Local silicon doping as a promoter of patterned electrografting of diazonium for directed surface functionalization

Abstract

We study the influence of locally doped silicon substrates on the electroreduction of diazonium salts. Our results show that the reduction of diazonium salts occurs at moderate potentials compared to the flat band potential of the semiconducting electrode. The underlying doping directs the electrografting, preferentially over doped areas of the substrate. High resolution spatially resolved X-ray photoelectron spectroscopy analysis using a new X-ray photoelectron emission microscope (XPEEM) and soft X-ray synchrotron radiation yields the thickness of the native oxide of the micron scale doped pattern on the substrate. The results as a function of both parameters—reduction potential compared to the flat band potential and thickness of the oxide layer—are discussed. These new results are then compared to data obtained on the localized electrografting of vinylic monomers.