n this paper, we investigate the effect of depletion and doping variation in the poly-silicon on the direct tunneling current of an ultra thin oxide n-MOSFET. The one dimension (1-D) poly silicon depletion effect has been analytically modeled. The tunneling probability is calculated by Wentzel—Kramers—Brilliouin (WKB) approximation. The results show a decrease in tunneling current density under poly depletion conditions and increase if the doping density in the poly increases. The results have also been compared with the numerically reported results which show good agreement.