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

We employed the local p-doped region with a concentration of 3 x 10(16) cm(-3), 5 x 10(16) cm(-3) and 7 x 10(16) 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 (I-D) 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 x 10(16) cm(-3) in the back-barrier layer can reduce the peak electric field by 3.06 x 10(5) V/cm, so that the BV is increased by about 11%, when the maximum drain-current density (I-Dmax) 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 x 10(16) 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.