On the Variability of the Front-/Back-Channel LF Noise in UTBOX SOI nMOSFETs

The low-frequency noise has been studied in ultrathin-buried-oxide silicon-on-insulator nMOSFETs, analyzing the impact of different silicon film thicknesses and the front-/back-channel coupling. Significant device-to-device spread has been observed in the noise performance as well as in
$V_{\rm th}$
and
$\mu_{N}$
features, pointing out the influence of a nonuniform silicon film thickness that also affects the quality of the
$ \hbox{Si/SiO}_{2}$
interface. The occurrence of generation–recombination centers has been ascribed to traps present not only in the silicon film but also in the front/back oxide since the Fermi level can be swept over a large fraction of the band gap, owing to the higher electrical coupling between both interfaces.