Abstract: A method for fabricating a semiconductor device, such as a GaN high electron mobility transistor (HEMT) device, including etching a thermal via into a back-side of a semiconductor substrate and depositing a diamond nucleation seed layer across the back-side of the substrate. The method further includes coating the diamond nucleation with a mask layer and removing mask material outside of the thermal via on the planar portions of the back-side of the substrate. The method includes removing portions of the diamond nucleation layer on the planar portions and then removing the remaining portion of the mask material in the thermal via. The method then includes depositing a bulk diamond layer within the thermal via on the remaining portion of the diamond nucleation layer so that diamond only grows in the thermal via and not on the planar portions of the substrate.

Abstract: Methods for forming a high-quality III-nitride passivation layer on an AlGaN/GaN HEMT. A III-nitride passivation layer is formed on the surface of an AlGaN/GaN HEMT by means of atomic layer epitaxy (ALE), either before or after deposition of a gate metal electrode on the AlGaN barrier layer. Depending on the gate metal and/or the passivation material used, the III-nitride passivation layer can be formed by ALE at temperatures between about 300° C. and about 850° C. In a specific embodiment, the III-nitride passivation layer can be an AlN layer formed by ALE at about 550° C. after deposition of a Schottky metal gate electrode. The III-nitride passivation layer can be grown so as to conformally cover the entire device, providing a hermetic seal that protects the against environmental conditions.

Abstract: A graphene base transistor with reduced collector area comprising an electron injection region, an electron collection region, and a base region wherein the base region comprises one or more sheets of graphene and wherein the base region is intermediate the electron injection region and the electron collection region and forms electrical interfaces therewith. A method of making a graphene base transistor with reduced collector area comprising forming an electron injection region, forming an electron collection region, and forming a base region wherein the base region comprises one or more sheets of graphene and wherein the base region is intermediate the electron injection region and the electron collection region and forms electrical interfaces therewith.

Abstract: A non-inverted P-channel III-nitride field effect transistor with hole carriers in the channel comprising a nitrogen-polar III-Nitride first material, a barrier material layer, a two-dimensional hole gas in the barrier layer, and wherein the nitrogen-polar III-Nitride material comprises one or more III-Nitride epitaxial material layers grown in such a manner that when GaN is epitaxially grown the top surface of the epitaxial layer is nitrogen-polar. A method of making a P-channel III-nitride field effect transistor with hole carriers in the channel comprising selecting a face or offcut orientation of a substrate so that the nitrogen-polar (001) face is the dominant face, growing a nucleation layer, growing a GaN epitaxial layer, doping the epitaxial layer, growing a barrier layer, etching the GaN, forming contacts, performing device isolation, defining a gate opening, depositing and defining gate metal, making a contact window, depositing and defining a thick metal.