Regensburg 2016 – scientific programme
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DS: Fachverband Dünne Schichten
DS 36: Focussed Session: Semiconductor Heteroepitaxy on Nanopatterned Substrates
(Joint session of DS and HL, organized by DS)
DS 36.7: Talk
Wednesday, March 9, 2016, 18:00–18:15, H11
Theoretical analysis of strain and misfit dislocation stability in axial-heteroepitaxial GaAs/InAs nanopillars — •Thomas Riedl1,2 and Jörg Lindner1,2 — 1University of Paderborn, Department of Physics, Warburger Straße 100, 33098 Paderborn, Germany — 2Center for Optoelectronics and Photonics Paderborn (CeOPP), Warburger Straße 100, 33098 Paderborn, Germany
Heteroepitaxial nanopillars and -wires represent a promising building block for advanced optoeletronic devices like dot-in-wire LEDs or lasers. Such structures offer a large surface-to-volume ratio and the possibility to accommodate considerable lattice mismatch in a pure elastic manner without formation of misfit relieving defects. As misfit dislocations are reported to occur in heterostructure nanowires in case of larger misfit and diameter, it is important to determine the critical wire dimensions for dislocation stability. In the present contribution we analyze this for the case of [111] orientied axial-heteroepitaxial GaAs/InAs nanopillars with zinc blende structure. Because of its applicability to various dislocation configurations and the availability of suitable parametrizations we use atomistic molecular statics simulation based on the Tersoff potential. We find that the defect-free elastically strained state is stable for small wire diameters (< 10 nm for a single 60° dislocation), whereas the dislocated state becomes favorable for larger diameters. In this presentation the influence of dislocation type, wire morphology and chemical width of the heterointerface on the coherent-semicoherent transition is analyzed and discussed. The results are compared with the literature.