Abstract
We report on Al0.65Ga0.35N/Al0.4Ga0.6N metal oxide semiconductor heterojunction field-effect transistor (MOSHFET) with high-k ZrO2 gate-dielectric deposited using atomic layer deposition process. As extracted from frequency dependent capacitance-voltage (CV) characteristics, the oxide gates resulted in an interfacial state trap density of ∼2 × 1012 cm−2. A comparative study, on the same material, shows the gate-leakage current of the ZrO2 MOSHFETs to be lower by five orders; their ON/OFF current ratio (∼107) to be higher by about four orders and their threshold voltage to decrease (less negative) by 3.5 V with respect to the Schottky gate devices.