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 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 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, in which crystals can be epitaxially grown on a ?-Ga2O3-based substrate with high efficiency to produce a high-quality ?-Ga2O3-based crystal film on the substrate; and a method for producing the crystal laminate structure are provided. The crystal laminate structure includes: a ?-Ga2O3-based substrate, of which the major face is a face that is rotated by 50 to 90° inclusive with respect to face; and a ?-Ga2O3-based crystal film which is formed by the epitaxial crystal growth on the major face of the ?-Ga2O3-based substrate.

Abstract: Provided is a high-quality Ga2O3 semiconductor element. Provided is, as one embodiment of the present invention, a Ga2O3 MISFET (10), which includes: an n-type ?-(AlxGa1-x)2O3 single crystal film (3), which is formed on an ?-Al2O3 substrate (2) directly or with other layer therebetween, and is composed of an ?-(AlxGa1-x)2O3 single crystal (0?x<1); a source electrode (12) and a drain electrode (13), which are formed on the n-type ?-(AlxGa1-x)2O3 single crystal film (3); contact regions (14, 15), which are formed in the n-type ?-(AlxGa1-x)2O3 single crystal film (3), and are connected to the source electrode (12) and the drain electrode (13), respectively; and a gate electrode (11), which is formed on a region between the contact region (14) and the contact region (15) in the n-type ?-(AlxGa1-x)2O3 single crystal film (3) with the gate insulating film (16) therebetween.

Abstract: Provided is a high-quality Ga2O3 semiconductor element. Provided is, as one embodiment of the present invention, a Ga2O3 MESFET (10), which includes: an n-type ?-(AlxGa1-x)2O3 single crystal film (3), which is formed on an ?-Al2O3 substrate (2) directly or with other layer therebetween, and is composed of an ?-(AlxGa1-x)2O3 single crystal (0?x?1); a source electrode (12) and a drain electrode (13), which are formed on the n-type ?-(AlxGa1-x)2O3 single crystal film (3); and a gate electrode (11), which is formed on a region between the source electrode (12) and the drain electrode (13) on the n-type ?-(AlxGa1-x)2O3 single crystal film (3).