Highly Efficient Rapid Annealing of Thin Polar Polymer Film Ferroelectric Devices at Sub-Glass Transition Temperature

An unexpected rapid anneal of electrically active defects in an ultrathin (15.5 nm) polar polyimide film at and below glass transition temperature (T _g) is reported. The polar polymer is the gate dielectric of a thin-film-transistor. Gate leakage current density (J _g) through the polymer initially increases with temperature, as expected, but decreases rapidly at T _g - 60 °C. After ≈2 min at T _g, the leakage is reduced by nearly three orders of magnitude. A concomitant observation is that the drain current (I _d)-gate voltage (V _g) hysteresis decreases with temperature, reaching zero at nearly the same temperature at which J _g collapses. As J _g drops further, the drain current hysteresis increases again but in the opposite direction. This combination strongly supports the interpretation of rapid defect annealing.