Abstract: A Ga2O3 based crystal film forming method includes epitaxially growing a Ga2O3 based crystal film over a Ga2O3 based substrate. A growth temperature for the crystal film is not lower than 560 degrees Celsius. A VI/III ratio in an atmosphere adjacent to a growing surface when the crystal film is grown is smaller than ½, or greater than 2. A crystal laminated structure includes a Ga2O3 based substrate including a first group IV element, and a Ga2O3 based crystal film including a second group IV element, the crystal film being formed over the substrate, and having a surface roughness (RMS) of smaller than 1 nm, and a thickness of not smaller than 300 nm. A coefficient of variation of a concentration distribution of the second group IV element in a depth direction in the crystal film is not more than 20 percent.

Abstract: A Ga2O3-based semiconductor element includes an undoped ?-Ga2O3 single crystal film disposed on a surface of a ?-Ga2O3 substrate, a source electrode and a drain electrode disposed on a same side of the undoped ?-Ga2O3 single crystal film, a gate electrode disposed on the undoped ?-Ga2O3 single crystal film between the source electrode and the drain electrode, and a region formed in the undoped ?-Ga2O3 single crystal film under the source electrode and the drain electrode and including a controlled dopant concentration.

Abstract: A Ga2O3 semiconductor element, includes: an n-type ?-Ga2O3 substrate; a ?-Ga2O3 single crystal film, which is formed on the n-type ?-Ga2O3 substrate; source electrodes, which are formed on the ?-Ga2O3 single crystal film; a drain electrode, which is formed on the n-type ?-Ga2O3 substrate surface on the reverse side of the ?-Ga2O3 single crystal film; n-type contact regions, which are formed in the ?-Ga2O3 single crystal film, and have the source electrodes connected thereto, respectively; and a gate electrode, which is formed on the ?-Ga2O3 single crystal film with the gate insulating film therebetween.

Abstract: A telephone reservation system includes a reservation receiving unit, a storage unit, an availability determination unit, and an authentication unit. The reservation receiving unit receives detailed reservation information pertaining to a shop selected by a user from among a plurality of shops and user information of the user from a user terminal of the user via a telephone line. The storage unit stores vacant seat information of each of the plurality of shops together with corresponding shop identification information. The availability determination unit determines whether a reservation that satisfies the received detailed reservation information is available on the basis of the vacant seat information stored in the storage unit. The authentication unit performs personal authentication through any one of pieces of the user information.

Abstract: As one embodiment, the present invention provides a method for growing a ?-Ga2O3-based single crystal film by using HVPE method. The method includes a step of exposing a Ga2O3-based substrate to a gallium chloride-based gas and an oxygen-including gas, and growing a ?-Ga2O3-based single crystal film on a principal surface of the Ga2O3-based substrate at a growth temperature of not lower than 900° C.

Abstract: A Ga2O3 semiconductor element includes: an n-type ?-Ga2O3 single crystal film, which is formed on a high-resistance ?-Ga2O3 substrate directly or with other layer therebetween; a source electrode and a drain electrode, which are formed on the n-type ?-Ga2O3 single crystal film; and a gate electrode, which is formed on the n-type ?-Ga2O3 single crystal film between the source electrode and the drain electrode.

Abstract: A crystal laminate structure includes an epitaxial growth substrate including a ?-Ga2O3-based single crystal and a (010) plane or a plane inclined at an angle not more than 37.5° with respect to the (010) plane as a main surface thereof and a high electrical resistance, and an epitaxial crystal formed on the main surface of the epitaxial growth substrate. The epitaxial crystal includes a Ga-containing oxide.

Abstract: A Ga2O3 semiconductor element includes: an n-type ?-Ga2O3 single crystal film, which is formed on a high-resistance ?-Ga2O3 substrate directly or with other layer therebetween; a source electrode and a drain electrode, which are formed on the n-type ?-Ga2O3 single crystal film; and a gate electrode, which is formed on the n-type ?-Ga2O3 single crystal film between the source electrode and the drain electrode.

Abstract: Provided is a Ga2O3-based semiconductor element having less leak current and a large on/off ratio. In one embodiment, provided is a Ga2O3-based MISFET having a ?-Ga2O3 single crystal layer formed on a high-resistance ?-Ga2O3 substrate, a source electrode and drain electrode formed on the ?-Ga2O3 single crystal layer, a gate electrode formed between the source electrode and drain electrode on the ?-Ga2O3 single crystal layer, and an insulating film that has an oxide insulator as the primary component and that covers the surface of the ?-Ga2O3 single crystal layer at the region between the drain electrode and the gate electrode and the region between the gate electrode and the source electrode.

Abstract: A method of forming a high-resistivity region in a Ga2O3-based single crystal includes ion-implanting Mg or Be into the Ga2O3-based single crystal, and annealing and activating the Mg or Be at a temperature of not less than 800° C. to form the high-resistivity region. A crystal laminate structure includes a Ga2O3-based high-resistivity crystal layer of not more than 750 nm (or 2000 nm as for Be) in thickness, the crystal layer including Mg (or Be) and a damage caused by ion implantation, and an impurity concentration inclined layer of not less than 100 nm in thickness formed under the Ga2O3-based high-resistivity crystal layer. The impurity concentration inclined layer includes a Mg (or Be) concentration lower than the Ga2O3-based high-resistivity crystal layer. The Mg (or Be) concentration is inclined in a depth direction.

