Performance limits of vertical GaN of conventional doped pn and natural polarization superjunction devices

We have determined and evaluated the specific on-resistance (Ron,sp) vs breakdown voltage (BV) trade-off limits of vertical GaN-based conventional doped pn superjunction (SJ) and natural polarization superjunction (PSJ) devices using analytical models and numerical simulations. We have obtained much better performance on the vertical natural polarization superjunction devices based on the AlGaN/GaN and AlInN/GaN heterostructures instead of the conventional superjunction devices with alternating doped p/n pillars. Our results show that the drift-region Ron,sp of vertical GaN-based superjunction devices is one to more than four orders of magnitude lower than the 1D limit of GaN conventional unipolar devices at the same BV. For 1 and 10 kV devices, the optimized specific on-resistance of the drift region is about 10 and 300 times lower for conventional superjunction devices, but 1000 and 20 000 times lower for natural polarization superjunction devices.