Generation of NV– Centers in Diamond Nanostructures: PL, ODMR, and Spin Coherence

Abstract

The nanolayers and nanomembranes with the 30–300 thickness and the 0.5 ppm NV^– center content were produced by 50 keV \({\text{H}}_{2}^{ + }\) ion implantation in Ib type (111) diamond plates and vacuum or high pressure annealing with subsequent lift-off process. The similar NV^– content nanolayers were formed by N⁺ ion implantation in IIa type (111) diamond plates and similar annealings. 〈111〉 oriented nanopillars were produced on both types of nanolayers using focused ion beam (FIB) with Ga⁺ 30 keV maskless milling. The unusual optically detected magnetic resonances (ODMRs) were measured in a single nanopillars with a height of 500‒700 nm and of 250 nm in diameter covered by an amorphous a-C:Ga nanolayer in the 0‒20 G magnetic field. They demonstrated both a significant decrease in the gyromagnetic ratio and the quenching of photoluminescence (PL) signal from the NV^– centers inclined to the nanopillar axis by the conductive a‑C:Ga nanolayer and stresses created by it. The multistep O₂ RIE plasma etching restored the normal ODMR resonance frequencies and intensities for all four NV^–center orientations in (111) diamond nanopillars.