Dissociative chemisorption of O₂ inducing stress corrosion cracking in silicon crystals

Fracture experiments to evaluate the cleavage energy of the (110)[1 1̄ 0] and (111)[1 1 2̄] cleavage systems in silicon at room temperature and humidity give 2.7±0.3 and 2.2±0.2 J/m2, respectively, lower than any previous measurement and inconsistent with density functional theory (DFT) surface energy calculations of 3.46 and 2.88 J/m2. However, in an inert gas environment, we measure values of 3.5±0.2 and 2.9±0.2 J/m2, consistent with DFT, that suggest a previously undetected stress corrosion cracking scenario for Si crack initiation in room conditions. This is fully confirmed by hybrid quantum-mechanics-molecular-mechanics calculations.