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Enhanced nitrogen-vacancy concentration in diamond through optimized electron irradiation


  Demitry Farfurnik [1,2]  ,  Nir Alfasi [3]  ,  Sergei Masis [3]  ,  Yaron Kauffman [4]  ,  Elad Farchi [5]  ,  Eyal Buks [3]  ,  Nir Bar-Gill [1,2,5]  
 [1] Racah Institute of Physics, Hebrew University, Jerusalem 9190401, Israel
[2] The Center for Nanoscience and Nanotechnology, Hebrew University, Jerusalem 9190401, Israel
[3] Andrew and Erna Viterbi Department of Electrical Engineering, Technion, Haifa 32000, Israel
[4] Department of Materials Science and Engineering, Technion, Haifa 32000, Israel
[5] Department of Applied Physics, Rachel and Selim School of Engineering, Hebrew University, Jerusalem 9190401, Israel

One of the most commonly used nano-characterization tool is the transmission electron microscope (TEM), offering sub-nanometer resolution microscopy. In this work, we use a typical 200 KeV TEM for a different purpose: Electron irradiation of diamonds is used to create vacancies inside the lattice. This process significantly increases the amount of NV centers, whose unique spin and optical properties provide ultra-sensitive magnetic sensing and quantum information building blocks.

We study the effect of electron irradiation with different doses on various types of HPHT and CVD diamond samples with different initial nitrogen concentrations. We observe an order of magnitude improvement in the NV concentration (up to ~10^10 NVs/cm^2), without any degradation in their coherence properties. By achieving about 5% conversion efficiency from N defects to NV centers in the diamond, we suggest the application of such irradiation processes for improving the sensitivity of DC and AC magnetometry, and pave the way toward the study of many body physics of ensembles of NV spins.