Photoassisted high-frequency capacitance-voltage characterization of the Si3N4/GaN interface

Abstract

A revised method to measure the interface state density of ${\text{Si}}_3{\text{N}}_4/\text{GaN}$ metal-insulator-semiconductor diodes is reported. The wide band gap of GaN suppresses hole generation at room temperature and consequently allows measurements in deep depletion. Using the method outlined in this paper, the total interface state density can be measured throughout the bandgap above the bias in deep depletion utilizing an above bandgap light source. We report a peak interface state density of $5.0\times {10}^{12}{\text{cm}}^{-2}{\text{eV}}^{-1}$ at $\sim 0.3\text{eV}$ using this procedure, whereas the Terman method reports a peak of $<2\times {10}^{11}{\text{cm}}^{-2}{\text{eV}}^{-1}$ for the same ${\text{Si}}_3{\text{N}}_4/\text{GaN}$ metal-insulator-semiconductor diode without illumination.