A semiconductor crystal substrate includes a crystal substrate that is formed of a material including GaSb or InAs, a first buffer layer that is formed on the crystal substrate and formed of a material including GaSb, the first buffer layer having n-type conductivity, and a second buffer layer that is formed on the first buffer layer and formed of a material including GaSb, the second buffer layer having p-type conductivity.

Provided is a semiconductor device including graphene. The semiconductor device includes: a substrate including an insulator and a semiconductor; and a graphene layer configured to directly grow only on a surface of the semiconductor, wherein the semiconductor includes at least one of a group IV material and a group III-V compound.

A nanowire structure includes a substrate, a graded planar buffer layer, a patterned mask, and a nanowire. The graded planar buffer layer is on the substrate. The patterned mask is on the graded planar buffer layer and includes an opening through which the graded planar buffer layer is exposed. The nanowire is on the graded planar buffer layer in the opening of the patterned mask. A lattice constant of the graded planar buffer layer is between a lattice constant of the substrate and a lattice constant of the nanowire. By providing the graded planar buffer layer, lattice mismatch between the nanowire and the substrate can be reduced or eliminated, thereby improving the quality and performance of the nanowire structure.

A semiconductor crystal substrate includes a crystal substrate that is formed of a material including one of GaSb and InAs, a first buffer layer that is formed on the crystal substrate and formed of a material including GaSb, and a second buffer layer that is formed on the first buffer layer and formed of a material including GaSb. The first buffer layer has a p-type conductivity, and the second buffer layer has an n-type conductivity.

A semiconductor crystal substrate includes a crystal substrate that is formed of a material including one of GaSb and InAs, a first buffer layer that is formed on the crystal substrate and formed of a material including GaSb, and a second buffer layer that is formed on the first buffer layer and formed of a material including GaSb. The first buffer layer has a p-type conductivity, and the second buffer layer has an n-type conductivity.

A method of producing graphene or other two-dimensional material such as graphene including heating the substrate held within a reaction chamber to a temperature that is within a decomposition range of a precursor, and that allows two-dimensional crystalline material formation from a species released from the decomposed precursor; establishing a steep temperature gradient (preferably >1000 C. per meter) that extends away from the substrate surface towards an inlet for the precursor; and introducing precursor through the relatively cool inlet and across the temperature gradient towards the substrate surface. The steep temperature gradient ensures that the precursor remains substantially cool until it is proximate the substrate surface thus minimizing decomposition or other reaction of the precursor before it is proximate the substrate surface. The separation between the precursor inlet and the substrate is less than 100 mm.

An apparatus includes a semiconductor substrate, a semiconductor layer, and a first conduction-type contact layer. The semiconductor layer that is provided above the semiconductor substrate, has a lattice constant different from a lattice constant of indium arsenide (InAs), and is formed from a semiconductor containing antimonide (Sb). The first conduction-type contact layer including a first conduction-type InAsSb layer provided over the semiconductor layer and a first conduction-type InAs layer provided over the first conduction-type InAsSb layer.

A method of producing graphene or other two-dimensional material such as graphene including heating the substrate held within a reaction chamber to a temperature that is within a decomposition range of a precursor, and that allows two-dimensional crystalline material formation from a species released from the decomposed precursor; establishing a steep temperature gradient (preferably >1000 C. per meter) that extends away from the substrate surface towards an inlet for the precursor; and introducing precursor through the relatively cool inlet and across the temperature gradient towards the substrate surface. The steep temperature gradient ensures that the precursor remains substantially cool until it is proximate the substrate surface thus minimizing decomposition or other reaction of the precursor before it is proximate the substrate surface. The separation between the precursor inlet and the substrate is less than 100 mm.

The present disclosure relates to a method of manufacturing a nanowire structure. According to an exemplary process, a substrate is firstly provided. An intact buffer region is formed over the substrate, and a sacrificial top portion of the intact buffer region is eliminated to provide a buffer layer with a planarized top surface. Herein, the planarized top surface has a vertical roughness below 10 . Next, a patterned mask with an opening is formed over the buffer layer, such that a portion of the planarized top surface of the buffer layer is exposed. A nanowire is formed over the exposed portion of the planarized top surface of the buffer layer through the opening of the patterned mask. The buffer layer is configured to have a lattice constant that provides a transition between the lattice constant of the substrate and the lattice constant of the nanowire.

A semiconductor crystal substrate includes: a crystal substrate whose principal surface is inclined relative to a (001) plane; and a superlattice structure layer including a first superlattice formation layer and a second superlattice formation layer, wherein the first superlattice formation layer is formed of Ga.sub.1-x1In.sub.x1As.sub.y1Sb.sub.1-y1 (0x10.1, 0y10.1), and a value of a standard deviation to a mean value of atomic step widths in an inclination direction is equal to or greater than 0 and equal to or smaller than 0.20, and the second superlattice formation layer is formed of Ga.sub.1-x2In.sub.x2As.sub.y2Sb.sub.1-y2 (0.9x21, 0.9y21), and a value of a standard deviation to a mean value of atomic step widths in an inclination direction is equal to or greater than 0 and equal to or smaller than 0.40.