# Tailoring spin defects in diamond

## TL;DR

This paper demonstrates that controlling the charge state of defects during implantation in diamond significantly enhances the coherence time and yield of nitrogen-vacancy centers, advancing quantum device engineering.

## Contribution

It introduces a method to suppress lattice damage and improve NV center properties by charging defects during implantation using a boron-doped structure.

## Key findings

- Tenfold increase in spin coherence time of NV centers.
- Twofold increase in NV center formation yield.
- Quantitative understanding of defect formation dynamics.

## Abstract

Atomic-size spin defects in solids are unique quantum systems. Most applications require nanometer positioning accuracy, which is typically achieved by low energy ion implantation. So far, a drawback of this technique is the significant residual implantation-induced damage to the lattice, which strongly degrades the performance of spins in quantum applications. In this letter we show that the charge state of implantation-induced defects drastically influences the formation of lattice defects during thermal annealing. We demonstrate that charging of vacancies localized at e.g. individual nitrogen implantation sites suppresses the formation of vacancy complexes, resulting in a tenfold-improved spin coherence time of single nitrogen-vacancy (NV) centers in diamond. This has been achieved by confining implantation defects into the space charge layer of free carriers generated by a nanometer-thin boron-doped diamond structure. Besides, a twofold-improved yield of formation of NV centers is observed. By combining these results with numerical calculations, we arrive at a quantitative understanding of the formation and dynamics of the implanted spin defects. The presented results pave the way for improved engineering of diamond spin defect quantum devices and other solid-state quantum systems.