Effective suppression of interface states in recessed-gate MIS-HEMTs by TMAH wet etching

Abstract

The effect of tetramethylammonium hydroxide (TMAH) treatment prior to gate dielectric deposition on the performance of recessed-gate AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) was investigated. By using of TMAH wet etching, low roughness etched surface of 0.173 nm was obtained. The capacitance-voltage characteristics of MIS heterostructures showed the interface states reduced by one order of magnitude. When temperature was increased to 473 K, the treated MIS-HEMTs delivered small threshold voltage shift (ΔVTH) of ~-0.53 V. From the dynamic measurement, ΔVTH obtained without treatment was observed more severely (~-1 V) when compared to the treated one (~-0.01 V).