Effect of initial crystallized silicon layer on the properties of microcrystalline silicon grown by internal inductively coupled plasma-type plasma enhanced chemical vapor deposition

Using an internal inductively coupled plasma (ICP)-type-plasma enhanced vapor deposition system, microcrystalline silicon thin films were deposited as a function of H₂/SiH₄ gas ratio at 180 °C. Especially, the effects of deposition with/without an initial thin silicon layer formed with a very high hydrogen percentage on the microstructure of the deposited silicon thin film were investigated. The deposited silicon thin film showed higher crystallization percentage at the higher hydrogen percentage in H₂/SiH₄ due to the high ratio of H/SiH in the plasma. At the same gas mixture of H₂/SiH₄, the deposition of silicon thin film after the formation of an initial silicon layer with a high hydrogen percentage on the glass substrate increased the crystallization percentage from 3 to 14%. The initial silicon layer deposited with a high hydrogen percentage showed a nanocrystalline grain structure; therefore, the nanocrystalline structure in the initial silicon layer appeared to act as a nucleation site for the growth of microcrystalline silicon thin films. Using the internal ICP-PECVD, the microcrystalline silicon having about 87% of crystallization could be deposited on the glass substrate at 180 °C with the 90% of hydrogen dilution percentage and with the thin initial silicon layer.