No abstract

We present an approach that takes into account lattice dynamical effects in calculating the optical response of semiconductors by averaging over several perturbed configurations of a supercell extracted from molecular dynamic simulations. The validity of this approach is confirmed by comparing our results for the dielectric function of bulk GaAs in the range of 0 - 700 K with our and other highly accurate ellipsometry measurements. The results of our approach resolve the serious discrepancy in energy and line shape between the latest optical models, all of which neglect lattice dynamics, and experiment

No abstract

Articles you may be interested inHopkins-Skellam index and origin of spatial regularity in InAs quantum dot formation on GaAs(001) Apparent critical thickness versus temperature for InAs quantum dot growth on GaAs(001) Appl. Phys. Lett. 88, 161903 (2006); 10.1063/1.2189915Planar InAs growth on GaAs(001) and subsequent quantum dot formation by a surface induced morphological instability J.Reflectance anisotropy spectroscopy ͑RAS͒ has been used to monitor the formation and development of InAs islands grown onto GaAs͑001͒ substrates by molecular beam epitaxy. Time resolved measurements show entirely different responses at different photon energies, corresponding to different aspects of the islanding process. At a photon energy of 2.6 eV RAS is sensitive to the onset of islanding, whereas the 4.0 eV signal appears to be sensitive to the continuous interisland wetting layer. Thus, by using the 4.0 eV signal it is possible to follow the real time development of the islanded surface. In particular, it is found that ͑1͒ during growth and immediately beyond the point of islanding, a fixed fraction of the incoming flux is directly transferred to the islands, and this fraction increases with increasing growth temperature up to 100%; ͑2͒ as a consequence of this, the wetting layer can increase in thickness beyond the 1.6 monolayers islanding thickness, to at least ϳ2 monolayers; ͑3͒ the importance of islands acting as sinks for the acquisition of material from the wetting layer is revealed; ͑4͒ the dynamic equilibrium set up between the islands and the wetting layer is such that the thickness of the latter increases significantly with sample temperature.

No abstract