High-Temperature Characteristics of AlxGa1-xN-Based Vertical Conducting Diodes

Abstract

We investigated the high-temperature characteristics for AlxGa1-xN-based (x=0–0.57) vertical conducting diodes. In the forward current–voltage (I–V) characteristics, the offset voltage decreases with temperature because of the reduction of the built-in potential due to the decrease in the bandgap energy with temperature. In spite of an increase in SiC substrate resistance with temperature because of a decrease in the electron mobility, the on-state resistance of the diode with Al0.22Ga0.78N is as low as 1.45 mΩ cm2 even at 250 °C because of the reduced resistance of the p-InGaN layer due to an increase in the hole concentration. In the reverse I–V characteristics, the breakdown voltage increases with increasing Al composition, x, of AlxGa1-xN layer because the higher the Al composition of the AlxGa1-xN layer is, the higher the critical electric field becomes. Although the reverse leakage current of AlxGa1-xN-based diodes increases with increasing temperature, the breakdown voltage at elevated temperatures is similar to that at room temperature. These features indicate the feasibility of AlxGa1-xN-based diodes for high-temperature operation.