Semiconductor device, electronic apparatus, and system

Abstract

[Problem] To provide a semiconductor device, an electronic apparatus, and a system having excellent electric characteristics useful for a power device or the like. [Solution] This semiconductor device has a laminated structure that includes a first semiconductor layer composed of a crystalline oxide containing germanium or a mixed crystal thereof as a main component, and a second semiconductor layer laminated on the first semiconductor layer directly or via another layer, the second semiconductor layer having the same crystal structure as the first semiconductor layer. The second semiconductor layer is an n- layer having a carrier concentration of 1×1018cm-3 or less, and the first semiconductor layer is an n+ layer having a carrier concentration of 5×1018cm-3 or more. The semiconductor device is applied to, for example, a power device or the like.

Description

Semiconductor Device, Electronic Apparatus, and System

[0001] The present invention relates to a semiconductor device useful for power devices and the like.

[0002] In recent years, rutile-structured germanium dioxide (r-GeO ２ ) has attracted attention as a wide-bandgap (UWBG) semiconductor promising for future power electronics devices. r-GeO ２ has a bandgap of 4.68 eV, can realize n-type and p-type semiconductors, and can be manufactured at 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. In addition, in Non-Patent Document 3, tin dioxide (r-SnO ２ ) that 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 it was difficult to control the composition of Ge and Sn. In addition, in Non-Patent Document 4, tin dioxide that is easy to crystallize and r-GeO ２ are mixed to form r-(Ge,Sn)O２ We are fabricating alloy thin films and creating prototype Schottky barrier diodes (SBDs). However, r-(Ge,Sn)O ２ In SBDs using alloy thin films, controlling the composition is difficult, controlling the electrical properties is difficult, and problems such as impaired semiconductor properties have occurred, making it difficult to realize industrially useful semiconductor devices. Therefore, industrially useful r-GeO ２ A strategy to obtain semiconductor devices using single-crystal films was eagerly 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). H. Takane, et al. , “Rutile-type Gex Sn1-x O2 alloy layers latticed to TiO2 substrates for device applications”, Applied Physics Express 17, 011008 (2024).

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

[0006] This invention provides GeO with excellent useful electrical properties. ２ The objective is to provide semiconductor devices.

[0007] As a result of diligent research to achieve the above objective, the present inventors have newly developed a mist CVD apparatus using a guide partition, and have used the mist CVD apparatus using the guide partition to construct a laminated structure in which a second semiconductor layer having the same crystal structure as the first semiconductor layer is laminated directly or via another layer on a first semiconductor layer made of a crystalline oxide mainly composed of germanium or a mixed crystal thereof, wherein the second semiconductor layer has a carrier concentration of 1 × 10 １８ cm －３ The following n － The first semiconductor layer has a carrier concentration of 5 × 10 １８ cm －３ n above ＋ By fabricating a layered structure, it is possible to form a semiconductor layer with excellent crystallinity across the entire surface of a 15 mm square substrate. Furthermore, it was discovered that semiconductor devices using the obtained layered structure exhibit excellent electrical properties, and that such semiconductor devices can solve the aforementioned conventional problems all at once. 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 semiconductor device comprising a laminated structure in which a second semiconductor layer having the same crystal structure as the first semiconductor layer is laminated directly or via another layer on a first semiconductor layer made of a crystalline oxide mainly composed of germanium or a mixed crystal thereof, wherein the second semiconductor layer has a carrier concentration of 1 × 10 １８ cm －３ The following n － The first semiconductor layer has a carrier concentration of 5 × 10 １８ cm －３ n above ＋ A semiconductor device characterized by being a layer. [2] The first semiconductor layer has a carrier concentration of 1 × 10１９ cm －３ n above ＋ [1] The semiconductor device described above, wherein the semiconductor layer is a layer. [3] The semiconductor device described above, wherein the second semiconductor layer is made of a crystalline oxide mainly composed of germanium or a mixed crystal thereof. [4] The semiconductor device described above, wherein the first semiconductor layer has a rutile-type structure. [5] The area of ​​the first semiconductor layer is 100 mm². ２ [1] The semiconductor device described above. [6] The semiconductor device described above, wherein the thickness of the first semiconductor layer is 500 nm or more. [7] The semiconductor device described above, wherein the thickness of the second semiconductor layer is 1.0 μm or more. [8] The semiconductor device described above, wherein the crystalline oxide mainly consists of germanium dioxide. [9] The semiconductor device described above, wherein an ohmic electrode is ohmic bonded with the first semiconductor layer.

