Characterization of Shot Noise Suppression in Nanometer MOSFETs

Shot noise contributes significantly to the drain current noise in short-channel MOSFETs. The transport of carriers at the source-side of the channel is dominated by diffusion, leading to shot noise. However, channel resistance introduces carrier scattering, which eventually causes suppression of shot noise. The degree of suppression is described by a scaling factor, known as the Fano factor. This paper presents a detailed experimental evaluation of the Fano factor for nanometer-scale MOSFETs across seven different technology nodes, ranging from 12 nm to 180 nm. The dependence of the Fano factor on device bias, gate length, and channel doping is studied. We find that it is a strong function of device bias when the MOSFET operates at or close to the minimum noise bias. We also find that it rises for shorter gate length devices and is dependent on channel doping. The dependence of the Fano factor on channel doping hints to possible temperature dependence.