NUMERICAL-ANALYSIS OF POLY-TFTS UNDER OFF CONDITIONS

Polycrystalline silicon thin-film transistors (poly-TFTs) are getting increasingly important for applications in active-matrix flat-panel di splays (AMFPDs) and, more generally, for large-area electronics. As th e leakage current requirements of poly-TFTs for large area application s become more stringent, it is important to improve our understanding of the physical effects which originate it. The purpose of this work i s that of investigating the anomalous behaviour of leakage-currents in poly-TFTs by numerical simulation, taking into account the effect of energy-distributed traps and field-enhanced generation mechanisms. In what follows, we show that the off current is due to the concomitant e ffects of Poole-Frenkel, trap-assisted and band-to-band tunneling gene ration mechanisms, and that each of them may be important at different temperature and bias conditions. (C) 1997 Elsevier Science Ltd.