Increased Schottky barrier heights for Au on n- and p-type GaN using cryogenic metal deposition

摘要

An enhancement of ～ 0.18 eV (an 18% increase) in Schottky barrier height was obtained for Au deposited at cryogenic temperatures on n-type GaN relative to conventional deposition at 300 K (barrier height of 1.0 eV). Enhancements of 0.04-0.11 eV were achieved for Au deposition on p-GaN under the same conditions. The increase in barrier height on n-GaN persists for annealing temperatures up to ～ 200 ℃. At higher annealing temperatures, both types of diodes show a deterioration in rectifying behavior. The reverse current of low temperature deposited diodes was approximately two orders of magnitude lower than conventional Au-GaN diodes. The ideality factor of the cryogenically processed n-type devices (～ 1.06) was similar to that for room temperature diodes (1.13). This simple process method has potential for improving output resistance and power gain and lowering gate leakage current and noise in GaN-based transistors.