Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 9: Poster 1
HL 9.42: Poster
Montag, 23. März 2009, 14:30–17:00, P2
The role of surface kinetics in achieving high non-equilibrium N concentrations in bulk GaAs — •Hazem Abu-Farsakh1,2 and Jörg Neugebauer1,2 — 1Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf, Germany — 2Universität Paderborn, Warburger Str. 100, 33098 Paderborn, Germany
Ternary GaAs1−xNx and quaternary InxGa1−xAs1−yNy alloys have attracted a considerable interest for applications including infrared laser diodes and photovoltaic solar cells. Despite the very low equilibrium solubility of N in bulk GaAs, N concentrations up to few percents can be achieved in MBE growth experiments. Ab-initio calculations indicate that N incorporation in the subsurface layer is thermodynamically most favorable, which can be utilized to achieve high concentrations by employing surface kinetics [1]. To explore possible roles for surface engineering we have calculated the kinetic barriers for various mechanisms and reaction paths of N at the GaAs(001) surface. Based on our results we propose a trapping mechanism that effectively prohibits N from getting incorporated in the subsurface layers. These results also allow (i) to identify the mechanism which controls the achievable enhancement in the bulk N concentration, (ii) to revise previous growth and incorporation models, and (iii) to provide a direct microscopic basis of the recently reported In-N compositional anti-correlation in InxGa1−xAs1−yNy quantum wells [2].
[1] H. Abu-Farsakh and J. Neugebauer, Phys. Rev. B (submitted).
[2] M. Albrecht, H. Abu-Farsakh et al., Phys. Rev. Lett. 99, 206103 (2007).