Excess charges in semiconductor nanocrystallites

摘要

The authors explore in this report the effects of excess electrons on the edge of the absorption spectrum of small semiconductor particles. The presence of these charges leads to strong bleaching of the absorption at the exciton region and to slight enhancement of the absorption on both sides of the bleaching. They show that the effect is independent of the origin of the charge; it occurs whether the charge is injected into the particle or only attached to its surface, and it appears even when the charge is deeply localized within the band gap. They conclude that the effect arises from the electric field associated with the charge and not from its presence in the band.