Dispersive diffusion controlled distance dependent recombination in amorphous semiconductors

TL;DR

This paper models dispersive diffusion and long-range tunneling in amorphous semiconductors to explain photoluminescence decay, deriving theoretical relations and comparing them with experimental data.

Contribution

It develops a theoretical framework for calculating reaction rates and survival probabilities for dispersive diffusion with long-range reactivity in amorphous semiconductors.

Findings

Derived the relation δ = α/2 + 1 for photoluminescence decay

Calculated tunneling recombination rates under dispersive diffusion

Compared theoretical rates with experimental photoluminescence decay data

Abstract

The photoluminescence in amorphous semiconductors decays according to power law $t^{-delta}$ at long times. The photoluminescence is controlled by dispersive transport of electrons. The latter is usually characterized by the power $alpha$ of the transient current observed in the time-of-flight experiments. Geminate recombination occurs by radiative tunneling which has a distance dependence. In this paper, we formulate ways to calculate reaction rates and survival probabilities in the case carriers execute dispersive diffusion with long-range reactivity. The method is applied to obtain tunneling recombination rates under dispersive diffusion. The theoretical condition of observing the relation $delta = alpha/2 + 1$ is obtained and theoretical recombination rates are compared to the kinetics of observed photoluminescence decay in the whole time range measured.