[10] The semiconductor device described above, wherein the ohmic electrode contains one or two metal elements selected from groups 4 to 13 of the periodic table.

[11] The semiconductor device described above, wherein a Schottky electrode is Schottky bonded with the second semiconductor layer.

[12] The semiconductor device described above, wherein the Schottky electrode contains one or two metal elements selected from groups 4 to 13 of the periodic table.

[13] The semiconductor device described above, wherein it is a power device.

[14] The semiconductor device described above, wherein it is a Schottky barrier diode (SBD).

[15] Electronic equipment including a semiconductor device, characterized in that the semiconductor device is the semiconductor device described in [1].

[16] System including electronic equipment, characterized in that the electronic equipment is the electronic equipment described in

[15] .

[0009] The semiconductor device of the present invention is useful for power devices and the like, and exhibits excellent electrical characteristics.

[0010] This is an example of a schematic diagram of a film-forming apparatus preferably used in the present invention. This is a schematic diagram showing an atomizing apparatus preferably used in the present invention. Example 1, part 1. n ＋This figure shows the 2θ / ω result in the XRD diffraction result due to the formation of a type semiconductor layer. This figure shows the ω scan result in the rocking curve measurement of XRD diffraction in Example 1. This figure schematically shows a preferred example of the Schottky barrier diode (SBD) of the present invention. This figure schematically shows a preferred example of the Schottky barrier diode (SBD) of the present invention. This is a schematic cross-sectional view showing a preferred example of the Schottky barrier diode (SBD) in Example 1. This figure shows a surface image of a sample in Example 1 in which electrodes have been formed on a crystal film. 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 the IV measurement in Example 1, with the vertical axis being current (A) and the horizontal axis being voltage (V). This table shows the relationship between carrier concentration and depth derived from the CV measurement results in Example 1, with the vertical axis being carrier concentration and the horizontal axis being depth. Example 1, 2. n － This figure shows the 2θ / ω result in the XRD diffraction result due to the formation of a type semiconductor layer. This figure shows the result of IV measurement of the ohmic characteristics of the SBD having a pseudo-vertical structure obtained from Example 1. This figure shows the result of TLM measurement of the SBD having a pseudo-vertical structure obtained from Example 1. This figure shows the result of secondary ion mass spectrometry (SIMS) of the SBD having a pseudo-vertical structure obtained from Example 1. This figure schematically shows a preferred example of the metal semiconductor field-effect transistor (MESFET) of the present invention. This figure schematically shows a preferred example of a power supply system. This figure schematically shows a preferred example of a system device. This figure schematically shows a preferred example of a power supply circuit diagram of a power supply device.

[0011] The semiconductor device of the present invention includes a laminated structure in which a second semiconductor layer having the same crystal structure as the first semiconductor layer is laminated directly or via another layer on a first semiconductor layer made of a crystalline oxide mainly composed of germanium or a mixed crystal thereof, wherein the second semiconductor layer has a carrier concentration of 1 × 10 １８ cm －３ The following n － The first semiconductor layer has a carrier concentration of 5 × 10 １８ cm －３ n above ＋It is characterized by being a layer. Furthermore, the first semiconductor layer has a carrier concentration of 5 × 10 １８ cm －３ n above ＋ Preferably, the first semiconductor layer has a carrier concentration of 1 × 10 １９ cm －３ n above ＋ It is more preferable that the layer is a layer. According to this preferred range, electrical properties such as better ohmic properties can be improved. In this specification, "layer" can be read as "film". 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.

[0012] In the present invention, the area of ​​the first semiconductor layer is 100 mm². ２ It is more preferable that the above conditions are met. Furthermore, it is preferable that the crystalline oxide film is a single crystal film. Within these preferred ranges, the breakdown voltage of the crystalline film can be improved, and superior electrical properties can be obtained.

