SCANNING-TUNNELING-MICROSCOPY AND SCANNING TUNNELING SPECTROSCOPY OF SELF-ASSEMBLED INAS QUANTUM DOTS

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