UNRAVELING THE MU-TAU-MYSTERY IN A-SI-H

The mu-tau-mystery is the large difference between mobility-lifetime products (mu-tau) in a-Si:H estimated from steady-state photoconductivity and transient photocharge measurements. We discuss whether this effect can be attributed to deep-trapping of electrons and subsequent re-emission prior to recombination. We present a simplified version of the re-emission model which shows that its principal assumptions can be checked using photocharge measurements over a sufficiently large time range. Measurements of the transient photocharge in a-Si:H are presented between 10(-8) and 10(2) s; the measurements show the same features as the re-emission model, and permit the characteristic emission time to be measured.