[0013] In the present invention, the carrier density of the second semiconductor layer is 1 × 10⁻⁶ １８ cm －３ Preferably the following: Also, the carrier concentration of the first semiconductor layer is 5 × 10 １８ cm －３ Preferably, it is 1 × 10 １９ cm －３ It is more preferable that the range is greater than or equal to the above. According to such a preferred range, semiconductor properties can be made better, and better electrical properties can be obtained.

[0014] The second semiconductor layer is preferably made of a crystalline oxide mainly composed of germanium or a mixed crystal thereof. For example, the mixed crystal is SnO ２ , TiO ２ , VO ２ , MnO ２ RuO ２ , CsO ２ IrO ２ , GeO２ CuO ２ , PbO ２ AgO ２ ,CrO ２ SiO ２ Examples of mixed crystals include those with the following characteristics.

[0015] In the present invention, "main component" means that the content of a crystalline oxide containing germanium or a mixed crystal thereof in the semiconductor layer is 50 at% or more in terms of the composition ratio of the semiconductor layer. In embodiments of the present invention, it is preferable that the content of the crystalline oxide film in the semiconductor layer is 70 at% or more in terms of the composition ratio of the semiconductor film, and more preferably 90 at% or more. Furthermore, it is preferable that the crystalline oxide contains germanium dioxide as the main component. The content of germanium dioxide in the crystalline oxide film means that it is 50 at% or more in terms of the composition ratio of the crystalline oxide film layer. In embodiments of the present invention, it is preferable that the content of germanium dioxide in the crystalline oxide is 70 at% or more in terms of the composition ratio of the crystalline oxide film, and more preferably 90 at% or more. According to such preferred ranges, the interface becomes better, the electrical properties can be made better, and the semiconductor properties can also be made better. Furthermore, the crystalline oxide may contain other metals other than germanium dioxide. Examples of the 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 germanium dioxide in the crystalline oxide is 0.5 or higher. Furthermore, the crystal structure of germanium dioxide is not particularly limited; it 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] Furthermore, the crystal structure of the first semiconductor layer is not particularly limited as long as it does not hinder the objectives of the present invention. It 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, it is preferable to have a rutile-type structure which is tetragonal. Within this preferred range, semiconductor properties can be improved.

[0017] The preferred laminated structure described above allows for easier doping control, for example, by using the film deposition apparatus shown in Figure 1. In the present invention, the area of ​​the semiconductor layer is 100 mm². ２ It is more preferable that the semiconductor layer has the above area. Furthermore, it is preferable that the semiconductor layer is a single crystal film. According to these preferred ranges, the semiconductor layer can have better breakdown voltage and superior electrical properties can be obtained. Furthermore, the thickness of the semiconductor layer is not particularly limited as long as it does not hinder the objective of the present invention, but in the present invention, it is preferable that the semiconductor layer is 500 nm or more, and the second semiconductor layer is 1.0 μm or more. By having such preferred thicknesses or areas, 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.

[0018] In the present invention, the semiconductor layer preferably contains a dopant, and the dopant is not particularly limited as long as it does not hinder the objectives of the present invention, but examples include elements of Group 15 of the periodic table or elements of Group 13 of the periodic table. In the present invention, it is preferable that the dopant contains elements of Group 15 of the periodic table. Examples of Group 15 elements of the periodic table include nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi). Examples of Group 13 elements of the periodic table include boron (B), aluminum (Al), gallium (Ga), and indium (In). According to such a preferred range, better electrical properties can be obtained and the material can be manufactured more easily.

