Abstract
Using state of the art time-dependent density functional theory and multireference second-order perturbation theory, we have accurately calculated (within 0.3 eV) in real space the optical gap of small silicon quantum dots, with diameters up to 25 Å. Our results, which support the quantum confinement hypothesis, are in excellent agreement with recent and earlier experimental data on oxygen-free samples and the conclusions of Wilcoxon et al. [Phys. Rev. B 60, 2704 (1999)]. We have found that the diameter of the smallest dot, which could emit photoluminescence in the visible region of the spectrum, is around 22 Å. Our work can resolve existing controversies and bridge diverse experimental and theoretical results.
- Received 30 April 2001
DOI:https://doi.org/10.1103/PhysRevLett.87.276402
©2001 American Physical Society