• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.27-28
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• 2009

In this study, we have fabricated the 3 wt% $Li_2CO3$ doped $(Ba,Sr)TiO_3$ thick films on the Ag/Pd printed $Al_2O_3$ substrates for the LTCCs (Low Temperature Co-fired Ceramics) applications. From the X-ray diffraion analysis, 3 wt% $Li_2CO3$ doped BST thick films on the Ag/Pd printed $Al_2O_3$ substrates, which sintered at 900 $^{\circ}C$ have perovskite structure without any pyro phase. The dielectric properties of 3 wt% $Li_2CO3$ doped BST thick films were measured from 1 kHz to 1 MHz. To investigate the electrical properties of 3 wt% $Li_2CO3$ doped BST thick films, we employed the impedance spectroscopy. The complex impedance of 3 wt% $Li_2CO3$ doped BST thick films were measured from 20 Hz to 1 MHz at the various temperatures.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.159-160
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• 2007

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.5
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• pp.1-7
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• 2007

AZO thin films have been fabricated on quartz substrate with various Al doping concentrations and annealing temperatures by sol-gel method. The bset condition of (002) orientation and smooth surface (rms = 1.082 nm) is obtained for the AZO thin film doped with 1 mol % Al and annealed at 550 $^{\circ}C$. The optical transmittance of AZO thin films is higher than 80 % in the visible region. We observe that the energy band gap extends with increasing the Al doping concentration. This phenomenon is due to the Burstein-Moss effect. Through the measurement of Hall effect, it is observed that the AZO thin film has larger carrier concentration and smaller electrical resistivity than the pure ZnO thin film. However, the AZO thin film shows the decrease of carrier concentration and the increase of resistivity with the increase of Al concentration, that is due to the segregation of Al at grain boundaries. The maximum carrier concentration of $1.80{\times}10^{19}\;cm^{-3}$ and the minimum resistivity of 0.84 ${\Omega}cm$ are obtained for the AZO thin film doped with 1 mol % Al and annealed at 550 $^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.11
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• pp.550-554
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• 2001

$(Ba_{0.6}Sr_{0.4}Ca_x)TiO_3 + yAl_2O_3$ wt% (x=0.10, 0.15, 0.20, y=0~3.0) ceramics were fabricated by the mixed-oxide method, and their structural and dielectric properties were investigated with variation of composition ratio and $Al_2O_3$ doping content. As results of the X-ray diffraction and microstructure analysis, all BSCT specimens showed dense and homogeneous structure without presence of the second phase. The sintered density was decreased with an increase of $Al_2O_3$ doping content. The Curie temperature and relative dielectric constant at room temperature were decreased with increasing $Al_2O_3$doping content. The dielectric loss is minimum at BSCT doped with 1.5wt% $Al_2O_3$content. The tunability was decreased with increasing an Ca content and the BSCT(50/40/10) specimen doped with 2.0wt% $Al_2O_3$content showed the maximum value of 4.2%.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4642-4646
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• 2023

The Tb³⁺ or Eu³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor were fabricated by funace at 1500 ℃ for 12 h using a solid state reaction. The XRD (X-ray diffraction_Panalytical X'Pert Pro) and FE-SEM (field emission scanning electron microscope) are measured to confirm the crystalline structure and surface morphology of the phosphor. The Tb³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor emits the lights in 470~650 nm wavelength range due to transitions from ⁵D₄ to ⁷F_j. Therefore, it shows the green region in the CIE chromaticity diagram under both UV and X-rays excitations. The Eu³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor emits the lights in 550~750 nm wavelength range because of ⁵D_i to ⁷F_j. The emission is confirmed to be in the red region using the CIE chromaticity diagram. The Tb³⁺ or Eu³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor shows the characteristic f-f transition with a long decay time, which is about several milliseconds. They have the high efficiency of light emission for X-ray because of their high effective Z number (Z_eff = 58.5) and density. Therefore, they are very much promising phosphors for X-ray imaging application in medical fields.

