Nondestructive characterization of dislocations and micropipes in high-resistivity 6H-SiC wafers by deep-level photoluminescence mapping

We demonstrated the effectiveness of deep-level photoluminescence (PL) mapping for nondestructive detection of dislocations and micropipes in high-resistivity 6H-SiC wafers. PL spectra of the wafers at room temperature were dominated by a broad band with a peak at 1.3 eV, which was traceable to the Si vacancy-related V1, V2, and V3 lines at 4.2 K. The intensity-mapping pattern agreed closely with the etch-pit pattern both on a wafer scale and on a microscopic scale. Large dark spots with one or two bright cores, small dark spots, and dark lines corresponded to micropipes, threading screw dislocations, and edge dislocations forming small angle grain boundaries, respectively. The intensity reduction around dislocations and micropipes was attributed to a decrease of the radiative centers for the 1.3 eV band, which occurred as a result either of the interaction between vacancies and dislocations or of the gettering effect of vacancy-related defects. (C) 2005 American Institute of Physics.