Electron Beam Patterning of GaAs Nanowires: Tailoring the Morphology of Semiconductor Nanowire Arrays for a Bio-mimetic Functionalization Approach

The superior chemical and physical properties of natural surfaces are frequently related to the multi-scale design of micro- and nano-structures on them. Following this bio-mimetic approach, the geometrical tailoring of semiconductor nanowire (NW) arrays allows rising a novel nanofabrication concept, where the semiconductor properties and the boosting effect of quantum properties merge into morphology-based functionalities. This contribution presents the results of Molecular Beam Epitaxy grown GaAs NW arrays locally patterned by the electron beam-mediated bending and by their adhesion-induced bundling. We explain the self-assembly of NWs into clusters in the frame of adhesion properties of natural contact surfaces (“gecko effect”), by generalizing the concept of “lateral collapse of fibrils”. We demonstrate how a careful choice of material properties and geometrical design of semiconductor NW arrays may turn the scanning electron microscope into a new patterning tool with nanoscale fine-tuning of the structure of NW-decorated surfaces. Additionally, the NW bending by the electron beam has further advantages in respect to the traditional elastocapillary method. In fact it allows to implement NW aggregation under vacuum ambient, so as to avoid the contamination of the delicate NW surface by external substances (liquids). The potential applications of tailored NW arrays range from energy conversion to nanoelectronics, chemical and biological sensing, and bioengineering.