The present disclosure provides techniques for epitaxial oxide materials, structures and devices. In some embodiments, an integrated circuit includes a field effect transistor (FET) and a waveguide coupled to the FET, wherein the waveguide comprises a signal conductor. The FET can include: a substrate comprising a first oxide material; an epitaxial semiconductor layer on the substrate, the epitaxial semiconductor layer comprising a second oxide material with a first bandgap; a gate layer on the epitaxial semiconductor layer, the gate layer comprising a third oxide material with a second bandgap, wherein the second bandgap is wider than the first bandgap; and electrical contacts. The electrical contacts can include: a source electrical contact coupled to the epitaxial semiconductor layer; a drain electrical contact coupled to the epitaxial semiconductor layer; and a first gate electrical contact coupled to the gate layer.

A nitride semiconductor device includes a nitride semiconductor layer including a first superlattice buffer layer, a second superlattice buffer layer formed above the first superlattice buffer layer, an electron transit layer formed above the second superlattice buffer layer and composed of a first nitride semiconductor, and an electron supply layer formed above the electron transit layer and composed of a second nitride semiconductor. The first superlattice buffer layer has a first superlattice structure including a first layer and a second layer alternately arranged. The first layer is composed of Al.sub.xGa.sub.1xN, where 0<x<1. The second layer is composed of GaN. The second superlattice buffer layer has a second superlattice structure including a third layer and a fourth layer alternately arranged. The third layer is composed of Al.sub.yGa.sub.1yN, where 0<y<x. The fourth layer is composed of GaN.

Fabrication methods and gallium nitride transistors, in which an electronic device includes a substrate, a buffer structure, a hetero-epitaxy structure over the buffer structure, and a transistor over or in the hetero-epitaxy structure. In one example, the buffer structure has an extrinsically carbon doped gallium nitride layer over a dual superlattice stack or over a multilayer composition graded aluminum gallium nitride stack, and a silicon nitride cap layer over the hetero-epitaxy structure.

An artificial double-layer two-dimensional material includes a first layered atomic structure and a second layered atomic structure. The first layered atomic structure includes a first middle atomic layer, a first lower atomic layer, and a first upper atomic layer. The first lower and the first upper atomic layers are disposed on lower and upper surfaces of the first middle atomic layer respectively. The second layered atomic structure includes a second middle atomic layer, a second lower atomic layer, and a second upper atomic layer. The second lower and the second upper atomic layers are disposed on lower and upper surfaces of the second middle atomic layer respectively. The first middle atomic layer and the second middle atomic layer are two-dimensional planar atomic structures formed of transition metals. The first lower and the first upper atomic layers are 2D planar atomic structures formed of heterogeneous atom.

An epitaxial group-ill-nitride buffer-layer structure is provided on a heterosubstrate, wherein the buffer-layer structure has at least one stress-management layer sequence including an interlayer structure arranged between and adjacent to a first and a second group-ill-nitride layer, wherein the interlayer structure comprises a group-ill-nitride interlayer material having a larger band gap than the materials of the first and second group-ill-nitride layers, and wherein a p-type-dopant-concentration profile drops, starting from at least 11018 cm-3, by at least a factor of two in transition from the interlayer structure to the first and second group-ill-nitride layers.

Techniques are disclosed for providing a low resistance self-aligned contacts to devices formed in a semiconductor heterostructure. The techniques can be used, for example, for forming contacts to the gate, source and drain regions of a quantum well transistor fabricated in III-V and SiGe/Ge material systems. Unlike conventional contact process flows which result in a relatively large space between the source/drain contacts to gate, the resulting source and drain contacts provided by the techniques described herein are self-aligned, in that each contact is aligned to the gate electrode and isolated therefrom via spacer material.

A method for making a semiconductor device may include forming a plurality of stacked groups of layers on a semiconductor substrate, with each group of layers including a plurality of stacked base semiconductor monolayers defining a base semiconductor portion and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions. The method may further include implanting a dopant in the semiconductor substrate beneath the plurality of stacked groups of layers in at least one localized region, and performing an anneal of the plurality of stacked groups of layers and semiconductor substrate and with the plurality of stacked groups of layers vertically and horizontally constraining the dopant in the at least one localized region.

Techniques are disclosed for forming a non-planar quantum well structure. In particular, the quantum well structure can be implemented with group IV or III-V semiconductor materials and includes a fin structure. In one example case, a non-planar quantum well device is provided, which includes a quantum well structure having a substrate (e.g. SiGe or GaAs buffer on silicon), a IV or III-V material barrier layer (e.g., SiGe or GaAs or AlGaAs), and a quantum well layer. A fin structure is formed in the quantum well structure, and an interfacial layer provided over the fin structure. A gate metal can be deposited across the fin structure. Drain/source regions can be formed at respective ends of the fin structure.

An epitaxial group-ill-nitride buffer-layer structure is provided on a heterosubstrate, wherein the buffer-layer structure has at least one stress-management layer sequence including an interlayer structure arranged between and adjacent to a first and a second group-ill-nitride layer, wherein the interlayer structure comprises a group-ill-nitride interlayer material having a larger band gap than the materials of the first and second group-ill-nitride layers, and wherein a p-type-dopant-concentration profile drops, starting from at least 11018 cm-3, by at least a factor of two in transition from the interlayer structure to the first and second group-ill-nitride layers.

A method for processing a semiconductor wafer in a single wafer processing chamber may include heating the single wafer processing chamber to a temperature in a range of 650-700 C., and forming at least one superlattice on the semiconductor wafer within the heated single wafer processing chamber by depositing silicon and oxygen to form a plurality of stacked groups of layers. Each group of layers may include a plurality of stacked base silicon monolayers defining a base silicon portion and at least one oxygen monolayer constrained within a crystal lattice of adjacent base silicon portions. Depositing the oxygen may include depositing the oxygen using an N.sub.2O gas flow.