Engineering shallow spins in diamond with nitrogen delta-doping
  We demonstrate nanometer-precision depth control of nitrogen-vacancy (NV) center creation near the surface of synthetic diamond using an in situ nitrogen delta-doping technique during plasma-enhanced chemical vapor deposition. Despite their proximity to the surface, doped NV centers with depths (d) ranging from 5 - 100 nm display long spin coherence times, T2 > 100 \mus at d = 5 nm and T2 > 600 \mus at d \geq 50 nm. The consistently long spin coherence observed in such shallow NV centers enables applications such as atomic-scale external spin sensing and hybrid quantum architectures. 
Kenichi Ohno, F. Joseph Heremans, Lee C. Bassett, Bryan A. Myers,   David M. Toyli, Ania C. Bleszynski Jayich, Christopher J...
cond-mat.mtrl-sci cond-mat.mes-hall quant-ph