Design and simulation of reverse-blocking Schottky-drain AlN/AlGaN HEMTs with drain field plate

In this paper, Schottky-drain reverse-blocking AlN/AlGaN HEMTs with drain field plate (FP) have been investigated by Silvaco-ATLAS tools. For HEMTs without FP, with the increase of Al mole fraction in AlGaN channel from 0 to 0.5, the reverse-blocking voltage increases from −158 V to −720 V. By using the drain field plate technique, a second electric field peak is introduced and the reverse-blocking voltage can be improved. Combined with the optimization of the SiN passivation thickness, optimal electric field management can be achieved to obtain the highest reverse-blocking voltage devices. Since HEMTs with different Al mole fractions possess different critical electric field values, the optimal SiN thickness are varied. With the increase of the Al mole fraction from 0 to 0.5, the reverse-blocking voltage increases from −510 V to −4500 V for HEMTs using drain FP and optimal SiN passivation thickness, and a high power figure-of-merit of 1.171 GW/cm2 is achieved. AlGaN channel HEMTs with Al mole fraction demonstrate great potential for power applications.