Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 10: Quantum Dots and Wires: Preparation and Characterization II (mainly Arsenides)
HL 10.3: Talk
Monday, March 26, 2012, 11:45–12:00, EW 202
Growth of an InAs shell around GaAs nanowires — •Torsten Rieger1,2, Mihail Ion Lepsa1,2, Thomas Schäpers1,2, and Detlev Grützmacher1,2 — 1Peter Grünberg Institute - 9, Forschungszentrum Jülich, 52425 Jülich, Germany — 2JARA-Fundamentals of Future Information Technology
Due to the small dimensions, nanowires are promising candidates for the combination of highly lattice mismatched materials such as GaAs and InAs. We present the growth of GaAs/InAs core/shell nanowires (NWs) by molecular beam epitaxy. The GaAs NW core is grown using the self-cataylzed growth method and has an almost pure zinc blende crystal structure. The growth of the InAs shell is analyzed using scanning and transmission electron microscopy. The As4 beam flux is found to be crucial for the growth of a continuous shell. The growth of InAs starts with islands along the NW, which merge and form a continuous layer after around 5 nm thickness. The strain due to the lattice mismatch of 7% is accommodated by the formation of misfit dislocations. Relaxation along the growth direction ([111]B) saturates at about 80%. Depending on the core diameter, the core/shell NWs bend during the growth. Special emphasis is given to different defects in the InAs shell. Apart from the pure core/shell NWs, we discuss briefly about some correlated structures: free-standing InAs nanotubes and GaAs NWs which are covered only on one side by InAs.