Melecular Dynamics Study of Stress Effects on Raman Frequencies of Crystalline Silicon

The effects of stress on the Raman frequencies of crystalline silicon are studied using molecular dynamics simulation, both for uniaxial stress along the [100] direction and for biaxial stress which is isotropic in the (001) plane. The Tersoff potential is used to represent the interaction among the silicon atoms. Simulation results showed that the stress causes the Raman frequencies to shift. The phenomenological coefficients which are needed to calculate the stress from the shifts of the Raman frequencies were obtained by comparing the simulation results with the dynamical equations for optical modes. The values obtained for the coefficients agreed well with the experimental values obtained by Chandrasekhar et al. [Phys. Rev., B17. (1978), 1623]. The obtained relationship between the uniaxial stress and the Raman frequency for vibration in the [001] direction also agreed well with the experimental result we obtained using microscopic Raman spectroscopy.