Electrical transport and noise in polyacene semiconductors

摘要

Measurements of electrical transport and excess current noise in semiconducting films of polyacenes revealed a superquadratic increase of the current and a sharp peak of the relative noise at voltage values corresponding to the trap-filling transition region. Recently, we formulated an explanation of these findings in terms of trapping and detrapping processes of the injected carriers by deep defect states. This interpretation was based on a phenomenologi-cal model that takes as input the measured I-V characteristic curve. Here we introduce a new percolative approach to transport and noise in these materials. In particular we develop two percolation models, differing in the voltage dependence of the trapping and detrapping rates: precisely, one model neglects and the other accounts for the Poole-Frenkel effect. We then discuss the results of both models in connections with experimental findings.