Depletion of nitrogen-vacancy color centers in diamond via hydrogen passivation

TL;DR

This study demonstrates that hydrogen plasma exposure significantly reduces nitrogen-vacancy (NV) center fluorescence in diamond by forming NVH centers, with hydrogen diffusing deeply into the diamond and affecting quantum applications.

Contribution

It provides the first experimental evidence of long-range hydrogen diffusion in high-purity diamond and elucidates how hydrogen passivation converts NV centers to NVH centers.

Findings

Hydrogen plasma reduces NV fluorescence by forming NVH centers.

Hydrogen diffuses at least 80mm into diamond during plasma exposure.

Fluorescence does not recover after high-temperature annealing.

Abstract

We show a marked reduction in the emission from nitrogen-vacancy (NV) color centers in single crystal diamond due to exposure of the diamond to hydrogen plasmas ranging from 700{\deg}C to 1000{\deg}C. Significant fluorescence reduction was observed beneath the exposed surface to at least 80mm depth after ~10 minutes, and did not recover after post-annealing in vacuum for seven hours at 1100{\deg}C. We attribute the fluorescence reduction to the formation of NVH centers by the plasma induced diffusion of hydrogen. These results have important implications for the formation of nitrogen-vacancy centers for quantum applications, and inform our understanding of the conversion of nitrogen-vacancy to NVH, whilst also providing the first experimental evidence of long range hydrogen diffusion through intrinsic high-purity diamond material.