The effect of uniaxial stress on band structure and electron mobility of silicon

The band structure of silicon (Si) under arbitrary stress/strain conditions is calculated using the empirical nonlocal pseudopotential method. The method is discussed with a special focus on the strain induced breaking of crystal symmetry. It is demonstrated that under general stress the relative movement of the sublattices has a prominent effect on the conduction band masses. This displacement, which cannot be determined from macroscopic strain, is extracted from ab initio calculations. The transport properties of strained Si are investigated by solving the semi-classical Boltzmann equation using the Monte Carlo (MC) method. It is shown that the change of the electron effective mass induced by uniaxial stress has to be included in accurate models of the electron mobility.