Vertical GaN-on-GaN pn power diodes with Baliga figure of merit of 27 GW/cm(2)

High power vertical GaN devices are in great demand recently due to their potential on extremely high-power conversion efficiency. Here, we show vertical GaN p-n power diodes fabricated on bulk GaN substrates with an optimized guard ring structure for electrical field management and high breakdown voltage. By using a low doped (similar to 10(15) cm(-3)) 28 mu m thick drift layer in combination with optimized ohmic contacts, a breakdown voltage (V-B) of 4.9 kV and a low specific on-resistance (R-ON) of 0.9 m Omega cm(2) were achieved. In combination with the high breakdown voltage and low specific on-resistance, the device demonstrated a Baliga figure of merit (V-B(2)/R-ON) of 27 GW/cm(2).