First-Principles Study of Hot Electron Dynamics in Silicon Quantum Dots

In our earlier study on effects of surface passivation on a small silicon quantum dot, a unique relaxation behavior of hot electron was found when the surface was terminated with fluorine atoms. In this work, we examine effects of the quantum dot size as well as the effect of decoherence on the hot electron relaxation process. Hot electron dynamics in silicon quantum dots is investigated using first-principles electron dynamics simulations in the framework of the fewest switches surface hopping method. The study shows that the interesting surface passivation effect on the hot electron relaxation is already diminished when the dot size is increased to a few nanometers as typically synthesized in experiments. Our study also shows that decoherence plays an important role in determining the relaxation rate. We will also discuss effects of passivating the quantum dot surface with organic molecules.