HIGH CRYSTALLINITY POLY-SIXGE1-X AT 450-DEGREES-C ON AMORPHOUS SUBSTRATES

The composition variation and strutural properties of poly-SiGe thin f ilms prepared by Reactive Thermal chemical vapor deposition (CVD) with Si2H6 and GeF4 were investigated. Deposition of the films at 450 degr ees C was carried out with various gas flow ratios of Si2H6 to GeF4 on amorphous substrates such as glass plates and oxidized silicon wafers . The structural profiles of films were characterized by X-ray diffrac tion (XRD) and Raman scattering spectroscopies, scanning electron micr oscopy (SEA I) and transmission electron microscopy (TER;I). All films show high crystallinity and (220) prefered orientation. The mole frac tions of Si in the SixGe1-x films were estimated to be from 0.95 to 0. 05 for a, using Vegard's law for the XRD peaks. Crystallinity in the S i-rich films was affected by growth rate and was greatly improved at l ower growth rates. TEM observation revealed that high crystallinity wa s well established, even in poly-Si0.95Ge0.05 film, owing to direct po lycrystalline layer growth on the substrate surface.