Scanning Electron Beam as a Patterning Tool for GaAs Nanowires

Scanning Electron Microscopy (SEM) is a powerful characterization method, especially for probing nanoscaled structures. Recently, new amazing applications have been demonstrated [1]. In this frame, this contribution deals with a study on GaAs nanowires (NWs), grown vertically aligned but subsequently driven to self-assembly during SEM observations. The electron beam induced bending has been rarely reported to affect post-growth NW orientation [2, 3] and few hypotheses have been advanced on the nature of the force which drives the NWs to bow [1, 2, 3]. No effort has been dedicated to understand the coupled bundling effect. We will elucidate the rising of NWs clusters into the frame of adhesion, friction, and compliance properties of natural and bio-mimetic contact surfaces [4]. We will report on the NWs bundling in the frame of lateral collapsing of fibrillar architectures [5]. We will demonstrate that the mechanical and surface properties of the NWs together with the geometrical design of the arrays play a key role in avoiding or favoring the NWs self-assembly. Besides, we will evidence that the electron beam-mediated bending coupled to adhesion-induced bundling of GaAs NWs shows thus the way to turn the SEM electron beam into a patterning tool for the selective fabrication and control of NW integration at the nanoscale. The possible applications range from NWs assembly on their growth substrate for in situ devices’ fabrication to the realization of sophisticated anisotropic surface designs leading to the engineering of anisotropic physical properties like wetting, electrical and thermal transport, electromagnetic polarization as well as cell and tissue growth.