On the a.c. conduction in evaporated SiO films

Abstract

It is now well established that the intrinsic bonding defects in amorphous SiO2 are normally charged (C1- with negative correlation energy and C3+ with positive correlation energy) and that they are different from those for amorphous chalcogenides. Intrinsic defects similar to those in amorphous SiO2 are expected to exist and contribute to a.c. conduction in amorphous SiO films. It is proposed here that the a.c. conduction in evaporated SiO films can be interpreted, using this model based on intrinsic bonding defects, in terms of correlated barrier hopping by single polarons (i.e. one-hole hopping between neutral and negatively charged defects). The expression obtained for the a.c. conductivity agrees with the experimental results. The densities of the defects are estimated from the model, and the results are supported by results from studies using ESR signals.