The generation and evolution of defects in 4H-SiC pn junctions, due to carrier injection under forward bias, were investigated by means of synchrotron white-beam X-ray topography, electroluminescence imaging and KOH etching. The defects were Shockley stacking faults with rhombic or triangular shapes, bounded by partial dislocation loops with dislocation lines along Peierls valleys (<11•0>) or along the intersection of the basal plane which contained the fault and diode surfaces. The Burgers vectors of all bounding partials were of 1/3<10•0>-type. Among the 6 possible types of partial dislocation having these properties, only 2 were observed in the volume of the epitaxial structure. One was tentatively identified as being a 30° C-core [C(g) 30°] and second as being a 30° Si-core [Si(g) 30°] partial dislocation. Only one of them, proposed to be the Si(g) 30° partial, was observed to move and emit light under forward bias. The other type of bounding dislocation, C(g) 30°, remained stationary during current injection. Low-angle grain boundaries were observed to act as one of a number of possible nucleation sites for stacking faults.

Recombination-Enhanced Defect Motion in Forward-Biased 4H–SiC p-n Diodes. M.Skowronski, J.Q.Liu, W.M.Vetter, M.Dudley, C.Hallin, H.Lendenmann: Journal of Applied Physics, 2002, 92[8], 4699-704