Origins of green band emission in high-temperature annealed N-doped ZnO

► Green band emission of ZnO shows doublet structures and negative thermal quenching effect. ► Doublet structures originate from ground and exited states of shallow donors to zinc vacancies. ► Negative thermal quenching effect is due to donor bound exciton dissociation. ► The origin of the green band emission is explained from another new perspective.