Atomically Smooth Stress-Corrosion Cleavage of a Hydrogen-Implanted Crystal

We present a quantum-accurate multiscale study of how hydrogen-filled discoidal “platelet” defects grow inside a silicon crystal. Dynamical simulations of a 10-nm-diameter platelet reveal that H₂ molecules form at its internal surfaces, diffuse, and dissociate at its perimeter, where they both induce and stabilize the breaking up of highly stressed silicon bonds. A buildup of H₂ internal pressure is neither needed for nor allowed by this stress-corrosion growth mechanism, at odds with previous models. Slow platelet growth up to micrometric sizes is predicted as a consequence, making atomically smooth crystal cleavage possible in implantation experiments.