A study on Al2O3 passivation in GaN MOS-HEMT by pulsed stress

This paper studies systematically the drain current collapse inAlGaN/GaN metal--oxide--semiconductor high electron mobilitytransistors (MOS-HEMTs) by applying pulsed stress to the device.Low-temperature layer of A1₂O₃ ultrathin film used as bothgate dielectric and surface passivation layer was deposited byatomic layer deposition (ALD). For HEMT, gate turn-on pulses inducedlarge current collapse. However, for MOS-HEMT, no significantcurrent collapse was found in the gate turn-on pulsing mode withdifferent pulse widths, indicating the good passivation effect ofALD A1₂O₃. A small increase in I_dd in the drainpulsing mode is due to the relieving of self-heating effect. Thecomparison of synchronously dynamic pulsed I_dd-V_dscharacteristics of HEMT and MOS-HEMT further demonstrated the goodpassivation effect of ALD A1₂O₃.