The charge-pumping technique for grain boundary trap evaluation in polysilicon TFTs

Polysilicon thin-film transistor (poly-Si TFT) characteristics were evaluated by using the charge-pumping technique. The recombination current at the grain boundary traps is measured as the charge-pumping current in this technique. Therefore, the influence of the grain boundary traps is directly evaluated. It was confirmed that a large number of acceptorlike and donorlike traps exist at the grain boundaries in poly-Si TFTs. The trap density is derived from the pulse falltime dependence of the charge-pumping current. The influence of process temperature on trap properties is examined using the charge-pumping technique.<
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