Multi-gate FinFETs and ultra-thin silicon body SOI FETs are considered as perfect candidates for future technology nodes. Strong size quantization leads to a formation of quasi-two-dimensional subbands in carrier systems within thin silicon films The employed Hensel-Hasegawa-Nakayama k p Hamiltonian accurately describes the bulk structure tip to the energies of 0.5-0.8 eV and includes a shear strain component. Shear strain is responsible for effective mass modification and is therefore an important source of the electron mobility enhancement in ultra-thin silicon films. The influence of shear strain on the subband structure in thin silicon films is investigated. (C) 2009 Elsevier Ltd. All rights reserved