[0019] Furthermore, the ohmic electrode is not particularly limited as long as it contains one or two metal elements selected from groups 4 to 13 of the periodic table, and may be a single metal layer or may contain two or more metal layers. The means for laminating the metal layers is not particularly limited and includes known methods such as vacuum deposition and sputtering. The metal constituting the ohmic electrode may also be an alloy. Preferably, the ohmic electrode contains one or two metal elements selected from groups 4 to 13 of the periodic table. Examples of one or more metallic elements belonging to any of Groups 4 through 13 of the periodic table include metallic elements of Group 4, Group 5, Group 6, Group 7, Group 8, Group 9, Group 10, Group 11, Group 12, Group 13, and alloys thereof. Examples of the metal elements belonging to any of Groups 4 to 13 of the periodic table include metal elements of Group 4, Group 5, Group 6, Group 7, Group 8, Group 9, Group 10, Group 11, Group 12, Group 13, and alloys thereof. Examples of the metals of Group 4 include titanium (Ti), zirconium (Zr), hafnium (Hf), and alloys thereof, but in the present invention, it is preferable to include titanium. Examples of the metals of Group 5 include vanadium (V), niobium (Nb), tantalum (Ta), and alloys thereof. Examples of metals in Group 6 of the periodic table include chromium (Cr), molybdenum (Mo), tungsten (W), and alloys thereof. Examples of metals in Group 7 of the periodic table include manganese (Mn), technetium (Tc), rhenium (Re), and alloys thereof. Examples of metals in Group 8 of the periodic table include iron (Fe), ruthenium (Ru), osmium (Os), and alloys thereof.Examples of metals in Group 9 of the periodic table include cobalt (Co), rhodium (Rh), iridium (Ir), and alloys thereof. Examples of metals in Group 10 of the periodic table include nickel (Ni), palladium (Pd), platinum (Pt), and alloys thereof. Examples of metals in Group 11 of the periodic table include copper (Cu), silver (Ag), gold (Au), and alloys thereof, but in the present invention, it is preferable to include gold (Au). Examples of metals in Group 12 of the periodic table include zinc (Zn), cadmium (Cd), and alloys thereof. Examples of metals in Group 13 of the periodic table include aluminum (Al), gallium (Ga), indium (In), and alloys thereof. Furthermore, in the present invention, it is preferable that the ohmic electrode contains Ti and / or Au, and more preferably Ti and Au. Such a favorable range allows for better semiconductor properties of the first semiconductor layer (e.g., durability, dielectric breakdown voltage, breakdown voltage, on-resistance, stability, etc.) and also allows for better ohmic properties.

[0020] The Schottky electrode is not particularly limited as long as it contains one or two metal elements selected from groups 4 to 13 of the periodic table, and may be a single metal layer or may contain two or more metal layers. The means for laminating the metal layers is not particularly limited and includes known methods such as vacuum deposition and sputtering. The metal constituting the Schottky electrode may also be an alloy. Preferably, the Schottky electrode contains one or two metal elements selected from groups 4 to 13 of the periodic table. Examples of one or more metallic elements belonging to any of Groups 4 to 13 of the periodic table include metallic elements of Group 4, Group 5, Group 6, Group 7, Group 8, Group 9, Group 10, Group 11, Group 12, Group 13, and alloys thereof. Examples of metals of Group 4 include titanium (Ti), zirconium (Zr), hafnium (Hf), and alloys thereof. Examples of metals of Group 5 include vanadium (V), niobium (Nb), tantalum (Ta), and alloys thereof. Examples of metals in Group 6 of the periodic table include chromium (Cr), molybdenum (Mo), tungsten (W), and alloys thereof. Examples of metals in Group 7 of the periodic table include manganese (Mn), technetium (Tc), rhenium (Re), and alloys thereof. Examples of metals in Group 8 of the periodic table include iron (Fe), ruthenium (Ru), osmium (Os), and alloys thereof. Examples of metals in Group 9 of the periodic table include cobalt (Co), rhodium (Rh), iridium (Ir), and alloys thereof. Examples of metals in Group 10 of the periodic table include nickel (Ni), palladium (Pd), platinum (Pt), and alloys thereof, but in the present invention, it is preferable to include Ni or Pt. Examples of metals in Group 11 of the periodic table include copper (Cu), silver (Ag), gold (Au), and alloys thereof.Examples of metals in Group 12 of the periodic table include zinc (Zn), cadmium (Cd), and alloys thereof. Examples of metals in Group 13 of the periodic table include aluminum (Al), gallium (Ga), indium (In), and alloys thereof. Furthermore, in the present invention, it is preferable that the Schottky electrode contains Au and / or Ni, and more preferably Au and Ni. Such a preferred range allows for better semiconductor properties (e.g., durability, dielectric breakdown voltage, breakdown voltage, on-resistance, stability, etc.) of the second semiconductor layer, and also allows for better Schottky properties.

