Engineering preferentially aligned nitrogen vacancy centre ensembles in CVD grown diamond

Here we report a method for improving the magnetic field sensitivity of an ensemble of Nitrogen Vacancy NV centres in C 12 enriched diamond aligned along the [111] crystal axis. The preferentially aligned NV centres are fabricated by a Plasma Enhanced Chemical Vapour Deposition PECVD process and their concentration is quantitatively determined by analysing the confocal microscopy images. We further observe that annealing the samples at high temperature 1500 degrees C in vacuum leads to a conversion of substitutional nitrogen into NV centres. This treatment also increases the coherence time of the NV centres electron spins up to 40 mu s, which corresponds to enhancement of the sensitivity by a factor of three. However, this procedure also leads to a loss of the preferential alignment by 3