Terminal Deuterium Atoms Protect Silicon from Oxidation

Abstract

In recent years, the hybrid silicon-molecular electronics technology has been gaining significant attention for applications in sensors, photovoltaics, power generation, and molecular electronics devices. However, Si–H surfaces, which are the platforms on which these devices are formed, are prone to oxidation, compromising the mechanical and electronic stability of the devices. Here, we show that when hydrogen is replaced by deuterium, the Si–D surface becomes significantly more resistant to oxidation when either positive or negative voltages are applied to the Si surface. Si–D surfaces are more resistant to oxidation, and their current–voltage characteristics are more stable than those measured on Si–H surfaces. At positive voltages, the Si–D stability appears to be related to the flat band potential of Si–D being more positive compared to Si–H surfaces, making Si–D surfaces less attractive to oxidizing OH– ions. The limited oxidation of Si–D surfaces at negative potentials is interpreted by the frequencies of the Si–D bending modes being coupled to that of the bulk Si surface phonon modes, which would make the duration of the Si–D excited vibrational state significantly less than that of Si–H. The strong surface isotope effect has implications in the design of silicon-based sensing, molecular electronics, and power-generation devices and the interpretation of charge transfer across them.

Formation of Organic Monolayers on KF-Etched Si Surfaces

“…KF could serve as the etching solution for silicon wafers when less toxic chemicals are needed. For this purpose, the silicon wafers were etched by either solution and then functionalised by 1,8-nonadiyne via a hydrosilylation reaction, followed by a click reaction of the terminal alkyne with azidomethylferrocene; a scheme showing oxide removal and the associated monolayer functionalization is shown in Figure 1 [30][31][32][33][34][35][36]. Cyclic voltammetry (CV) was used to study the ferrocene surface coverages, and electrochemical impedance spectroscopy (EIS) allowed for the determination of electron transfer kinetics (k et ).…”