Diamond-defect engineering of NV- centers using ion beam irradiation

TL;DR

This study demonstrates how MeV-range ion beam irradiation combined with thermal annealing can effectively create high densities of NV- centers in diamond without damaging the material, advancing quantum sensor technology.

Contribution

It introduces a method using ion beam irradiation and annealing to control NV- center formation in diamond, avoiding graphitization and improving quantum sensing applications.

Findings

High NV- densities achieved after annealing.

Vacancy-nitrogen recombination is facilitated by thermal treatment.

Ion beam parameters influence NV- creation efficiency.

Abstract

The interplay between ion beam modification techniques in the MeV range and the controlled generation of negatively charged nitrogen-vacancy (NV-) centers in nitrogen-doped synthetic diamond crystals is explored. An experimental approach employing both light (H+) and heavy (Br+6) ions was followed to assess their respective impacts on the creation of NV- centers, using different ion energies or fluences to generate varying amounts of vacancies. Photoluminescence spectroscopy was applied to characterize NV- and neutral NV0 centers. Initially, no NV centers were detected post-irradiation, despite the presence of substitutional nitrogen and vacancies. However, after annealing at 800C (and in some cases at 900C), most samples exhibited a high density of NV0 and especially NV- centers. This demonstrates that thermal treatment is essential for vacancy-nitrogen recombination and NV- formation, often through electron capture from nearby nitrogen atoms. Notably, we achieved high NV- densities without graphitization, which is essential for preserving the material's properties for quantum applications. This study underscores and quantifies the effectiveness of MeV-range ions in controlling vacancy distributions and highlights their potential for optimizing NV- center formation to enhance the sensitivity of diamond-based quantum magnetic sensors.