# CVD-growth of ultra-pure diamond, generation of NV centers by ion-implantation and their spectroscopic characterization for quantum technological applications

## TL;DR

This paper details a comprehensive method for the controlled growth, implantation, and spectroscopic characterization of NV centers in diamond, enhancing their potential for quantum technological applications by improving coherence times and precise defect placement.

## Contribution

It introduces a novel ultra high vacuum hot implantation technique and a microwave-assisted CVD process for high-purity diamond growth with controlled NV center creation.

## Key findings

- Successful demonstration of in situ UHV NV implantation without graphitization
- Enhanced NV center coherence times using dynamical decoupling sequences
- Precise spatial control of NV center distribution across large diamond areas

## Abstract

Abstract Applications of nitrogen-vacancy (NV) centers in diamond in quantum technology have attracted considerable attention in recent years. Deterministic generation of ensembles of NV centers can advance the research on quantum sensing, many-body quantum systems, multipartite entanglement and so on. Here we report the complete process of controlled generation of NV centers in diamond as well as their characterisation: growing diamond films through chemical vapor deposition (CVD), ion implantation and spectroscopic characterization of the defect centers using a confocal microscope. A microwave-assisted CVD set-up is presented which we constructed for the preparation of single-crystalline homoepitaxial diamond films. The films were prepared with minimized nitrogen concentration, which is confirmed through photoluminescence measurements. We demonstrate an in situ ultra high vacuum (UHV) implantation and heating process for creation of NV centers using a novel experimental set-up. For the first time hot implantation has been shown which prevents surface charging effects. We do not observe graphitization due to UHV heating. By optimizing the implantation parameters it has been possible to implant NV centers in a precise way. We present large area mapping of the samples to determine the distribution of the centers and describe the characterization of the centers by spectroscopic techniques. Reducing the decoherence caused by environmental noise is of primary importance for many applications in quantum technology. We demonstrate improvement on coherence time T_{2} of the NV spins by suppression of their interaction with the surrounding spin-bath using robust dynamical decoupling sequences.