Scaling size of the interplay between quantum confinement and surface related effects in nanostructured silicon

Si nanocrystals (NCs) embedded in a SiO2 matrix provide an exemplar curved nanostructured interface to evidence the competition between surface states and quantum confinement (QC) effects. The study of the energy band alignment as a function of NCs size (<5 nm) clarifies their interplay and identifies, with subnanometric resolution, three different regimes. Primarily QC affects the conduction band, then surface effects pin the conduction states, and finally QC starts to modify the valence band. A way to study how different nanoscale configurations compete with pure quantum properties is established.