Low interface trap density for remote plasma deposited SiO2 on n-type GaN

Metal-oxide-semiconductor capacitors were prepared with remote plasma-enhanced chemical vapor deposition of SiO2 at ∼300 °C on an n-type GaN epitaxial layer grown by atmospheric pressure metalorganic chemical-vapor deposition on a sapphire substrate. No hysteresis was observed in the high-frequency capacitance-voltage (C−V) measurements, and the measured C−V curve agreed with the C−V behavior calculated for an ideal oxide with the same flat-band voltage as the measured C–V curve. The absence of hysteresis and stretchout in the measured C–V curve and the increase of capacitance with incident ultraviolet light while in deep depletion suggest a low concentration of interface traps. These results demonstrate previous predictions of the absence of Fermi-level stabilization at the interface for the ionic crystal GaN.