It was recalled that 100-fold reductions in III-N heterofilm threading dislocation density, achieved by growth on top of (00▪1) 4H-SiC mesas completely free of atomic scale steps, had previously been reported. Here, the electroluminescence (EL) outputs of GaN pn junctions grown on top of 4H-SiC mesas, with and without such steps, were compared. An average of 49% enhancement of the ultraviolet luminescence (380nm) was observed in step-free mesas over comparable so-called stepped counterparts. Despite the intense electroluminescence 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.

Improved Ultraviolet Emission from Reduced-Defect Gallium Nitride Homojunctions Grown on Step-Free 4H-SiC Mesas. J.D.Caldwell, M.A.Mastro, K.D.Hobart, O.J.Glembocki, C.R.Eddy, N.D.Bassim, R.T.Holm, R.L.Henry, M.E.Twigg, F.Kub, P.G.Neudeck, A.J.Trunek, J.A.Powell: Applied Physics Letters, 2006, 88[26], 263509 (3pp)