Induced strain mechanism of current collapse in AlGaN/GaN heterostructure field-effect transistors

Gated transmission line model pattern measurements of the transient current-voltage characteristics of AlGaN/GaN heterostructure field-effect transistors (HFETs) and metal-oxide-semiconductor HFETs were made to develop a phenomenological model for current collapse. Our measurements show that, under pulsed gate bias, the current collapse results from increased source-gate and gate-drain resistances but not from the channel resistance under the gate. We propose a model linking this increase in series resistances (and, therefore, the current collapse) to a decrease in piezoelectric charge resulting from the gate bias-induced nonuniform strain in the AlGaN barrier layer. (C) 2001 American Institute of Physics.