Scanning tunneling spectroscopy of cleaved InAs/GaAs quantum dots at low temperatures

We investigate the electronic structure of cleaved InAs quantum dots that are embedded in GaAs by means of scanning tunneling spectroscopy at low temperatures. By using a structure containing arrays of quantum dots surrounded by p-type buffer layers, spatial mapping of the empty states shows the electronic structure of the conduction band states and reveals states lying at lower energy with an interfacial localization at the top of the dot. From the knowledge of the structural properties of the dots that are obtained from transmission electron microscopy experiments, tight-binding calculations of the electronic structure of cleaved dots are performed. The observed square of the wave functions for the different states are compared to the ones that are obtained by the tight-binding calculations.