A semiconductor device and a method of manufacturing the semiconductor device are included. The method of manufacturing the semiconductor device includes forming a hafnium oxide layer on a substrate and crystallizing the hafnium oxide layer by using a hafnium cobalt oxide layer as a seed layer. According to the method of manufacturing the semiconductor device, a thin-film hafnium oxide layer may be easily crystallized.

Semiconductor structures and methods for forming those semiconductor structures are disclosed. For example, a semiconductor structure with a p-type superlattice region, an i-type superlattice region, and an n-type superlattice region is disclosed. The semiconductor structure can have a polar crystal structure with a growth axis that is substantially parallel to a spontaneous polarization axis of the polar crystal structure. In some cases, there are no abrupt changes in polarisation at interfaces between each region. At least one of the p-type superlattice region, the i-type superlattice region and the n-type superlattice region can comprise a plurality of unit cells exhibiting a monotonic change in composition from a wider band gap (WBG) material to a narrower band gap (NBG) material or from a NBG material to a WBG material along the growth axis to induce p-type or n-type conductivity.

A thin film transistor may be manufactured by forming a gate electrode in an insulating layer over a substrate, forming a gate dielectric over the gate electrode and the insulating layer, forming an active layer over the gate electrode, and forming a source electrode and a drain electrode contacting a respective portion of a top surface of the active layer. A surface oxygen concentration may be increased in at least one of the gate dielectric and the active layer by introducing oxygen atoms into a surface region of a respective one of the gate dielectric and the active layer.

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.

The present disclosure provides techniques for epitaxial oxide materials, structures and devices. In some embodiments, a semiconductor structure includes an epitaxial oxide heterostructure, comprising: a substrate; a first epitaxial oxide layer comprising Li(Al.sub.x1Ga.sub.1−x1)O.sub.2 wherein 0≤x1≤1; and a second epitaxial oxide layer comprising (Al.sub.x2Ga.sub.1−x2).sub.2O.sub.3 wherein 0≤x2≤1.

The present disclosure describes epitaxial oxide integrated circuits. In some embodiments, an integrated circuit comprises: a field effect transistor (FET), comprising: a substrate comprising a first oxide material; an epitaxial buried ground plane on the substrate and comprising a second oxide material; an epitaxial buried oxide layer on the epitaxial buried ground plane and comprising a third oxide material; an epitaxial semiconductor layer on the epitaxial buried oxide layer and comprising a fourth oxide material with a first bandgap; a gate layer on the epitaxial semiconductor layer and comprising a fifth oxide material with a second bandgap; electrical contacts; and a waveguide coupled to the field effect transistor. The waveguide can comprise: the epitaxial buried ground plane; the epitaxial buried oxide layer; and a signal conductor, wherein the epitaxial buried oxide layer is between the signal conductor and the epitaxial buried ground plane.

The present disclosure provides techniques for epitaxial oxide materials, structures and devices. In some embodiments, a semiconductor structure includes an epitaxial oxide heterostructure, comprising: a substrate; a first epitaxial oxide layer comprising (Ni.sub.x1Mg.sub.y1Zn.sub.1−x1−yl).sub.2GeO.sub.4 wherein 0≤x1≤1 and 0≤y1≤1; and a second epitaxial oxide layer comprising (Ni.sub.x2Mg.sub.y2Zn.sub.1−x2−y2).sub.2GeO.sub.4 wherein 0≤x2≤1 and 0≤y2≤1. In some cases, either: x1≠x2 and y1=y2; x1=x2 and y1≠y2; or x1≠x2 and y1≠y2. In some embodiments, a semiconductor structure includes an epitaxial oxide heterostructure, comprising: a substrate; a first epitaxial oxide layer comprising (Mg.sub.x1Zn.sub.1−x1)(Al.sub.y1Ga.sub.1−y1).sub.2O.sub.4 wherein 0≤x1≤1 and 0≤y1≤1; and a second epitaxial oxide layer comprising (Ni.sub.x2Mg.sub.y2Zn.sub.1−x2−y2).sub.2GeO.sub.4 wherein 0≤x2≤1 and 0≤y2≤1.