Morphology of InAs self-organized islands on AlAs surfaces

We report an in situ molecular-beam epitaxy-scanning tunneling microscopy s tudy of three-dimensional (3D) self-organized InAs islands on AlAs surfaces . The evolution of the density and morphology of these islands is investiga ted as a function of the InAs coverage and substrate temperature. It is sho wn that the 2D island density is already high just prior to 3D island forma tion and remains constant for 3D structures as the InAs coverage is increas ed. This observation contrasts with the InAs/GaAs system and makes possible the growth of very high densities of small quantum dots. (C) 1999 American Institute of Physics. [S0003-6951(99)00329-0].