Optimization of charge pumping technique in polysilicon TFTs for geometric effect elimination and trap state density extraction

Charge pumping (CP) technique is optimized to minimize the geometric component in the CP current in polysilicon TFTs, by taking into account the pulse waveform and its transition times. Based on the optimization, ideal CP curves similar to those in MOSFETs are obtained. Important information on the trap state density of polysilicon TFTs, i.e., the mean value as well as the energy distribution within the band-gap, can be reliably extracted in different ways.