Thin-film coalescence in hydrogenated amorphous silicon probed by spectroscopic ellipsometry with millisecond-scale resolution

Abstract

New developments in spectroscopic ellipsometry (1.5\ensuremath{\le}h\ensuremath{\nu}\ensuremath{\le}4.3 eV) now provide quantitative information on thin films with a time resolution of 16 ms. We report submonolayer sensitivity to a surface smoothening effect associated with nuclei coalescence in the early stages of hydrogenated amorphous silicon (a-Si:H) preparation by plasma-enhanced chemical vapor deposition. An investigation of a-Si:H prepared on c-Si and Cr substrates under different conditions of substrate temperature and plasma power discloses a clear correlation between the magnitude of this effect and the ultimate bulk properties of the material.