Effect of reactive ion etching on the photoluminescence intensity of nitrogen-vacancy color centers in microwave plasma chemical vapor deposition diamond films

The nitrogen-vacancy (NV) color center in diamond, a luminescent defect with exceptional optical and spin properties, is critical for room-temperature solid-state quantum sensing but limited by low photoluminescence (PL) intensity. This study demonstrates an integrated approach to enhance NV center performance through crystal orientation engineering and plasma-based nanostructuring. Computational simulations revealed that atomic nitrogen preferentially adsorbs on the (100) diamond surface during growth, promoting subsurface formation of NV centers within the diamond bulk rather than at the surface. Guided by this insight, microwave plasma chemical vapor deposition parameters were optimized to synthesize (100)-oriented NV-doped diamond films with efficient nitrogen incorporation. Stopping and range of ions in matter modeling showed that argon (Ar+) ions dominate physical sputtering to sculpt micro/nanostructures, while hydrogen (H+) ions passivate surface defects to reduce nonradiative recombination. By tailoring reactive ion etching with Ar + H2 plasma, (100)-oriented diamond films with controlled micro/nanomorphologies were fabricated, significantly enhancing NV center PL intensity through a balance of surface contaminant removal and subsurface NV preservation. These findings highlight the critical role of crystal surface-mediated nitrogen adsorption in facilitating bulk defect formation and demonstrate how plasma chemistry can optimize surface properties to boost NV center luminescence. The proposed strategy provides a practical framework for improving photon collection efficiency in diamond-based quantum devices, advancing applications in precision sensing and quantum information technologies.