ELECTRONIC-STRUCTURE INVESTIGATIONS OF SILOXENIC CLUSTERS AND FILMS

Calculations on two forms of siloxenic clusters and periodic films hav e been performed to address the unusual luminescence in porous silicon and to further investigate how the optical gap varies as a function o f hydroxyl- or hydrogen-passivator concentration. Within conventional approximations to the density functional theory, our optimized cluster calculations confirm that low-dimensional siloxenic complexes, of sto ichiometry [Si]:[O]:H] = 2:1:2, are most stable when the oxygen atoms form bridging bonds with pairs of silicon atoms. To aid in experimenta l characterization of siloxenic films, we present equilibrium geometri es, electronic structures, chemically induced core-level shifts, and j oint densities of states for two forms of siloxenic clusters.