Violet emission in ZnO nanorods treated with high-energy hydrogen plasma.

Violet photoluminescence was observed in high-energy hydrogen-plasma-treated ZnO nanorods at 13 K. The photoluminescence spectrum is dominated by a strong violet emission and a shoulder attributed to excitonic emission. The violet emission shows normal thermal behavior with an average lifetime of about 1 μs at 13 K. According to the time-resolved and excitation density-dependent photoluminescence, it was found that the violet emission is determined by at least two emitting channels, which was confirmed by annealing experiments. Evidence was also given that the violet emission is related to hydrogen. We suggested that the hydrogen-related complex defects formed under high-energy hydrogen plasma treatment are responsible for this violet emission.