Surface modification by Chlorine-chemistry during atomic layer etching of Aluminium Nitride: A first principles-based analysis

Using first-principles density functional theory (DFT) calculations in combination with the climbing-image nudged elastic band (CI-NEB) method, we investigated the adsorption, desorption, and diffusion of atomic chlorine (Cl) and molecular chlorine (Cl₂) on the Al‑terminated 0001 surface of aluminum nitride (AlN). Our results reveal that both atomic Cl and Cl₂ exhibit a chemisorption character with high binding energies. Calculations revealed that the splitting pathway of Cl₂ on the Al‑terminated AlN 0001 surface is a barrierless and exothermic process. These findings provide new microscopic‑scale insights into halogen-insulator surface interactions and opportunities for new strategies in optimizing AlN atomic layer etching process in semiconductor fabrication.