Characteristiscs of Nanocrystalline Silicon films deposited by Cat-CVD below 100 °C

Nanocrystalline Silicon (nc-Si) films were deposited by catalytic chemical vapor deposition (Cat-CVD) at a low substrate temperature (100 °C) for use as an active layer in bottom-gate thin-film transistors (TFTs). Hydrogen dilution technique was attempted to increase the crystalline volume fraction (Xc). The hydrogen dilution ratio, R_H = [H₂]/[SiH ₄], was varied from 44 to 74. In order to obtain nc-Si film with a high XC, a thin incubation layer and a fast deposition rate simultaneously, we varied RH and pressure as the deposition proceeded. When the pressure was set to 50 mTorr during the initial stage and changed to 60 mTorr for the rest of the deposition, the incubation layer thickness was suppressed to 4 nm.