Insight into the effects of surface oxidation and carbonization on the electronic properties of silicon quantum dots and silicon slabs: a density functional study
In this work, we investigated the effects of surface backbond-oxygen oxidation and surface substitute-carbon carbonization on carrier recombination and transportation of 10-, 12- and 14 Å Si quantum dots (QDs). In general, surface oxidation lowered the density of states (DOS) near the Fermi level and induced the inward shift of the frontier-level isosurface, whereas surface carbonization induced the opposite effects. As indicated by the calculation, surface oxidation suppressed carrier recombination and carrier transportation, while surface carbonization enhanced it. Our further studies revealed that the effects of surface oxidation and carbonization were also applicable to Si slabs with different orientations. In summary, our work suggested that to dope a certain amount of oxygen into surface carbonized Si quantum-dots or Si bulk material might be a pathway to passivate surface defects by means of surface oxidation.