Analysis on Trap States in p-Metal-Oxide-Semiconductor Capacitors with Ultraviolet/Ozone-Treated GaN Interfaces Through Frequency-Dispersion Capacitance-Voltage Measurements

Abstract

The trap states at ultraviolet/ozone (UV/O-3)-treated Al2O3/GaN interfaces of p-type metal-oxide-semiconductor capacitors (pMOSCAPs) are analyzed through a frequency-dispersion capacitance-voltage (C-V) measurements. X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy are applied to confirm a formation of ultrathin oxide layer (Ga2Ox) on GaN surface by the UV/O-3 treatment. The trapped charge density and interface trap density improved from 7.30 x 10(11) to 2.79 x 10(11) cm(-2) eV(-1) averaged over the bandgap of GaN and from 1.28 x 10(13) to 4.08 x 10(12) cm(-2) eV(-1) near the conduction band edge of GaN, respectively, owing to the passivation of Ga2Ox layer at the Al2O3/GaN interfaces. Mechanism for the improved trap states in pMOSCAPs is identified based on the reduced defect states at both Al2O3/Ga2Ox and Ga2Ox/GaN interfaces.