• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2007.11a
• /
• pp.75-76
• /
• 2007

ZnS:Cu,Cl phosphor was coated by solid-gel reaction with $SiO_2$ outside layer. The effect of $Cu^{2+}$-doping concentration has been investigated on the luminescence characteristics of ZnS:Cu,Cl blue-green phosphors for inorganic electro luminescent device. Also, SiO2 coated layers' effect on luminescence characteristics. Evaluation of luminescence characteristics dependent on the synthesis conditions is important to get high-performance phosphors properties. EL and PL properties such as luminescence intensity and chromaticity of ZnS:Cu,Cl phosphors synthesized with different concentration of activator, $Cu^{2+}$, were analysed separately

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.396-399
• /
• 2003

In this paper, the purpose is to develop imaging technique of synchrotron radiation using CMOS image sensor. The detector using hybrid method to be research in this lab was used, in order to increase image signal. We made experiments with 1B2 Whitebeam/microprobe beamline in PAL (Pohang Accelerator Laboratory). Phosphor materials such as ZnS:(Ag,Li), ZnS:(Cu,Al), $Y_2O_2S:Eu$ were produced by spin coating on glass. Synchrotron radiation images were acquired and evaluated from monochromatic light from monochromoator in PAL 1B2line. From obtained object and phantom, MTF was 0.15 in ZnS:(Ag,Li) phosphor, and 0.178 in ZnS:( Cu,Al) at 151p/mm. MTFs were unsystematic because thickness of phosphor and uniformity of surface were not optimized. It's expected to improve MTF and the qualify of images as uniformity's optimized.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.719-723
• /
• 2004

Silica coating on ZnS particles with buffer solution has been investigated. Diluted sodium silicate in water was used as the precursor material and it was diluted in water. Sodium silicate was added drop-wise in the continuously stirred suspension of ZnS in the buffer solution at room temperature. Smooth and evenly distributed silica coated ZnS phosphors has been obtained when the pH of buffer solution was 10, the concentration of sodium silicate in water was 20 wt%, firing temperature was 500 $^{\circ}C$.

• Korean Journal of Materials Research
• /
• v.16 no.4
• /
• pp.248-252
• /
• 2006

An investigation is reported on the coating of ZnS:Cu,Cl phosphors by $HfO_2$ using atomic layer deposition method. Hafnium oxide films were prepared at the chamber temperature of $280^{\circ}C$ using $Hf[N(CH_3)_2]_4\;and\;O_2$ as precursors and reactant gas, respectively. XPS and ICP-MS analysis showed the surface composition of coated phosphor powder was hafnium oxide. In FE-SEM analysis, the surface morphology of uncoated phosphors became smoother and clearer as the number of ALD cycle increased from 900 to 1800. The photoluminescence intensity for coated phosphors showed $7.3{\sim}13.4%$ higher than that of uncoated. The effect means that the reactive surface is uniformly coated with stable hafnium oxide to reduce the dead surface layer without change of bulk properties and also its absorptance is almost negligible due to ultrathin(nano-scaled) films. The growth rate is about $1.1{\AA}/cycle$.

• Current Optics and Photonics
• /
• v.1 no.4
• /
• pp.284-288
• /
• 2017

In order to investigate the ultraviolet-excited photoluminescence properties of phosphor coatings and their relationship to thickness, Lumogen coatings with different thicknesses were deposited on quartz substrates and charge-coupled device chips by thermal evaporation. The variation of the film thickness affected the crystallite size, surface roughness and fluorescence signal. It was found that the Lumogen coating with the thickness of 420 nm has the largest luminescent signal and conversion efficiency, and the corresponding coated charge-coupled devices had the maximum quantum efficiency in the ultraviolet. These results provided one key parameter for improving the sensitivity of Lumogen coated charge-coupled devices to ultraviolet light.

• Journal of Powder Materials
• /
• v.26 no.6
• /
• pp.463-470
• /
• 2019

Fe₃O₄/SiO₂/YVO₄:Eu³⁺ multifunctional nanoparticles are successfully synthesized by facile stepwise sol-gel processes. The multifunctional nanoparticles show a spherical shape with narrow size distribution (approximately 40 nm) and the phosphor shells are well crystallized. The Eu³⁺ shows strong photoluminescence (red emission at 619 nm, absorbance at 290 nm) due to an effective energy transfer from the vanadate group to Eu. Core-shell structured multifunctional nanoparticles have superparamagnetic properties at 300 K. Furthermore, the core-shell nanoparticles have a quick response time for the external magnetic field. These results suggest that the photoluminescence and magnetic properties could be easily tuned by either varying the number of coating processes or changing the phosphor elements. The nanoparticles may have potential applications for appropriate fields such as laser systems, optical amplifiers, security systems, and drug delivery materials.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07b
• /
• pp.1534-1535
• /
• 2005

Highly luminescent efficiency phosphors have been successfully produced by surface modification and microwave irradiation treatment. The SEM image and XRD analysis reveal that the surface morphology of the white-light phosphors can be notably modified by microwave irradiation and exhibit with better crystalline property. The VUV PL spectra show that the microwave irradiation treatment can effectively enhance the luminescent efficiency by a factor of 1.5 times for intensity compared to that without microwave treatment. A further improvement in all visible emission can be made by modifying surface composition through MgO coating on the phosphor powder. These results demonstrate that such a simple approach can provide for improving luminescent efficiency of phosphors for the optoelectronic devices.

• Transactions on Electrical and Electronic Materials
• /
• v.3 no.4
• /
• pp.16-20
• /
• 2002

The high bias voltage associated with the thick layer (typically 500-1000 ㎛) of selenium required to have an acceptable x-ray absorption in radiography and fluoroscopy applications may have some practical inconvenience. A hybrid x-ray detector with zinc sulfide-amorphous selenium structure has been developed to improve the x-ray sensitivity of a a-Se based flat-panel digital imaging detector. Photoluminescence(PL) characteristic of a ZnS:Ag phosphor layer showed a light emission peak centered at about 450 nm, which matches the sensitivity spectrum of selenium. The dark current of the hybrid detector showed similar characteristics with that of a a-Se detector. The x-ray sensitivity of hybrid and a-Se x-ray detector was 345 pC/㎠/mR and 295 pC/㎠/mR at an applied voltage of 10 V/㎛, respectively. The purpose of this study was to evaluate the pertinence of a solution using a thin selenium layer, as a photosensitive converter, with a thick coating of silver doped zinc sulfide phosphor.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.3C no.4
• /
• pp.136-139
• /
• 2003

The positive column of a discharge tube filled with a mixture of mercury-xenon has a tendency to become contracted at room temperature. However, once the tube temperature is raised over 50 [$^{\circ}C$], the positive column changes from a contracted state to a diffused state. The xenon emission is stronger in the contracted positive column than in the diffused column. Alternatively, the mercury emission is more intense in the diffused positive column, and the luminance of the phosphor coating on the inner surface of the tube is higher than that in the contracted positive column. Moreover, higher luminance can be obtained by increasing the xenon pressure.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.1272-1273
• /
• 2009

We demonstrate conformal phosphor coating and patterning methods on light emitting diodes (LEDs) using image processing based optofluidic maskless lithography (IP-OFML) system in microfluidic channels. IP-OFML allows a real-time detection and dynamic mask generation for packaging of randomly dispersed microchips. Our system detects each chip by considering rotation of the chip through image processing regardless of their arrangement error. Therefore, it precisely packages the chip making conformal polymer layer.