Spintronics attracts much attention because of the potential to build novel spin-based devices which are superior to nowadays charge-based microelectronic devices. Silicon, the main element of microelectronics, is promising for spin-driven applications. Understanding the details of the spin propagation in silicon structures is a key for building novel spin-based nanoelectronic devices. We investigate the surface roughness- and phonon-limited electron mobility and spin relaxation in ultra-thin silicon films. We show that the spin relaxation rate due to surface roughness and phonon scattering is efficiently suppressed by an order of magnitude by applying tensile stress. We also demonstrate an almost twofold mobility increase in ultra-thin (001) SOI films under tensile [110] stress, which is due to the usually neglected strain dependence of the scattering matrix elements. (C) 2015 Elsevier Ltd. All rights reserved.