Calculation of Surface Potential and Subthreshold Current in Short Channel Nano MOSFETs

Using an analytical model based on the solution of two dimensional Poisson''s equation، the exponential surface potential of two short channel n and p MOSFETs has been calculated and plotted. The surface potential shows considerable variation along the channel length of 1μm MOSFETs، and this behavior is attributed to short channel effects while it is constant in the same region for that of 3μm MOSFET. Then we have calculated the drain sub-threshold current and threshold voltage against channel length، showing that the threshold voltage decreases for short channel MOSFETs. Comparison between the calculated surface potential and the subthreshold current to the calculated results of other models presented in this work and the experimental data of an n channel MOSFET shows reasonable agreement among them.