NMR Technique for Determining the Depth of Shallow Nitrogen-Vacancy Centers in Diamond

TL;DR

This paper presents a precise experimental method using NMR signals from surface protons to determine the depth of individual shallow NV centers in diamond with about 1 nm accuracy.

Contribution

The study introduces a robust NMR-based technique to accurately measure the depth of single NV centers, improving upon previous indirect or less precise methods.

Findings

NV center depths can be determined with ~1 nm uncertainty.

The measured NV depths agree with ion implantation simulations.

The method is applicable to individual NV centers on diamond surfaces.

Abstract

We demonstrate a robust experimental method for determining the depth of individual shallow Nitrogen-Vacancy (NV) centers in diamond with $\sim1$ nm uncertainty. We use a confocal microscope to observe single NV centers and detect the proton nuclear magnetic resonance (NMR) signal produced by objective immersion oil, which has well understood nuclear spin properties, on the diamond surface. We determine the NV center depth by analyzing the NV NMR data using a model that describes the interaction of a single NV center with the statistically-polarized proton spin bath. We repeat this procedure for a large number of individual, shallow NV centers and compare the resulting NV depths to the mean value expected from simulations of the ion implantation process used to create the NV centers, with reasonable agreement.