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RISS 인기검색어
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- 저자 : 신종언(Johngeon Shin) (검색결과 4 건)
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SrSnO<sub>3</sub>:Dy<sup>3+</sup> 백색광 형광체의 발광 특성
신종언,조신호,Shin, Johngeon,Cho, Shinho 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.11
New white-light-emitting $SrSnO_3:Dy^{3+}$ phosphors were prepared using different concentrations of $Dy^{3+}$ ions via a solid-state reaction. The phase structure, luminescence, and morphological properties of the synthesized phosphors were investigated using X-ray diffraction analysis, fluorescence spectrophotometry, and scanning electron microscopy, respectively. All the synthesized phosphors crystallized in an orthorhombic phase with a major (020) diffraction peak, irrespective of the concentration of $Dy^{3+}$ ions. The excitation spectra were composed of a broad band centered at 298 nm, ascribed to the $O^2-Dy^{3+}$ charge transfer band and five weak bands in the range of 350~500 nm. The emission spectra of $SrSnO_3:Dy^{3+}$ phosphors consisted of three bands centered at 485, 577, and 665 nm, corresponding to the $^4F_{9/2}{\rightarrow}^6H_{15/2}$, $^4F_{9/2}{\rightarrow}^6H_{13/2}$, and $^4F_{9/2}{\rightarrow}^6H_{11/2}$ transitions of $Dy^{3+}$, respectively. As the $Dy^{3+}$ concentration increased from 1 to 15 mol%, the intensities of all the emission bands gradually increased, reached maxima at 15 mol% of $Dy^{3+}$ ions, and then decreased rapidly at 20 mol% due to concentration quenching. The critical distance between neighboring $Dy^{3+}$ ions for concentration quenching was calculated to be $9.4{\AA}$. The optimal white light emission by the $SrSnO_3:Dy^{3+}$ phosphors was obtained when the $Dy^{3+}$ concentration was 15 mol%.
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열처리 온도에 따른 Zn<sub>2</sub>SnO<sub>4</sub> 박막의 특성
신종언 ( Johngeon Shin ),조신호 ( Shinho Cho ) 한국열처리공학회 2019 熱處理工學會誌 Vol.32 No.2
Zn<sub>2</sub>SnO<sub>4</sub> thin films were deposited on quartzs substrates by using radio-frequency magnetron sputtering system. Thermal treatments at various temperatures were performed to evaluate the effect of annealing temperatures on the properties of Zn<sub>2</sub>SnO<sub>4</sub> thin films. Surface morphologies were examined by using field emission-scanning electron microscopy and showed that sizes of grains were slightly increased and grain boundaries were clear with increasing annealing temperatures. The deposited Zn<sub>2</sub>SnO<sub>4</sub> thin films on quartzs substrates were amorphous structures and no distinguishable crystallographic changes were observed with variations of annealing temperatures. The optical transmittance was improved with increasing annealing temperatures and was over 90% in the wavelength region between 350 and 1100 nm at the annealing temperature of 600℃. The optical energy bandgaps, which derived from the absorbance of Zn<sub>2</sub>SnO<sub>4</sub> thin films, were increased from 3.34 eV to 3.43 eV at the annealing temperatures of 450℃ and 600℃, respectively. As the annealing temperature was increased, the electron concentrations were decreased. The electron mobility was decreased and resistivity was increased with increasing annealing temperatures with exception of 450℃. These results indicate that heat treatments at higher annealing temperatures improve the optical and electrical properties of rf-sputtered Zn<sub>2</sub>SnO<sub>4</sub> thin films. (Received February 18, 2019; Revised March 14, 2019; Accepted March 15, 2019)
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신종언 ( Johngeon Shin ),황인주 ( Injoo Hwang ),조신호 ( Shinho Cho ) 한국열처리공학회 2020 熱處理工學會誌 Vol.33 No.1
Annealing effects on the properties of Bi-doped ZnO thin films were investigated. Bi- doped ZnO thin films were deposited on quartzs substrates at 300oC by using radio-frequency magnetron sputtering system. Post heat treatments at 600, 700, and 800oC were performed to evaluate the effect of annealing temperatures on the structural, optical, and electrical properties of Bi-doped ZnO thin films. FE-SEM images showed the dramatic surface morphology changes by rearrangement of elements at high heat treatment temperature of 800oC. X-ray diffraction analysis indicated that the peaks of the Bi-doped ZnO thin films were same as the peaks of the (002) planes of ZnO peak-positioned at 2θ=34.0° and peak intensities and FWHMs were improved as the annealing temperatures increased. The optical transmittance was improved with increasing annealing temperatures and was over 80% in the wavelength region between 435 and 1100 nm at the annealing temperature of 700 and 800oC. With increasing annealing temperature, the electron concentrations and electron mobilities were increased. On the other hand, electric resistivity of the films were decreased with increasing annealing temperatures. These results showed that the heat treatment temperature is an important parameter to improve the structural, optical, and electrical properties of Bi-doped ZnO thin films. (Received December 16, 2019; Revised December 26, 2019; Accepted December 31, 2019)
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활성제 이온의 농도 변화에 따른 La₂MoO<SUB>6</SUB>:RE<SUP>3+</SUP> (RE = Eu, Sm) 형광체의 발광 특성
김가연(Gayeon Kim),신종언(Johngeon Shin),조신호(Shinho Cho) 한국표면공학회 2017 한국표면공학회지 Vol.50 No.4
Eu<SUP>3+</SUP>- or Sm<SUP>3+</SUP>-doped La₂MoO6 phosphors were synthesized with different concentrations of activator ions via a solid-state reaction. The X-ray diffraction patterns exhibited that crystalline structures of all the phosphors were tetragonal systems with the dominant peak occurring at (103) plane, irrespective of the concentration and the type of activator ions. The crystallites showed the pebble-like crystalline shapes and the average crystallite size increased with a tendency to agglomerate as the concentration of Eu<SUP>3+</SUP> ions increased. The excitation spectra of Eu<SUP>3+</SUP>-doped La₂MoO6 phosphors contained an intense charge transfer band centered at 331 nm in the range of 250-370 nm and three weak peaks at 381, 394, and 415 nm, respectively, due to the <SUP>7</SUP>F0→<SUP>5</SUP>L7, SUP>7</SUP>F0→<SUP>5</SUP>L6, and <SUP>7</SUP>F0→<SUP>5</SUP>D₃ transitions of Eu<SUP>3+</SUP> ions. The emission spectra under excitation at 331 nm exhibited a strong red band centered at 620 nm and two weak bands at 593 and 704 nm. As the concentration of Eu<SUP>3+</SUP> increased from 1 to 20 mol%, the intensities of all the emission bands gradually increased. For the Sm<SUP>3+</SUP>-doped La₂MoO6 phosphors, the emission spectra consisted of an intense emission band at 607 nm arising from the ⁴G5/2→<SUP>6</SUP>H7/2 transition and three relatively small bands at 565, 648, and 707 nm originating from the ⁴G5/2→<SUP>6</SUP>H5/2, ⁴G5/2→<SUP>6</SUP>H9/2, and ⁴G5/2→<SUP>6</SUP>H11/2 transitions of Sm3<SUP>+</SUP>, respectively. The intensities of all the emission bands approached maxima when concentration of Sm<SUP>3+</SUP> ions was 5 mol%. These results indicate that the optimum concentrations for highly-luminescent red and orange emission are 20 mol% of Eu<SUP>3+</SUP> and 5 mol% of Sm<SUP>3+</SUP> ions, respectively.
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