Probing electron trapping by current collapse in GaN/AlGaN FETs utilizing quantum transport characteristics

GaN is expected to be a key material for next-generation electronics due to its interesting properties. However, current collapse poses a challenge to the application of GaN FETs to electronic devices. In this study, we investigate the formation of quantum dots in GaN FETs under current collapse. By comparing the Coulomb diamond between standard measurements and those under current collapse, we find that the gate capacitance is significantly decreased under current collapse. This suggests that the current collapse changes the distribution of trapped electrons at the device surface, as reported in the previous study by operando x-ray spectroscopy. In addition, we show external control of quantum dot formation, previously challenging in an FET structure, by using current collapse.