Stuffing of Noble Metals into Anodized Porous Silicon by Direct Evaporation

Abstract

Silver and Gold were evaporated onto porous Si prepared on a Si(100) substrate (2–6 ohm·cm) by means of an anodic reaction in hydrofluoric acid electrolyte (HF:H₂O:C₂H₅OH=1:1:2) with a suitable anodic current (20–40 mA/cm²). Under a ultra-high vacuum condition, metal up to ∼ 100 Å thick was deposited over as-prepared, as-sputtered and as-annealed porous films at room and elevated temperatures, and the stuffing of the deposited metal atoms was examined by means of AES and ELS techniques. After room-temperature deposition, the distribution of gold, a reactive metal with Si, had much wider depth profiles than that of a Au/bulk Si system, except for as-prepared specimens. In the case of Ag, a much less reactive metal than Au, the same tendency was observed. These results are discussed with regards to atomic diffusions through pores and to the pore size distribution of a porous substrate with different treatments.