Current-voltage and reverse recovery characteristics of bulk GaN p-i-n rectifiers

p-i-n rectifiers were fabricated on epitaxial layers grown on free-standing GaN substrates. The forward turn-on voltage, V-F was similar to5 V at 300 K and displayed a positive temperature coefficient. The specific on-state resistance (R-ON) was similar to5 mOmega cm(2) at 300 K, with an ideality factor of similar to2 and activation energy for low forward current density of similar to1.6 eV. This is consistent with carrier recombination in the space charge region via a midgap deep level. The figure-of-merit, V-B(2)/R-ON, where V-B is the reverse breakdown voltage, was 0.32 MW cm(-2). The reverse recovery time was less than or equal to600 ns at 300 K. The improved forward characteristics relative to previous heteroepitaxial p-i-n GaN rectifiers show the advantages of employing a GaN substrate to make a true vertical transport geometry device. (C) 2003 American Institute of Physics.