A backside metallized compound semiconductor device includes a compound semiconductor wafer and a metal layered structure. The compound semiconductor wafer includes a substrate having opposite front and back surfaces, and a ground pad structure formed on the front surface. The substrate is formed with a via extending from the back surface to the front surface to expose a side wall of the substrate and a portion of the ground pad structure. The metal layered structure is disposed on the back surface, and covers the side wall and the portion of the ground pad structure. The metal layered structure includes an adhesion layer, a seed layer, a gold layer, and an electroplated copper layer that are formed on the back surface in such order. The method for manufacturing the backside metallized compound semiconductor device is also disclosed.

A method includes following steps. First transistors are formed over a substrate. An interconnect structure is formed over the plurality of first transistors. A dielectric layer is formed over the interconnect structure. 2D semiconductor seeds are formed over the dielectric layer. The 2D semiconductor seeds are annealed. An epitaxy process is performed to laterally grow a plurality of 2D semiconductor films respectively from the plurality of 2D semiconductor seeds. Second transistors are formed on the plurality of 2D semiconductor films.

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.

Examples of a method for producing a semiconductor device includes: forming a barrier layer having a composition of InAlN or InAlGaN over a channel layer; forming a transition layer having a composition of InGaN on the barrier layer while raising a growth temperature; and forming a cap layer of GaN on the transition layer.