Modeling the threshold voltage of ultra-thin-body(UTB) long channel symmetric double-gate (DG) MOSFETs

The authors define the threshold voltage of undoped-body UTB DG MOSFET as the gate voltage at which the mid-channel (center of the film) potential begins to saturate. A center potential based approach is proposed to determine the threshold voltage which is quite physical, as the centroid of the inversion layer charge is closer to the center of the silicon film for UTB devices of the film thickness range considered (1-20 nm). It is shown that this model is valid for both classical and quantum cases. Also, by using a rigorous numerical solution as the basis of the approach, they are able to obtain an accurate definition of the threshold voltage, taking quantum effects into account.