Theoretical Analysis of a-Si:H Based Multilayer Structure Thin Film Transistors

In this paper we show that the experimentally observed increase in the field-effect mobility in superlattice TFTs can be accounted for by a simple classical model based on Poisson's equation, including the presence of interface states at every interface. The field-effect mobility enhancement is a direct consequence of the different potential and electric field distibutions among the various layers, if compared with a single layer structure with the same total active layer thickness. The results of the calculations fit well experimental data already reported. Furthermore, the analysis of the single layer structure shows a similar field-effect mobility enhancement, suggesting the reduction of the active layer thickness as a key factor.