Photoionization spectroscopy in AlGaN/GaN high electron mobility transistors

Abstract

A model is developed to describe the light-induced restoration of the drain current from current collapse in AlGaN/GaN high electron mobility transistors. The model assumes that the collapse results from a transfer at large drain bias of hot carriers from the gate-drain region of the two-dimensional electron gas to deep traps in the high-resistivity GaN layer. Application of the model provides a means of determining the photoionization cross sections and the areal densities of the responsible traps. Where multiple trapping species are involved, it is shown that photoinduced transitions between trapping sites can significantly alter the response of the drain current to light illumination, and must therefore be taken into account. © 2002 American Institute of Physics.