Anomalous Low-Frequency C-V Behaviour in Polysilicon TFTs

The inter-electrode capacitances and conductances of polysilicon devices are greatly influenced by the presence of the trap states; accurate numerical simulations of TFT devices show that the peaks exhibited by the low-frequency gate-to-source C-V and g-V curves in the subthreshold regime are associated to large fluctuations of the charge at the edge of the channel due to the trapping-detrapping by deep states; due to their high response time, such variations rapidly vanish at increasing frequencies.