Conduction, diffusion and noise of electrons in amorphous chalcogenides   at low electric fields
  The low-field electron diffusion, noise, and the conduction in amorphous chalcogenides are investigated by means of a Monte Carlo implementation of a full three- dimensional variable-range hopping transport model between localized states. Quantities like the carrier-velocity autocorrelation function, the noise power spectrum, the diffusion coefficient and the ohmic conductivity are obtained from numerical simulations at room temperatures and lower. Some interesting features of the linear-response regime typical of hopping transport are observed and discussed for the case of the amorphous Ge2Sb2Te5. 
Fabrizio Buscemi, Enrico Piccinini, Rossella Brunetti, Massimo Rudan,   and Carlo Jacoboni
cond-mat.mtrl-sci cond-mat.mes-hall physics.comp-ph