[0021] In the present invention, the first semiconductor layer may be formed directly on the substrate, but a layer different from the first semiconductor layer (for example, an n-type semiconductor layer, n ＋ type semiconductor layer, n － The first semiconductor layer may be formed on other layers after laminating other layers such as a semiconductor layer (including a semi-insulating layer), an insulating layer (including a semi-insulating layer), or a buffer layer. In particular, a buffer layer can be suitably used to mitigate the difference in lattice constants between the underlying substrate and the semiconductor 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.

[0022] The laminated structure in the semiconductor device can be more easily obtained by, for example, using the film deposition apparatus shown in Figure 1 to deposit a semiconductor layer mainly composed of a crystalline oxide film containing germanium or a mixed crystal thereof. Doping can also be appropriately performed using the film deposition 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 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 p-type dopants include aluminum (Al), gallium (Ga), or indium (In). In the present invention, the laminated structure obtained in this manner is also included.

[0023] 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. The ohmic electrode and the Schottky electrode may be a single layer of metal or may contain two or more metal films. The means for laminating the ohmic electrode and the Schottky electrode are not particularly limited and include known methods such as vacuum deposition, sputtering, and mist CVD. The semiconductor device is preferably a power device, and examples of such power devices include Schottky barrier diodes (SBDs) and MESFETs. 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 lateral device, in which the electrode is formed on one side of the semiconductor layer, and a vertical device, in which the electrode is 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 lateral and a vertical device.

[0024] Hereinafter, examples of semiconductor devices suitably used in the present invention will be described more specifically with reference to the drawings, but the present invention is not limited to these examples. In addition, preferred examples when using the semiconductor device in the present invention are shown below.

[0025] When a reverse bias is applied to the SBD in FIG. 5, a depletion layer (not shown) spreads in the n-type semiconductor layer 101a, resulting in a high-voltage SBD. When a forward bias is applied, electrons flow from the ohmic electrode 105b to the Schottky electrode 105a. The SBD using the laminated structure in this way is excellent for high-voltage and high-current applications, has good Schottky characteristics, a fast switching speed, and excellent withstand voltage and reliability.

[0026] FIG. 6 － shows a preferred example of a Schottky barrier diode (SBD) including an n ＋ -type semiconductor layer 101a, an n

[0027] -type semiconductor layer 101b, a p-type semiconductor layer 102, a metal layer 103, an insulator layer 104, a Schottky electrode 105a, and an ohmic electrode 105b. The metal layer 103 is made of a metal such as Al, for example, and covers the Schottky electrode 105a. ４ As materials for the insulator layer 104, for example, GaO, AlGaO, InAlGaO, AlInZnGaO ２ O ３ , AlN, Hf ２ O ３ , SiN, SiON, Al ２ O ３ , MgO, GdO, SiO ４ or Si －It is provided between the semiconductor layer 101 and the Schottky electrode 105a. The insulating layer can be formed by known means such as sputtering, vacuum deposition, or CVD. Other configurations are the same as those of the SBD in Figure 5. The SBD in Figure 6 has even better insulating properties and higher current controllability compared to the SBD in Figure 5.

[0028] (MESFET) Figure 16 shows an example of a metal-semiconductor field-effect transistor (MESFET) used in the present invention. The MESFET in Figure 16 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.

[0029] The gate electrode preferably has Schottky properties, and in the present invention, such a Schottky electrode can be suitably used as the gate electrode. Furthermore, the drain electrode preferably has ohmic properties, and such an ohmic electrode can be suitably used as the drain electrode.

[0030] In the MESFET shown in Figure 16, 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.

