Abnormal Output Characteristics of p-Type Low Temperature Polycrystalline Silicon Thin Film Transistor Fabricated on Polyimide Substrate

We report on an abnormal output characteristics in p-type low temperature polycrystalline silicon thin-film transistors fabricated on polyimide (PI); negative differential conductance behavior is often observed in saturation region of drain current from large width devices. To understand such abnormal output characteristics, device dimension dependence was studied in a systematic way. As a result, we found that enhanced self-heating is mainly responsible originating from the poor thermal conductivity of PI substrate. A related degradation model is also proposed.