Direct imaging of quantum wires nucleated at diatomic steps

Atomic steps at growth surfaces are important heterogeneous sources for nucleation of epitaxial nano-objects. In the presence of misfit strain, we show that the nucleation process takes place referentially at the upper terrace of the step as a result of the local stress relaxation. Evidence for strain-induced nucleation comes from the direct observation by postgrowth, atomic resolution, Z-contrast imaging of an InAs-rich region in a nanowire located on the upper terrace surface of an interfacial diatomic step.This work was supported by the DOE Office of Basic Energy Sciences, Division of Materials Sciences and Engineering (MV and SJP), the SANDiE European Network of Excellence (Contract No. NMP4-CT-2004-500101), the Spanish MEC (TEC2005-05781-C03-01 y 02, NAN2004-09109-C04-01, and Consolider-Ingenio 2010 CSD2006-00019), the CAM (S 0505ESP 0200), and the Junta de Andalucia (PAI research groups TEP-120 and TIC-145; Project No. PAI05-TEP-00383).Peer reviewe