Double-gate devices are best candidates for the MOSFET scaling down to the deca-nanometer range. The motivation of this work is to investigate the coupling effects in FinFETs and to extract the carrier mobility in each of the four possible channels. The coupling of the lateral, front and back interfaces is analyzed based on experimental results in FinFETs with various geometries. The influence of the substrate bias on the front and lateral surface potentials is especially emphasized. The back-gate action is minimized in ultra-narrow fins. Finally, the transport properties at each interface are presented and compared. The electron and hole mobilities are significantly lower on the fin edges than at the top and bottom interfaces. (C) 2003 Elsevier Ltd. All rights reserved.