Analysis of trap states in AlGaN/GaN self-switching diodes via impedance measurements

Abstract

The presence of trap states in self-switching diodes (SSD) based on an AlGaN/GaN heterojunction has been identified by means of their AC characterization between 75 kHz to 30 MHz in a wide temperature range, from 80 K to 300 K. Measurements allow us to determine two different characteristic energies of the traps, 12 meV and 61 meV, being associated to a distribution of surface states and one discrete bulk trap, respectively. The impact of the trapping effects on microwave detection at zero-bias has also been analyzed in the same temperature range, the measured responsivity showing an unusual enhancement and a low-frequency roll-off at low temperatures.