LUMINESCENCE AND ENERGY TRANSFER MECHANISMS IN Mn~(+2), Cr~(+3) AND Eu~(+3) DOPED ZnGa_2O_4

摘要

One of the critical issues facing field emission display (FED) technologies is the selection of appropriate low voltage cathodoluminescent (CL) materials. One of the most widely studied CL phosphors is ZnGa_2O_4. Because ZnGa_2O_4 is oxide-based, many of the degradation problems associated with sulfide-based phosphors are obviated. ZnGa_2O_4 has a normal spinel crystal structure (space group is Fd3m (O~7_h)), and is an intrinsic blue emitter (CIE coordinates: x = 0.170 and y = 0.130) with a peak wavelength of ～450 nm and efficiencies as high as 0.7 lm/W at 30V dc have been reported. The intrinsic blue emission originates from octahedral Ga-O_6 ligand-to-metal transitions, which emits efficiently due to the large Stokes shift in the absorption and emission spectrum. This paper investigates the CL properties of Mn~(+2), Eu~(+3) and Cr~(+3) activators in ZnGa_2O_4. Photoluminescence excitation spectra were also measured to understand the energy transfer between the ZnGa_2O_4 host and the Mn~(+2), Eu~(+3) and Cr~(+3) activators.