Analysis of electrical characteristics of polycrystalline silicon thin-film transistors under static and dynamic conditions

Polycrystalline silicon TFT technology is rapidly emerging for large-area electronic applications, because of the relatively large mobility values of charge carriers with respect to the corresponding values in amorphous silicon. In contrast, because of the complex energy distribution of localized states within the energy gap, and the resulting space-charge effects, the TFT electrical characteristics are difficult to model, and a numerical approach is needed in order to better understand the physical effects which influence the device performances. In this article we perform numerical simulations of TFTs at different temperatures under static and dynamic conditions and, by fitting experimental data, extract the energy distribution and the capture cross-section of the grain-boundary traps and the parameters of the impact-ionization model. As opposed to single-crystal silicon SOI devices, we find that the TFT current and transconductance increase as temperature increases. (C) 1997 Elsevier Science Ltd.