Transition Metal Dichalcogenide MoS₂: Oxygen and Fluorine Functionalization for Selective Plasma Processing

Low-temperature plasma processing is a promising technique for tailoring transition metal dichalcogenides (TMDs). For chalcogen substitution processing, a key challenge is to identify the ion energy window that enables selective chalcogen removal while preserving the metal lattice. Using ab initio molecular dynamics (AIMD), we demonstrate that oxygen and fluorine functionalization widen the processing window by significantly lowering the sulfur sputtering energy threshold (E_sputt,S) of MoS₂ from ∼30 to ∼10 eV via formation of sputtering products such as SO₂ and SF_n. Additionally, we show that experimentally relevant cryogenic temperatures strongly affect E_sputt,S(T). The dependence is confirmed via AIMD and also predicted by a mechanistic parameter-free theory, suggesting that E_sputt (T) generalizes to other TMDs, functionalizations, and surface impact conditions. Our results highlight oxygen/fluorine functionalization, ionic impact angle, and material temperature to be key control parameters for selective, damage-controlled chalcogen removal in TMD processing.