Bundling of GaAs Nanowires: A Case of Adhesion-Induced Self-Assembly of Nanowires

The origin of deflections of semiconductor nanowires (NWs) induced by electron beam in scanning electron microscopy (SEM) has been object of different interpretations. Similarly, the subsequent clumping together of NWs into bundles is frequently observed, but no interpretation has been yet advanced. Here we present results about the bundling of NWs following the intentional bending by an electron beam. Furthermore, we extend the concept of lateral collapse, usually applied to fibrillar architectures mimicking the adhesiveness of natural surfaces (the so-called Gecko effect), to analyze the mechanism of the NW bundle formation. We demonstrate how the geometry of the NW arrays and the mechanical properties of the composing materials govern bundling, and how these parameters should be taken into account in the design of NW arrays both for avoiding vertical misalignment when detrimental, as well as for achieving patterning of NW arrays into nanoarchitectures.