Increased negatively charged nitrogen-vacancy centers in fluorinated diamond

We investigated the effect of fluorine-terminated diamond surface on the charged state of shallow nitrogen vacancy defect centers (NVs). Fluorination is achieved with CF4 plasma, and the surface chemistry is confirmed with x-ray photoemission spectroscopy. Photoluminescence of these ensemble NVs reveals that fluorine-treated surfaces lead to a higher and more stable negatively charged nitrogen vacancy (NV−) population than oxygen-terminated surfaces. NV− population is estimated by the ratio of negative to neutral charged NV zero-phonon lines. Surface chemistry control of NV− density is an important step towards improving the optical and spin properties of NVs for quantum information processing and magnetic sensing