Effect of post‐gate RTA on leakage current (Ioff) in GaN MOSHEMTs

Abstract

AbstractEffect 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 Iofffrom 10‐4 to 10‐6 mA/mm (at Vgs = ‐8 V, Vd= 6 V) was observed after post‐gate RTA at 600 °C, indicating an excellent ON/OFF drain current ratio (Ion/Ioff) up to 108. The reduction of Ioffis mainly dominated by the decreased reverse‐biased gate leakage current, as indicated by the strong dependence of Ion/Ioff 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 Al2O3. 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. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)