DIELECTRIC-CONSTANTS OF SILICON QUANTUM DOTS

Quantum mechanical pseudopotential calculations of the absorption spectra and static dielectric constant epsilon(s) of Si quantum dots with approximately 100- 1300 atoms are presented. The predicted epsilon(s) is found to be significantly reduced relative to the bulk value, but is considerably larger than the value deduced from currently available model calculations. A convenient parametrization of epsilon(s) vs size R is provided. We find that for quantum dots with R < 20 angstrom the electron-hole pair is confined by the physical dimension of the dot, not by the Coulomb attraction.