Investigation on the Kink Effect in Poly-TFTs

Similarly to c-Si SOI devices, in the output characteristics of poly-TFTs at high drain voltages a rapid increase of the drain current occurs. In this paper we investigate the nature of this current increase and show that it can be explained by the action of a parasitic bipolar transistor in the back-channel region, which enhances the effect of impact ionization occurring at the drain junction.