Fabrication and cathodoluminescent properties of the ZnO-Cu,Ga and ZnS-Cu,Ga film phosphors (original) (raw)
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Thin ZnS:Cu,Ga and ZnO:Cu,Ga film phosphors
A new technique for electro-and cathodoluminescent screen fabrication with the application of a new method of doping ZnS:Cu and ZnO:Cu thin film phosphors is proposed. Thin films of ZnS:Cu were grown by electron-beam evaporation (EBE) from a ZnS:Cu target on substrates heated to 150-2008C, and the Cu concentration in the target was varied from 0.06 to 0.25 wt.%. BaTiO and sapphire single crystal substrates were used. The film thickness varied from 0.6 to 9 mm. Parameters of 3 ZnS:Cu films grown by EBE were modified by the use of non-vacuum annealing at 700-10008C in S-rich or O-rich atmosphere 2 2 both with and without Ga co-doping. The measurement of electroluminescent (EL) and cathodoluminescent (CL) parameters, as well as X-ray diffraction (XRD) techniques and atomic force microscopy (AFM) were used for this research. The EL ZnS:Cu,Ga blue color emission film with a luminance of 30 cdym and green (yellow) color emission film with a luminance of 800 cdym 2 2 were obtained. Devices with such films have a threshold voltage of 10 V. The CL luminance was 200 cdym for ZnS:Cu,Ga and 2 1100 cdym for ZnO:Cu,Ga films at 300 K and 3700 cdym for ZnO:Cu,Ga films at 77 K. The films show a deeper green color 2 2 than commercial phosphors. Clarification that gallium co-doping affects the luminance, since Ga influences on recrystallization process, has been carried out.
Structural investigations of annealed ZnS:Cu, Ga film phosphors
Semiconductor Physics, Quantum Electronics and Optoelectronics
X-ray and atomic force microscopy techniques were used for investigations of crystalline structure and nano-morphology of ZnS:Cu thin films. The films were deposited by electron beam evaporation on substrates of various types (glass, BaTiO 3 , silicon). New nonvacuum method of annealing was applied for improvement electro-physical parameters of ZnS:Cu based thin film electroluminescent devices. The annealing was carried out at the temperature of 850 °C. Ga co-doping was applied for the same structures in the course of the annealing process. It was shown that recrystallization process at annealing leads to improvement of ZnS:Cu films structural perfection without changes of crystal structure. This improvement provides tenfold increase of photo-and electroluminescence brightness and decrease of threshold voltage down to 10 V, as well as enhancement of device stability against degradation.
Chemically produced ZnS: Cu films: Structure, properties, and mechanism of electroluminescence
Technical Physics, 2002
ZnS : Cu films are prepared with a chemical nonvacuum technique by joint pyrolysis of zinc and copper dithiocarbamates at a substrate temperature between 260 and 300 ° C. It is shown that the films have the hexagonal lattice and are polycrystalline, with grains oriented mostly in the 〈0 001 〉 direction. The luminancevoltage characteristics, charge-voltage characteristics, brightness waveforms, electroluminescence spectrum, and degradation characteristics of the phosphors are investigated. A mechanism of electroluminescence and the degradation type are discussed. It is concluded that the MOCVD technique is promising for fabricating ZnS : Cu electroluminescent films. © 2002 MAIK "Nauka/Interperiodica".
Developing High-Efficiency Zn2SiO4:Mn Thin-Film Phosphors for Flat-Panel Cathodoluminescent Displays
1997
Zn 2 SiO 4 :Mn thin films were produced and studied for their potential application as thin-film phosphors for high-resolution flat-panel cathodoluminescent displays. Crystallized films with improved electrical conductivity were obtained after conventional and rapid thermal annealings in an N 2 environment at 850 to 1100 °C for 0.25 to 60 min. A maximum cathodoluminescent efficiency of 1.3 lm/W was achieved under dc excitation at 1500␣ V. The luminescent emission from these thin films peaked around 525␣ nm. The decay time of these films was controlled in the range of 2 to 10␣ ms by variation of the deposition and annealing parameters. Because their fast response time overcomes the long decay limitation of the Zn 2 SiO 4 :Mn␣ powder phosphor, these thin films will be suitable for practical display applications.
Preparation of and photo- and electroluminescence characteristics of ZnS: Cu phosphor
Pigment and Resin Technology, 2003
ZnS:Cu phosphors were prepared by co-precipitating Cu along with ZnS using H 2 S and thiourea. Phosphors giving luminescence at around 530 nm were prepared. The difference in the characteristic properties among the samples prepared appeared to be due to the formation of nanoparticles during the preparation of the samples by different methods.
Film Preparation Conditions and Characterization of co-Deposited Tungsten Doped Zinc Oxide Phosphor
MRS Proceedings, 1999
ABSTRACTNeed for efficient blue light emitting source for optoelectronic device applications such as flat panel displays has made the research in luminescent material ever so important. Tungsten doped zinc oxide (ZnO:W) has been identified as a blue light emitting phosphor exhibiting cathodoluminescence near 490 nm. This paper details work done on ZnO:W phosphor preparation conditions for efficient light emission from the phosphor. Material characterization to identify the possible source of blue light emission will also be discussed.
An Analysis of ZnS:Cu Phosphor Layer Thickness Influence on Electroluminescence Device Performances
International Journal of Photoenergy, 2017
Electroluminescence (EL) device is a new technology; its thickness is within micrometer range which can bend more easily and emit light. However, the thickness of ZnS:Cu phosphor layer may affect the light intensity, so we have analyzed the thickness of ZnS:Cu phosphor layer on EL device. The EL devices consist of ITO:PET/ZnS:Cu phosphor/insulator (BaTiO3)/Ag electrode. The EL devices were fabricated in changing thickness 10 μm, 30 μm, and 50 μm. At 100 V 400 Hz, the luminance of EL devices was 51.22 cd/m2 for thickness 30 μm more than that of 45.78 cd/m2 (thickness: 10 μm) and 42.58 cd/m2 (thickness: 50 μm). However, the peak light intensity was achieved at wavelength of 507 nm which was not influenced by the thickness of the ZnS:Cu phosphor. The use of the ZnS:Cu phosphor layer at thickness 30 μm in the EL device significantly improves the luminescence performance.
Journal of Applied Physics, 2002
The photo-and cathodoluminescence properties of epitaxial lithium-doped zinc gallate thin-film phosphors grown on ͑100͒ MgO single crystal substrates using pulsed laser ablation were investigated. The addition of lithium to both undoped and Mn-doped ZnGa 2 O 4 films significantly enhanced the photo-and low-voltage cathodoluminescent intensity. Cathodoluminescent efficiencies for as-deposited undoped and Mn-doped lithium zinc gallate films as high as 0.21 lm/W and 0.29 lm/W, respectively, were achieved for 1 kV and 2.26 A/cm 2. Based on these results, lithium-doped zinc gallate thin-film phosphors appear to be attractive for applications in low-voltage field emission display devices.