The influence of hopping on modulated photoconductivity

We have developed equations taking into account both multiple-trapping and hopping processes for describing transport phenomena in disordered semiconductors. These equations have been introduced into a numerical simulation to model the steady state dark conductivity and photoconductivity as well as the modulated photoconductivity. The influence of parameters such as the density of states and attempt-to-hop frequency on the results of these experiments has been investigated. Steady state and modulated photoconductivity experiments have been performed on a hydrogenated amorphous silicon film in the temperature range 18-300 K and the results have been compared with those from the numerical simulation. This comparison shows that the latter provides a suitable interpretation of the experimental behaviours observed in both experiments.