Current collapse associated with surface states in GaN based HEMT's. Theoretical / experimental investigations

The effect of air/AlGaN and GaN/substrate polarization charges on the performances of GaN-based HEMTs have been investigated. We find that surface charges and, with a minor extend, GaN/substrate charges are responsible for the observed premature saturation of the dc output characteristics. Moreover, our work show that the polarization charges and holes trap appear as the source of the drain current collapse observed in GaN-based HEMTs