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内容記述 |
The magnetic sensitivity of the negatively charged nitrogen-vacancy (NV-) center in diamond depends on the concentration of NV- center and spin coherence time (T2). It is generally known that electron beam irradiation into type-Ib diamond containing high concentration of isolated substitutional nitrogen (P1 center) is a useful method to create high concentration of NV-. We studied on creation of NV- centers by post and in-situ annealing into type-Ib diamond to improve magnetic sensitivity of NV- centers. As a result, by post annealing at 1200-1400°C, T2 of NV- center in type-Ib diamond was extended because of reduction of P1 centers as decoherence source. Nevertheless, reduction of NV- centers occurred at the same time. At 800-1200°C, relative magnetic sensitivity showed the highest value by 1200 min annealing time. Whereas the conversion efficiency from P1 center to NV- center was enhanced by in-situ annealing at 800 and 1000°C compared to post annealing after RT irradiation. In addition, the relative magnetic sensitivity was higher at 800°C than 1000°C by the irradiation fluence of 5.0 x 1018 electrons/cm2, because T2 was at the same level and concentration of NV- was higher at 800°C than 1000°C. These results suggest that annealing treatments have possibility to increase concentration of NV- centers more and extend T2 longer, which makes the NV magnetometer more sensitive. |
