Nanopatterning of Si/SiGe electrical devices by atomic force microscopy oxidation

Two nanopatterning methods for silicon/silicon-germanium (Si/SiGe) heterostructures are demonstrated: (1) direct atomic force microscopy (AFM) oxidation on SiGe layers and (2) AFM oxidation on silicon followed by selective wet etching of SiGe. When directly oxidizing SiGe alloys, minimum linewidths of 20 nm were achieved by adjusting the bias voltage of the AFM tip. By AFM oxidation and selective wet etching, a 10-nm-thick conducting SiGe layer was patterned to form features under similar to50 nm. Fabricated SiGe quantum dots with side gates exhibited Coulomb blockade oscillation. (C) 2002 American Institute of Physics.