Printable single-crystal silicon micro/nanoscale ribbons, platelets and bars generated from bulk wafers

This article demonstrates a method for fabricating high quality single-crystal silicon ribbons, platelets and bars with dimensions between ∼100 nm and ∼ 5 cm from bulk (111) wafers by using phase shift and amplitude photolithographic methods in conjunction with anisotropic chemical etching procedures. This "top-down" approach affords excellent control over the thicknesses, lengths, and widths of these structures and yields almost defect-free, monodisperse elements with well defined doping levels, surface morphologies and crystalline orientations. Dry transfer printing these elements from the source wafers to target substrates by use of soft, elastomeric stamps enables high yield integration onto wafers, glass plates, plastic sheets, rubber slabs or other surfaces. As one application example, bottom gate thin-film transistors that use aligned arrays of ribbons as the channel material exhibit good electrical properties, with mobilites as high as - 200 cm² V^-1 s^-1 and on/off ratios > 10⁴.