Electrical and Optical Properties of Amorphous and Microcrystalline Hydrogenated Silicon Films Deposited Using Saddle Field Glow Discharge

Amorphous (a-Si:H) and microcrystalline (μc-Si:H) hydrogenated silicon films were obtained using DC saddle field glow discharge. The structure of the films was determined by Raman spectroscopy, SEM and TEM. The optoelectronic characteristics of both a-Si:H and μcSi:H were investigated using FTIR, UV/VIS spectroscopy, dark electrical conductivity (σd) and photoconductivity (σph) measurements. Boron and phosphorous doping of a-Si:H and μc-Si:H films was also investigated. The results show that both a-Si:H and μc-Si:H undoped films are highly resistive (σd=10-8-10-10 Ω-1cm-1). The doping efficiency of μc-Si:H films is much higher than a-Si:H films. The Tauc gap for a-Si:H was in the range 1.8-1.9 eV and for μc-Si:H films it was in the range 1.9-2.5 eV. The photoconductivity measurements of undoped films indicate a higher photosensitivity of a-Si:H films (σph/σd=104)than that of μc-Si:H films (σph/σd=10-100).