title: Highly conducting phosphorous doped Nc-Si:H thin films deposited at high deposition rate by hot-wire chemical vapor deposition method.
abstract: In this paper, we report the synthesis of highly conducting phosphorous doped hydrogenated nanocrystalline silicon (nc-Si:H) films at substantially low substrate temperature (200 degrees C) by hot-wire chemical vapor deposition (HW-CVD) method using pure silane (SiH4) and phosphine (PH3) gas mixture without hydrogen dilution. Structural, optical and electrical properties of these films were investigated as a function of PH3 gas-phase ratio. The characterization of these films by low-angle X-ray diffraction, Raman spectroscopy and atomic force microscopy revealed that, the incorporation of phosphorous in nc-Si:H induces an amorphization in the nc-Si:H film structure. Fourier transform infrared spectroscopy analysis indicates that hydrogen predominately incorporated in phosphorous doped n-type nc-Si:H films mainly in di-hydrogen species (Si-H2) and poly-hydrogen (Si-H2)n bonded species signifying that the films become porous, and micro-void rich. We have observed high band gap (1.97-2.37 eV) in the films, though the hydrogen content is low (< 1.4 at.%) over the entire range of PH3 gas-phase ratio studied. Under the optimum deposition conditions, phosphorous doped nc-Si:H films with high dark conductivity (sigma Dark -5.3 S/cm), low charge-carrier activation energy (E(act) - 132 meV) and high band gap (- 2.01 eV), low hydrogen content (- 0.74 at.%) were obtained at high deposition rate (12.9 angstroms/s).
authors: School of Energy Studies, University of Pune, Pune 411007, India.
authors: V S
authors: VS
authors: Waman
authors: M M
authors: MM
authors: Kamble
authors: S S
authors: SS
authors: Ghosh
authors: Azam
authors: A
authors: Mayabadi
authors: V G
authors: VG
authors: Sathe
authors: D P
authors: DP
authors: Amalnekar
authors: H M
authors: HM
authors: Pathan
authors: S R
authors: SR
authors: Jadkar
mesh_terms: D003460:Crystallization / Q000379:methods*; D004553:Electric Conductivity; D005740:Gases / Q000737:chemistry*; D006358:Hot Temperature; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008567:Membranes, Artificial; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D010758:Phosphorus / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D005740:Gases; D046911:Macromolecular Substances; D008567:Membranes, Artificial; D010758:Phosphorus; D012825:Silicon