Imaging of the electronic states of self-assembled InxGa1-xAs quantum dots by scanning tunneling spectroscopy

A combination of scanning tunneling microscopy and spectroscopy has been employed to directly image the charge density of the confined electronic states of In0.5Ga0.5As quantum dots produced by epitaxial Stranski-Krastanow growth. Room-temperature measurements have been made of intact, uncapped quantum dots, in a planar geometry. The tunneling current images have been compared with calculated tunneling current profiles and the observed tunneling current contrast has been associated with the localized quantum dot states and the delocalized wetting layer states.