Effect of swirl‐like resistivity striations in n + ‐type Sb doped Si wafers on the properties of Ag/porous silicon SERS substrates

Porous silicon (PS) represents the prospective template for the fabrication of metal/PS nanostructures. However n+-type Sb doped Si Czochralski wafers widely used to fabricate PS may contain resistivity striations and as-grown microdefects with specific spiral distribution which influence Si dissolution during the formation of PS by anodizing. This may strongly affect on the PS microstructure and repeatability of metal/PS properties causing an increase of risk of a device failure. In the present research we studied the morphology and SERS-activity of Ag/PS nanostructures formed by Ag immersion deposition on PS. SEM investigation revealed unequal distribution of pore diameters in the surface regions of PS which corresponds to spiral swirl-like distribution of resistivity revealed in Si wafer by anodizing. Morphological changes of Ag deposit on spiral areas were found to cause decreasing of intensity of SERS signal. Additional implantation of Sb ions followed by high temperature annealing has shown to be a technique to improve homogeneity of Ag/PS SERS substrates. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)