Design and Simulation of Enhancement-Mode Vertical Superjunction GaN HEMT with Improved Ron and Cut-Off Frequency

GaN-based vertical superjunction high electron mobility transistors (HEMT) are recent avenues for power transistors. In this work, an enhancement mode vertical superjunction GaN-HEMT with gradient doping (GDP-SJ HEMT) is proposed and analyzed. In the GDP-SJ HEMT, the n-pillar doping concentration increases in a gradient manner from top to bottom. Whereas the concentration of the p-pillar is uniform and equivalent to the doping of the middle of the n-pillar. By optimizing the device design and doping profile, the specific-on resistance (Ron,sp) of the device has been reduced from 5.0 mΩ-cm2 to 3.79 mΩ-cm2. To the best of our knowledge, the frequency performance of vertical SJ HEMT has not been documented in the literature. As a result, we also performed a frequency study. The cut-off frequency (fT) of the proposed device is 78 MHz and the maximum frequency (fMAX) is 71 MHz. The device optimization increases the fT by 89% i.e. 148 MHz and fMAX by 67% i.e. 119 MHz.