Direct patterning of noble metal nanostructures with a scanning tunneling microscope

We demonstrate in this article the controlled deposition of noble metal dots and lines using local chemical vapor deposition in the tip-sample Sap of a scanning tunneling microscope. 3 nm diam rhodium dots have been patterned by local decomposition of an inorganic precursor, which was synthesized on purpose. Deposition is obtained on gold surfaces by applying a series of negative voltage pulses on the sample exceeding a voltage threshold of 1.9 V. The influence of kinetics parameters (pulse voltage duration and number, as well as the effect of gas pressure) are presented. In a second step, the deposition process has been applied on hydrogenated silicon (100) surfaces. These samples were previously hydrogen passivated using two different wet etching operations, leading surface dangling bonds saturated by either mono- or di-hydride bonds. The difference in the deposition processes observed in both cases is discussed. (C) 2000 American Vacuum Society. [S0734-211X(00)06903-1].