Nano-patterned silicon surfaces for the self-organanized growth of metallic nanostructures

The aim of this work is to obtain a very regular alignment of metallic and magnetic nanostructureswith high density and a narrow size distribution via a self-organised growth process. The methodconsists of combining microelectronic processes which will provide a periodic surface pattern, withself-assembled growth on the so-obtained surface. The structured surface serves as a template forthe controlled positioning of the nanostructures. Concerning the silicon template preparation, thesurface periodicity should be of the same order of magnitude as the atomic surface diffusion lengthused during subsequent growth. These surface patterns were obtained on vicinal silicon surfaces byoptimising electron-beam nanolithography and reactive ion etching, to create arrays of nano-holestypically 50 nm in diameter with a 50 nm spacing. A subsequent sample annealing under ultrahighvacuum conditions is studied in order to obtain a corrugated surface mimicking the lithographypattern. As a model system, the growth of Au on vicinal Si(111) surfaces has been chosen. Afterhigh temperature annealing, clean Si surfaces present arrays of straight step bunches each separatedby ∼50 nm. We discuss the formation of Au islands on these step bunches during growth and/orannealing at a temperature between 300 and 500 ◦C.