Density of glow discharge amorphous silicon films determined by spectroscopic ellipsometry

Abstract

The dielectric function of thin-film hydrogenated amorphous silicon (a-Si:H) grown on fused silica at different substrate temperatures has been investigated by spectroscopic ellipsometry. An improved interpretation of the ellipsometric data is based on a tetrahedron model that takes into account the influence of hydrogen incorporation in the amorphous network. It is shown that the film density can be derived from an accurate data interpretation, whereas the maximum value of the imaginary part of the dielectric function ε2max and the void volume fraction are not proportional to the density of a-Si:H films.