Theoretical Design of a Shallow Donor in Diamond by Lithium-Nitrogen   Codoping
  We propose a new substitutional impurity complex in diamond composed of a lithium atom that is tetrahedrally coordinated by four nitrogen atoms (LiN_4). Density functional calculations are consistent with the hydrogenic impurity model, both supporting the prediction that this complex is a shallow donor with an activation energy of 0.27 +/- 0.06 eV. Three paths to the experimental realization of the LiN_4 complex in diamond are proposed and theoretically analyzed. 
Jonathan E. Moussa, Noa Marom, Na Sai, James R. Chelikowsky
cond-mat.mtrl-sci