Current crowding and 1/f noise in polycrystalline silicon thin film transistors

Here we investigate dc characteristics, impedance versus frequency, and low frequency noise. The effect of current distribution on 1/f noise in polycr ystalline silicon thin film transistors (TFTs) is discussed. We show that t he channel impedance versus frequency roll induces spectra that could be mi sinterpreted above a corner frequency in terms of a frequency index gamma i n 1/f(gamma) with gamma higher than 2. Moreover, ignoring the inhomogeneous current distribution leads to overestimation of the noise parameter. Where as it seemed evident that the noise in TFTs can be interpreted in terms of carrier number fluctuation, the noise parameter variation versus the gate b ias can be also understood in terms of mobility fluctuations by including t he potential barrier evolution. (C) 2001 American Institute of Physics.