Imaging and spectroscopy of artificial-atom states in core/shell nanocrystal quantum dots

Electronic wave functions in InAs/ZnSe core/shell nanocrystals were observed using imaging scanning tunneling microscopy. Images taken at a bias corresponding to the s conduction band state revealed that it is localized in central core region. It was found by the analysis of images taken at higher bias that p-state extends to the shell. Same results were observed by optical and tunneling spectroscopy. A similarity between the images and atomlike envelope wave functions of quantum dot was observed, where calculations were done within a particle in a box model.