The enhancement of both direct-current (dc) and microwave characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) were demonstrated by conventional furnace annealing at 400 degrees C for 5 min. Due to the improvement in Ni/Au Schottky contact properties by furnace annealing, about 17%, 34%, 23%, and 25% of enhancements in maximum drain current density, maximum extrinsic transconductance (g(m max)), cutoff frequency and maximum oscillation frequency were observed, respectively. A positive threshold voltage shift and the increase in g(m max) can also be correlated to the improved Schottky parameters such as ideality factor and barrier height. The annealed devices exhibited low reverse gate-leakage-current by more than three orders of magnitude and low drain-leakage-current by two orders of magnitude. Correspondingly, the devices exhibited 55% of higher breakdown voltage after annealing. The furnace annealing is an effective and viable means to enhance both dc and microwave characteristics of AlGaN/GaN HEMTs.
2006. Vol. 88, no 2