THE INFLUENCE OF HYDROGEN SURFACE-REACTIONS ON THE GROWTH OF EVAPORATED A-SI-H FILMS

Thin a-Si:H films are deposited by a direct reaction of evaporated silicon with atomic hydrogen. It is shown that a definite ratio of the number of incoming Si and H atoms is necessary to obtain material without microstructure and with a clear dominance of diluted monohydride bonding configurations. An adequate hydrogen etching process has to take place at the surface of the growing film in order to produce high quality material by the evaporation technique. A steric model is presented which explains the selective etching of SiH//2 and SiH//3 bonding sites by atomic hydrogen.