Ultra-long silicon nanostructures, and methods of forming and transferring the same

Abstract

Under one aspect, a plurality of silicon nanostructures is provided. Each of the silicon nanostructures includes a length and a cross-section, the cross-section being substantially constant along the length, the length being at least 100 microns. Under another aspect, a method of making nanostructures is provided that includes providing a silicon wafer including a thickness and first and second surfaces separated from one another by the thickness; forming a patterned layer of metal on the first surface of the silicon wafer; generating a current through the thickness of the silicon wafer, the metal oxidizing the silicon wafer in a region beneath the patterned layer of the metal; and exposing the silicon wafer to an etchant in the presence of the current, the etchant removing the oxidized region of the silicon wafer so as to define a plurality of nanostructures. Methods of transferring nanowires also are provided.