• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.115-120
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• 2009

The 3wt.% Al-doped zinc oxide (AZO) thin films were fabricated on Coming 1737 substrates at a fixed oxygen pressure of 200 mTorr with various substrate temperatures ($100\;{\sim}\;250^{\circ}C$) by using pulsed laser deposition in order to investigate the microstructure, optical, and electrical properties of AZO thin films. All thin films were shown to be c-axis oriented, exhibiting only a (002) diffraction peak. The AZO thin film, fabricated at 200 mTorr and $250^{\circ}C$, showed the highest (002) orientation and the full width at half maximum (FWHM) of the (002) diffraction peak was $0.44^{\circ}$. The optical transmittance in the visible region was higher than 85 %. The Burstein-Moss effect, which shifts to a high photon energy, was observed. The electrical property indicated that the highest carrier concentration ($3.48{\times}10^{20}cm^{-3}$) and the lowest resistivity ($1.65{\times}10^{-2}{\Omega}cm$) were obtained in the AZO thin film fabricated at 200 mTorr and $250^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.7 no.5
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• pp.372-376
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• 1998

We developed a pulsed laser deposition(PLD) apparatus for depositing various thin films. In this study, the formation of $NbS_2$ thin film was performed in the vacuum chamber by PLD method. $Al_2O_3$(012) and Si(111) were used as the substrates. In order to investigate the growth conditions of a high crystalline $NbS_2$ thin film, the S/Nb composition ratio was varied from 2.0 to 5.25 and the substrate temperature was varied from the room temperature to $600^{\circ}C$. From the result of X-ray diffraction studies of the prepared $NbS_2$ thin films, it was reported that the $NbS_2$, thin film showed a good crystallinity at substrate temperature $600^{\circ}C$ and with S/Nb composition ratio 4.0 on $Al_2O_3$(012) but did not on Si(111). The films exhibited c-axis orientation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.355-356
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• 2008

In this work, ZnO films doped with different contents of Indium (0.1at.%, 0.3at.%, 0.6at.%, respectively) were deposited on Si (111) substrate that has 1~20 $\Omega$cm by pulsed laser deposition (PLD) at $600^{\circ}C$ for 30min. The thickness of the films are about 250 nm. The structural, optical and electrical properties of the films were investigated using X-ray Diffraction (XRD), Atomic force microscope (AFM), Photoluminescence (PL) and Hall measurement. It has been found that RMS of the films is decreased and grain size is increased with increasing the contents of doped Indium. The results of the Photoluminescence properties were indicated that the films have UV emission about 380nm and shows a little red shitf with increasing contents of doped indium. The result of the Hall measurement shows that the concentration and resisitivity in doped ZnO are as changing as one order, respectively ${\sim}10^{18}/cm^2$, ${\sim}10^{-2}cm{\Omega}cm$.

• Journal of Sensor Science and Technology
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• v.7 no.1
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• pp.61-66
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• 1998

High quality c-axis oriented $YBa_{2}Cu_{3}O_{7}$ films were prepared using the pulsed laser deposition on $SrTiO_{3}$(100) substrate. The atomically smooth $SrTiO_{3}$surface with terraces one unit cell in height could be obtained by a high temperature annealing. $YBa_{2}Cu_{3}O_{7}$ thin films deposited on the substrates exhibited layer-by-layer growth with a c-axis unit cell height. $YBa_{2}Cu_{3}O_{7}$ thin films thus prepared showed critical temperature ${\ge}90$ K with transition width ${\le}0.6$ K, room temperature resistivity of ${\sim}300{\mu}{\Omega}cm$, and critical current density ${\sim}4.6{\times}10^{6}A/cm^{2}$ at 77 K.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.357-357
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• 2012

박막트랜지스터의 전극으로 Au, Ag, Mo, ITO와 같은 물질들이 이미 많이 연구되어 왔으며, 투명 Source/Drain 전극을 활용한 물질로는 ITO에 초점이 맞춰져 왔다. 하지만 ITO의 높은 가격과 Indium의 인체 유해한 독성 때문에 ITO를 대체하는 물질에 대해 많은 연구가 진행되고 있다. 그 중 Al이 도핑된 ZnO (AZO) 는 가시광 영역에서 85% 이상의 높은 투과율과 높은 전도성, 낮은 비저항으로 다양한 광전소자의 전극과 윈도우 물질로 많은 응용 가능성을 보여주고 있다. 본 실험에서는 고 품질의 박막성장이 가능하고, 박막의 두께를 세밀하게 조절할 수 있는 Pulsed Laser Deposition (PLD) 을 이용하여 온도변화에 따라 AZO 박막을 성장시키고 구조적, 전기적, 광학적 특성을 조사하였다. 또한 온도변화가 AZO 박막 특성에 미치는 영향을 분석하여 Source/Drain 전극으로 사용하기 위한 조건을 최적화하였고, 실제 투명박막트랜지스터 제작을 통해 소자의 I-V Curve 와 Transfer 특성을 확인하고, Transfer Length Method 방법을 이용하여 투명박막트랜지스터의 접촉저항, 채널 비저항 등을 확인해 보았다. 소결된 타겟으로는 99.99%의 순도를 갖는 ZnO-$Al_2O_3$ (98:2 wt%) 타겟을 이용하였으며, 장비조건으로는 355 nm의 파장대역을 갖는 Nd:YAG 레이저를 사용하였고, 실험변수로는 온도범위 RT, $200^{\circ}C$, $400^{\circ}C$, $600^{\circ}C$에서 실험을 진행하였다. AZO 박막의 구조적, 전기적 특성을 분석하기 위해 각각 X-Ray Diffraction (XRD), Hall measurement 장비를 사용하였으며, 광학적 특성을 분석하기 위한 투과도의 측정은 UV-Visible spectrophotometer 장비를 사용하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.354-354
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• 2012

