RTS Noise in MOSFETs: Mean Capture Time and Trap Position

RTS noise in MOSFETs is given by drain current fluctuation due to charge carrier capture and emission by a single active trap. From the drain voltage dependence of the ratio of capture tauC and emission tauE times the longitudinal trap position in the channel can be calculated. According to the Shockley-Read-Hall statistic, tauC is inversely proportional to the concentration of charge carriers n and in most noise papers, drain current ID is commonly supposed to be proportional to n and used to express concentration. Then we should expect tauC to decrease with increasing current, however, opposite dependence is usually experimentally found. In order to explain this discrepancy, we present a model of non-uniform charge carrier density distribution in channel with concentration decreasing towards the drain electrode.