Dispersive transport from negatively correlated defect centers

Abstract

The transient current response arising from time-of-flight experiments on a material whose trapping levels are predominantly associated with a well-defined negatively correlated defect is calculated. The resulting behavior is controlled by the relative magnitude of two characteristic times, the transit time, τ t, and the time necessary for interconversion of a neutral acceptor to a neutral donor, τ. If τ t < τ, nondispersive transport results. In contrast, if τ t > τ, two kinks characterize I( t). The current is initially independent of time, but eventually becomes dispersive, decaying as t −1 2 prior to τ t and as t −3 2 afterwards. The dispersion results from the spread of times necessary to interconvert the neutral defects.