Fabrication of a nanometer-scale Si-wire by micromachining of a silicon-on-insulator substrate

Air-bridge-structured Si wires were fabricated by using a silicon-on-insula tor (SOI) substrate and electrically characterized, The SOI substrate used had a sandwich structure of a 200-nm-thick p-type Si layer (SOI layer), a 4 00-nm-thick buried oxide layer (BOX layer) and a p-type Si substrate. The w ires were made by conventional photolithography process followed by dry etc hing and thermal oxidation thinning of the SOI layer The Si wins were isola ted from the substrate by an air gap made in the BOX layer and had dimensio ns of typically 20 nm in width, 40 nm in height and 150 nm in length, It wa s found from the measurements of current-voltage characteristics that the c urrent through the wires much increased by illumination with a He-Ne laser and reached about 20 nA at a bias of 1 V.