A STUDY ON INFRARED EMISSION DEVICE USING ERBIUM DOPED ZINC OXIDE THIN FILMS

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A possibility of ZnO thin films as a new host material for Er doping has been investigated in this research. Erbium doped ZnO (ZnO : Er) thin films were fabricated by KrF excimer laser ablation that is a useful and simple technique to dope Er atoms of the order of 10^<20> cm^<-3> into a host material. As-prepared ZnO : Er films are observed to have hexagonal crystalline structure with strong c-axis orientation, and exhibit low electrical resistivity of 6.4x10^<-3> Ωcm. The sharp intense photoluminescence (PL) at 1.54 μm originating from the intra-4f shell transition in Er^<3+> ions as well as PL in UV region from the ZnO host was observed even at room temperature. Erbium-related 1.54 μm emission dynamics was investigated for the different excitation conditions. The excitation was achieved either by exciting indirectly Er^<3+> ions due to electron-hole mediated process or exciting directly discrete energy levels of Er^<3+> ions. There is no change in 1.54 μm, emission spectrum feature in spite of the different excitation conditions, whereas dramatic change can be seen in the rise time of 1.54 μm emission. The shorter rise time of 1.54 μm emission observed for indirect excitation implies an excitation efficiency superior to direct excitation of Er^<3+> ions.It should be emphasized that the ZnO film is, because of its high electrical conductivity and high excitation efficiency of Er^<3+> ions, one of the promising candidates for Er doping host to be incorporated into optoelectronic devices utilizing carrier injection.