FORMATION OF INAS GAAS QUANTUM DOTS BY MOLECULAR-BEAM EPITAXY - REVERSIBILITY OF THE ISLANDING TRANSITION/

We report a study of the dynamics of coherent island formation in InAs /GaAs films grown by molecular beam epitaxy. A comparison of the tempe rature dependence of the critical layer thickness for islanding betwee n the migration-enhanced and the continuous growth modes confirms that surface adatom diffusion and indium desorption are the controlling pr ocesses which determine the variation of the measured critical layer t hickness with temperature. We find that under conditions in which indi um desorption is significant, the islanding transition is reversible, which provides a new way to study the dynamics of the islanding transi tion. Applying this technique, we find that the size distribution of t he three-dimensional islands evolves into a bimodal distribution durin g the reverse process. (C) 1997 American Institute of Physics.