Effect of post-gate RTA on leakage current (I off) in GaN MOSHEMTs

Effect of post-gate rapid thermal annealing (RTA) on GaN metal-oxide semiconductor high electron mobility transistors (MOSHEMTs) performance has been investigated. For devices with 1-μm gate length and 10-μm gate width, a significant reduction of I offfrom 10 -4 to 10 -6 mA/mm (at V gs = -8 V, V d= 6 V) was observed after post-gate RTA at 600 °C, indicating an excellent ON/OFF drain current ratio (I on/I off) up to 10 8. The reduction of I offis mainly dominated by the decreased reverse-biased gate leakage current, as indicated by the strong dependence of I on/I off on reverse-biased gate leakage current. The reduced gate leakage after post-gate RTA probably stems from the increased gate barrier height as a result of gate metal reaction with Al 2O 3. The degradation in pulse I-V characteristics may be due to defect formation in devices during post-gate RTA at 600 °C. Nearly complete recovery was achieved by further post-gate RTA at 400 °C for 10 minutes