Istituto dei materiali per l'elettronica ed il magnetismo     
Ercolani D., Li A., Roddaro S., Beltram F., Sorba L., Rossi F., Salviati G., Grillo V. Defect-free zinc blende InSb nanowires. In: NGW 2009 - 4th Nanowire Growth Workshop (NWG) 2009 (Paris (France), 26-27 Ottobre 2009).
Among the III-V semiconductors, InSb has the smallest bandgap, highest bulk electron mobility, smallest effective mass, and largest Landé g-factor [1]. These properties make this material suited for many applications in high-speed devices, magnetoresistors, magnetic sensors, and infrared detectors. Yet very few reports on InSb NWs have so far appeared in literature. Notably, a recent paper on InAs/InSb heterostructures grown on InAs(111)B substrates by metal-organic vapor phase epitaxy [2] showed controlled growth direction, and perfect zincblende (ZB) crystal structure, free of defects. We shall report our results on the growth of InAs-InSb nanowire heterostructures (NWs). Chemical beam epitaxy technique was employed for Au-assisted growth on InAs(111)B substrates in a Riber Compact-21 system. The NWs are composed of two sections of different diameter; the lower one (InAs, as confirmed by EDXS) has a smaller diameter, while the upper one (InSb) has a larger diameter, comparable with the catalyst particle diameter. The structure and the crystalline quality of the NWs were investigated by TEM. A typical HRTEM image of the InAs/InSb interfacial region viewed along <112> InSb zone axis is shown in Fig. 1(a). The associated fast Fourier transform, shown in Fig. 1(b) indicates that the InAs base (blue spots) grows with wurtzite (WZ) structure with the c axis along the NW growth direction, whereas the InSb segment on top (red spots) crystallizes in the ZB phase with the <111> direction aligned to the NW axis. TEM analysis of the interfacial region (see Fig. 1(c)) highlights the abruptness of the interface and the good crystalline quality of the NWs in the near-interface region. Furthermore, we have performed post-growth studies investigating the NW tip composition following different cool-down protocol after InSb growth. We have found that the catalyst particle composition is AuIn2, and it can be varied to an AuIn alloy by cooling down the samples under TDMASb flux. [1] S. J. Chung, K. J. Goldammer, S. C. Lindstrom, M. B. Johnson, and M. B. Santos, J. Vac. Sci. Technol. B 17, 1151 (1999). [2] P. Caroff, J. Wagner, K. Dick, H. Nilsson, M. Jeppsson, K. Deppert, L. Samuelson, L.Wallenberg, and L.Wernersson, Smal l 4, 878 (2008).
vedi abstract inglese
URL: http://sites.google.com/site/nwg42009/
Subject Nanowires

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