• Journal of the Korean Ceramic Society
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• v.41 no.10 s.269
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• pp.742-748
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• 2004

Isopropanol of low boiling point was used as a solvent to prepare Al-doped ZnO(AZO) thin films. A homogeneous and stable sol was made from Zn acetate a solute whose mole concentration was 0.7mol/$\iota$ and Al chloride as a dopant. Al-doped ZnO thin films were prepared by sol-gel method as a function of post-heating temperature from 500 to $700^{\circ}C$ and the optical and electrical properties were investigated. The c-axis orientation along (002) plane was enhanced with the increasing of post-heating temperature and the surface morphology of the films showed a homogeneous and nano-sized microstructure. The optical transmittance of the films post-heated below $650^{\circ}C$ was over $86\%$, but decreased at $700^{\circ}C$. The electrical resistivity of the thin films decreased from 73 to 22 $\Omega$-cm as the post-heating temperature increased up to $650^{\circ}C$, but increased greatly to 580 $\Omega$-cm at $700^{\circ}C$. XPS analysis indicated that the deterioration of electrical and optical properties was attributed to the precipitation of $Al_2O_3$ phase on the surface of AZO thin film. This result suggests that the optimum post-heating temperature to improve electrical and optical properties is $600^{\circ}C$.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.175-175
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• 2009

AZO, GZO, ZIO 박막은 DC 마그네트론 법으로 각각의 소결체 타겟을 사용하여 유리 기판위에 증착되었다. 상온에서 증착된 GZO 박막의 경우 $1.61{\times}10^{-3}{\Omega}cm$ 의 가장 낮은 비저항을 나타내었다. 전기적 특성을 향상시키기 위하여 기판온도를 상승하였을 때 역시 GZO 박막이 가장 낮은 $6.413{\times}10^{-4}{\Omega}cm$ 을 나타내었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.1
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• pp.50-55
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• 2008

AI-doped ZnO(AZO) thin films have been fabricated on glass substrate by sol-gel method, and the effect of Al precursors and post-annealing temperature on the characteristics of AZO thin films was investigated. The sol was prepared with zinc acetate, EtOH, MEA and Al precursors. In order to dope Al in ZnO, two types of aluminum nitrate and aluminum chloride were used as Al precursor. Zinc concentration was 0.5 mol/l and the content of Al precursor was 1 at% of Zn in the sol. The sol was spin-coated on glass substrate, and the coated films were annealed at 550ue for 2 hand were post-annealed at temperature ranges of $300{\sim}500^{\circ}C$ for 2 h in reducing atmosphere ($N_2/H_2$= 9/1). Structural, electrical and optical propertis of the fabricated AZO thin films were analyzed by XRD, FE-SEM, AFM, hall effect measurement system and UV-visible spectroscopy. Optical and electrical properties of AZO thin films prepared with aluminum nitrate as Al precursor were better than those of films prepared with aluminum chloride. The electrical resistivity and the optical transmittance of films decreased with increasing post-annealing temperatures. The minimum electrical resistivity of $2{\times}10^{-3}$ and the maximum optical transmittance of 91% were obtained for the AZO thin films post-annealed at $550^{\circ}C\;and\;300^{\circ}C$, respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.8
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• pp.1236-1241
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• 2017

We deposited Al-doped ZnO (ZnO:Al) thin films on glass substrates ($200mm{\times}200mm$) by using in-line magnetron sputtering system. Effects of various deposition parameters such as working pressure, deposition power and substrate temperature on optoelectronic characteristics including surface-texture etching profiles were carefully investigated in this study. We found that relatively low working pressure and high deposition power offered to obtain enhanced conductivity and optical transmittance. Haze properties showed similar trend with the transmittance. Furthermore, surface-texture etching study exhibited good morphologies when the films were deposited at $200-300^{\circ}C$. On the basis of these optimizations, we could find the deposition region that produces highly transparent and conductive properties including efficient light scattering capability.

• The Korean Journal of Ceramics
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• v.7 no.2
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• pp.85-92
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• 2001

Thin films of ZnO and Al doped ZnO were prepared by rf magnetron sputter techniques. When the oxygen fraction in Ar-O$_2$ sputter gas was about 2.0%, the films exhibited the composition of Zn:O=1.05:1. The films prepared at 250 W contain larger grains than the films grown at 100 W. However, high deposition rate seems to deteriorates the crystallinity as well as Al-substitution, resulting in lower concentration of mobile electrons. The Al-doped ZnO films which were deposited at $500^{\circ}C$ show resistance of 1$\times$10$^-2$ Wcm; optical band gap of the films ranges from 3.25 to 3.40 eV. These electrical and optical features are related with microstructural as well as crystalline characteristics of the films.