The frequency response of an inhomogeneous amorphous semiconductor

Abstract

Calculations are reported of the frequency response of an amorphous semiconductor in which potential fluctuations lower the conduction band edge in local regions of the material. The calculations are performed using a three-dimensional effective-medium method. For an exponential distribution of potential fluctuations with energy parameter k_BT₀ the calculations predict a power-law frequency response with exponent 1 — T/T₀ and a loss peak close to the transition from non-dispersive to dispersive behaviour. The calculations are consistent with, but more physically realistic than, those performed using a recent one-dimensional model. The results are in qualitative agreement with recently reported measurements of the response of intrinsic hydrogenated amorphous silicon.