The roles of atomic hydrogen played in "the chemical annealing" for fabrication of a-Si:H

A systematic study has been performed to reveal the role of atomic hydrogens in "chemical annealing", where the deposition of thin layer and treatment with atomic hydrogen are repeated alternately for fabrication of a stable structure. Relaxation resulting from impingement of atomic hydrogen on the growing surface are distinguished into two pieces, viz., relaxation on the surface and the sub-surface depending on the conditions for deposition of thin layer and the flux of atomic hydrogen. The structural changes within the sub-surface resulted in either formation of wider gap films or crystallization at rather low substrate temperature (Ts:100-150 C). At high Ts, on the other hand, the structural relaxations are mainly promoted on the growing surface, resulting in formation of the narrower optical gap a-Si:H and stimulating the grain growth.