Hopping conduction and the continuous-time random-walk model

摘要: The results of calculations the short-time and infinite-time hopping conductivity model disordered systems are used as basis a critical examination single-site approximation scheme (SSA) that has been employed extensively to study time-dependent transport phenomena in insulators. Scher Montroll theory dispersive transport, which successfully interpret transient photoconductivity experiments, invokes this identify problem with continuous-time random walk on an ordered lattice. Present indicate that, while SSA yields exact limit, it underestimates, sometimes seriously, long-time or dc conductivity. In particular, decay function time mean drift velocity photoexcited carriers through narrow band localized states is considered here. Lower bounds placed often far larger than smallest predicted by SSA. implications failure for interpretation experiment also discussed.