Electron confinement and optical enhancement in Si/SiO2 superlattices -: art. no. 195330

We have performed first-principles calculations of Si/SiO2 superlattices in order to examine their electronic states, confinement, and optical transitions, using linearized-augmented-plane-wave techniques and density-functional theory. Two atomic models having fairly simple interface structure are considered. They differ in the way dangling bonds at interfaces are satisfied. The real and imaginary parts of the dielectric function are calculated at the Fermi-golden-rule level and used to estimate the absorption coefficients. Confinement is demonstrated by the dispersionless character of the electronic band structures in the growth direction. Optical enhancement is shown to exist by comparing the direct and indirect transitions in the band structures with the related transitions in bulk Si. The role played by the interface on the optical properties is assessed by comparing the absorption coefficients from the two models.