ELASTO-OPTICAL CONSTANTS OF SI

The three independent components of the piezo-optical tensor P(ijkl)(o mega) have been determined in uniaxially stressed Si using rotating-an alyzer ellipsometry. This tensor, with only three complex independent components in the case of Si, links the changes in the real and imagin ary parts of the dielectric tensor DELTAepsilon(ij)(omega) to an arbit rary stress X = X(kl) [i.e., DELTAepsilon(ij)(omega) = P(ijkl)(omega) X(kl)]. Using the experimental values Of P(ijkl)(omega)), several rela ted functions and parameters were derived and compared with previous p iezoreflectance, ac-stress-modulated reflectivity, Raman spectroscopy work, and theoretical estimates. Deformation-potential constants for t he optical transitions between 3 and 4 eV were obtained using the elli psometric data. In addition, the different components of the piezoopti cal tensor were calculated using the empirical pseudopotential method and reasonable agreement between theory and experiment was found. Our data also clarify previous problems and errors in the existing literat ure.