On the performance limits for si mosfet's: a theoretical study

Performance limits of silicon MOSFET's are examined by a simple analytical theory augmented by selfconsistent SchrödingerPoisson simulations. The oncurrent transconductance and draintosource resistance in the ballistic limit (which corresponds to the channel length approaching zero) are examined. The ballistic transconductance in the limit that the oxide thickness approaches zero is also examined. The results show that as the channel length approaches zero (which corresponds to the ballistic limit) the oncurrent and transconductance approach finite limiting values and the channel resistance approaches a finite minimum value. The source velocity can be as high as about 1.5 x 107 cm/s. The limiting oncurrent and transconductance are considerably higher than those deduced experimentally by a previous study of MOSFET's with channel lengths greater than 0.2 pm. At the same time the transconductance to current ratio is substantially lower than that of a bipolar transistor.