Abstract: A method of forming a Ga2O3-based crystal film includes epitaxially growing a Ga2O3-based crystal film on a (001)-oriented principal surface of a Ga2O3-based substrate at a growth temperature of not less than 750° C. A crystal multilayer structure includes a Ga2O3-based substrate with a (001)-oriented principal surface, and a Ga2O3-based crystal film formed on the principal surface of the Ga2O3-based substrate by epitaxial growth. The principal surface has a flatness of not more than 1 nm in an RMS value.

Abstract: Provided are a Ga2O3-based single crystal substrate including a Ga2O3-based single crystal which has a high resistance while preventing a lowering of crystal quality and a production method therefor. According to one embodiment of the present invention, the production method includes growing the Ga2O3-based single crystal while adding a Fe to a Ga2O3-based raw material, the Ga2O3-based single crystal (5) including the Fe at a concentration higher than that of a donor impurity mixed in the Ga2O3-based raw material, and cutting out the Ga2O3-based single crystal substrate from the Ga2O3-based single crystal (5).

Abstract: Provided is a method for controlling a donor concentration in a Ga2O3-based single crystal body. In addition, an ohmic contact having a low resistance is formed between a Ga2O3-based single crystal body and an electrode. A donor concentration in a Ga2O3-based single crystal body is controlled by a method which includes a step wherein Si, which serves as a donor impurity, is introduced into the Ga2O3-based single crystal body by an ion implantation method at an implantation concentration of 1×1020 cm?3 or less, so that a donor impurity implanted region is formed in the Ga2O3-based single crystal body, the donor impurity implanted region having a higher donor impurity concentration than the regions into which Si is not implanted, and a step wherein Si in the donor impurity implanted region is activated by annealing, so that a high donor concentration region is formed.

Abstract: A ?-Ga2O3-based single crystal, including a first region that has side and bottom surfaces and is controlled so as to have a first donor concentration; and a second region that surrounds the side and bottom surfaces of the first region and is controlled so as to have a second donor concentration lower than the first donor concentration.

Abstract: Provided is a substrate for epitaxial growth, which enables the improvement in quality of a Ga-containing oxide layer that is formed on a ?-Ga2O3 single-crystal substrate. A substrate (1) for epitaxial growth comprises ?-Ga2O3 single crystals, wherein face (010) of the single crystals or a face that is inclined at an angle equal to or smaller than 37.5° with respect to the face (010) is the major face. A crystal laminate structure (2) comprises: the substrate (1) for epitaxial growth; and epitaxial crystals (20) which are formed on the major face (10) of the substrate (1) for epitaxial growth and each of which comprises a Ga-containing oxide.

Abstract: A method of forming a Ga2O3-based crystal film includes epitaxially growing a Ga2O3-based crystal film on a (001)-oriented principal surface of a Ga2O3-based substrate at a growth temperature of not less than 750° C. A crystal multilayer structure includes a Ga2O3-based substrate with a (001)-oriented principal surface, and a Ga2O3-based crystal film formed on the principal surface of the Ga2O3-based substrate by epitaxial growth. The principal surface has a flatness of not more than 1 nm in an RMS value.

Abstract: A ?-Ga2O3-based single crystal, including a first region that has side and bottom surfaces and is controlled so as to have a first donor concentration; and a second region that surrounds the side and bottom surfaces of the first region and is controlled so as to have a second donor concentration lower than the first donor concentration.

Abstract: A method for controlling the concentration of a donor in a Ga2O3-based single crystal includes: a step in which a Group IV element is implanted as a donor impurity in a Ga2O3-based single crystal by ion implantation process to form, in the Ga2O3-based single crystal, a donor impurity implantation region that has a higher concentration of the Group IV element than the region in which the Group IV element has not been implanted; and a step in which annealing at 800 C or higher is conducted to activate the Group IV element present in the donor impurity implantation region and thereby form a high-donor-concentration region. Thus, the donor concentration in the Ga2O3-based single crystal is controlled.

Abstract: A Ga2O3 crystal film is epitaxially grown on a Ga2O3 crystal substrate using an MBE method, while controlling the n-type conductivity with high accuracy. Provided is a method for producing a Ga2O3 crystal film, wherein a conductive Ga2O3 crystal film is formed by epitaxial growth using an MBE method. This method for producing a Ga2O3 crystal film comprises a step wherein a Ga2O3 single crystal film containing Sn is grown by producing a Ga vapor and an Sn vapor and supplying the Ga vapor and the Sn vapor to the surface of a Ga2O3 crystal substrate as molecular beams The Sn vapor is produced by heating Sn oxide that is filled in a cell of an MBE apparatus.

Abstract: Provided is a substrate for epitaxial growth, which enables the improvement in quality of a Ga-containing oxide layer that is formed on a ?-Ga2O3 single-crystal substrate. A substrate (1) for epitaxial growth comprises ?-Ga2O3 single crystals, wherein face (010) of the single crystals or a face that is inclined at an angle equal to or smaller than 37.5° with respect to the face (010) is the major face. A crystal laminate structure (2) comprises: the substrate (1) for epitaxial growth; and epitaxial crystals (20) which are formed on the major face (10) of the substrate (1) for epitaxial growth and each of which comprises a Ga-containing oxide.