Oxidation-induced changes of mechanochemical reactions at GaAs–SiO₂ interface: The competitive roles of water adsorption, mechanical property, and oxidized structure

Mechanochemical reactions at gallium arsenide-silica (GaAs-SiO₂) interface in micro-/nano-scales during ultra-precision manufacturing process offer novel phenomena of fundamental interests. Here, atomic structures, chemical, and mechanical properties of as-received, hydrochloric acid-etched, and ultraviolet-irradiated GaAs surfaces were characterized, and their roles in atomic attrition dominated by mechanochemical reactions were revealed at atomic scale. Experimental results suggested that, compared with water adsorption and mechanical property, oxidized structure plays a more crucial role in the mechanically-stimulated chemical reactions at GaAs–SiO₂ interface. Analyzing the mechanochemical reactions with the stress-assisted Arrhenius-type kinetics model and contact mechanics implies that, the oxidized layer with thermodynamically more stable structure than GaAs crystal increases the energy barrier of mechanochemical reactions and suppresses the atomic removal. These finding provide a deep insight into the mechanochemical removal mechanism of GaAs and a broad cognition for regulating the mechanochemical reactions widely existing in scientific and engineering applications.