Preparation of Phosphorus Doped Hydrogenated Microcrystalline Silicon Thin Films by Inductively Coupled Plasma Chemical Vapor Deposition and Their Characteristics for Solar Cell Applications

Intrinsic and phosphorus-doped hydrogenated microcrystalline silicon (microc-Si:H) films were prepared using inductively coupled plasma chemical vapor deposition (ICP-CVD) method. Structural, electrical and optical properties of these films were studied as a function of silane concentration, ICP source power and PH3/SiH4 gas ratio. Characterization of these films from Raman spectroscopy and X-ray diffraction revealed that the conductive film exists in microcrystalline phase embedded in an amorphous network. The condition of electrical properties (sigma(d): approximately 10(-7) S/cm, sigma(ph): approximately 10(-4) S/cm) and activation energy (0.55 eV), satisfied with properties of intrinsic microc-Si:H, was obtained at 1200 W of ICP power and 2% of silane concentration, respectively. At PH3/SiH4 gas ratio of 0.09%, dark conductivity has a maximum value of approximately 18.5 S/cm and optical bandgap also a maximum value of approximately 2.39 eV. The deposition rate was not satisfactory (4.9 angstroms/s) at same condition.