INFLUENCE OF TRAPS ON THE CHARACTERISTICS OF THIN-FILM TRANSISTORS

In this paper we present numerical simulations, in good agreement with experimental data, of the characteristics and performance of a range of thin film transistors used in large area electronics. All these devices, whether fabricated from amorphous, micro or poly-crystalline silicon, have characteristics which are determined by the relatively high density of localized states or traps in the band gap of the material. Very good fits to the experimental data of the current-voltage characteristics of n-channel a-Si devices, as well as both n and p channel polycrystalline TFTs, are obtained by modeling all these materials assuming an effective medium approach. Finally we show how the traps have a strong impact on their bipolar bevaviour, in particular the "kink" effect of polysilicon TFTs and the photoconductivity of amorphous silicon devices.