Fluorine-Passivated Silicon Nanocrystals: Surface Chemistry versus Quantum Confinement

Abstract

The technological importance of silicon nanocrystals (Si NCs) largely originates from their remarkable optical properties. However, the detailed mechanisms for the optical behavior of Si NCs remain controversial. The controversy mainly centers on the interplay between quantum confinement and surface chemistry. By using a model system of fluorine (F)-passivated Si NCs in the framework of density functional theory, we demonstrate how both quantum confinement and surface chemistry impact the optical properties of Si NCs with sizes (diameters) 50%) increasingly enables the effect of surface chemistry to prevail over that of quantum confinement. For a very small Si NC (<1.4 nm) at ground state, however, the quantum confin...