Investigation of low-frequency noise in nanoscale Schottky-barrier (SB)-based field-effect transistors (SB-FETs) is of prime importance due to its large amplitude in emerging bottom-up devices. In addition, noise can give additional information on charge transport mechanisms. In this paper, we study the 1/ f noise in nanoscale silicon-on-insulator SB-FETs. An unexpected feature is the clear contribution of the SB to the noise even if the barrier height is lower than 100 meV. Barrier modulation techniques such as dopant segregation are used to tune the barrier height. We propose a generic formulation for low-frequency noise that is applicable to any diffusive SB-FETs.