Electrical hysteresis in p-GaN metal–oxide–semiconductor capacitor with atomic-layer-deposited Al₂O₃ as gate dielectric

The electrical hysteresis in current–voltage ( I – V ) and capacitance–voltage characteristics was observed in an atomic-layer-deposited Al 2 O 3 /p-GaN metal–oxide–semiconductor capacitor (PMOSCAP). The absolute minimum leakage currents of the PMOSCAP for forward and backward I – V scans occurred not at 0 V but at −4.4 and +4.4 V, respectively. A negative flat-band voltage shift of 5.5 V was acquired with a capacitance step from +4.4 to +6.1 V during the forward scan. Mg surface accumulation on p-GaN was demonstrated to induce an Mg–Ga–Al–O oxidized layer with a trap density on the order of 10 13 cm −2 . The electrical hysteresis is attributed to the hole trapping and detrapping process in the traps of the Mg–Ga–Al–O layer via the Poole–Frenkel mechanism.