Highly Conductive and Wide Band GaP Microcrystalline Silicon Films Prepared by Photochemical Vapor Deposition and Applications to Devices

Abstract

Doped hydrogenated microcrystalline silicon (μc-Si:H) and fluorinated hydrogenated microcrystalline (μc-Si:F:H) films were prepared by the mercury photosensitized decomposition of a disilane-hydrogen or a difluorosilane-hydrogen gas mixture, respectively. The maximum dark conductivity and optical band gap of μc-Si:H films were respectively 20 S•cm−1 and ∼2.0 eV for n-type and 1 S•cm−1 and 2.3 eV for p-type. A higher dark conductivity as much as 50 S•cm−1 and a wide gap of 2.0 eV were obtained for n-type μc-Si:F:H. It is most significant that the gaseous ratio of hydrogen to disilane should be enhanced to obtain such a highly conductive and wide gap film. The crystallinity of the photo-deposited μc-Si:H films appeared to be improved in comparison with that of films by the conventional plasma glow discharge technique.