Magnetic Resonance Express Analysis and Control of NV− Diamond Wafers for Quantum Technologies

Magnetic resonance methods for express analysis and control of diamond wafers with NV⁻ centers for quantum technologies were developed. The scanning NV⁻-based ODMR spectrometer was built to analyze NV⁻ local concentration, coherent properties, stress/strain, nitrogen content, electron-nuclear interactions in diamond wafers for quantum technologies. As an example, a 3D image of the ODMR and PL maps was presented for a non-uniform distribution of NV⁻ centers in a diamond wafer, which had several growth zones with significantly different concentrations of nitrogen. The local stress/strain map was obtained by measuring the splitting of the ODMR line in zero magnetic field at room temperature. The double ODMR line is a consequence of the stress-induced splitting of the doublet with projections M_S = + 1 and M_S = − 1 in the ground triplet state of the NV⁻ center. Local concentration of nitrogen donors (in EPR literature it is designated as N or P1 centers) was estimated from the ratio of the intensity of satellites caused by interaction with nitrogen donors and the central line of ODMR. The central line has a 2E split into two overlapping lines, the intensity of one of the lines is selected. The spectrometer is also designed to perform pulsed measurements of Rabi oscillations, spin–lattice and spin–spin relaxation times at wafer points isolated by focused laser excitation. A new option for using a spectrometer was introduced for measuring the ODMR of NV⁻ centers in a linearly polarized light, which allowed to distinguish PL for centers of a certain orientation and suppress the PL from others.