Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 22: Epitaxie und Wachstum I
O 22.4: Vortrag
Dienstag, 25. März 2003, 15:45–16:00, FOE/ORG
Surface Diffusion in InAs/GaAs(001) Heteroepitaxy — •Sladjana Stojković, Evgeni Penev, Peter Kratzer, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck-Gessellschaft, Berlin
In recent years, the heteroepitaxial growth of InAs/GaAs(001) has attracted substantial interest, since the large lattice misfit of this system induces a growth mode transition from a two-dimensional wetting layer (WL) to three-dimensional islands which can be functionalized as self-assembled quantum dots (QD). To achieve a quantitative understanding of QD growth, information about material transport on the WL is required, which is difficult to obtain experimentally due to the complex structure of the WL.
We have studied diffusion of an In adatom on a pseudomorphic In2/3Ga1/3As(001)-(n × 3) reconstructed WL theoretically, employing density functional theory. The choice of these surfaces is motivated both by the experimental observation of alloying and by a theoretical stability analysis of the WL. The potential energy surface has been determined by first-principles total energy calculations, using the generalized gradient approximation for the electronic exchange and correlation. The hopping rates between binding sites connected via saddle points are found by applying transition state theory, while the diffusion tensor is determined from the continuous-time random walk formalism. The obtained microscopic parameters are very suitable to serve as input to kinetic Monte Carlo simulations, and to study In diffusion on a disordered WL, as well as possible consequences for QD growth.