Improved ultraviolet emission from reduced defect gallium nitride homojunctions grown on step-free 4H-SiC mesas

We previously reported 100-fold reductions in III-N heterofilm threading dislocation density achieved via growth on top of (0001) 4H-SiC mesas completely free of atomic scale steps. This letter compares the electroluminescent (EL) output of GaN pn junctions grown on top of 4H-SiC mesas with and without such steps. An average of 49% enhancement of the ultraviolet luminescence (380nm) was observed in step-free mesas over comparable “stepped” counterparts. Despite the intense EL from the step-free devices, significant leakage was observed through the periphery of the device, possibly due to the lack of GaN junction isolation processing.