Influence of (N,H)-terminated surfaces on stability, hyperfine structure, and zero-field splitting of NV centers in diamond

TL;DR

This study uses density functional theory to analyze how (N,H)-terminated surfaces affect the stability and quantum properties of NV centers in diamond, revealing optimal conditions for quantum sensing applications.

Contribution

It provides new insights into how surface termination ratios influence NV center stability and properties near diamond surfaces, guiding better quantum sensor design.

Findings

Stable NV$^-$ centers can exist at least 8 Å from the surface with 25% or more substitutional nitrogen.

NV centers near 100% N-terminated (111) surfaces are least affected by surface proximity.

Surface termination significantly impacts the hyperfine and zero-field splitting parameters of NV centers.

Abstract

We present a density functional theory analysis of the negatively charged nitrogen-vacancy (NV$^-$) defect complex in diamond located in the vicinity of (111)- or (100)-oriented surfaces with mixed (N,H)-terminations. We assess the stability and electronic properties of the NV$^-$ center and study their dependence on the H:N ratio of the surface termination. The formation energy, the electronic density of states, the hyperfine structure and zero-field splitting parameters of an NV$^-$ center are analyzed as function of its distance and orientation to the surface. We find stable NV$^-$ centers with bulk-like properties at distances of at least $\sim8$ Angstroem from the surface provided that the surface termination consists of at least 25\% substitutional nitrogen atoms. Our results indicate that axial NV centers near a flat 100\% N-terminated (111) surface are the optimal choice for NV-based quantum sensing applications as they are the least influenced by the proximity of the surface.