Transverse-optical phonons excited in Si using a high-numerical-aperture lens

Abstract

We demonstrate excitation of transverse-optical (TO) phonons in a strained-Si on insulator (SSOI) by using a high-numerical-aperture oil-immersion lens. Using this technique, the TO phonons are excited, even under the (001) Si backscattering configuration. The wave numbers of the TO phonons in SSOI thus excited are different from that of the longitudinal-optical (LO) phonon. This result indicates the coefficients of Raman wave number shift and biaxial stress are different in the LO- and TO-phonon modes. The excitation of the TO phonons allows us to study stress tensors in Si.