Fast photoluminescence decay processes of doped ZnO phosphors
Lifetime measurements have been carried out for ZnO doped with killer impurities (Fe, Co or Ni) having doping concentrations 0.05 to 1.00% by weight using a pulsed UV laser (nitrogen laser) as the excitation source having a short pulse width and a high photon flux density. The high photon flux density of the laser is very useful to excite the short-lived shallow trapping states which otherwise would be impossible to excite. Fast photoluminescence emission in the microsecond time domain has been obtained due to killer impurities at room temperature. The effect of killer dopants as well as the effect of their concentrations on lifetime values has been observed. Other optical parameters such as trap depth and decay constant are also reported in the present context. Lifetime values are found to be in the microsecond time domain and a reverse trend is obtained with increase in concentration of killer impurities.
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