The transition from generation–recombination noise in bulk semiconductors to discrete switching in small-area semiconductors

Abstract

Scaling down the dimensions of Metal–Oxide–Semiconductor​ Field-Effect Transistors (MOSFETs) evinces discrete switching usually referred to as random telegraph signal (RTS). Such RTSs are usually attributed to the capture and emission of charge carriers by a single active trap located in an oxide layer. Machlup calculated the noise spectrum caused by these charge carriers based on probabilistic arguments. In this paper, we derive Machlup’s noise spectrum differently: the g–r​ noise is attributed to a random succession of elementary g–r pulses. This enables g–r bulk noise to be interpreted in terms of the numbers of traps. The transition from g–r bulk noise to discrete switching is found by reducing the number of traps to just one single active trap. The resulting g–r noise spectrum is shown to be equivalent to Machlup’s noise spectrum. The probability of an overlap of succeeding g–r pulses is calculated. Such an overlap is attributed to occupation of an empty single trap by an electron transferred from a neighboring trap. We simulate a g–r pulse train and find a large variety of patterns similar to those observed in MOSFETs. Excluding overlapping g–r pulses, the up-and-down distribution of succeeding g–r pulses is estimated.