Berlin 2015 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 81: Heterostructures and interfaces

HL 81.7: Vortrag

Donnerstag, 19. März 2015, 16:45–17:00, EW 201

Strain-relaxation in GaAs / InGaAs core-shell nanowire heterostructures grown by MBE onto Si(111) — •Ali Al Hassan¹, Andreas Biermanns¹, Emmanouil Dimakis², Ryan B. Lewis², Lutz Geelhaar², and Ullrich Pietsch¹ — ¹Naturwissenschaftlich-Technische Fakultät der Universität Siegen, 57068 Siegen, Germany — ²Paul-Drude- Institute für Festkörperelektronik, Hausvogteiplatz 3, 10117 Berlin, Germany

Core-shell semiconductor nanowires (NW) can be grown onto various substrates without inclusion of misfit dislocations due to the strain release towards the NW side planes. This approach offers the possibility to form radial hetero-structures (HS) between highly lattice-mismatched materials but the process of strain relaxation is not fully understood.

We investigate strain interaction and relaxation in GaAs/InxGa1-xAs/GaAs NWHS grown by MBE onto silicon (111). X-ray diffraction measurements along [111] show, independent from GaAs core and InGaAs shell thickness ratio (x_In= 25% in shell thickness of 17nm), only one out-of plane Bragg peak corresponding to a solid solution with the total In content composed in the NW (Vegards law). On the other hand, X-ray measurements along the (1-10) and (2-1-1) NW side plane show separate peaks for core and shell materials with a mismatch corresponding to an In content in the shell closer to the nominal value but different along the direction normal to NW side planes and normal to NW edges. The data are interpreted in terms of finite element calculations revealing the complexity of strain relaxation mechanism.