The present invention relates to a method for reducing structural damage to the surface of monocrystalline aluminium-nitride substrates, according to which the substrate undergoes thermal treatment in a crucible in an autoclave, during which treatment the aluminum-nitride substrate is sublimated in the damaged regions of the surface of the substrate and is removed. The method is used to prepare the surface of monocrystalline aluminium-nitride (AlN), in particular the aim of the invention is to eliminate, or at least significantly reduce near-surface structural damage to the monocrystalline material caused by mechanical processing. The invention also relates to aluminium-nitride substrates that are treated in this way.

An electrical device includes an aluminum nitride passivation layer for a mercury cadmium telluride (Hg.sub.1-xCd.sub.xTe) (MCT) semiconductor layer of the device. The AlN passivation layer may be an un-textured amorphous-to-polycrystalline film that is deposited onto the surface of the MCT in its as-grown state, or overlying the MCT after the MCT surface has been pre-treated or partially passivated, in this way fully passivating the MCT. The AlN passivation layer may have a coefficient of thermal expansion (CTE) that closely matches the CTE of the MCT layer, thereby reducing strain at an interface to the MCT. The AlN passivation layer may be formed with a neutral inherent (residual) stress, provide mechanical rigidity, and chemical resistance to protect the MCT.

A capacitor is provided for high temperature systems. The capacitor includes: a substrate formed from silicon carbide material; a dielectric stack layer, including a first layer deposited on the substrate and a second layer deposited on the first layer; a Schottky contact layer deposited on the second layer; and an Ohmic contact layer deposited on the substrate. The first layer is formed with aluminum nitride (AlN) epitaxially, and the second layer is formed with aluminum oxide (Al.sub.2O.sub.3). AlN and Al.sub.2O.sub.3 are ultrawide band gap materials, and as a result, they can be use as the dielectric in the capacitor, allowing the capacitance changes to be less than 10% between −250° C. and 600° C., which is very effective for the high temperature systems.

An epitaxial wafer according to the present disclosure includes: a substrate; a buffer layer formed of a crystal having the composition formula represented by Al.sub.xGa.sub.yIn.sub.zN (x+y+z=1, y>0) on the substrate; a back-barrier layer formed of a crystal having the composition formula represented by Al.sub.xGa.sub.yIn.sub.zN (x+y+z=1, y>0, z>0) on the buffer layer; a channel layer formed of a crystal having the composition formula represented by Al.sub.xGa.sub.yIn.sub.zN (x+y+z=1, y>0) on the back-barrier layer; and an electron-supply layer formed of a crystal having the composition formula represented by Al.sub.xGa.sub.yIn.sub.zN (x+y+z=1, x>0) on the channel layer. The channel layer is constituted with an upper channel layer underneath the electron-supply layer and a lower channel layer on the back-barrier layer, and the lower channel layer has a C concentration higher than the upper channel layer and contains Si.

A group III nitride single crystal substrate comprises: a first main face; and a first back face opposite to the first main face, wherein an absolute value of a radius of curvature of the first main face of the substrate is 10 m or more; an absolute value of a radius of curvature of a crystal lattice plane at a center of the first main face of the substrate is 10 m or more; and a 1/1000 intensity width of an X-ray rocking curve of a low-incidence-angle face at the center of the first main face of the substrate is 1200 arcsec or less.

An epitaxial structure includes a substrate, a nucleation layer on the substrate, a buffer layer on the nucleation layer, and a nitride layer on the buffer layer. The nucleation layer consists of regions in a thickness direction, wherein a chemical composition of the regions is Al.sub.(1-x)In.sub.xN, where 0≤x≤1. A maximum value of the x value in the plurality of regions is the same, a minimum value of the x value in the plurality of regions is the same, and an absolute value of a gradient slope of each of the regions is 0.1%/nm to 50%/nm. A thickness of the nucleation layer is less than a thickness of the buffer layer. A roughness of a surface of the nucleation layer in contact with the buffer layer is greater than a roughness of a surface of the buffer layer in contact with the nitride layer.

A method for obtaining mesas that are made at least in part of a nitride (N), the method includes providing a stack comprising a substrate and at least the following layers disposed in succession from the substrate a first layer, referred to as the flow layer, and a second, crystalline layer, referred to as the crystalline layer; forming pads by etching the crystalline layer and at least one portion of the flow layer such that: —each pad includes at least: —a first section, referred to as the flow section, formed by at least one portion of the flow layer, and a second, crystalline section, referred to as the crystalline section, framed by the crystalline layer and overlying the flow section, the pads are distributed over the substrate so as to form a plurality of sets of pads; and epitaxially growing a crystallite on at least some of said pads and continuing the epitaxial growth of the crystallites until the crystallites carried by the adjacent pads of the same set coalesce.

The invention relates to methods for the chemical application of coatings by the decay of gaseous compounds, in particular to methods for injecting gases into a reaction chamber. The invention also relates to means for feeding gases into a reaction chamber, said means providing for the regulation of streams of reactive gases, and ensures the possibility of obtaining multi-layer epitaxial structures having set parameters and based on nitrides of group III metals while simultaneously increasing the productivity and cost-effectiveness of the process of the epitaxial growth thereof. Before being fed into a reactor, all of the gas streams are sent to a mixing chamber connected to the reactor, and are then fed into the reactor via a flux former under laminar flow conditions. The mixing chamber and the flux former are equipped with means for maintaining a set temperature. As a result of these solutions, a gaseous mixture with set parameters is fed into the reactor, and the formation of vortices is simultaneously prevented. The maximum allowable volume of the mixing chamber is chosen to take into account the process parameters and the required rarity of heterojunctions.

A wafer carrier includes a pocket sized and shaped to accommodate a wafer, the pocket having a base and a substantially circular perimeter, and a removable orientation marker, the removable orientation marker comprising an outer surface and an inner surface, the outer surface having an arcuate form sized and shaped to mate with the substantially circular perimeter of the pocket, and the inner surface comprising a flat face, wherein the removable orientation marker further comprises a notch at a first end of the flat face.

There is provided a method for manufacturing a nitride semiconductor template constituted by forming a nitride semiconductor layer on a substrate, comprising: (a) forming a first layer by epitaxially growing a nitride semiconductor containing aluminum on the substrate; (b) applying annealing to the first layer in an inert gas atmosphere; and (c) forming a second layer by epitaxially growing a nitride semiconductor containing aluminum on the first layer by a vapor phase growth after performing (b), and constituting the nitride semiconductor layer by the first layer and the second layer.