High drain-current-density and high breakdown-field Al0.36Ga0.64N-channel heterojunction field-effect transistors with a dual AlN/AlGaInN barrier layer. (1st May 2022) - Inoue, Akiyoshi
Abstract : In this study, we fabricated and characterized heterojunction field-effect transistors (HFETs) based on an Al0.36 Ga0.64 N-channel heterostructure with a dual AlN/AlGaInN barrier layer. The device fabrication was accomplished by adopting a regrown n ++ -GaN layer for ohmic contacts. The fabricated HFETs with a gate length of 2 μ m and a gate-to-drain distance of 6 μ m exhibited an on-state drain current density as high as approximately 270 mA mm −1 and an off-state breakdown voltage of approximately 1 kV, which corresponds to an off-state critical electric field of 166 V μ m −1 . This breakdown field, as a comparison in devices without field-plate electrodes, reaches approximately four-fold higher than that for conventional GaN-channel HFETs and was considered quite reasonable as an Al0.36 Ga0.64 N-channel transistor. It was also confirmed that the devices adopting the dual AlN/AlGaInN barrier layer showed approximately one order of magnitude smaller gate leakage currents than those for devices without the top AlN barrier layer.