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MM: Fachverband Metall- und Materialphysik

MM 44: Mechanical properties III

MM 44.4: Vortrag

Freitag, 30. März 2007, 13:15–13:30, H6

compatible composition profiles and critical sizes of alloyed quantum dots — •huiling duan — Institute of Nanotechnology, Forschungszentrum Karlsruhe, D-76133 Karlsruhe, Germany

The assessment of composition profiles and strains is important to both the identification of the dominant growth mechanisms and the modeling of the confining potential of alloyed quantum dots (QDs). We present first a compatibility equation for the misfit strains in alloyed QDs induced by the mismatch in the lattice constants or the thermal expansion coefficients of their alloying elements and show that it imposes some important restrictions on the alloy composition profiles. We then solve the strain field in embedded alloyed QDs induced by the nonuniform misfit strains. It is found that the induced field is uniform if the misfit strains satisfy the compatibility equation, but not otherwise. Finally, we consider the energy of nucleation of a circular prismatic dislocation loop to relieve the misfit strain and calculate the critical size of a dislocation-free alloyed QD. We show that this size is much larger when the alloy composition meets the restrictions imposed by the strain compatibility equation than when it does not.