Structural characterization of oriented crystalline silicon film grown on SiO 2 , Sapphire, TiO 2 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 SiO 2 , ii) oriented TiO 2 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 SiH 4 :H 2 in the ratio 1∶20 at 400°C, followed by b) thickening step at 540°C, in which SiH 4 :H 2 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.