Recombination at high charge carrier concentrations in a-Si : H films

The recombination at high excess charge concentrations (higher than 10(18) cm(-3)) in a-Si:PI has been studied by comparison of the excess electron co ncentration obtained by contactless transient photoconductivity measurement s with numerical calculations. The first stage of the recombination process is described satisfactorily by a recombination between mobile excess elect rons and all excess holes. In later stages this simple model predicts a too high recombination rate. A better description has been obtained if the rec ombination rate parameter depends on the energy of the hole. (C) 2001 Elsev ier Science B.V. All rights reserved.