided in which electrodes are provided on both sides of a disc-shaped piezoelectric element, and when an oscillator is connected to the electrodes and the oscillation frequency is changed, ultrasonic waves having a resonance frequency in the thickness direction and a resonance frequency in the radial direction of the piezoelectric transducer are generated. Within such a preferred range, the particle size of the mist generated by atomization can be made smaller, and the atomization efficiency can be made better.

[0046] The raw material partition in the present invention is not particularly limited as long as it is capable of containing the atomizing raw material. In the present invention, it is preferable that the raw material partition is bottomless, and that the bottom surface of the raw material partition is closed by the ultrasonic transparent substrate so that the raw material partition and the ultrasonic transmission liquid tank are fitted or screwed together via an ultrasonic transparent substrate, thereby enabling the raw material partition to contain the atomizing raw material liquid. For example, if the ultrasonic transparent substrate is a polymer film, the polymer film is sandwiched so that the bottom surface of the raw material partition is closed by the ultrasonic transparent substrate, and this closure enables the raw material partition to contain the atomizing raw material liquid. The means for fitting or screwing the raw material partition and the ultrasonic transmission liquid tank are not particularly limited as long as they do not hinder the objective of the present invention, and may be known means. Examples of fitting means include providing recesses, protrusions, or uneven surfaces in the raw material partition and providing corresponding fitting parts in the ultrasonic transmission fluid tank, or providing recesses, protrusions, or uneven surfaces in the ultrasonic transmission fluid tank and providing corresponding fitting parts in the raw material partition. Examples of screwing means include providing a male screw portion in the raw material partition and a female screw portion in the ultrasonic transmission fluid tank, or providing a male screw portion in the ultrasonic transmission fluid tank and a female screw portion in the raw material partition. In the present invention, known members may be used to fit and screw the raw material partition and the ultrasonic transmission fluid tank. It is preferable that the raw material partition and the ultrasonic transmission fluid tank have substantially the same cross-sectional shape and substantially the same cross-sectional area, in order to use the ultrasonically transparent substrate more effectively.

[0047] Furthermore, in the present invention, it is preferable that the raw material partition is a lidded cylindrical body having a lid. The shape of the lid is not particularly limited as long as it can serve as a lid for the raw material partition, but it is preferable that the lid is capable of sealing the space inside the raw material partition, as this further improves atomization efficiency and mist controllability. The constituent material of the lid is also not particularly limited and may be the same material as the raw material partition or a different material. It may be a known material, an inorganic material or an organic material. In the present invention, it is preferable that the constituent material of the lid mainly contains glass, quartz, and a fluororesin, and more preferably mainly contains a fluororesin. Examples of fluororesins include polytetrafluoroethylene, modified polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, or ethylene-tetrafluoroethylene copolymer.

[0048] In the present invention, as described above, it is preferable that the raw material partition is a lidded cylindrical body. When the raw material partition has a lid, the inside of the raw material partition can be sealed, and the atomizing raw material can be replenished using the space pressure. More specifically, when the liquid level of the atomizing raw material drops due to atomization, the space pressure inside the raw material partition rises, causing the liquid level to reach the end of the pipe. The space inside the raw material partition and the space inside the replenishment container, which stores the replenishment atomizing raw material, are in communication via the pipe, and the gas inside the space inside the raw material partition can be extracted into the space inside the replenishment container via the pipe, while the atomizing raw material inside the replenishment container can be replenished into the raw material partition. Having such a replenishment means is also one of the preferred embodiments of the present invention.

