Structural characterization of oriented crystalline silicon film grown on SiO2, Sapphire, TiO2 and Nickel Substrate by Hot Wire Chemical Vapour Deposition

We have investigated the possibility of growing oriented crystalline silicon films, 2 to 3 micron thick, from silane-hydrogen mixture, by hot wire chemical vapour deposition (HWCVD). Several substrates i) amorphous SiO₂, ii) oriented TiO₂ layer on glass, iii) textured nickel-5% tungsten metal strip, and iv) crystalline sapphire have been used in this work. The growth is performed in two stages; a) nucleation step using dilute mixture SiH₄:H₂ in the ratio 1:20 at 400°C, followed by b) thickening step at 540°C, in which SiH₄:H₂ ratio is gradually enhanced to 8:20. The nucleation step promotes directional growth and leads to (220) oriented thick layers. Several characterization techniques, scanning electron microscopy (SEM), x-ray diffraction (XRD) have been used for structural investigations such as preferred crystal orientation, grain size, grain shape and surface topography.