An analytic model for calculating trapped charge in amorphous silicon

We present a simple analytic model for calculating the trapped‐charge density as a function of free‐carrier concentration for realistic density‐of‐states distributions in hydrogenated amorphous silicon. This is necessary to understand the behavior of amorphous silicon devices as their characteristics are largely determined by the high concentration of charge trapped by the localized stages in the band gap. Such a model is useful as an aid in exploring the nature of the charge‐trapping process and for the efficient numerical simulation of amorphous‐silicon devices such as thin‐film transistors.