Electrical effects of plasma damage in p-GaN

Abstract

The reverse breakdown voltage of $\mathrm{p-}\mathrm{GaN}$ Schottky diodes was used to measure the electrical effects of high density Ar or ${\mathrm{H}}_{\mathrm{2}}$ plasma exposure. The near surface of the $\mathrm{p-}\mathrm{GaN}$ became more compensated through introduction of shallow donor states whose concentration depended on ion flux, ion energy, and ion mass. At high fluxes or energies, the donor concentration exceeded ${10}^{19} {\mathrm{cm}}^{\mathrm{-3}}$ and produced p-to-n surface conversion. The damage depth was established as ∼400 Å based on electrical and wet etch rate measurements. Rapid thermal annealing at 900 °C under a ${\mathrm{N}}_{\mathrm{2}}$ ambient restored the initial electrical properties of the $\mathrm{p-}\mathrm{GaN}.$