Micro-Raman scattering study of strain induced by compositional variation in single crystalline Si_1-xGe_x discs

Micro-Raman scattering (MRS) study has been made to investigate residual strain in single crystalline Si_1-xGe_x discs. It is found that the residual strain is induced by the compositional variation along the radial direction of disc sample, although there is no strain when the composition is uniform over the disc sample. It is also found that the induced strain is relaxed near the edge of disc sample. The residual strain value is evaluated to be of the order of 10^-3 for the parabolic-like variation of composition ranged from 0.112 at the center to the 0.143 at the edge of the disc sample.