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Theoretical Design of a Shallow Donor in Diamond by Lithium-Nitrogen Codoping

Jonathan E. Moussa, Noa Marom, Na Sai, James R. Chelikowsky

TL;DR

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 0.06 eV and three paths to the experimental realization of the LiN(4) complex in diamond are proposed and theoretically analyzed.

Abstract

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.

Theoretical Design of a Shallow Donor in Diamond by Lithium-Nitrogen Codoping

TL;DR

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 0.06 eV and three paths to the experimental realization of the LiN(4) complex in diamond are proposed and theoretically analyzed.

Abstract

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.

Paper Structure

This paper contains 8 equations, 3 figures, 2 tables.

Figures (3)

  • Figure 1: (color online) Predicted structures of the $X$N$_n$ donors. First and second neighbors from $X$ are displayed. Bonds are omitted for unbonded carbon-nitrogen neighbors, all of which are separated by $2.0$ Å . The remaining C-N bonds vary in length from $1.46 - 1.54$ Å . The $X$-(C/N) bonds lengthen from right to left on the periodic table: $1.50 - 1.60$ Å for B, $1.57 - 1.65$ Å for Be, and $1.72$ Å for Li.
  • Figure 2: (color online) Top and side views of (a) isolated Li and 1,7-diazacyclododecane-4,10-diamine, (b) Li bound to 1,7-diazacyclododecane-4,10-diamine, and (c) Li bound to the $V$N$_4$ defect in diamond. Relative formation energies of Li (and Li$^+$ in parentheses) are reported in eV, from PBE total energies (and PBE-$\epsilon$ ionization energy for Li$^+$ in (c)). The structures for Li$^+$ are similar to the neutral structures shown.
  • Figure 3: PBE and PBE-$\epsilon$ band structures of LiN$_4$ in a $6 \times 6 \times 6$ supercell in the spin channel where the donor impurity band is occupied. Only the donor impurity band and the lowest branch of the conduction band are shown. The conduction band is similar at both levels of theory and only one is plotted.