Dynamics of band tail holes in amorphous As2Se3: direct measurement of hopping relaxation time

Abstract The temperature-dependent hopping relaxation-times are evaluated directly from the experimental data of ac photoconductivity measured between 20 and 300 K in evaporated amorphous As 2 Se 3 . The relaxation time is a constant, 5×10 −2 s, between 20 and 150 K and then decreases with increasing temperature to 5×10 −5 s at 300 K. The dependence of the transport energy on temperature is estimated by assuming exponential band tail states, is not consistent with that expected from the dc photoconductivity. The temperature variation of the diffusion coefficient estimated from ac photoconductivity is found to be similar to that of dc photoconductivity.