Evidence of reduced interface states in Al2O3/AlGaN MIS structures via insertion of ex situ regrown AlGaN layer

Abstract

Abstract We report on the impact of the 3 nm thick ex situ AlGaN regrown layer prior to insulator deposition on the interfacial properties of Al2O3/AlGaN/GaN metal–insulator–semiconductor (MIS) structures. MIS-capacitors (MIScaps) with regrown AlGaN layer exhibited anomalously excessive threshold voltage shift compared to reference sample without regrown AlGaN, suggesting highly reduced interface states density (D it). Moreover, MIScaps with regrown AlGaN layer exhibited “spill-over” in the capacitance–voltage profiles, further evidencing the improved Al2O3/AlGaN interfaces. Fabricated three-terminal MIS-HEMTs with regrown AlGaN showed less hysteresis in transfer curves, enhanced maximum drain current, and increased linearity over the reference device.