Suppression of leakage currents in AlGaN/GaN HEMTs by optimizing the thermal ramping rate during the Ohmic RTP process

In this research, we investigated the effects of ramp rates in the rapid thermal annealing process (RTP) on the drain and the gate leakage currents in AlGaN/GaN High Electron Mobility Transistors (HEMTs) on silicon substrates. Varying the ramp rates during the Ohmic alloy process affect leakage currents by one or two orders of magnitude. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) analyses show that the AlGaN surfaces (composition, surface states, morphology) are modified due to thermal stress during RTP, which is one of the prime origins of the leakage currents in the devices.