One-by-one trap activation in silicon nanowire transistors

TL;DR

This paper reports the observation of individual trap activation in silicon nanowire MOSFETs and introduces a new noise model that accounts for Coulomb repulsion effects, leading to significant noise reduction.

Contribution

It presents the first experimental evidence of one-by-one trap activation and proposes a new low-frequency noise theory for nanoscale FETs.

Findings

Trap activation is controlled by gate voltage.

Coulomb repulsion prevents simultaneous trap activation.

Noise reduction exceeds tenfold in nanoscale FETs.

Abstract

Flicker or 1/f noise in metal-oxide-semiconductor field-effect transistors (MOSFETs) has been identified as the main source of noise at low frequency. It often originates from an ensemble of a huge number of charges trapping and detrapping. However, a deviation from the well-known model of 1/f noise is observed for nanoscale MOSFETs and a new model is required. Here, we report the observation of one-by-one trap activation controlled by the gate voltage in a nanowire MOSFET and we propose a new low-frequency-noise theory for nanoscale FETs. We demonstrate that the Coulomb repulsion between electronically charged trap sites avoids the activation of several traps simultaneously. This effect induces a noise reduction by more than one order of magnitude. It decreases when increasing the electron density in the channel due to the electrical screening of traps. These findings are technologically useful for any FETs with a short and narrow channel.