EPR study on paramagnetic species in nitrogen-doped ZnO powders prepared by a mechanochemical method

Nitrogen-doped ZnO (N-ZnO) powders prepared by a mechanochemical method show two kinds of EPR signals due to a singly ionized nitrogen (N2-) and a shallow donor. Visible light irradiation of the N-ZnO particles reveals a reversible response of reduction of the EPR signal of the N2- radical site and an increase due to a shallow donor.