Semiconductor devices with doped regions functioning as enhanced resistivity regions or diffusion barriers, and methods of fabrication therefor

Abstract

A semiconductor device includes a base substrate, a doped region at an upper surface of the base substrate, and a transistor over the upper surface of the base substrate and formed from a plurality of epitaxially-grown semiconductor layers. The doped region includes one or more ion species, and has a lower boundary above a lower surface of the base substrate. The base substrate may be a silicon substrate, and the transistor may be a GaN HEMT formed from a plurality of heteroepitaxial layers that include aluminum nitride and/or aluminum gallium nitride. The doped region may be a diffusion barrier region and/or an enhanced resistivity region. The ion species may be selected from phosphorus, arsenic, antimony, bismuth, argon, helium, nitrogen, and oxygen. When the ion species includes oxygen, the doped region may include a silicon dioxide layer formed from annealing the doped region after introduction of the oxygen.