Leo Tarhay

Preparation of solar-grade amorphous silicon from fluorinated silanes☆

Abstract Fluorinated silane derivatives were synthesized and used as precursors for preparing amorphous silicon (a-Si) thin films in a glow discharge deposition reactor. In addition to intrinsic material, doped a-Si films were generated by gas phase admixture of diborane and phosphine to the precursor. Measurements of photoconductivity and the temperature dependence of dark conductivity were performed to characterize the films. Photoresponse, optical absorption and electron microscopy data were also obtained. Representative samples of a-Si:H:F prepared by glow discharge from difluorosilane show high photoconductivity in the range of 10 −4 S cm −1 (under simulated sunlight), whereas the dark conductivity (at room temperature) is typically 10 −8 S cm −1 . The mobility-lifetime product, derived from the photoresponse at 640 nm, reaches typical values of 2 × 10 −6 cm 2 V −1 .