Dissociative chemisorption of O2 inducing stress corrosion cracking in silicon crystals

Fracture experiments to evaluate the cleavage energy of the (110)[1 1 0] and (111)[1 1 2] cleavage systems in silicon at room temperature and humidity give 2.7 ± 0.3 and 2.2 ± 0.2 J/m(2), respectively, lower than any previous measurement and inconsistent with density functional theory (DFT) surface energy calculations of 3.46 and 2.88 J/m(2). However, in an inert gas environment, we measure values of 3.5 ± 0.2 and 2.9 ± 0.2 J/m(2), 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.