Fig. 2
a 1/C 2 -V G characteristic on Al2O3/GaN MOS device measured at frequency of 1 MHz. The dashed dot line is the linear fitting of the linear part of the 1/C 2 -V G curve and the deviation from the linear slope as highlighted in the curves suggesting trap-dominated regions. b Two trap-dominated regions highlighted in the C-V G curve and marked with deep depletion and subthreshold region