Addressable photocharging of single quantum dots assisted with atomic force microscopy probe

Here we report on addressable photocharging of individual cadmium selenide quantum dots (QDs). The charging is a result of synergetic action of light and an atomic force microscope (AFM) probe. The probe squeezes the coating layer of QDs helping the photoelectron to tunnel to either conductive AFM probe or substrate. The charge can be induced on individual QDs by locating the QDs with AFM. The charges are stable in ambient conditions. These results may be of interest for QDs based sensors, memory, and solar cell applications. For instance, this method could provide recording information at a density of 1 Tb/ cm².