Raman scattering characterization of Ge-composition in bulk Si_(1-x)Ge_x with compositional variation

摘要

Raman scattering (RS) characterization has been made to determine the Ge-composition in crystalline bulk S_(1-x)Ge_x with compositional variation along the radial direction in round-shaped wafer. The Raman integrated intensity ratio (RIIR) of phonons is found to have radial compositional dependence in the experimental results. It is also found from the precise RS experiments that the shift in optical phonons is dependent on the composition and the residual strain due to the radial variation of composition. Using the RIIR of Si-Ge to Si-Si phonons, the compositions are evaluated along the diameter of the sample. Independently, the compositions are evaluated taking into account of strain effect in the shift of optical phonons and the energy band gap measured by optical transmission experiments. The results obtained from the two different methods are found to be in excellent agreement.