Electron Transport Mechanisms in Nickel Schottky Barrier Contacts to Hydrogenated Amorphous Silicon

Abstract

ABSTRACTDark J-V characteristics of Ni Schottky diodes on a-Si:H films of various thicknesses were measured as a function of device temperature. Room-temperature photoconductivity and sub-bandgap absorption v. wavelength measurements of the intrinsic layers were also performed. Detailed numerical modelling was employed to determine the nature, density and energy distribution of sub- bandgap states. Best-fit modelling of photoconductivity, sub-bandgap absorption and dark JR-VR indicates that Nc=Nv=2.5×1020 cm-3, vR=2×106 cm/s, μn=33 cm2/V-s and μp=0.15 cm2/V-s for these films. It is found that a joint thermionic emission-drift/diffusion mechanism, as envisaged by Crowell and Sze, appears to be the most accurate picture of electron transport in Schottky diodes on intrinsic a-Si:H films.