[0049] The atomizing raw material is not particularly limited as long as it can be atomized, and may be a known atomizing raw material liquid, including a liquid dispersion medium such as a sol. It may be a raw material liquid containing an organic compound, or a raw material liquid containing an inorganic compound. In the present invention, it is preferable that the atomizing raw material liquid is a raw material liquid for film formation, and more preferably that it contains a metal. Examples of the metal include gold (Au), silver (Ag), platinum (Pt), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), palladium (Pd), cobalt (Co), rhodium (Rh), ruthenium (Ru), chromium (Cr), molybdenum (Mo), gallium (Ga), indium (In), vanadium (V), germanium (Ge), titanium (Ti), tin (Sn), zirconia (Zr), vanadium (V), yttrium (Y), zinc (Zn), magnesium (Mg), and zinc (Scan). Examples include one or more metals selected from zinc (Sc), hafnium (Hf), antimony (Sb), bismuth (Bi), tantalum (Ta), iridium (Ir), tungsten (W), niobium (Nb), lanthanum (La), cerium (Ce), and aluminum (Al). Preferably, one or more metals selected from gallium, germanium, titanium, tin, niobium, vanadium, antimony, bismuth, tantalum, aluminum, and indium are used. In the present invention, it is preferable that the atomizing raw material liquid is a film-forming raw material liquid, and more preferably a mist CVD raw material liquid, as it can exhibit an excellent film-forming effect. Furthermore, the atomizing raw material liquid may be one type or two or more types. For example, when two or more types of raw material liquids are used, at least one type may be a raw material liquid containing an inorganic compound, and the other types may be raw material liquids containing organic compounds.

[0050] The ultrasonic transmission fluid tank in the present invention is not particularly limited as long as it can contain the ultrasonic transmission fluid. The shape of the ultrasonic transmission fluid tank is also not particularly limited, but in the present invention, it is preferably cylindrical or substantially cylindrical or polygonal tubular or substantially polygonal tubular, more preferably cylindrical or substantially cylindrical, and most preferably cylindrical. The constituent material of the ultrasonic transmission fluid tank is also not particularly limited and may be an inorganic material or an organic material, but in the present invention, it is preferably that the constituent material of the ultrasonic transmission fluid tank mainly consists of glass, quartz, or fluororesin, and more preferably mainly consists of fluororesin. The ultrasonic transmission fluid is not particularly limited as long as it is a liquid capable of transmitting ultrasound, and may include liquid dispersion media such as sols. Examples of the ultrasonic transmission fluid include inorganic solvents and organic solvents, but in the present invention, it is preferably an inorganic solvent, and more preferably water. More specifically, the aforementioned water includes, for example, pure water, ultrapure water, tap water, well water, mineral water, hot spring water, spring water, freshwater, and seawater. Examples of water that have been treated, such as by purification, heating, sterilization, filtration, ion exchange, electrolysis, osmotic pressure adjustment, or buffering (for example, ozonated water, purified water, hot water, ion-exchanged water, physiological saline, phosphate buffer, phosphate-buffered physiological saline, etc.), are also included. In the present invention, it is preferable to seal the inside of the ultrasonic transmission liquid tank, and by forming a sealed space, atomization efficiency and mist controllability can be improved.

[0051] The ultrasonically transparent substrate is not particularly limited as long as it does not hinder the objective of the present invention, and may be a known ultrasonically transparent substrate. Examples of the ultrasonically transparent substrate include polymer films. Examples of constituent materials for the ultrasonically transparent substrate include thermoplastic resins and thermosetting resins, but in the present invention, thermoplastic resins are preferred. Examples of the thermoplastic resin include polyolefins and fluororesins, but it is preferable that it mainly contains a fluororesin. Examples of the polyolefin include polyethylene and polypropylene. Examples of the fluororesin include polytetrafluoroethylene, modified polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, or ethylene-tetrafluoroethylene copolymer. In the present invention, it is preferable that the fluororesin is at least one selected from polytetrafluoroethylene, modified polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and ethylene-tetrafluoroethylene copolymer. According to this preferred range, ultrasonic waves can be efficiently transmitted to the atomizing raw material, and the amount of atomization can be increased.

