On the creation of near-surface nitrogen-vacancy centre ensembles by implantation of type Ib diamond

TL;DR

This study investigates methods for creating high-quality, near-surface nitrogen-vacancy (NV) centre ensembles in diamond, emphasizing the importance of surface termination control and comparing implantation into type Ib versus pure diamond substrates.

Contribution

It evaluates the effectiveness of nitrogen implantation into type Ib diamond for near-surface NV ensemble creation and highlights the critical role of surface termination control during annealing.

Findings

Implantation into type Ib diamond offers limited benefits over pure diamond for near-surface NV creation.

Surface termination during annealing is crucial for high-yield NV ensemble formation.

Control of surface chemistry may enable better NV ensemble quality in future work.

Abstract

Dense, near-surface (within 10 nm) ensembles of nitrogen-vacancy (NV) centres in diamond are rapidly moving into prominence as the workhorse of a variety of envisaged applications, ranging from the imaging of fast-fluctuating magnetic signals to the facilitation of nuclear hyperpolarisation. Unlike their bulk counterparts, near-surface ensembles suffer from charge stability issues and reduced NV formation efficiency due to the diamond surface's role as a vacancy sink during annealing and an electron sink afterwards. To this end, work is ongoing to determine the best methods for producing high-quality ensembles in this regime. Here we examine the prospects for creating such ensembles cost-effectively by implanting nitrogen-rich type Ib diamond with electron donors, aiming to exploit the high bulk nitrogen density to combat surface-induced band bending in the process. This approach has previously been successful at creating deeper ensembles, however we find that in the near-surface regime there are fewer benefits over nitrogen implantation into pure diamond substrates. Our results suggest that control over diamond surface termination during annealing is key to successfully creating high-yield near-surface NV ensembles generally, and implantation into type Ib diamond may be worth revisiting once that has been accomplished.