Vertical distribution of nitrogen-vacancy centers in diamond formed by   ion implantation and annealing
  Etching experiments were performed that reveal the vertical distribution of optically active nitrogen-vacancy (NV) centers in diamond created in close proximity to a surface through ion implantation and annealing. The NV distribution depends strongly on the native nitrogen concentration, and spectral measurements of the neutral and negatively-charged NV peaks give evidence for electron depletion effects in lower-nitrogen material. The results are important for potential quantum information and magnetometer devices where NV centers must be created in close proximity to a surface for coupling to optical structures. 
Charles Santori, Paul E. Barclay, Kai-Mei C. Fu, Raymond G. Beausoleil