Formation of gold-capped silicon nanocolumns on silicon substrate

Gold-capped silicon nanocolumns regularly distributed over silicon substrate were obtained. The columns length was roughly 100 nm; their deviation from perpendicular axis was less than 2°. The diameter of the columns was of the order of 10 nm or below of that. The proposed procedure of nanostructuring included the following main steps: deposition of aluminum thin layer (100–500 nm) by magnetron sputtering on (100) oriented Si wafers; formation of porous self-ordered alumina structures by electrochemical anodizing of the Al film in oxalic acid; electroless inversion of Au in alumina pores; and reactive ion etching. The obtained Si–Au structures are of importance as the platforms for biosensing applications, while the gold-free structures are of interest in photovoltaics.