[0031] (Semiconductor System) The semiconductor devices described above are used in semiconductor systems, such as systems using power supply devices. The power supply device can be manufactured by connecting the semiconductor devices to wiring patterns, etc., using known means. Figure 17 shows an example of a power supply system. In the example shown in Figure 17, a power supply system is configured using a plurality of the power supply devices and control circuits. The power supply system can be used in combination with electronic circuits to form a system device, as shown in Figure 18. An example of a power supply circuit diagram for a power supply device is shown in Figure 19. Figure 19 shows the power supply circuit of a power supply device consisting of a power circuit and a control circuit. This power supply circuit switches the DC voltage at high frequency using an inverter (composed of MOSFETs A to D) to convert it to AC, then performs isolation and voltage transformation with a transformer, rectifies with rectifier MOSFETs (A to B), smooths with DCLs (smoothing coils L1, L2) and capacitors, and outputs a DC voltage. At this time, the output voltage is compared with a reference voltage using a voltage comparator, and the inverter and rectifier MOSFETs are controlled by a PWM control circuit to obtain the desired output voltage.

[0032] (Example 1) 1. n ＋Formation of a Semiconductor Layer 1-1. Film Forming Apparatus Figure 1 shows 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 to be formed 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, an atomizing raw material solution 24a, an ultrasonic transmitting 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 shows 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 forming. The atomizing apparatus 30 consists of a raw material partition 24, an atomizing raw material solution 24a, an ultrasonically transparent substrate 24b, a stand 24c, an ultrasonic transducer 26, a guide partition 31, an ultrasonic transmission liquid tank 35, and an ultrasonic transmission liquid 36. The sample stand 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 stand 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 24. The guide partition 31 is in contact with the ultrasonically transparent substrate 24b. Figure 9 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 9 consists of a raw material partition 24, an ultrasonically transparent substrate 24b, a stand 24c, an ultrasonic transducer 26, a guide partition 31, and an ultrasonic transmission liquid tank 35. The guide partition 31 is in contact with the ultrasonic transmission liquid tank 35. Here, the ultrasonic transducer is surrounded by the guide partition until it reaches the ultrasonically transparent substrate, and 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] The atomizing raw material is not particularly limited as long as it can be atomized, and may be a known atomizing raw material liquid, and may also include 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), germanium (Ge), titanium (Ti), tin (Sn), zirconia (Zr), vanadium (V), yttrium (Y), zinc (Zn), magnesium (Mg), scandium (Sc), hafnium ( Examples include one or more metals selected from Hf, antimony (Sb), bismuth (Bi), tantalum (Ta), iridium (Ir), tungsten (W), niobium (Nb), lanthanum (La), cerium (Ce), and aluminum (Al), but preferably one or more metals selected from gallium, germanium, titanium, tin, niobium, vanadium, antimony, bismuth, tantalum, aluminum, and indium. 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 1-2. Preparation of the atomizing raw material solution When preparing the atomizing raw material solution, the concentration in the atomizing raw material solution was adjusted to 0.02 M biscarboxygermanium sesquioxide. During the adjustment, 10% by volume of hydrochloric acid was added, and this was used as the atomizing raw material solution. Furthermore, the concentration of antimony chloride used as an n-type dopant was adjusted to 3 mol% relative to the concentration of biscarboxygermanium sesquioxide in the atomizing raw material solution.

[0042] 1-3. Preparation for film formation Next, the atomizing raw material solution 24a obtained in 1-2. Preparation of atomizing raw material solution was placed in the raw material partition wall 24. As the film-forming sample 20, a GeO2 crystal with a rutile-type crystalline structure was used, with sides of 17 mm and an average thickness of 500 μm. ２ TiO with a rutile-type crystalline structure with a crystalline film 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 TiO having a rutile-type crystal structure, in the same manner as described above, except that antimony chloride is not used as the n-type dopant. ２ (001) GeO having a rutile-type crystal structure on a substrate ２ It was obtained by forming a crystalline film.

[0043] 1-4. Formation of Oxide Semiconductor Crystal Film Next, the ultrasonic transducer 26 was vibrated at 3.0 MHz, and the vibration was propagated through the ultrasonic transmitter 25a to the atomizing raw material solution 24a, 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 form tetragonal GeO2 on the sample 20. ２ A crystalline film was formed. The film thickness was 500 nm.

