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

Abstract

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.

Current Rectification and Photo-Responsive Current Achieved through Interfacial Facet Control of Cu2O–Si Wafer Heterojunctions

“…It also suggests that the interfacial band bending situation can change significantly, even when there is no chemical bond formed at the junction. Previously, current-rectifying I–V curves have been observed for Cu 2 O cubes and octahedra deposited on 1,8-nonadiyne-treated amorphous silicon substrate, so the silicon substrate does not have a well-defined crystal plane. − Next, the combination of a Cu 2 O rhombic dodecahedron on a Si {100} wafer did not produce any current (Figure d). A small current of 1 nA was observed at 3 V under light illumination.…”

Impermeable Graphene Oxide Protects Silicon from Oxidation

“…The effect of traces of SiO x on the electrochemical and electrical properties of Si is well-documented. For example, traces of oxide affect the thermodynamics of electrochemical redox reactions , as well as the current–voltage response of M–S junctions . We now measure the effect of oxide and the protective GO x layer on the electrical response of a metal–Si junction.…”

Nanotip Formation from Liquid Metals for Soft Electronic Junctions

“…However, mercury volatility and toxicity are significant obstacles for future usages. Other wetting techniques in electrolyte solutions are also reported for surface characterization using soft junctions . At nanoscale, platinum and tungsten hard metals have been widely used as conductive probes for electrical measurements and nanomanipulations. , Particularly, atomic force microscopy (AFM) using platinum electrodes has recently been employed as sliding metal–semiconductor contacts in the formation of triboelectric nanogenerators. , However, the use of hard metals has been reported to damage the surface of the semiconducting materials .…”