title: High pressure growth of nanocrystalline silicon films.
abstract: Nanocrystalline silicon thin films were grown using gaseous mixture of 5% silane (SiH4) diluted in hydrogen (H2) and argon (Ar) in a radio frequency (13.56 MHz) plasma enhanced chemical vapor deposition technique. These films were deposited as a function of pressure and were characterized using AFM, Laser Raman, UV-VIS transmission, photoluminescence and electrical conductivity techniques. AFM micrographs shows that these films contain nanocrystallites of 30-60 nm size. Laser Raman peaks at 520 cm(-1) and photoluminescence peaks at 2.75 and 2.85 eV have been observed. The crystalline fraction in these films was varied from 30% to 80% with the variation of deposition pressure from 2 Torr to 8 Torr. There is an optimum pressure of 4 Torr where the maximum growth of nanocrystalline phases was observed. It has been found that nanocrystallites in these film enhanced the optical band gap and electrical conductivity. Also a voltage-current (V-I) probe was used to evaluate the various electrical parameters of the plasma used to deposit the nc-Si:H films for the present investigation. Growth via a SiH3 precursor, diffusion of hydrogen in the sub-surface and argon etching of weak bonds are some of the processes that may be involved in the nano crystallization process.
authors.affiliation: Plasma Processed Materials Group, National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012, India.
authors.forename: Sushil
authors.initials: S
authors.lastname: Kumar
authors.forename: Jhuma
authors.initials: J
authors.lastname: Gope
authors.forename: Aravind
authors.initials: A
authors.lastname: Kumar
authors.forename: A
authors.initials: A
authors.lastname: Parashar
authors.forename: C M S
authors.initials: CM
authors.lastname: Rauthan
authors.forename: P N
authors.initials: PN
authors.lastname: Dixit