AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Monday Sessions
       Session NS2-MoM

Paper NS2-MoM7
Direct Atomically Resolved Imaging of Nanowire Heterostructures and Nanowire Substrate Interaction

Monday, October 31, 2005, 10:20 am, Room 210

Session: Nanowires
Presenter: A. Mikkelsen, Lund Universty, Sweden
Authors: A. Mikkelsen, Lund Universty, Sweden
J. Eriksson, Lund University, Sweden
L. Ouattara, Lund University, Sweden
E. Lundgren, Lund University, Sweden
T. Knaapen, Eindhoven Technical University, The Netherlands
N. Skold, Lund University, Sweden
W. Seifert, Lund University, Sweden
L. Samuelson, Lund University, Sweden
Correspondent: Click to Email
Self-assembled semiconductor nanowires are a among the most interesting systems for doing low dimensional physics, as well as for realizing many future electronic and optoelectronic devices.@footnote 1@ Due to efficient strain relaxation a wide range of heterostructures, not possible in the bulk, can be grown in nanowires, and as a result, a multitude of complex nanowire based heterostructure devices has been realized in recent year. Very recently it has even been possible to grow optically active III-V structures on Silicon substrates.@footnote 2@ Because of the seeding type growth process of the wires, it is further possible to grow the wires by self-assembly in well defined positions for example on a chip. Using Scanning Tunneling Microscopy (STM), we address both the issue of heterostructure growth, the initial growth of the nanowire on the substrate and the influence of nanowire growth on the substrates - with atomic scale resolution. We apply our newly developed scheme to image individual atoms inside III-V semiconductor nanowires using a combination of STM and embedding.@footnote 3@ Using this method we have imaged GaInAs segments in GaAs wires with atomic resolution. We show that while the GaInAs segments are in principle perfectly defined on the atomic scale, an In distribution exists above the segment and also on the side facets of the wire. We further image GaAs nanowires at the GaAs(001) substrate interface, revealing intriguing details about both the initial growth of the nanowire along the surface, and the subsequent growth of the out-of-plane free standing wire. Finally we have investigated the influence of the nanowire growth, by Au seed particles, on the surrounding substrate - revealing that significant structural changes can occur. @FootnoteText@ @footnote 1@ L. Samuelson, Mater. Today 6 (2003) 22.@footnote 2@ T. Maartensson et al, Nano Lett 4 (2004) 1987@footnote 3@ A. Mikkelsen, et al, Nature Materials. 3 (2004) 519.