Modulated photocurrent as a powerful method to reveal predominant transport by the majority carriers of disordered semiconductors and to resolve all the kinds of probed gap states

A basic difficulty in the interpretation of photoconductivity measurements may arise from possible mixed contributions of both carriers to the photocurrent. In this work it is demonstrated that a universal behavior in the simulated spectra of the out of phase modulated photocurrent signal is observed in cases where the majority carriers dominate. In these cases, a general formula can be used to evaluate the densities of various species of states using the data from all frequencies. Deviations from the universal behavior can be observed when there are contributions from both carriers. The applicability of our analysis is demonstrated in a-Si:H.