[0052] The constituent material of the guide partition is not particularly limited as long as it does not hinder the objective of the present invention, and examples include metals and polymers. Examples of polymers include natural resins, thermoplastic resins, and thermosetting resins. The surface of the guide partition may also be coated with metal. Examples of metals include Al, Cu, Ag, Ti, W, Mo, Fe, Ni, Cr, Zn, Sn, Rh, Pt, and Au. According to this preferred range, ultrasonic vibrations can be transmitted more efficiently and effectively. The shape of the guide partition is not particularly limited as long as it does not hinder the objective of the present invention, but according to this embodiment, it is preferably cylindrical or substantially cylindrical or polygonal cylindrical or substantially polygonal cylindrical, and it is also preferably frustoconical, more preferably frustoconical or substantially cylindrical, and most preferably frustoconical. Furthermore, the guide partition is not particularly restricted as long as it does not hinder the objective of the present invention, and it is preferably penetrating. According to this preferred range, ultrasonic waves irradiated from the ultrasonic transducer can be transmitted more efficiently and effectively to the ultrasonically transmitted substrate. The guide partition is not particularly limited as long as it does not hinder the objective of the present invention, and may be configured to be detachable or installed on the ultrasonic radiation surface, but in the present invention, it is preferred that it be configured to be detachable. According to this preferred range, the atomizing apparatus of the present invention can be cleaned more easily.

[0053] When preparing the atomizing raw material solution, 2.093 g of germanium dioxide powder having a hexagonal crystal structure at a concentration of 0.02 mol / L was dissolved in ultrapure water, and during the preparation, 20% by volume of hydrochloric acid was added to adjust the solution to become an aqueous germanium dioxide solution. This was used as the atomizing raw material solution.

[0054] Next, as the film-forming sample 20, a rutile-type crystalline structure TiO2 with sides of 15 mm and an average thickness of 500 μm is used. ２(001) The substrate was placed on the sample stage 21, and the heater 28 was activated to raise the temperature inside the deposition chamber 27 to 700°C. Next, the flow control valve 23 was opened to supply carrier gas from the carrier gas source 22 into the deposition chamber 27, and after the atmosphere inside the deposition chamber 27 had been sufficiently replaced with carrier gas, the flow rate of the carrier gas was adjusted to 1 L / min. Nitrogen gas was used as the carrier gas. Note that the above-mentioned GeO having a rutile-type crystal structure ２ TiO with a rutile-type crystalline structure with a crystalline film ２ (001) The substrate is prepared by adding 0.02 mol / L of bis[2-carboxyethylgermanium(IV)]sesquioxide (C) to the atomizing raw material solution instead of the germanium dioxide aqueous solution. ６ H １０ Ge ２ O ７ Except for using an atomizing raw material solution containing 20% ​​hydrochloric acid by volume in an aqueous solution of ) a rutile-type crystalline TiO ２ (001) GeO having a rutile-type crystal structure on a substrate ２ It was obtained by forming a crystalline film.

[0055] Next, the ultrasonic transducer 26 was vibrated at 3.0 MHz, and the vibration was transmitted to the atomizing raw material solution 24a through the ultrasonic transmitter 25a, thereby atomizing the raw material solution 24a into fine particles and generating raw material fine particles. These raw material fine particles were introduced into the deposition chamber 27 by a carrier gas, and reacted in the deposition chamber 27, resulting in a CVD reaction on the deposition surface of the sample 20 to deposit tetragonal GeO2 on the sample 20. ２ A crystalline film was formed. The film thickness was 900 nm.

[0056] The obtained GeO ２ The crystalline film was measured using an X-ray diffractometer. Figure 3 shows the 2θ / ω result in the XRD diffraction. The XRD diffraction results are shown. As is clear from Figure 3, the obtained crystalline film has a (002) oriented tetragonal rutile structure. ２ It was a single-crystal film. Figure 4 shows the results of the ω scan in the X-ray diffraction measurement. From Figure 4, r-GeO ２The full width at half maximum of the rocking curve at the 002 diffraction peak was 474 arcsec. These results suggest that TiO has a rutile-type crystal structure. ２ (001) GeO having good crystallinity on a substrate ２ A crystalline film had formed.

[0057] Furthermore, the obtained GeO ２ When the surface of the crystalline film was observed using an atomic force microscope (AFM), as shown in Figure 5, the surface roughness (RMS) according to JIS B0601 was 24.5 nm, indicating superior surface smoothness.

[0058] Furthermore, the obtained GeO ２ The surface of the crystalline film was observed using a scanning electron microscope (SEM). Figure 6 shows the SEM image. As is clear from Figure 6, the GeO has excellent surface smoothness and good crystallinity. ２ Crystals were formed. Furthermore, when the surface of the obtained crystalline film was evaluated using EDS, as shown in Figure 7, a crystalline film of 100 mm was found covering the entire surface. ２ It was found that the formation extended over the above-mentioned area.

