Nanowires (and similarly termed constructions) are a fruitful field of study, and numerous papers have been produced dealing with their growth, characterization, and physical properties. Nanowires grown via self-assembly form a small, yet promising segment of the much broader field. Numerous techniques for growing self-assembled wires have been discovered, whether it is by directed or non-directed methods, but as always the crucial issue is the placement of these wires. To make use of a nanowire's predicted properties; it must be assembled in the appropriate environment, i.e. a circuit. Hence the nucleation and growth of the wires must be understood at a fundamental level, so that growth conditions can be tailored appropriately.
We present here simulational results from the study of anisotropic corner crossing barriers in 2D wire growth from terrace edges on an fcc-(001) plane. The motivation for this work stems from the observation of anisotropic wire-like features growing at step edges on the HOPG surface [1]. Using KMC simulations, a study of wire growth has been carried out as a function of all the relevant parameters i.e. flux, total coverage, system size and shape, and edge and corner crossing barriers. An obvious improvement in the wire-like morphology appears when the growth conditions evolve from anisotropic edge diffusion barriers (the explanation of the experimental results originally suggested in [1]), to anisotropic corner crossing barriers. In fact, it is found that the wires require anisotropic corner crossing barriers in order to exhibit the experimentally observed behavior. This result is surprising and we are not aware of any previous reports of such behaviour in 2D, although it is noted that corner crossings are of course very important in 3D island growth [2].
[1] Scott, S. A. et al, Phys. Rev B 72, 205423 (2005).
[2] Schweobel, R. and Shipsey, E. J. Appl. Phys. 37, 3682 (1966) |