Hi Eric,

You cannot directly deposit poly-Si by PECVD. Direct deposition using this
technique can get microcrystalline silicon (uc-Si:H) with SiH4 and H2
dilution. Without H2 dilution, it is amorphous silicon (a-Si:H). For
indirect method, after a-Si:H dep., you can use eximer laser annealing
(ELA) to recrystallize the film. Or, you can use post-dep (with or without
metal-induced) thermal annealing methods. If you want direct deposition of
poly-Si, you use thermal CVD methods, like LPCVD.

Yours sincerely,

Isaac Chan, Ph.D.
University of Waterloo