Provided is a group III nitride laminate for improving device characteristics, including: an underlying substrate; a first layer that is formed on the underlying substrate and is made of aluminum nitride; and a second layer that is formed on the first layer and is made of gallium nitride, wherein the first layer has a thickness of more than 100 nm and 1 μm or less, a full width at half maximum of (0002) diffraction determined through X-ray rocking curve analysis is 250 seconds or less, and a full width at half maximum of (10-12) diffraction determined through X-ray rocking curve analysis is 500 seconds or less.

It is an object to provide a method for producing a diamond substrate effective for reducing various defects including dislocation defects and a foundation substrate used for the same. This object is achieved by a foundation substrate for forming a diamond film by a chemical vapor deposition method, wherein an off angle is provided to the surface of the foundation substrate with respect to a predetermined crystal plane orientation.

A method includes: providing a bottom layer; depositing a first seed layer over the bottom layer, the first seed layer having at least one of a tetragonal crystal phase and an orthorhombic crystal phase; depositing a dielectric layer over the bottom layer adjacent to the first seed layer, the dielectric layer including an amorphous crystal phase; depositing an upper layer over the dielectric layer; performing a thermal operation on the dielectric layer; and cooling the dielectric layer, wherein after the cooling the dielectric layer becomes a ferroelectric layer.

A method for manufacturing a nitride semiconductor substrate, including: a step of preparing a base substrate; a step of forming a mask layer having a plurality of openings on the main surface of the base substrate; a first step of growing a first layer whose surface is composed only of inclined interfaces; and a second step of epitaxially growing a single crystal of a group III nitride semiconductor on the first layer, making the inclined interfaces disappear, and growing a second layer having a mirror surface, wherein in the first step, at least one valley and a plurality of tops are formed at an upper side of each of the plurality of openings of the mask layer by forming a plurality of concaves on a top surface of the single crystal and making the (0001) plane disappear.

Layered structures described herein include electronic devices with 2-dimensional electron gas between polar-oriented cubic rare-earth oxide layers on a non-polar semiconductor. Layered structure includes a semiconductor device, comprising a III-N layer or rare-earth layer, a polar rare-earth oxide layer grown over the III-N layer or rare-earth layer, a gate terminal deposited or grown over the polar rare-earth oxide layer, a source terminal that is deposited or epitaxially grown over the layer, and a drain terminal that is deposited or grown over the layer.

A semiconductor device includes a substrate, a first semiconductor fin and a gate stack. The first semiconductor fin is over the substrate and includes a first germanium-containing layer and a second germanium-containing layer over the first germanium-containing layer. The first germanium-containing layer has a germanium atomic percentage higher than a germanium atomic percentage of the second germanium-containing layer. The gate stack is across the first semiconductor fin.

The present disclosure describes epitaxial oxide high electron mobility transistors (HEMTs). In some embodiments, a HEMT comprises: a substrate; a template layer on the substrate; a first epitaxial semiconductor layer on the template layer; and a second epitaxial semiconductor layer on the first epitaxial semiconductor layer. The template layer can comprise crystalline metallic Al(111). The first epitaxial semiconductor layer can comprise (Al.sub.xGa.sub.1-x).sub.yO.sub.z, wherein 0≤x≤1, 1≤y≤3, and 2≤z≤4, wherein the (Al.sub.xGa.sub.1-x).sub.yO.sub.z comprises a Pna21 space group, and wherein the (Al.sub.xGa.sub.1-x)O.sub.z comprises a first conductivity type formed via polarization. The second epitaxial semiconductor layer can comprise a second oxide material.

The present disclosure describes methods and epitaxial oxide devices with impact ionization. A method can comprise: applying a bias across a semiconductor structure using a first electrical contact and a second electrical contact; injecting a hot electron, from the first electrical contact, through a second semiconductor layer, and into a conduction band of a first epitaxial oxide material; and forming an excess electron-hole pair in an impact ionization region of the first semiconductor layer via impact ionization. The semiconductor structure can comprise: the first electrical contact; the first semiconductor layer with the first epitaxial oxide material with a first bandgap coupled to the first electrical contact; a second semiconductor layer with a second epitaxial oxide material with a second bandgap coupled to the first semiconductor layer; and a second electrical contact coupled to the second semiconductor layer, wherein the second bandgap is wider than the first bandgap.

The present disclosure provides techniques for epitaxial oxide materials, structures and devices. In some embodiments, a semiconductor structure includes an epitaxial oxide heterostructure, including: a substrate; a first epitaxial oxide layer comprising (Ni.sub.x1Mg.sub.y1Zn.sub.1-x1-y1)(Al.sub.q1Ga.sub.1-q1).sub.2O.sub.4 wherein 0≤x1≤1, 0≤y1≤1 and 0≤q1≤1; and a second epitaxial oxide layer comprising (Ni.sub.x2Mg.sub.y2Zn.sub.1-x2-y2)(Al.sub.q2Ga.sub.1-q2).sub.2O.sub.4 wherein 0≤x2≤1, 0≤y2≤1 and 0≤q2≤1. In some cases, at least one condition selected from x1≠x2, y1≠y2, and q1≠q2 is satisfied.

The present disclosure describes epitaxial oxide devices with impact ionization. In some embodiments, a semiconductor device comprises: a first semiconductor layer; a second semiconductor layer coupled to the first semiconductor layer; and a first and a second electrical contact coupled to the second and first semiconductor layers, respectively. The first semiconductor layer can comprise a first epitaxial oxide material with a first bandgap and an impact ionization region. The second semiconductor layer can comprise a second epitaxial oxide material with a second bandgap that is wider than the first bandgap.