Electronic structure studies of plasma-deposited amorphous silicon

Amorphous Si :H films have been prepared, under highly controlled conditions, in a multipole d.c. discharge. The electronic state distributions have been determined by soft X-ray spectroscopy and the dielectric functions have been measured by spectroscopic ellipsometry. The results are compared to similar measurements performed on microcrystalline silicon. Comparisons between valence-band densities of states show that SinH+ m ion bombardment during'film growth, whatever the substrate temperature, results in a strong modification of local order, in the absence of large-scale microcrystallinity as fevealed by spectroscopic ellipsometry.