Low thermal budget V/Al/Mo/Au ohmic contacts for improved performance of AlGaN/GaN MIS-HEMTs

Abstract

We report on highly improved performance of Al2O3/AlGaN/GaN MIS-HEMTs using V/Al/Mo/Au metal stack as ohmic electrodes. Transfer length method (TLM) test structures using V/Al/Mo/Au metal stack annealed at temperature of 660 °C revealed highly linear current-voltage curves and smooth surface morphology. Compared with reference MIS-HEMTs using Ti/Al/Mo/Au annealed at standard RTA temperature of 880 °C, V-based devices exhibited less hysteresis of transfer curves and showed higher gate controllability of drain current, suggesting highly improved Al2O3/AlGaN interface. Measurements and analyses of capacitance-voltage characteristics of corresponding MIS-capacitors corroborated these findings. V-based ohmic contact could open new avenues towards enhanced GaN-based MIS-HEMTs performance.