RANDOM TELEGRAPH SIGNALS IN DEEP-SUBMICRON N-MOSFETS

Random telegraph signals (RTS) in the drain current of deep-submicron n-MOSFET's are investigated at low and high lateral electric fields. R TS are explained both by number and mobility fluctuations due to singl e electron trapping in the gate oxide. The role of the type of the tra p (acceptor or donor), the distance of the trap from the Si/SiO2 inter face, the channel electron concentration (which is set by the gate bia s) and the electron mobility (which is affected by the drain voltage) is demonstrated. The effect of capture and emission on average electro n mobility is demonstrated for the first time. A simple theoretical mo del explains the observed effect of electron heating on electron captu re. The mean capture time depends on the local velocity and the nonequ ilibrium temperature of channel electrons near the trap. The differenc e between the forward and reverse modes (source and drain exchanged) p rovides an estimate of the effective trap location along the channel.