Influence of Structural Defects on Carrier Lifetime in 4H Epitaxial Layers, Studied by High Resolution Optical Lifetime Mapping
Thick 4H-SiC epitaxial layers have been characterized using high-resolution lifetime mapping. The lifetime maps are obtain by the detection of photoluminescence decay of the band gap emission. Full wafers mappings with 200 m resolution reveal lifetime variations that can be associated with structural defects replicated from the substrate, and variations in epitaxial growth conditions due to the susceptor design. High resolution mapping over smaller regions with down to 20 m step size, reveals local lifetime reductions associated with different structural defects in the epitaxial layer. Identified defects that influence the lifetime are the carrot defect, different types of in-grown stacking faults, and an unidentified defect associated with a pair of basal plane dislocations on the surface. Also clusters of threading screw dislocations, probably originating from a dissociated micropipe in the substrate, are found to reduce the lifetime.
Amador Pérez-Tomás, Philippe Godignon, Miquel Vellvehí and Pierre Brosselard
J. ul Hassan and P. Bergman, "Influence of Structural Defects on Carrier Lifetime in 4H Epitaxial Layers, Studied by High Resolution Optical Lifetime Mapping", Materials Science Forum, Vols. 615-617, pp. 255-258, 2009