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. Through the use of TMAH wet etching, a low roughness etched surface of 0.173 nm was obtained. The capacitance–voltage characteristics of MIS heterostructures showed that the interface states reduced by one order of magnitude. When the temperature was increased to 473 K, the treated MIS-HEMTs delivered a small threshold voltage shift (ΔV TH) of ∼−0.53 V. From the dynamic measurement, the ΔV TH obtained without treatment was observed more severely (∼−1 V) when compared to the treated one (∼−0.01 V).