COHERENT-TO-INCOHERENT TRANSITION IN SURFACTANT-MEDIATED GROWTH OF INAS QUANTUM DOTS

In this letter, we present an atomic force microscopy study of a serie s of Te-mediated InAs/GaAs samples with InAs coverage ranging from 1.5 to 3 monolayers. We were able to directly identify the growth mode tr ansition and the mechanism of relaxed island formation. At the limit o f coherent growth mode, strained quantum dots aggregate, forming twin quantum dots (TQDs), which are structures of two, or more, dots virtua lly bonded together, separated by less than 3 nm. The onset of the inc oherent mode is then unambiguously characterized by the coalescence of individual TQDs forming initially small, and then larger, relaxed isl ands. (C) 1998 American Institute of Physics. [S0003-6951(98)00414-8].