The decay of photoconductivity in amorphous As₂Se₃ following repetitive-pulse excitation

Experimental results are presented for the decay of photoconductivity in amorphous As₂Se₃ following single-pulse, repetitive-pulse and steady-state illumination, at various temperatures. The observed decays are compared with calculations using a discretized density of band-tail states decaying exponentially into the band gap. The connection between the decays after repetitive-pulse and steady-state illumination is described. It is shown that agreement between calculation and experiment requires a band tail which extends deep into the band gap, and that the presence of a deep band tail can be inferred from measurements made on relatively short time scales.