Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 17: Poster Session

MM 17.52: Poster

Montag, 26. März 2012, 17:00–19:00, Poster B

Microstructure of InAs nano-crystals embedded in Si — •Mingjian Wu¹, Achim Trampert¹, Tariq Al-Zoubi², Muhammad Usman², Mohamed Benyoucef², and Johann Peter Reithmaier² — ¹Paul-Drude-Institut für Festköperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin, Germany — ²Institute of Nanostructure Technologies and Analytics, CINSaT, Universität Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany

In this work, the structural properties of InAs nano-crystals embedded in a Si matrix are investigated by transmission electron microscopy (TEM). The InAs is grown on Si (001) by molecular beam epitaxy at 400 ^∘C and subsequently overgrown by Si at 700 ^∘C. Depending on the nominally deposited amount of InAs, the embedded clusters show spherical and truncated octahedral-like shapes with {111} and {001} facets, which are significantly different to the initially flat InAs islands. The bulk lattice mismatch of 10.4 % is relieved by dislocation loops along the interface consisting of perfect 60^∘-type dislocations and partial dislocation with stacking faults inside the InAs clusters. By two-dimensional strain mapping derived from high-resolution TEM structure images, no strain gradients in the Si matrix around InAs clusters are detectable. On the other hand, anisotropic lattice distortions inside the InAs clusters are identified, which are characterized by compressive and tensile strain distributions in the two mapped directions, i.e. parallel and perpendicular to the growth direction. This residual strain is discussed based on the thermal mismatch between InAs and Si.