Controlled deposition of gold nanodots using non-contact atomic force microscopy

摘要

A technique for highly reproducible deposition of nanoscale sized gold dots in an atomic force microscopy (AFM) configuration is described. This is achieved by precisely controlling the tip-sample separation, using feedback control enabled by the application of an external electrostatic servo force. Application of a voltage pulse of either polarity to a gold coated oscillating cantilever tip leads to the deposition of the Au dot. Dimensions for the, fabricated dots are 6-100 nm in width, and < 1 - 10 nm in height. The well controlled deposition process allowed the study of dot formation and the obtaining of relevant statistics. We found that the deposition process is the field emission of Au ions. Nevertheless, threshold values obtained are higher than previously reported ones and were found to be dependent on the tip shape. Depositions are independent of substrate morphology and lithographically patterned lines formed by overlapping Au nanodots as long as 55 mu m have been fabricated.