The Linear Combination of Bulk Bands-Method for Electron and Hole Subband Calculations in Strained Silicon Films and Surface Layers

A generalization of the "Linear Combination of Bulk Bands" method for the calculation of the electron and hole subband structure including strain and spin-orbit interaction is presented. Using the full band structure obtained numerically with the empirical pseudopotential method it is demonstrated that, contrary to the effective mass approximation, the unprimed subbands with the same quantum number in a (001) thin silicon film are not equivalent. It is shown that shear strain modifies the subband effective masses and introduces a large splitting between the unprimed subbands. The generalized method provides accurate subband dispersions for holes demonstrating a large potential for applications.