The charge relaxation in an electron capture process on the continuously distributed gap states in a-Si:H has been analyzed. It is shown that a process of charge redistribution among the gap states occurs during a filling pulse, causing the thermal emission energy of the trapped electrons shift deeper into the mobility gap. For an exponential distribution of gap states, an electron’s thermal emission time is proportional to the filling pulse width. These results provide a natural explanation for the recently reported results on a junction capacitance transient experiment, which were attributed to a novel defect relaxation process.

• Received 21 June 1993

DOI:https://doi.org/10.1103/PhysRevLett.71.2979