Surface stability of InGaN-channel based HFETs

Kelvin probe microscopy in switching experiments was used to measure transients in the relative surface potential of GaN/InGaN/GaN-channel FETs to identify charge build-up at the surface between gate and drain. In contrast to conventional AlGaN/GaN-FETs the surface potential remains unchanged under the switching conditions employed. This is in agreement with the absence of the current and power slump effect in InGaN-channel devices. The reasons for the different behaviour to AlGaN/GaN FET structures are discussed.