Scanning tunneling microscopy and scanning tunneling spectroscopy of self assembled InAs quantum dots

We present cross-sectional scanning tunneling microscopy images and scanning tunneling spectroscopy results of InAs quantum dots grown on GaAs. The samples contain 12 arrays of quantum dots. The analysis of the scanning tunneling microscope images reveals the self-alignment of the dots as well as the different dot interfaces with the under- and overgrown GaAs layers. We measure the strain distribution along the [001] direction in the (110) plane. The roughness of the dot interfaces along the [(1) over bar 10] direction is also estimated and local spectroscopy of the dots evidences the electronic confinement (measured gap of 1.25 eV compared with 0.4 eV for bulk InAs). (C) 1998 American Institute of Physics.