Type of presentation: Poster

MS-8-P-1439 Strain relaxation mechanisms at interfaces in III-As and III-Sb heterostructure nanowires by atomic resolution STEM

de la Mata M.1, Magen C.2, Shtrikman H.3, Caroff P.4,5, Arbiol J.1,6
1Instituto de Ciencia de Materiales de Barcelona, ICMAB-CSIC 08193 Bellaterra, Spain, 2Laboratorio de Microscopías Avanzadas, Instituto de Nanociencia de Aragon-ARAID, Universidad de Zaragoza, 50018 Zaragoza, Spain, 3Braun Center for Submicron Research, Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel, 4Institut d’Électronique, de Microélectronique et de Nanotechnologie, UMR CNRS , 5Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, 6Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, CAT, Spain
mmata@icmab.es

Semiconductor nanowires (NWs) have attracted huge attention during last years. Due to their wide range of applicability and modified physical properties when compared to planar structures, they are used in fields such as nanoelectronics, optoelectronics or biosensing [1]. Also they can be used as platform for the study of condensed matter physics [2]. Their synthesis allows for the combination of highly mismatched materials, otherwise not achievable. On this way, it is possible to combine different materials in a NW to create axial as well as radial heterostructures.
III-V semiconductors have been extensively synthesized and probed in this context, especially arsenide combinations. On the other hand, antimonides are of extreme interest as among them are the highest hole mobility (GaSb) and the narrower band gap and the highest electron bulk mobility (InSb) III-Vs materials, extending the operability range of the related devices.
The final NW properties will be influenced by the material quality, closely related to the presence of strain as a consequence of combining different materials. Through careful inspections of the crystal structures and thanks to the employ of aberration corrected STEM techniques, we are able to study the mechanisms that allow for the strain relaxation at atomic scale in these NWs in three different cases: i) radial InAs/GaAs NWs; ii) axial InAs/InSb NWs; and iii) axial GaAs/GaSb NWs. Flat or bended interphases were found depending on the material combinations, but in all of the studied systems, the partial/total relaxation takes place through the formation of misfit dislocations. These defects could be directly identified and analyzed by means of geometrical phase analyses (GPA) [3]. Given the spatial resolution achieved in aberration corrected STEM, we can also resolve the dumbbells and identify the elemental constituents within the crystalline structure, allowing a polarity study in the combined materials and through the interfaces [4,5]. Then, it is possible to get a deeper understanding on the heterostructural properties and their direct influence on the electronic behavior.

References:
[1] M. de la Mata, et al., J. Mat. Chem. C, 1, 4300 (2013)
[2] M. Heiss, et al., Nature Materials, 12, 439 (2013)
[3] M. J. Hÿtch, et al., Ultramicroscopy, 74, 131 (1998)
[4] M. de la Mata, et al., Nano Letters, 12, 2579 (2012)
[5] M.I.B. Utama, M. de la Mata, et al., Adv. Funct. Mat., 23, 1636 (2013)

MdlM would like to acknowledge CSIC for the JAE-PreDOC scholarship

Fig. 1: a) General HAADF STEM view of the InAs/InSb axial heterostructured NW. b) GPA deformation map obtained in the same region. c) Rotation map obtained by GPA. d) HAADF STEM image of the core-shell InAs/GaAs NW. e) GPA deformation map obtained in the same region. f) Corresponding Rotation map.