[0059] Furthermore, the obtained GeO ２ The carbon concentration in the single crystal film was confirmed by SIMS measurement to be 1 × 10⁻⁶ １８ cm －３ The following conditions were observed. Within such a favorable range, a single-crystal film with superior crystallinity can be obtained.

[0060] (Example 2) GeO contained in the atomizing raw material solution ２ Antimony chloride (SbCl) is prepared so that the molar ratio of germanium dioxide contained in the aqueous solution is 0.5 mol%. ３ The film was prepared in the same manner as in Example 1, except that the ) was added. The obtained crystalline film was measured using an X-ray diffractometer. Figure 8 shows the 2θ / ω result in the XRD diffraction. As is clear from Figure 8, the obtained crystalline film has a (002) oriented tetragonal rutile structure. ２ It was a single crystal film. From Figure 9, r-GeO ２The full width at half maximum of the rocking curve at the (002) diffraction peak was 433 arcsec. TiO having a rutile-type crystal structure ２ (001) GeO having good crystallinity on a substrate ２ A crystalline film had been formed. The film thickness was 190 nm.

[0061] The electrical properties of the obtained film were evaluated by measuring the Hall effect using the van der pauw method. The measurement environment was room temperature with an applied magnetic field frequency of 50 mHz. As a result, the carrier density was 1.46 × 10⁻¹⁶. ２０ (1 / cm ３ ) and the mobility is 21 (cm ２ The value was / V・s). Also, the sheet resistance was 1.08 × 10 ２ The ratio was (Ω / □). The electrical resistivity was 2.06 × 10⁻⁶. ―３ The coefficient was Ωcm. The carrier type was "n". These results indicate that the obtained crystalline film possesses superior electrical properties.

[0062] An ohmic electrode was formed on the obtained crystal film using indium, as shown in Figure 22, and an ohmic measurement was performed. The results are shown in Figure 23. As is clear from Figure 23, it was found to have excellent ohmic properties.

[0063] Furthermore, the obtained GeO ２ The carbon concentration in the single crystal film was confirmed by SIMS measurement to be 1 × 10⁻⁶ １８ cm －３ The results were as follows:

[0064] (Example 3) Film deposition was carried out in the same manner as in Example 2, except that the carrier gas was changed to oxygen gas. The obtained crystalline film was measured using an X-ray diffractometer. Figure 10 shows the 2θ / ω result in the XRD diffraction. As is clear from Figure 10, the obtained crystalline film has a (002) oriented tetragonal rutile structure. ２ It was a single crystal film. From Figure 11, r-GeO ２ The full width at half maximum of the rocking curve at the 002 diffraction peak was 690 arcsec. TiO with a rutile-type crystal structure２ (001) GeO having good crystallinity on a substrate ２ A crystalline film had been formed. The film thickness was 80 nm.

[0065] The electrical properties of the obtained film were evaluated by measuring the Hall effect using the van der pauw method. The measurement environment was room temperature with an applied magnetic field frequency of 50 mHz. As a result, the carrier density was 1.12 × 10⁻¹⁶. １９ (1 / cm ３ ) and the mobility is 19 (cm ２ The value was / V・s). Also, the sheet resistance was 3.75 × 10 ３ The ratio was (Ω / □). The electrical resistivity was 3.00 × 10⁻⁶. ―２ The coefficient was Ωcm. The carrier type was "n". These results indicate that the obtained crystalline film possesses superior electrical properties.

[0066] An ohmic electrode was formed on the obtained crystal film using indium, as shown in Figure 26, and an ohmic measurement was performed. The results are shown in Figure 27. As is clear from Figure 27, it was found to have excellent ohmic properties.

