INTERFACE BROADENING AND RAMAN SCATTERING IN SI1-XGEX/SI SUPERLATTICES

摘要

The dispersion curves and scattering efficiency of folded longitudinal acoustic phonons in semiconductor superlattices with broadend interfaces have been calculated by solving the elastic wave and diffusion equations simultaneously. The Raman spectra were measured from Si1-xGex/Si superlattices with different interface widths acid were analyzed in detail. The energy gap near the edge of the Brillouin zone is observed to shrink with interface width, in quantitative agreement with the theoretical calculation. Although the scattering intensity is a complicated function of superlattice structure, phonon branch index, and its wave vector, the change in intensity with interface width is similar to that predicted by a simpler model. The diffusion coefficient as a function of temperature and the activation energy for interdiffusion are derived by comparing the measured Raman intensities with the calculated results. [References: 23]