Nanoscale depth-resolved cathodoluminescence spectroscopy (DRCLS) of Ni diode arrays on 4H-SiC epitaxial wafers revealed a striking correspondence between deep level defects and electrical transport measurements on a diode-by-diode basis. Current-voltage measurements display both ideal and non-ideal diode characteristics due to multiple barriers within individual contacts. Near-interface DRCLS demonstrates the presence of three discrete mid-gap defect levels with 2.2, 2.45, and 2.65eV emission energies whose concentrations varied on a sub-micron scale among and within individual diodes, correlating with barrier inhomogeneity. These results also suggested that SiC native defect levels could accounted for the maximum range of n-type barrier heights.

Defect-Driven Inhomogeneities in Ni/4H–SiC Schottky Barriers. S.Tumakha, D.J.Ewing, L.M.Porter, Q.Wahab, X.Ma, T.S.Sudharshan, L.J.Brillson: Applied Physics Letters, 2005, 87[24], 242106 (3pp)