Longitudinal electron drift mobility of hydrogenated amorphous silicon/silicon nitride multilayer structures revealed by time-of-flight measurements

Electron drift mobility longitudinal to hydrogenated amorphous silicon/silicon nitride multilayer structures has been measured by the time-of-flight method. Transient photocurrent shows a clear kink corresponding to the transit time. The room-temperature electron mobility in multilayer structures is smaller by three or four orders of magnitude than that observed in bulk a-Si:H. The room-temperature electron mobility decreases with decreasing well layer width at constant layer thickness of 13 Å, while the activation energy of the mobility increases. The lifetime of electrons tends to increase when the well layer thickness is reduced.