Synthesis and characterization of a self-assembled nanostructured silicon/metal composite

Abstract

A silicon/metal nanocomposite is fabricated by electrochemical deposition of a metal (Ni, Co) into the pores of mesoporous silicon prepared from n +-silicon consisting of highly oriented channels which are tunable in a range between 40 nm and 100 nm in their diameter and a concomitant interpore spacing. Fourier transform infrared (FTIR) measurements give details about the top surface as well as the interior surface of the pore walls. IR optical investigations are used to determine the optical parameters like the refractive index, depending on the porosity of the porous silicon (PS) layer. Porosities between 25% and 80% exhibit an estimated refractive index between 3 and 1.7. The channels of the obtained nanostructured semiconductor are galvanically loaded with a metal of a metal-salt solution. The selective precipitation of metal-nanostructures is performed by pulsed deposition technique with varying electrochemical parameters depending on the deposited metal (Ni, Co). Metal loaded PS specimens show significant different transmission compared to bare PS. Additional absorbance peaks appear in the spectra which are due to the deposition process leading to a modification of the Si/SiOx/metal- interface. Magnetic characterization of the samples has been performed by SQUID-magnetometry. © 2008 IOP Publishing Ltd.