Electrophysical properties of polycrystalline diamond films deposited from an abnormal glow discharge

Abstract

Electrophysical properties of polycrystalline diamond films (PDF), deposited from the abnormal glow discharge, were obtained. The energetic and kinetic characteristics of surface dark and photoconductivity of PDF and their temperature, field and spectral dependences were investigated. Dominant carrier transport mechanisms, their type and the energetic spectrum of localized defect states were established. Current-voltage characteristics, photosensitivity and activation energy are determined by conductivity of PDF, which varies from 10{-14} to 10{-4} S depending on deposition conditions. Vacuum annealing of films up to 600-800 K stabilizes the electrical characteristics. Thermal stability of PDF properties higher than semiconductor films, deposited under nonequilibrium conditions by pulsed laser and ion ablation. PDF films not inferior on properties to films, obtained by alternative CVD methods. Electrical characteristics, mechanism of charge transport of PDF were caused by defects of different nature, the energetic levels of which are continuously distributed on energy in the band gap. Dominant n-type of activation conduction is complemented by hopping mechanism through the localized states distributed near the Fermi level with density 5.6x10{17}-2.1x10{21} eV{-1} cm{-3}. Trapping and recombination centers are heterogeneously distributed on grain boundaries.