Nitrogen deep accepters in ZnO nanowires induced by ammonia plasma

Nitrogen doping in ZnO nanowires was achieved through ammonia plasma treatment followed by thermal annealing. The strong dependence of the red light emission from the nanowires excited by 2.4 eV on the nitrogen concentration, suggests that the red light emission originates from nitrogen related defects. The mechanism responsible for the red light emission is in good agreement with the deep-acceptor model of nitrogen defects, clarifying that nitrogen atoms caused deep accepters in ZnO nanowires. Based on this model, the enhanced green emission from defects in nitrogen-doped samples (excited by 325 nm line) can be well explained by the increase of the concentration of activated oxygen vacancies resulting from the compensation of nitrogen deep acceptors.