Determination of density of localized states in a-Si : H from the time relaxation of space-charge-limited conductivity

A new technique is described, which is suitable for the evaluation of the b ulk density of localized states in undoped a-Si:H from the time relaxation of the conductivity limited by the space charge prepared by a previous inje ction of electrons. Time relaxations of the conductivity were measured for different values of bias applied across an n(+)-i-n(+) device with thick un doped layer. The density of states determined from the measured data was co mpared with that extracted from the steady-state space-charge-limited curre nt (SCLC) characteristics.