Structural and optical investigations of nc‐Si:H thin films prepared by hot‐wire method

Structural and optical properties of hydrogenated nanocrystalline silicon (nc‐Si:H) films have been carefully studied as a function of hydrogen dilution of silane (⁠$RH.$⁠) Raman spectroscopic analysis showed that with increase in $RH,$ the crystalline fraction in the films increases whereas crystallite size remains almost constant (∼8.7 nm). Also, the Raman spectra shows a blue shift of transverse optic (TO) phonon mode indicating that the films are stressed and the induced stress is compressive. The FTIR spectroscopic analysis revealed that the hydrogen predominantly incorporated in $Si‐H2$ and $(Si‐H2)n$ bonding configuration. We have obtained high band gap (1.88‐2.07 eV) at low hydrogen content (< 2.5 at. %) over the entire range of $RH$ studied at reasonably high deposition rate (7.4‐9.5 Å/s).