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.