Temperature-dependent electrical characteristics of bulk GaN Schottky rectifier

The temperature-dependent electrical characteristics of Schottky rectifiers fabricated with a $\mathrm{Si}{\mathrm{O}}_2$ field plate on a freestanding $n^{-}$ gallium nitride (GaN) substrate were reported in the temperature range of $298–473\mathrm{K}$ . The Schottky barrier heights evaluated from forward current-voltage measurement revealed an increase of Schottky barrier height and series resistance but a decrease of ideality factor $\left(n\right)$ with increasing temperature. However, the Schottky barrier heights evaluated from capacitance-voltage measurement remained almost the same throughout the temperature range measured. The Richardson constant extrapolated from $\ln (J_0∕T^2)$ vs $1∕T$ plot was found to be $0.029\mathrm{A}{\mathrm{cm}}^{-2}{\mathrm{K}}^{-2}$ . A modified Richardson plot with $\ln (J_0∕T^2)$ vs $1∕\mathit{nT}$ showed better linearity, and the corresponding effective Richardson constant was $35\mathrm{A}{\mathrm{cm}}^{-2}{\mathrm{K}}^{-2}$ . The device showed a high reverse breakdown voltage of $560\mathrm{V}$ at room temperature. The negative temperature coefficients were found for reverse breakdown voltage, which is indicative of a defect-assisted breakdown.