Vertical GaN-on-GaN pn power diodes with Baliga figure of merit of 27 GW/cm2

Abstract

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 (∼1015 cm-3) 28 μm thick drift layer in combination with optimized ohmic contacts, a breakdown voltage (VB) of 4.9 kV and a low specific on-resistance (RON) of 0.9 mω cm2 were achieved. In combination with the high breakdown voltage and low specific on-resistance, the device demonstrated a Baliga figure of merit (V2B/RON) of 27 GW/cm2.