Breakdown Voltage Enhancement in AlGaN HEMTs with Local p-Doped Region in the Back-Barrier

Abstract

We employed the local p-doped region with a concentration of 3 × 1016 cm−3, 5 × 1016 cm−3 and 7 × 1016 cm−3 in the back-barrier of full-AlGaN high electron mobility transistors (HEMTs). Further enhancement of the breakdown voltage (BV) with less influence on drain–current density (ID) is demonstrated. The 2D simulation results show that the BV increases with the doping concentration due to the weakening of the electric field. Compared with the traditional Al0.18Ga0.82N back-barrier structure, p-type doping with the concentration of 7 × 1016 cm−3 in the back-barrier layer can reduce the peak electric field by 3.06 × 105 V/cm, so that the BV is increased by about 11%, when the maximum drain–current density (IDmax) of the device is maintained at 717.8 mA/mm. Furthermore, the BV is closely connected to the geometric characteristics of the local p-doped region. The optimal distance between the doped region and the channel is found to be 150 nm for the doping concentration of 7 × 1016 cm−3. The length of the doped region and the distance between the region and the drain is also found to vary linearly with the BV of the device.