[0044] 1-5. Evaluation of GeO obtained by forming oxide semiconductor crystal films as described in 1-4 above. ２ The crystalline film was measured using an X-ray diffractometer. Figure 3 shows the 2θ / ω result in the XRD diffraction. As is clear from Figure 3, the obtained crystalline film has a (002) oriented tetragonal rutile structure. ２It 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 ２ The full width at half maximum of the rocking curve at the 002 diffraction peak was 350 arcsec. These results suggest that TiO has a rutile-type crystal structure. ２ (001) GeO having good crystallinity on a substrate ２ The crystalline film is n ＋ It was formed as a semiconductor layer.

[0045] Furthermore, the Hall effect was measured using the van der pauw method to evaluate the electrical properties of the obtained film. The measurement environment was room temperature with an applied magnetic field frequency of 50 mHz. As a result, the carrier density was 9.28 × 10⁻⁶. １９ (1 / cm ３ ) and the mobility is 24 (cm ２ The value was / V・s). Also, the sheet resistance was 4.6 × 10 １ The coefficient was (Ω / □). The electrical resistivity was 2.76 × 10⁻⁶. ―３ The value was Ωcm. The carrier type was "n". From these results, the obtained GeO ２ The crystalline film is n ＋ It possessed good electrical properties as a semiconductor layer.

[0046] 2. n － Without adding antimony chloride to the raw material solution for atomizing the semiconductor layer, the substrate was prepared as described in 1.n. ＋ n obtained by forming a type semiconductor layer ＋ Type GeO ２ TiO with crystalline film ２ (001) Other than the use of a substrate, the above 1. n ＋ A semiconductor layer was formed in the same manner as the formation of a type semiconductor layer.

[0047] 2-1. Evaluation The formed semiconductor layer was measured for crystal film using an X-ray diffractometer. Figure 12 shows the 2θ / ω result in the XRD diffraction. As is clear from Figure 12, the obtained crystal film has a (002) oriented tetragonal rutile structure. ２ It was a single-crystal film. It was a TiO2 film with a rutile-type crystal structure. ２(001) r-GeO having good crystallinity on a substrate ２ A crystalline film was formed. Also, the obtained n － The thickness of the semiconductor layer was 1.00 μm.

[0048] 2. Electrode Formation A pseudo-vertical structure SBD was fabricated using photolithography and dry etching as shown in Figure 7. The electrodes were formed by EB deposition. The electrode formation conditions are shown below. Figure 8 shows a surface image of a sample with electrodes formed on a crystal film. (Ohmic electrode formation conditions) Lithography HMDS 5000rpm 20s LOR5A 5000rpm 60s, 180oC 5min AZ5214E ​​5000rpm 60s, 110oC 1min DWL 66+ 10mm, Int 50%, Filter 100% TMAH 2.38wt%, 2 min Rinse Descum UV Ozone 2min EB Deposition Ti 75nm, 0.2nm / s Au 75nm, 0.2nm / s Lift-off NMP 80oC 30min, IPA, IPA, Rinse RTA N2 0.5 slm, 550°C, 60 s (Schottky electrode formation conditions) Lithography HMDS 5000 rpm 20 s LOR5A 5000 rpm 60 s, 180°C 5 min AZ5214E ​​5000 rpm 60 s, 110°C 1 min DWL 66+ 10 mm, Int 50%, Filter 100% TMAH 2.38 wt%, 2 min Rinse UV Ozone ashing, 2 min EB Deposition Ni 100 nm, 0.2 nm / s Au 50 nm, 0.2 nm / s Lift-off NMP 80oC 30min, IPA, IPA, Rinse

[0049] IV measurements were performed on the SBD having the pseudo-vertical structure obtained as described above. The results are shown in Figure 10. From Figure 10, it was confirmed that the Schottky characteristics were good. From these results, it can be seen that Example 1 has excellent semiconductor characteristics and Schottky characteristics.

