Floating body effects in polysilicon thin-film transistors

Floating body effects in polycrystalline silicon thin film transistors (poly-TFTs) are investigated by means of numerical simulations. The current increase in the output characteristics at large V_DS, usually referred to as the “kink effect” is explained by impact ionization occurring in the high-field region at the drain end of the channel. Its effect is enhanced by the action of a parasitic bipolar transistor in the back-channel region, whose base current arises from the impact generated holes. The dependence of the kink on the recombination kinetics is also investigated