[0067] Furthermore, the obtained GeO ２ The carbon concentration in the single crystal film was confirmed by SIMS measurement to be 1 × 10⁻⁶ １８ cm －３ The results were as follows:

[0068] (Comparative Example 1) Atomizing raw material solution is bis[2-carboxyethylgermanium(IV)]sesquioxide (C ６ H １０ Ge ２ O ７ A atomizing raw material solution is prepared by adding 20% ​​by volume of hydrochloric acid to a 0.02 mol / L aqueous solution of bis[2-carboxyethylgermanium(IV)]sesquioxide, and antimony chloride (SbCl) is added to the atomizing raw material solution so that the molar ratio is 3.0 mol% relative to the molar concentration of bis[2-carboxyethylgermanium(IV)]sesquioxide in the atomizing raw material solution. ３The film was prepared in the same manner as in Example 1, except that a ) was added. The electrical properties of the obtained film were evaluated by the van der pauw method, and the Hall effect was measured. The measurement environment was room temperature with an applied magnetic field frequency of 50 mHz. As a result, the carrier density was 1.12 × 10⁻¹⁶. ２０ (1 / cm ３ ) and the mobility is 6 (cm ２ The value was / V・s). Also, the sheet resistance was 2.88 × 10 ３ The ratio was (Ω / □). The electrical resistivity was 5.76 × 10⁻⁶. ―３ The value was Ωcm. The carrier type was "n".

[0069] GeO obtained from Comparative Example 1 ２ The carbon concentration in the crystalline film was confirmed by SIMS measurement to be 1 × 10⁻⁶ １９ / cm ３ That was all.

[0070] A comparison of Example 2 and Comparative Example 1 revealed that Example 2 exhibited improved mobility, lower electrical resistivity, and superior electrical characteristics.

[0071] (Test Example 1) As a comparative example, the atomizing raw material solution was prepared as bis[2-carboxyethylgermanium(IV)]sesquioxide (C ６ H １０ Ge ２ O ７ The atomizing raw material solution was prepared by adding 20% ​​hydrochloric acid by volume to a 0.02 mol / L aqueous solution of TiO2 (hereinafter referred to as Solution A), in the same manner as in Example 1. ２ (001) GeO ２ A crystalline film was fabricated. The film thickness was 440 nm. Also, as a comparative example, GeO ２ After fabricating the crystalline film, the fabricated GeO ２ Using the atomizing raw material solution used in Example 1 (hereinafter referred to as Solution B) on a crystalline film, GeO was used as an example. ２ A crystalline film was prepared. The preparation conditions were the same as in Example 1. ２ The thickness of the crystalline film was 660 nm. Subsequently, SIMS measurement was performed, and the carbon content in the crystalline film prepared with solution B was 3.57 × 10⁻⁶.１７ The concentration was atoms / cc. Furthermore, the carbon content in the crystalline film prepared with solution A was 6.55 × 10⁻⁶. １９ The result was atoms / cc. The SIMS measurement results are shown in Figure 25. From these results, it can be concluded that using a germanium dioxide aqueous solution will produce GeO ２ We were able to obtain a crystalline film in which the carbon content in the crystalline film was reduced.

[0072] The single-crystal film and multilayer structure of the present invention are suitably used, for example, in semiconductor devices.

[0073] 19 Film-forming apparatus 20 Sample to be film-formed 21 Sample stage 22a Carrier gas source 22b Dilution gas source 23a Flow control valve 23b Flow control valve 24 Raw material partition 24a Atomization raw material solution 24b Ultrasonic transmission substrate 24c Stand 26 Ultrasonic transducer 27 Film-forming chamber 28 Heater 30 Atomization apparatus 31 Guide partition 33 Dilution gas supply pipe 34 Carrier gas supply pipe 35 Ultrasonic transmission liquid tank 36 Ultrasonic transmission liquid 37 Film-forming chamber 101a n － Semiconductor layer 101b n ＋ 102 p-type semiconductor layer 103 metal layer 104 insulator layer 105a Schottky electrode 105b ohmic electrode 111a n － Semiconductor layer 111b n ＋ n-type semiconductor layer 114 Semi-insulating layer 115a Token electrode 115b Source electrode 115c Drain electrode 118 Buffer layer 121a Wide bandgap n-type semiconductor layer 121b Narrow bandgap n-type semiconductor layer 121c n ＋ P-type semiconductor layer 123 p-type semiconductor layer 124 semi-insulating layer 125a gate electrode 125b source electrode 125c drain electrode 128 buffer layer 129 substrate 131a n － Semiconductor layer 131b First n ＋ Semiconductor layer 131c Second n ＋P-type semiconductor layer 132 p-type semiconductor layer 134 gate insulating film 135a gate electrode 135b source electrode 135c drain electrode 138 buffer layer 139 semi-insulating layer 141a n － Semiconductor layer 141b First n ＋ Semiconductor layer 141c Second n ＋ p-type semiconductor layer 142 p-type semiconductor layer 145a gate electrode 145b source electrode 145c drain electrode 151 n-type semiconductor layer 151a n － Semiconductor layer 151b n ＋ 152 p-type semiconductor layer 154 gate insulating film 155a gate electrode 155b emitter electrode 155c collector electrode 161 n-type semiconductor layer 162 p-type semiconductor layer 163 light-emitting layer 165a first electrode 165b second electrode 167 light-transmitting electrode 169 substrate 1010a n － Semiconductor type 1010b n ＋ Semiconductor 1020 Ohmic electrode 1030 Schottky electrode 1030a Metal layer 1030b Metal layer 1030c Metal layer 1060 Electrolytic relaxation region

