The a-Si:H and the μc-Si:H films were prepared by plasma enhanced chemical vapor deposition (PECVD). The deposition conditions were as follows. The a-Si:H films were deposited under 200℃, 30W, 0.7 torr and the μc-Si:H films were deposited under 200℃, 30W, 0.3 torr. Polycrystalline silicon films were formed by the recrystallization of μc-Si:H film and a-Si:H film. It took about 15 hours for the nucleation of the a-Si:H at 600℃. Crystallization was completed after 60 hours of annealing treatment. Any distinct change of morphology was not observed after 15 hours of annealing treatment at 650℃ for μc-Si:H. This means that the grain of as-deposited μc-Si:H films does not act as a seed. And crystallization was not complished even after 45h at 650℃. According to these results, it was concluded that μc-Si:H film was more difficult to be crystallized than a-Si:H. Different microstructure of μc-Si:H film may results in different solid phase crystallization(SPC) behaviors. From the micro- structure of μc-Si:H it was found that submicron size silicon crystallites were embedded in the amorphous silicon matrix. From the results of hydrogen evolution experiment, it was suggested that strong SiH and $SiH_2$ bondings mainly existed in silicon crystallite and weak $(SiH_2)_n$ bondings existed in amorphous matrix near the crystallite. During annealing treatment weak $(SiH_2)_n$ bondings were broken and hydrogen evolved. After H2 evolution the remained sites were so defective that it was difficult for silicon atom to rearrange. Since SiH or $SiH_2$ bondings were strong, the removal of H was difficult. It is supposed that the crystallization of μc-Si:H is hindered by the defective structure and/or the strong bondings between hydrogen and silicon. In fact, activation energy of hydrogen evolution for μc-Si:H and a-Si:H are 132.7 KJ/mole and 105 KJ/mole, respectively.
