Correlation Between Structural and Photo Electrical Properties of a-Si1−xGex:H Alloy Films - New Interpretation Concerning the Preferential Attachment of Hydrogen

Abstract

ABSTRACTa—Si1−xGex:H alloy films with 0 > × > 1 have been prepared by reactive co— sputtering (rf—magnetron) from separate targets. The preparation conditions which have been optimized for each composition x must be changed from a—Si:H—like (0 > × > 0.4) to a—Ge:H—like (× < 0.7) to obtain the best photoelectrical quality of the alloy material. The preferential attachment of hydrogen was quantitatively investigated by detailed ir—spectrometric studies. Its monotonic change with x is attributed to fundamental preferential attachment of hydrogen to silicon superimposed by a further preferential attachment to the respective minority alloy partner. The preferential attachment of hydrogen essentially influences the microstructure of the film and thus the material properties.