Calculating the Adiabatic Charge Transition Level for the NV^- to NV⁰ Transition in the Presence of Substitutional N or P in Diamond

Electroluminescence from color centers such as the nitrogen vacancy in diamond (NV^-) is desirable as it would allow for nanometer scale spin qubit control. However, even when a point defect shows the signature of NV^- in photoluminescence only the NV⁰ signature is observed in electroluminescence. Such an observation suggests ionization of the NV^- before it achieves fluorescence. We have developed a formalism for calculating the adiabatic charge transition level for the NV^- to NV⁰ transition in the presence of a substitutional N or P donor. When the NV^- is in the presence of a substitutional P donor or a high concentration of substitutional N donors we indeed find that the calculated adiabatic charge transition levels correspond to ionization energies for the NV^- that are smaller than the energy of its zero-phonon line.¹