Investigation of High‐Density Nitrogen Vacancy Center Ensembles Created in Electron‐Irradiated and Vacuum‐Annealed Delta‐Doped Layers

Abstract

The creation of localized ensembles of nitrogen vacancy (NV) centers by nitrogen delta doping of chemical vapor deposition diamond with subsequent irradiation of the delta layer by an electron beam with electron energy of 200 keV and annealing at a temperature of 1200 °C is investigated. The concentration of created NV centers is determined as a function of the irradiation dose, and their spin properties are studied. The creation of 2D ensembles of NV centers with a surface density of ≈2500 μm−2 and spin coherence time T2 ≈ 33 μs is demonstrated.

Impact of Helium Ion Implantation Dose and Annealing on Dense Near-Surface Layers of NV Centers

“…In addition, this method suffers from electron donor deficit leading to lower NV 0 to NV − charge-state conversion efficiency [19], since it is usually applied to diamonds with a low initial concentration of nitrogen. Another widely used method is electron irradiation [20][21][22][23], which creates vacancies in crystals with already sufficient nitrogen concentration. Such electron irradiation produces a minimum of undesirable defects, but the large electron energies required to create vacancies limit the control of the depth; therefore, this method is good for fabricating sensors with uniform NV distribution, where the sensing volume matches the volume of the bulk diamond.…”

“…In many applications, it is desirable to keep high spatial resolution by creating well localized NV ensembles [22,24,26,27], for example, thin NV layers for magnetic imaging [8,28,29]. In addition, dense NV ensembles are desirable since the sensitivity scales with the square root of the number of NV − centers.…”

Impact of helium ion implantation dose and annealing on dense near-surface layers of NV centers

“…In addition, this method, since it is usually applied to diamonds with low initial concentration of nitrogen, suffers from electron donor deficit leading to lower NV 0 to NV − charge-state conversion efficiency [18]. Another widely used method is electron irradiation [19][20][21][22], which creates va- * Electronic address: andris.berzins@lu.lv cancies in crystals with already sufficient nitrogen concentration. Such electron irradiation produces minimum of undesirable defects, but large electron energies required to create vacancies limit the control of the depth.…”

“…In many applications is desirable to keep high spatial resolution by creating well localized NV ensembles [21,23,25,26], for example, thin NV layers for magnetic imaging [8,27,28]. In addition, dense NV ensembles are desirable since the sensitivity scales with square root of the number of NV − centers.…”

“…There is a body of publications using annealing in temperature interval 750 • C to 900 • C and annealing times from 1 to 2 hours [29,30,34,35] under vacuum or Ar and H 2 mixture. Some researches apply longer annealing times [36,37] and higher temperatures [11,31,33,38] or both [17,21,27]. It is likely that in many cases the temperature range 750 • C to 900 • C is defined by maximum temperature achievable by majority of conventional ovens.…”