A New Model for the $1/f$ Noise of Polycrystalline Silicon Thin-Film Transistors

An alternative model for the 1/f noise of polycrystalline Si thin-film transistors (poly-Si TFTs) is developed. The model adequately incorporates the grain boundary (GB) effect, different from previous work, however, the current noise is attributed to fluctuations in both carrier number and the GB barrier caused by carrier trapping/detrapping between the channel inversion carriers and the intragrain traps within the GB depletion region. The large dispersion of the trapping time constants in the 1/f noise behavior is attributed to the variation in carrier tunneling distance. The model fits the noise data very well in the low-drain current region. Based on the model, the effective density of states of the intragrain traps is obtained, providing a feasible method to evaluate the grain quality of poly-Si TFTs.