Electroreflectance spectroscopy of strained Si1-xGex layers on silicon

Electroreflectance spectroscopy was used to measure the direct transitions in strained Si1-xGex layers in the energy range from 3-6 eV. We were able to detect the transitions E(1), E(1) + Delta(1), E(0), E(0), E(0) + Delta(0), E(2)(X), E(2)(Sigma) and E(1)' for multiple samples with germanium concentrations from 12.5-28.1% for temperatures from 10-300 K. The transitions E(1) + Delta(1), E(0), E(0) + Delta(0), E(2)(Sigma) and E(1) were detected for the first time in attained Si1-xGex layers and it was also the first investigation of the temperature dependence of direct transitions id-strained Si1-xGex. Good agreement with theoretical calculations of strain shifts was found for the E(0) transition, while deviations occur for the E(1) transition.