Strong red up-conversion in Er3+ doped zinc oxide powder prepared by fluoride salt decomposition method

Er3+:ZnO powder has been prepared by fluoride salt decomposition method. Upon continuous wave excitation around 980 nm, Er3+:ZnO powder exhibit intense red emission originating from the 4F9/2 level of Er3+. The ratio of integrated emission at 650 nm to that at 540 nm is 21:1 with excitation of a diode laser of 10 mW at room temperature. The up-conversion mechanism has been discussed. It is believed the energy transfer processes that occur among the Er3+ ions bring out the strong red emission.