Analysis of the dispersive diffusion of atoms in disordered solids

In the theoretical analysis of dispersive transport, it is essential to take account of the actual initial conditions. In transient photoconductivity experiments, all the particles are initially in a transport state, but in those on atomic diffusion the atoms are often initially in thermal equilibrium at a temperature less than that at which the diffusion is measured. We show that the multiple-trapping model, which explains well the photoconductivity results, cannot account for those on the diffusion of H atoms in a-Si:H, for which it has often been proposed.