Intervalley splittings of Si quantum wells

Intervalley splittings of Si quantum wells are studied using a multivalley effective mass theory and a finite element method. It is found that the contributions to the valley splitting mainly come from the quantum well interfaces and the external field. Especially the derivatives of the confinement potential which appears in the valley coupling Hamiltonian cause the periodic oscillation of the splitting with the well width. Theoretical predictions are in reasonably good agreement with the recent experimental observation of valley splitting in a SiO2 /Si/ SiO2 quantum well, which proves the validity of our approach.