Structural and Electronic Properties of Hydrogen-Passivated Silicon Quantum Dots: Density Functional Calculations

Density functional theory (DFT) by numerical basis-set calculations of silicon quantum dots (Si-QDs) passivated by hydrogen, ranging in size up to 1.9 nm are presented. These DFT computation results are used to examine and deduce the properties of 14 spherical Si-QDs including its density of state (DOS), and energy gap from the HOMO-LUMO results. The atomistic model of each silicon QDs was constructed by repeating crystal unit cell of face-centered cubic (FCC) structure, then the QDs surface was passivated by hydrogen atoms. The model was relaxed and optimized using Quasi-Newton method for each size of Si-QDs to get an ideal structure. Exchange-correlation potential (Vxc) of electrons were approximated in this system using the Local Density Approximation (LDA) functional and Perdew-Zunger (PZ) functional. Finally, all results were compared with previous experimental data and other similar theoretical approaches, and these results augured well