Anisotropic biaxial stress states in Si1xGex /Si mesa structures were evaluated by oil-immersion Raman spectroscopy. Using a high-numericalaperture lens, the electrical field component perpendicular to the surface, i.e., z-polarization, can be obtained. The z-polarization enables the excitation of the forbidden optical phonon mode, i.e., the transverse optical (TO) phonon mode, even under the backscattering geometry from (001)-oriented diamond-type crystals. The anisotropic biaxial stress evaluation of Si1xGex was considered difficult compared with that of Si, because many unknown parameters exist for Si1xGex , e.g., phonon deformation potentials (PDPs), the Ge concentration x, and the factor of Raman shift on x. In this study, PDPs and the Ge concentration in Si1xGex were investigated in detail. As a result, using precise PDPs and x, a clear dependence of anisotropic biaxial stress states in Si1xGex on the mesa structure shape was observed.
ASJC Scopus subject areas
- Physics and Astronomy(all)