Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 81: Heterostructures and interfaces

HL 81.10: Talk

Thursday, March 19, 2015, 17:30–17:45, EW 201

Structural investigations of graded buffer systems in the TEM — •Florian Aumeier, Josef Loher, Christian Neumann, Dominique Bougeard, Daniel Henzler, Johannes Wild, Felix Schwarzhuber, and Josef Zweck — Institute of Experimental and Applied Physics, Regensburg, Germany

We investigated quantum well (QW) structures in epitaxially grown GaAs and SiGe graded buffer systems with [001] as growth direction. In these systems the strain induced by the lattice constant mismatch is relaxed by intentional defects in a metamorphic buffer system. The aim was to analyze the crystal quality of the system, in particular the defect free growth of the QW itself. Our focus lies on the detection and characterization of crystal defects with transmission electron microscopy (TEM). Besides the normal Bright Field investigations we used the weak beam dark field (WBDF) method to characterize the different perfect and partial dislocations. Normally such systems are observed in the [110] direction. By looking also at the [100] direction it has been found, that defects, which are clearly visible in one direction are nearly invisible in the other. This may lead to a misinterpretation of the structural perfection, if one considers only one direction.