Design space and origin of off-state leakage in GaN vertical power diodes

Variable-range-hopping through dislocations was identified as the main off-state leakage mechanism for GaN vertical diodes on different substrates. The behavior of leakage current for vertical devices as a function of dislocation density and electric field was derived by TCAD simulations, after careful calibration with experiments and literature data. Designed GaN vertical diodes demonstrate 2-4 orders of magnitude lower leakage current while supporting 3-5 times higher electric field, compared to GaN lateral, Si and SiC devices.