Single-Electron Transistors made by chemical patterning of silicon dioxide substrates and selective deposition of gold nanoparticles

We describe a method to pattern SiO$_2$ surfaces with colloidal gold nanoparticles by e-beam lithography and selective nanoparticle deposition. The method allows us to deposit nanoparticles in different shapes, including long continuous lines just one nanoparticle wide. We contact the pre-positioned nanoparticles with metal leads to form Single Electron Transistors. The Coulomb blockade pattern surprisingly does not show the parasitic ``offset charges'' at low temperatures, indicating relatively little surface contamination.