In this study, we report the vertically aligned ZnO nanowires by using different type of Ga-doped ZnO (GZO) thin films as seed layers to investigate how the underlying GZO film micro structure affects the distribution of ZnO nanowires. Arrays of highly ordered ZnO nanowires have been synthesized on GZO thin film seed layer prepared on p-Si substrates ($7-13{\Omega}cm$) with utilize of a pulsed laser deposition (PLD). With the vapor-liquid-solid (VLS) growth process, the ZnO nanowire synthesis carries out no metal catalyst and is cost-effective; furthermore, The GZO seed layer facilitates the uniform growth of well-aligned ZnO nanowires. The influence of the growth temperature and various thickness of GZO seed layer have been analyzed. Crystallinity of grown seed layer was studied by X-Ray diffraction (XRD); diameter and morphology of ZnO nanowires on seed layer were investigated by field emission scanning electron microscopy (FE-SEM). Our results suggest that the GZO seed layer with high c-axis orientation, good crystallinity, and less lattice mismatch is key parameters to optimize the growth of well-aligned ZnO nanowire arrays.

• Journal of the Korean institute of surface engineering
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• v.42 no.2
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• pp.68-72
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• 2009

We report on the growth of $CuCrO_2$ films using pulsed laser deposition and their structural and electrical transport properties. $CuCrO_2$ thin films were doped with 5 at% Mg for p-type properties. Epitaxial films of $CuCr_{0.95}Mg_{0.05}O_2$ were grown on c-plane sapphire substrates. The effects of growth temperature and oxygen pressure on film properties were investigated. The main phase of delafossite $CuCr_{0.95}Mg_{0.05}O_2$ was appeared above the growth temperature of $600^{\circ}C$. The thin film grown at $500^{\circ}C$ showed the highest conductivity, reaching 19.6 S/cm while higher growth temperatures over $500^{\circ}C$ led to lower conductivity; the thin film grown at $700^{\circ}C$ showed 0.02 S/cm.

• Journal of Sensor Science and Technology
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• v.8 no.2
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• pp.184-188
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• 1999

PbTe thin films of high quality were deposited on HF-treated Si(100) substrates at various substrate temperature by pulsed laser deposition technique. XRD patterns showed that PbTe layers were well-crystallized to a cubic phase with (h00) preferred orientation with the substrate temperature up to $300^{\circ}C$. PbTe films could not form at substrate temperature above $400^{\circ}C$ because of reevaporation of the Pb. According to AFM image, the surface of films was composed of small granular crystals and flat matrix. According to the increase of substrate temperature, the grain size at film surface becomes larger. By Hall-effect measurement, the carrier concentration and Hall mobility of n-type PbTe films grown by $T_{sub}=300^{\circ}C$ were $3.68{\times}10^{18}cm^{-3}$ and $148\;cm^2/Vs$, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.434-436
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• 2013

Ga-doped ZnO (GZO) was substitutes of the SnO2:F films on soda lime glass substrate in the photovoltaic devices such as CIGS, CdTe and DSSC due to good properties and low cost. However, it was reported that the electrical resistivity of GZO is unstable above $300^{\circ}C$ in air atmosphere. To improve thermal stability of GZO thin films at high temperature above $300^{\circ}C$ an $TiO_2$ thin film was deposited on the top of GZO thin films as a barrier layer by Pulsed Laser Deposition (PLD) method. $TiO_2$ thin films were deposited at various thicknesses from 25 nm to 100 nm. Subsequently, these films were annealed at temperature of $300^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$ in air atmosphere for 20 min. The XRD measurement results showed all the films had a preferentially oriented ( 0 0 2 ) peak, and the intensity of ( 0 0 2 ) peak nearly did not change both GZO (300 nm) single layer and $TiO_2$ (50 nm)/GZO (300 nm) double layer. The resistivity of GZO (300 nm) single layer increased from $7.6{\times}10^{-4}{\Omega}m$ (RT) to $7.7{\times}10^{-2}{\Omega}m$ ($500^{\circ}C$). However, in the case of the $TiO_2$ (50 nm)/GZO (300 nm) double layer, resistivity showed small change from $7.9{\times}10^{-4}{\Omega}m$ (RT) to $5.2{\times}10^{-3}{\Omega}m$ ($500^{\circ}C$). Meanwhile, the average transmittance of all the films exceeded 80% in the visible spectrum, which suggests that these films will be suitable for photovoltaic devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.27-27
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• 2008

The different concentration Indium doped ZnO:Al films were grown on glass substrates (Corning 1737) at $200^{\circ}C$ by pulsed laser deposition. The indium doping in AZO films shows the critical effect on the crystallinity, resistivity, and optical properties of the films. The AZO films doped with 0.3 atom % indium content exhibit the highest crystallinity, the lowest resistivity of $4.5\times10^{-4}\Omega$-cm, and the maximum transmittance of 93%. The resistivity of the indium doped-AZO films is strongly related with the crystallinity of the films. The carrier concentration in the indium doped-AZO films linearly increases with increasing indium concentration. The mobility of the AZO films with increasing indium concentration was reduced with an increase in carrier concentration and the decrease in mobility was attributed to the ionized impurity scattering mechanism. In an optical transmittance, the shift of the optical absorption edge to shorter wavelength strongly depends on the electronic carrier concentration in the films.