High field and ac properties of steric acid films

Abstract

Electrical measurements are reported on multimolecular layer stearic acid films sandwiched evaporated metal electrodes, under high field dc conditions and small signal ac conditions over a wide range of frequencies down to 10^-4 Hz. Measurements were taken in the temperature range 105-373 K. DC measurements show the characteristic Poole's law dependence I varies as exp(esE/kT) where 2s is the distance between Poole centres, I is the current and E the field. The ac measurements give the ac conductivity sigma ( omega ) varies as omega ⁿ, where the exponent n tends to unity at low temperatures and to 0.5 at high temperatures. These results appear to be consistent with the behaviour expected of hopping carriers.