Common Background Signals in Voltammograms of Crystalline Silicon Electrodes are Reversible Silica-Silicon Redox Chemistry at Highly Conductive Surface Sites.

The electrochemical reduction of bulk silica, due to its high electrical resistance, is of limited viability, namely, requiring temperatures in excess of 850 °C. By means of electrochemical and electrical measurements in atomic force microscopy, we demonstrate that at a buried interface, where silica has grown on highly conductive Si(110) crystal facets, the silica-silicon conversion becomes reversible at room temperature and accessible within a narrow potential window. We conclude that parasitic signals commonly observed in voltammograms of silicon electrodes originate from silica-silicon redox chemistry. While these findings do not remove the requirement of high temperature toward bulk silica electrochemical reduction, they redefine for silicon the potential window free from parasitic signals and, as such, significantly restrict the conditions where electroanalytical methods can be applied to the study of silicon surface reactivity.

Reduced graphene oxide-silicon interface involving direct Si-O bonding as a conductive and mechanical stable ohmic contact.

Metal-semiconductor junctions are essential contacts for semiconductor devices, but high contact junction resistance is a limiting operational factor. Here, we establish an ohmic contact of low resistance of <4 × 10-6 Ω cm2 between platinum and n-type Si (111)-H surfaces. This involved Si-O covalent bonding a monolayer of graphene oxide (GO) to the Si surface followed by electrochemical reduction to form reduced graphene oxide (rGO). Current-voltage plots demonstrate that the GO/rGO transformation is associated with a change from a rectifying to an ohmic contact. The process is a viable method for constructing semiconductor-rGO interfaces and demonstrates that GO/rGO monolayers can be used as active components in tuning the contact resistance of metal-semiconductor junctions.