Calculation of Optical Characteristics for Si 1-x GE x Alloy

In the framework of virtual crystal approximation using the empirical pseudopotential theory optical transitions of Si 1 -x Ge x have been calculated. The effects of hydrostatic and uniaxial stress, and alloy stoichiometry on the optical gaps were investigated. Since the mechanical stress and material composition affect the distinctive behaviour of different optical transitions it allows to put forward a spectral measurement technique for determination of crystal lattice strain and alloy parameter x simultaneously.