Fabrication of locally thinned down silicon nanowires

We report a new and controlled top-down fabrication process to prepare locally thinned down silicon nanowire field-effect devices at wafer-scale. In this process, a low temperature size reduction method based on optimized tetramethylammonium hydroxide wet-etching has been developed on silicon (100) to yield slow (similar to 0.5 nm s(-1)) and controllable etching speed as well as an ultra-smooth silicon surface morphology (rms similar to 0.15 nm). Combined with electron beam lithography, arrays of monocrystalline silicon nanowires with locally confined thicknesses down to sub-20 nm, lateral dimensions of 150 nm, and lengths of 10 mm were reliably prepared and used. This novel fabrication process provides an alternative route for the fast and reliable preparation of ultrathin silicon nanostructures that can be easily integrated into nanodevices.