Mathematical Modelling for Double-Gate MOSFETs

An analytical model has been developed to represent undoped symmetric double gate field effect transistors (DGFET). Simple 1D Poisson´s equation has been solved in the gate-to-gate direction. The solution gives direct expressions of potential profiles along the silicon thickness. It has been shown that, strong volume inversion of the channel can be achieved for silicon thickness of the order of 5 nm, resulting in enhanced current density. Surface potential and the lateral electric field profile along the channel direction have been calculated. Enhancement of the drain end electrical field values above the critical level has been correlated with the formation of the pinch-off region. A quasi 2D analysis has been used to find out the potential distribution in the silicon region. The expression has been used to relate the threshold voltage with device parameters. Agreement of threshold voltage roll-off criterion, as well as the silicon thickness dependence of the threshold voltage with simulation results has been observed.