Structure of amorphous silicon investigated by EXAFS

The local structure of amorphous Si (a-Si) formed by ion implantation has been investigated at the Si K edge with extended X-ray absorption fine structure spectroscopy (EXAFS). The first four cumulants of the interatomic distance distribution have been determined using the Cumulant method. The structural parameters (bondlength, coordination number and Debye-Waller factor) compared favorably to previous EXAFS investigations of a-Si prepared by sputtering methods, however, in the ion implanted case, no asymmetry was detectable in the radial distribution function for a-Si. The present results are in excellent agreement with recent high resolution X-ray diffraction measurements of a-Si, but were found to differ in regards the ion dose dependent structure of another Group IV semiconductor: a-Ge. Specifically, no ion dose dependence of the a-Si structural parameters were observed. (C) 2002 Elsevier Science B.V. All rights reserved.