Fabrication of nano-crystalline silicon thin film at low temperature by using a neutral beam deposition method

Low temperature (<80 °C) neutral beam deposition (LTNBD) was investigated as a new approach to the fabrication and development of nano-crystalline silicon (nc-Si), which has better properties than that of amorphous silicon (α-Si). The difference between LTNBD and conventional PECVD is that the film formation energy of the nc-Si in LTNBD is supplied by controlled neutral beam energies at a low temperature rather than by heating. Especially, in this study, the characteristics of the nc-Si thin film were investigated by adding 10% of an inert gas such as Ne, Ar or Xe to SiH ₄/H₂. Increasing the beam energy resulted in an increase in the deposition rate, but the crystallinity was decreased, due to the increased damage to the substrate. However, the addition of a higher mass inert gas to the gas mixture at a fixed beam energy resulted not only in a higher deposition rate but also in a higher crystallization volume fraction. The high resolution transmission electron microscopy image showed that the grown film is composed of about 10 nm-size grains.