1ST PRINCIPLES CALCULATION OF THE OPTICAL-PROPERTIES AND STABILITY OF HYDROGENATED SILICON CLUSTERS

Optical properties and stability of hydrogenated silicon clusters are investigated using density functional pseudopotential calculation. The dipole transitions between the band-edge orbitals are allowed, in contrast to the indirect gap in bulk silicon. Evolution of a small amount of hydrogen atoms enhances the dipole transition, increasing the photoluminescence intensity. Further dehydrogenation creates gap states due to dangling bonds, which may decrease the photoluminescence intensity via nonradiative recombination processes. The Stokes shift is also estimated by calculating the relaxed structure of the excited state within the local density approximation. (C) 1994 John Wiley & Sons, Inc.