Strategy for off-current suppression in thin-film transistors

Field induced trap assisted band-to-band tunneling in poly-silicon thin-fil m transistors is studied using a two-dimensional model. Both the space depe ndence and the effect of graded doping are investigated. A graded doping pr ofile results in a moderate reduction in the current, while a much larger r eduction is achieved by increasing the thickness of the gate oxide near the drain region. In this way, the on/off ratio of the thin-film transistor sh ould be greatly improved.