In Situ IR Absorption Study of H Bonding in a-Si:H Thin Films

Abstract
We have used real time, in situ infrared reflectance spectroscopy to study the evolution of Si-H bonding during the growth of hydrogenated amorphous silicon (a-Si:H) by dc magnetron reactive sputtering. The surface Si-H stretching mode (2100 cm-l) is observed in films 5 Å thick and the 2000 cm-l mode, which has been attributed to isolated monohydrides in the bulk, appears for thickness (d) < 10–15 Å For larger thicknesses the intensity of both modes increases approximately linearly. These trends are interpreted in terms of the nucleation and coalescence of islands for d> 15 Å followed by bulk-like growth.