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