Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 76: Heterostructures
HL 76.4: Vortrag
Donnerstag, 29. März 2012, 10:15–10:30, EW 202
Strain relaxation in metamorphic InAlAs buffers — •Boris Landgraf, Slobodskyy Taras, Christian Heyn, and Wolfgang Hansen — Institut für Angewandte Physik, Universität Hamburg, 20355 Hamburg, Germany
Modulation-doped high-mobility InAs heterostructures are of current interest owing to the small effective mass and strong spin-orbit coupling [1]. The heterostructures are prepared on molecular beam epitaxy grown virtual substrates strain engineered to match the lattice constant of the electronically active layers. The virtual substrates contain metamorphic buffer layers to compensate for the lattice mismatch. Recent developments in the design of the metamorphic buffers have made possible high-quality epitaxial InAs heterostructures.
This talk will be about the strain relaxation in metamorphic InxAl1−xAs buffers with and without an underneath grown AlAs/Gas superlattice. The structure of the virtual substrate was analyzed using high-resolution x-ray diffraction. Pole figures were collected to characterize the strain relaxation and twist in the metamorphic buffer layers, AlAs/GaAs superlattice and GaAs substrate. Our results indicate that an AlAs/GaAs superlattice in the virtual substrate is essential for strain relaxation in these virtual substrates.
[1]
S. Löhr et al., Highly anisotropic transport in shallow InGaAs heterostructures, Physical Review B 67, 045309 (2003)