OPTICAL INVESTIGATION OF THE SELF-ORGANIZED GROWTH OF INAS GAAS QUANTUM BOXES/

By studying the optical properties of highly strained InAs/GaAs multil ayers as a function of the deposited quantity of InAs, a high resoluti on probing of the change from two-dimensional to three-dimensionnal mo rphology of the InAs layers has been performed. We show that the criti cal thickness for the onset of three-dimensional growth is very well d efined for given growth conditions. The nucleation of the islands is, however, asynchronous, due to the spatial fluctuations of the deposite d quantity of InAs. A fast initial growth of the InAs islands leads wi thin a few seconds to a quasi-equilibrium morphology for InAs. Asynchr onous nucleation and fast initial growth combined are shown to be the major origin of the size fluctuations of InAs quantum boxes in GaAs ob tained by self-organized growth under standard molecular beam epitaxy (MBE) growth conditions.