Dimension scaling of low frequency noise in the drain current of polycrystalline silicon thin-film transistors

Experimental results of low frequency noise in polycrystalline silicon thin-film transistors (polysilicon TFTs) with varying gate dimensions (constant gate width W and varying gate length L) are presented. The power spectral density of the drain current fluctuations SI was found to depend linearly on the inverse of the effective gate area Ag,eff which is related to the gate area W×L and the number of grains present within the transistor channel. This result implies localization of the low frequency noise sources on the gate oxide-polysilicon interface and on the grain boundaries. The 1/Ag,eff scaling law must be taken into account for correct estimation of trap densities in polysilicon TFTs.