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Published online by Cambridge University Press: 25 February 2011
High purity epitaxial silicon samples, grown on indium doped and on ultrahigh resistivity silicon substrates, were analyzed for impurity content using photoluminescence spectroscopy (PL) and spreading resistance analysis (SRA). Calibrated SRA indicated typical net carrier concentrations of < 3×1012cm-3 in the epitaxial layers, and about 7×1011 cm-3 in the substrates. Impurities were identified by collecting highly resolved, very clean no-phonon and TO-phonon replica PL spectra at liquid helium temperatures. Spectra were taken on the substrate material alone and on substrates with epitaxy. Ga, As, A1, B and P contamination was evident in the epitaxy. Correlation of SRA and PL results on samples with various levels of contamination at the epitaxy substrate interface identified Al as the main interfacial impurity.