Effect of structural parameters on the performance and variations of nanosizes PNIN tunneling field effect transistor

The characteristics of PNIN tunneling field effect transistor (TFET) with nanometer sizes are investigated using TCAD simulation. The results show that the performance and variations of the device strongly depends on the key parameters such as the thickness and the doping of the middle N layer. (1) An increase in the thickness of the N layer to ~5 nm will effectively enhance the drive current, reduce the electric field normal to the Si/SiO₂ interface (Ex), and reduce the variation of the threshold voltage induced by the variation in the N layer thickness. (2) A decrease in the thickness of Si film down to ~5 nm will also reduce Ex, but with minor effect on the on current. Therefore, the overall characteristic of PNIN devices improves with reducing the Tsi. (3) A proper doping such as ~2×10¹⁹ cm^-3 in the N layer can remove the dependence and therefore the variation of the threshold voltage on the thickness of Si film.