Regrowth dynamics of InAs quantum dots on the GaAs circular mesa

We report MBE regrowth of InAs quantum dots on GaAs circular mesas, prepared by optical lithography. Because of better strain relaxation, the possibility of quantum dots growth near the lithographic edge is high. Under controlled growth conditions, quantum dots appear only close to the edge. Under these conditions, we discuss the possible influence of crystal orientation to the quantum dots formation, as well as geometrical factors, such as the lateral size of the mesa, and the depth and steepness of the lithographic step. With the full control of the quantum dots formation, we measured the photoluminescence spectrum of the buried dots, as well as the real space image from a CCD camera. The results indicate that quantum dots only form at the edge. Besides the physical location, all the other parameters are quite similar to self-assembled quantum dots formed on planar surfaces.