InAs quantum dots nucleation on (100) and anisotropic (631)-oriented GaAs substrates

Different mechanisms of adatoms nucleation are studied for the self-assembling of InAs quantum dots (QDs) on smooth and nanoscale faceted GaAs surface morphologies. The experiments were performed on GaAs(100) and GaAs(631), and prior to the arrival of InAs the GaAs surface morphology was intentionally altered by changing the growth temperature of the buffer layer, TBL. For the reflection high-energy electron diffraction (RHEED) analysis, an equilibrium interlayer mass transport model is proposed through which, the critical thickness (Hc) and the InAs diffusion length can be estimated. For InAs growth on (100) substrates the Hc did not show significant dependence on TBL, but the adatoms diffusion length slightly reduced as TBL increases, which is in agreement with the changes on QDs density as observed by atomic force microscopy (AFM). For samples grown on GaAs (631)-oriented substrates it was found that both the nucleation mode of InAs and the Hc depends on TBL. The changes are associated to the growth of InAs on GaAs surface faceted corrugation that allows the self-organizing InAs QDs along [-113].