Optimal size regime for oxidation-resistant silicon quantum dots.
First-principles computations have been carried out to predict that appropriately terminated silicon quantum dots with diameters in the range of 1.2-2 nm will offer a superb resistance to oxidation. This is because surface treatments can produce dangling bond defect densities sufficiently low that dots of this size are unlikely to have any defect at all. On the other hand, these dots are large enough that the severe angles between facets do not expose bonds that are vulnerable to subsequent oxygen attack. The absence of both surface defects and geometry-related vulnerabilities allows even very short passivating ligands to generate an effective barrier, an important consideration for charge and exciton transport within quantum dot assemblies. Our computations, which employ many-body perturbation theory using Green functions, also indicate that dots within this size regime have optical and electronic properties that are robust to small amounts of inadvertent oxidation, and that any such oxygen incorporation is essentially frozen in place.
Department of Physics, Colorado School of Mines, Golden, Colorado 80401, United States.
Huashan
H
Li
Mark T
MT
Lusk
Reuben T
RT
Collins
Zhigang
Z
Wu
D003198:Computer Simulation; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010316:Particle Size; D045663:Quantum Dots; D012825:Silicon / Q000737:chemistry*
D012825:Silicon