Study of the optimal conditions for NV- center formation in type 1b diamond, using photoluminescence and positron annihilation spectroscopies

TL;DR

This study investigates optimal conditions for creating high concentrations of NV- centers in type 1b diamond using proton irradiation and annealing, providing insights for quantum sensing applications.

Contribution

It identifies the effects of irradiation and annealing parameters on NV- formation and estimates positron trapping coefficients, advancing diamond defect engineering.

Findings

High NV- concentrations up to 2.3 x 10^18 cm^-3 achieved.

Complex vacancy defects limit NV- formation at high proton fluences.

Positron trapping coefficient by NV- was estimated.

Abstract

We studied the parameters to optimize the production of negatively-charged nitrogen-vacancy color centers (NV-) in type~1b single crystal diamond using proton irradiation followed by thermal annealing under vacuum. Several samples were treated under different irradiation and annealing conditions and characterized by slow positron beam Doppler-broadening and photoluminescence (PL) spectroscopies. At high proton fluences another complex vacancy defect appears limiting the formation of NV-. Concentrations as high as 2.3 x 10^18 cm^-3 of NV- have been estimated from PL measurements. Furthermore, we inferred the trapping coefficient of positrons by NV-. This study brings insight into the production of a high concentration of NV- in diamond, which is of utmost importance in ultra-sensitive magnetometry and quantum hybrid systems applications.