Temperature and time dependent threshold voltage characterization of AlGaN/GaN high electron mobility transistors

Abstract

AbstractHigh electron mobility transistors (HEMTs) based on the AlGaN/GaN heterostructure were fabricated with treatments of either CF4 plasma or 19F+ implantation prior to gate deposition. The post‐treatment threshold voltage VT was shifted positively from ‐4.06 V to 0.25 V and ‐0.34 V, respectively. Subsequent 400 °C, up to 10 min furnace annealing increased the transconductance gm in both samples, leading to a two order of magnitude increase in drain current density. The implanted sample improved its VT to ‐0.16 V, whereas the VT of the CF4 plasma‐treated one reverted to ‐1.95 V. Annealing a commercial power HEMT (EPC1012, Efficient Power Conversion Corp.) under identical conditions resulted in stable VT within 1.4% (VT,Rated = 1.4 V). As the ambient temperature was increased to 150 °C, VT of our samples remained within 10% of the room‐temperature values. Reliability stress measurements were performed by applying a VSTRESS of ±1 V or ±2 V for up to 10 minutes. VT of EPC HEMTs increased with temperature and stress polarity, but remained close to specification up to the maximum rated temperature (125 °C) (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)