Low temperature growth and structural characterization of nanocrystalline silicon films

Abstract

Growth of nanocrystalline silicon films at substrate temperatures below 210°C using SiCl 4/H 2 in a hot-wire chemical vapor deposition (HW-CVD) reactor is reported here. Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed to investigate the microstructure of the silicon films. TEM analyses reveal that nanocrystalline silicon film with grain sizes in a range 7–10 nm was deposited at a substrate temperature of 150°C. A 45-nm-thick amorphous interfacial layer was formed on the glass substrate prior to the nanocrystalline film. Raman scattering measurement determines that the deposition of nanocrystalline silicon film with a 90% crystalline fraction is achieved at 150°C. A nanocrystalline film with a 77% crystalline fraction is formed at a substrate temperature of 90°C. The advantages of this process and roles of Cl and H radicals in the formation of crystalline silicon films are discussed.