Storage and release of buffer charge in GaN-on-Si HEMTs investigated by transient measurements

Abstract

This letter investigates the kinetics of the non-monotonic trapping mechanisms responsible for dynamic on-resistance (R DS,ON) in GaN-on-Si enhancement-mode HEMTs. We describe the time-dependences of electron trapping at carbon on the nitrogen site (CN) acceptors and for the first time we investigate the kinetics of the build-up of positive charge at the buffer/strain-relief layer interface. Part of the analysis is carried out on two-terminal ohmic devices, by a novel setup capable of measuring current transients (from 10 μs to 10 s) after stressing with a negative substrate bias.