[0050] Furthermore, the ohmic characteristics of the obtained SBD with a pseudo-vertical structure were measured by IV measurement. The results are shown in Figure 13. From Figure 13, it was confirmed that an ohmic contact was formed. In addition, when TLM measurement was performed on the obtained SBD with a pseudo-vertical structure, the contact resistance was found to be 6.6 × 10⁻⁶. －５ Ωcm ２ The results were as follows. Figure 14 shows the TLM measurement results. From these results, it was found that it has better contact resistance. Therefore, the present invention has a contact resistance of 10 × ―５ Ωcm ２ The following is true, and it has excellent electrical properties.

[0051] Furthermore, the n of the obtained SBD having a pseudo-vertical structure － CV measurements were performed on the semiconductor layer, and the carrier concentration was calculated from the results. In Example 1, the carrier concentration was 1 × 10⁻⁶. －１６ ~3 x 10 －１７ cm －３ It was within the range. From this, it can be seen that the carrier concentration can be easily controlled in the present invention. Figure 11 shows the relationship between carrier concentration and depth calculated from the CV measurement results of Example 1.

[0052] Furthermore, the obtained SBD having a pseudo-vertical structure was analyzed by secondary ion mass spectrometry (SIMS) to obtain r-GeO ２ An analysis of the impurity concentration contained in the thin film was performed. The results are shown in Figure 15. From Figure 15, n － Layer r-GeO ２ The thin film contains 2.6 × 10⁻⁶ Sb １５ atoms / cm ３ It can be seen that it is included to a certain extent. ＋ Layer r-GeO ２ The thin film contains 5.76 × 10⁻¹⁶ Sb １８ atoms / cm ３ It can be seen that it is included to a certain extent. From this, it can be seen that in the present invention, n － The layer contains Sb 2.6 × 10 １５ atoms / cm ３ It is included to a certain extent, n ＋ Layer r-GeO ２ The thin film contains 5.76 × 10¹⁶ Sb １８ atoms / cm３ It can be seen that it is included to some extent.

[0053] The semiconductor device, electronic device, and system of the present invention are suitably used, for example, in power devices and the like.

[0054] 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

Claims

1. A semiconductor device comprising a laminated structure in which a second semiconductor layer having the same crystal structure as the first semiconductor layer is laminated directly or via another layer on a first semiconductor layer made of a crystalline oxide mainly composed of germanium or a mixed crystal thereof, wherein the second semiconductor layer has a carrier concentration of 1 × 10 １８ cm －３ The following n － The first semiconductor layer has a carrier concentration of 5 × 10 １８ cm －３ n above ＋ A semiconductor device characterized by having layers.

2. The first semiconductor layer has a carrier concentration of 1 × 10 １９ cm －３ or more and is an n ＋ layer. The semiconductor device according to claim 1 3. The semiconductor device according to claim 1, wherein the second semiconductor layer is made of a crystalline oxide mainly composed of germanium or a mixed crystal thereof.

4. The semiconductor device according to claim 1, wherein the first semiconductor layer has a rutile-type structure.

5. The area of ​​the first semiconductor layer is 100 mm². ２ The semiconductor device according to claim 1, wherein the above is true.

6. The semiconductor device according to claim 1, wherein the thickness of the first semiconductor layer is 500 nm or more.

7. The semiconductor device according to claim 1, wherein the thickness of the second semiconductor layer is 1.0 μm or more.

8. The semiconductor device according to claim 1, wherein the crystalline oxide mainly comprises germanium dioxide.

9. The semiconductor device according to claim 1, comprising an ohmic electrode that is ohmic-bonded to the first semiconductor layer.

10. The semiconductor device according to claim 1, wherein the ohmic electrode comprises one or two metallic elements selected from groups 4 to 13 of the periodic table.

11. The semiconductor device according to claim 1, comprising a Schottky electrode that is Schottky bonded to the second semiconductor layer.

12. The semiconductor device according to claim 1, wherein the Schottky electrode comprises one or two metal elements selected from Groups 4 to 13 of the periodic table.

13. The semiconductor device according to claim 1, which is a power device.

14. The semiconductor device according to claim 1, wherein the Schottky barrier diode (SBD) is used.

15. Electronic equipment including a semiconductor device, characterized in that the semiconductor device is the semiconductor device described in claim 1.

16. A system including an electronic device, characterized in that the electronic device is the electronic device described in claim 15.

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