Influence of thermal noise on drain current in very small Si-MOSFETs

We investigate the intrinsic current fluctuations in very small Si-metal-ox ide-semiconductor field-effect-transistors (MOSFETs) using Monte Carlo devi ce simulation. It is demonstrated that the temporal fluctuation of the drai n current in small Si-MOSFETs attains a significant fraction of the average d drain current when the device width is scaled down to the deep sub-mu m r egime. This enhancement of current fluctuation is caused by the drastic dec rease in the number of channel electrons underneath the fate. It is also de monstrated that current fluctuation is physically associated with the quasi -equilibrium thermal noise in the heavily doped source and drain regions. M ore significantly, the current fluctuation is intrinsically unavoidable and could be a critical issue for further device shrinkage.