Browsing by Author "Yu, CF"

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A.c. powder electroluminescence devices using ZnGa2O4 : Mn phosphor
(1998-04-01)
Yu, CF
;
Lin, P
;
材料科學與工程學系
;
電子工程學系及電子研究所
;
Department of Materials Science and Engineering
Luminescent characteristics of ZnGa2O4:Mn phosphor thin films grown by radio-frequency magnetron sputtering
(1996-11-01)
Yu, CF
;
Lin, P
;
材料科學與工程學系
;
電子工程學系及電子研究所
;
Department of Materials Science and Engineering
Mn-doped ZnGa2O4 phosphor thin films on Si(100) were prepared by rf sputtering at 500 degrees C, Under UV light excitation, the deposited films showed a green emission band with a peak at 508 nm. Monitored at 508 nm, the excitation spectrum of the films showed a primary absorption at 245 nm. The spectra were similar to those of zinc gallate powder but with a larger band width. The films exhibited a high resistivity whether or not under the UV excitation. The possible energy transfer processes occurring in the material were discussed, and the resonance process was considered the dominant mechanism. From the spectral transmittance of undoped zinc gallate films sputtered on quartz glass, the evaluated indirect-transition optical gap was found to be 4.25 eV. The absorption by Ga3+ ions at 245 nm in the excitation spectrum was identified with the band-to-band transition of ZnGa2O4 host lattice.
Manganese-activated luminescence in ZnGa2O4
(1996-05-01)
Yu, CF
;
Lin, P
;
材料科學與工程學系
;
電子工程學系及電子研究所
;
Department of Materials Science and Engineering
Manganese-activated ZnGa2O4, prepared at a sintering temperature of 1375 degrees C with 0.1% MnO dopant, emitted red and green light with peaks at 566 and 508 nm when excited with a laser source (325 nm). The luminescence centers of red emission were ascribed to Mn4+ ions in the octahedral (B) sites of spinel-structure zinc gallate. Monitored at these two peaks, the sample exhibited absorption bands at 342 and 464 nm (for red) and 245 and 290 nm (for green) when excited with radiation from a xenon discharge lamp, indicating an excitation process occurring in Mn4+ ions distinct from that of Mn2+ ions (in A sites) which were known to be responsible for the green emission. Cathodoluminescence spectra showed that the integrated intensity of an UV band (peak at 349 nm) increased steadily with beam current while the green light intensity saturated at high current ranges. Several possible saturation mechanisms were discussed. The variation of the intensities versus current was interpreted and formulated based on an energy process between Ga-O groups and Mn2+ ions. Good fittings between the calculated curves and measured intensity data were attained with appropriate parameter values in the calculation. Assuming a resonant transfer process with electric dipole-dipole interaction prevailing between the Mn2+ and Ga3+ ions, a critical interaction distance of similar to 9.9 Angstrom for the ions was derived from an associated relation and the parameters used. (C) 1996 American Institute of Physics.
Manganese-activated luminescence in ZnGa2O4
(1996-05-01)
Yu, CF
;
Lin, P
;
材料科學與工程學系
;
電子工程學系及電子研究所
;
Department of Materials Science and Engineering
Manganese-activated ZnGa2O4, prepared at a sintering temperature of 1375 degrees C with 0.1% MnO dopant, emitted red and green light with peaks at 566 and 508 nm when excited with a laser source (325 nm). The luminescence centers of red emission were ascribed to Mn4+ ions in the octahedral (B) sites of spinel-structure zinc gallate. Monitored at these two peaks, the sample exhibited absorption bands at 342 and 464 nm (for red) and 245 and 290 nm (for green) when excited with radiation from a xenon discharge lamp, indicating an excitation process occurring in Mn4+ ions distinct from that of Mn2+ ions (in A sites) which were known to be responsible for the green emission. Cathodoluminescence spectra showed that the integrated intensity of an UV band (peak at 349 nm) increased steadily with beam current while the green light intensity saturated at high current ranges. Several possible saturation mechanisms were discussed. The variation of the intensities versus current was interpreted and formulated based on an energy process between Ga-O groups and Mn2+ ions. Good fittings between the calculated curves and measured intensity data were attained with appropriate parameter values in the calculation. Assuming a resonant transfer process with electric dipole-dipole interaction prevailing between the Mn2+ and Ga3+ ions, a critical interaction distance of similar to 9.9 Angstrom for the ions was derived from an associated relation and the parameters used. (C) 1996 American Institute of Physics.