Schottky barrier engineering in III–V nitrides via the piezoelectric effect

Abstract

A method for enhancing effective Schottky barrier heights in III–V nitride heterostructures based on the piezoelectric effect is proposed, demonstrated, and analyzed. Two-layer ${\mathrm{GaN/Al}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{N}$ barriers within heterostructure field-effect transistor epitaxial layer structures are shown to possess significantly larger effective barrier heights than those for ${\mathrm{Al}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{N},$ and the influence of composition, doping, and layer thicknesses is assessed. A ${\mathrm{GaN/Al}}_{\mathrm{0.25}}{\mathrm{Ga}}_{\mathrm{0.75}}\mathrm{N}$ barrier structure optimized for heterojunction field-effect transistors is shown to yield a barrier height enhancement of 0.37 V over that for ${\mathrm{Al}}_{\mathrm{0.25}}{\mathrm{Ga}}_{\mathrm{0.75}}\mathrm{N}.$ Corresponding reductions in forward-bias current and reverse-bias leakage are observed in current–voltage measurements performed on Schottky diodes.