Investigation of the effect of varying growth pauses on the structural and optical properties of InAs/GaAs quantum dot heterostructures

摘要

Effect of growth pause or ripening time on structural and optical properties of self-assembled InAs/GaAs quantum dot (QD) heterostructures grown by solid state molecular beam epitaxy (MBE) technique with two different growth rates of InAs (0.032 MLs~(-1) and 0.197 MLs~(-1)) has been investigated. The QD heterostructures were grown at 520 ℃ with InAs monolayer coverage of 2.7 ML The results were explained on the basis of high angle annular dark field scanning transmission electron microscope (HAADF-STEM), scanning electron microscope (SEM) and photoluminescence (PL) measurements. Introduction of growth pause leads the QD system towards a thermodynamic equilibrium state which in turn makes interesting changes on the morphology of the samples. Coagulation of some smaller dots occurs because of ripening to produce evolved QDs and the dot density reduces with growth pause.