Effect of Localized Interface Charge on the Threshold Voltage of Short-Channel Undoped Symmetrical Double-Gate MOSFETs

An analytical threshold-voltage model of short-channel undoped symmetrical double-gate metal-oxide-semiconductor field-effect transistors including positive or negative interface charges near the drain is presented. The threshold-voltage model is derived based on an analytical solution for the potential distribution along the channel in the subthreshold region. Both potential and threshold-voltage models are compared with the Atlas simulation results, with variables being the device dimensions, the interface-charge region length and the interface-charge density. A good agreement between the model and simulation results has been observed by calibrating as a constant parameter the gate voltage included in the position of the minimum potential and the carrier charge-sheet density at the potential minimum that is adequate to achieve the turn-on condition.