ABSTRACT
Silicon quantum dots have been intensively studied dating back to the 1980s. Stability of silicon nanostructures is important because a stable nanosized silicon cluster maintains its properties and functionality. Unsaturated silicon clusters cause the structural instability and the lack of crystalline tetrahedral, symmetry. Hydrogen, the simplest element in the periodic table, can passivate the dangling bonds of unsaturated silicon nanostructures. This chapter focuses on the studies of fully hydrogenated silicon nanocrystals and partially hydrogenated silicon nanoclusters. It addresses the ground state and excited-state properties of silicon nanoparticles. The reduced coordination of surface silicon atoms results in unsaturated dangling bonds which make the surface of the nanoparticles very reactive and unstable. The fully hydrogenated silicon surfaces are commonly believed to be inert or passive to other materials. Based on the study of the silicon nanoclusters, the fully hydrogenated silicon nanocrystals are the most stable structures compared to those of partially hydrogenated ones.