Claims

1. A single crystal film mainly composed of a metal oxide containing germanium, wherein the carbon concentration in part or all of the film is 1 × 10⁻¹⁶ １８ cm －３ A single crystal film characterized by the following:

2. The single crystal film according to claim 1, wherein the metal oxide has a rutile structure.

3. The single crystal film according to claim 1, wherein the film thickness is 500 nm or more.

4. The single crystal film according to claim 1, wherein the full width at half maximum of the rocking curve measured by X-ray diffraction in the oriented crystal axis direction is 600 arcsec or less.

5. The single crystal film according to claim 1, comprising a dopant.

6. Carrier density is 1 × 10⁻⁶ ２２ cm －３ The single crystal film according to claim 1, wherein the following applies:

7. The single crystal film according to claim 1, wherein the electrical resistivity is 0.03 Ωcm or less.

8. Mobility is 15 cm ２ A single crystal film according to claim 1, wherein the saturation is ≥ / V·s.

9. The single crystal film according to claim 1, wherein the sheet resistance is 300 Ω / □ or less.

10. Area is 100 mm² ２ The single crystal film according to claim 1, as described above.

11. The single crystal film according to claim 1, wherein the surface roughness is 25 nm or less.

12. A laminated structure in which single crystal films mainly composed of a metal oxide containing germanium are laminated on a crystalline substrate directly or via other layers, wherein the carbon concentration in part or all of the single crystal films is 1 × 10⁻¹⁶ １８ cm －３ A laminated structure characterized by the following:

13. The laminated structure according to claim 12, wherein the crystalline substrate has a rutile-type crystalline structure.

14. The laminated structure according to claim 12, wherein the single crystal film has a rutile-type crystal structure.

15. The laminated structure according to claim 12, wherein the area of the single crystal film is 100 mm ２ or more.

16. The laminated structure according to claim 12, wherein the thickness of the single crystal film is 500 nm or more.

17. A semiconductor device comprising a single crystal film or a multilayer structure, wherein the single crystal film is the single crystal film described in claim 1, and the multilayer structure is the multilayer structure described in claim 12.

18. The semiconductor device according to claim 17, wherein the single crystal film or the single crystal film of the stacked structure is bonded to an ohmic electrode to form an ohmic contact.

19. The semiconductor device according to claim 17, wherein the ohmic electrode comprises one or more metal elements selected from the d-block and / or p-block metal elements of the periodic table.

20. The semiconductor device according to claim 17, which is a power device.

21. The semiconductor device according to claim 17, which is a Schottky barrier diode (SBD), a junction barrier Schottky diode (JBS), a metal-semiconductor field-effect transistor (MESFET), an electrostatic induction transistor (SIT), a high electron mobility transistor (HEMT), a metal-oxide-semiconductor field-effect transistor (MOSFET), a junction field-effect transistor (JFET), an insulated gate bipolar transistor (IGBT), or a light-emitting diode (LED).

22. Electronic equipment including a semiconductor device, characterized in that the semiconductor device is the semiconductor device described in claim 17.

23. A system including an electronic device, characterized in that the electronic device is the electronic device described in claim 22.

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