High Performance Vertical GaN-on-GaN p-n Power Diodes With Hydrogen-Plasma-Based Edge Termination

This letter reports the first implementation of a hydrogen-plasma-based edge termination technique (HPET) in vertical GaN p-n power diodes grown on bulk GaN substrates using metalorganic chemical vapor deposition. The device with a 9-μm-thick drift layer exhibited a high breakdown voltage (V
_bd
) of 1.57 kV, a low ON-resistance (R
_ON
) of 0.45 mQ · cm
²
(or 0.70 mQ · cm
²
with current spreading considered) and a high Baliga's figure-of-merit (V
_bd
²
/R
_ON
) of 5.5 GW/cm
²
(or 3.6 GW/cm
²
) without passivation or field plate, which are close to the theoretical limit of GaN. This technique enabled a significant reduction in leakage current (-10
⁶
times at -300 V) and a huge enhancement in V
_bd
(from -300 V to 1.57 kV). Furthermore, the device showed good forward characteristics with a turn-ON voltage of 3.5 V, an ON-current of -2 kA/cm
²
(or 1.3 kA/cm
²
), an ON/OFF ratio of -10
⁹
, and an ideality factor of 1.4. This work shows the HPET can serve as an effective, low cost, and easy-to-implement edge termination technique for high voltage and high power GaN p-n power diodes.