Electrical conduction mechanism in semi-insulating polycrystalline silicon films

Abstract

A scanning Auger microprobe (SAM) has been used to measure the equipotential lines and the potential profile across semi-insulating polycrystalline silicon (SIPOS) film structures, and the electron beam parameters required to prevent charging effects and to minimize beam current relative to sample current have been determined. The conduction process in these SIPOS films was related to Frenkel generation of carriers. This field-enhanced emission from a localized state results in a field-dependent current which is added to an ohmic current. The potential profiles obtained with the SAM are in reasonable agreement with those predicted by this model. The effects of potential screening by charge at the SiO2-SIPOS interface are discussed and related to location-dependent variations in the potential profile. A zero-field conductivity of 1.4×10−6 (Ω cm)−1 was obtained for our films.