AMBIENT AFM OBSERVATIONS OF THE CRATER FORMATION IN INAS QUANTUM DOTSON GAAS(001) VICINAL SURFACES AFTER EVAPORATION IN UHV

We report on the first observation of the evaporation of InAs quantum dots (QDs) on the GaAs surface under moderate heating in UHV. InAs lay ers 2.3 ML thick were MBE-grown on GaAs (001) surfaces exactly oriente d and misoriented in the [010] direction and annealed at 350 degrees C in UHV without an As flux. Ambient AFM studies have revealed the form ation of craters in the center of InAs QDs grown on the GaAs surface. The inner walls of the craters show clear faceting along the main crys tallographic planes. Evaporation craters develop through the center of the QDs down to the GaAs substrate. Complete evaporation of the QDs l eaves the GaAs surface patterned with tiny wells at the former QD posi tions. A tentative explanation of the observed effects is given, takin g into account the strain distribution in the strained system of InAs QDs on the GaAs surface.