Remote CF<sub>4</sub> Plasma Fluorination of Graphene for Low-Damage Spin-Orbit Engineering.

Lee, Chae-Gun; Shin, Seung-Hyun; Choi, Changmin; Jang, Seong; Choi, Hee Cheul; Lee, Gil-Ho · Nano Lett · 2026

basic_science · Level V

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Abstract

Defect functionalization is a promising route to enhance spin-orbit coupling (SOC) in graphene, but achieving controllable fluorination while suppressing irreversible lattice damage remains challenging. Here we demonstrate low-damage fluorination of monolayer graphene using a remote CF<sub>4</sub> plasma process that suppresses ion-bombardment-induced lattice damage. Raman spectroscopy with defect-activation analysis and an annealing-reversibility test identifies a processing window where fluorination predominantly yields reversible sp<sup>3</sup> C-F functionalization while minimizing vacancy formation. Nonlocal transport measurements show that the nonlocal resistance increases in fluorinated graphene and decays exponentially with channel length, consistent with spin diffusion and yielding a spin relaxation length of ∼0.4 μm. Within the Elliott-Yafet framework, we estimate an effective SOC energy scale of 4-9 meV. These results provide a Raman-validated, tunable process route for enhancing SOC in graphene while suppressing vacancy damage.