• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.419-420
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• 2008

In this study, high quality (Al,N)-codoped p-type ZnO thin films were obtained by DC magnetron sputtering. The film on buffer layer grown in 80% $N_2$ ambient shows highest hole concentration of $2.93\times10^{17}cm^{-3}$. The films show hole concentration in the range of $1.5\times10^{15}$ to $2.93\times10^{17}cm^{-3}$, resistivity of 131.2 to 2.864 $\Omega$cm, mobility of 3.99 to 31.6 $cm^2V^{-1}s^{-1}$. The films on Si show easier p-doping in ZnO than those on buffer layer. The film on Si shows the highest quality of optical photoluminescence (PL) characteristics. The donor energy level $(E_d)$ of (Al,N)-codoped ZnO films is about 50 meV and acceptor energy level $(E_a)$ is in the range of 63 to 71 meV. It will help to improve p-type ZnO films.

• Clean Technology
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• v.23 no.4
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• pp.429-434
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• 2017

To investigate the effect of magnesium oxide addition, $Cu/ZnO/MgO/Al_2O_3$ (CZMA) catalysts were prepared using co-precipitation method with fixed molar ratio of Cu/Zn/Mg/Al as 45/45/5/5 mol% for low-temperature water gas shift reaction. Synthesized catalysts were characterized by using BET, $N_2O$ chemisorption, XRD, $H_2-TPR$ and $NH_3-TPD$ analysis. The catalytic activity tests were carried out at a GHSV of $28,000h^{-1}$ and a temperature range of $200{\sim}320^{\circ}C$. At the same condition, magnesium oxide added catalyst (CZMA 400) showed that the lowest reduction temperature and stable presence of $Cu^+$, that is active species and abundant weak acid site. Also magnesium oxide added catalysts (CZMA) showed higher catalytic activity at temperature range above $240^{\circ}C$ than the catalyst without magnesium oxide (CZA). Consequently, CZMA 400 catalyst is considered to be excellent catalyst showing CO conversion of 77.59% without deactivation for about 75 hours at $240^{\circ}C$, GHSV $28,000h^{-1}$.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.55-55
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• 2018

Recently, amorphous oxides such as InGaZnO (IGZO) and InZnO (IZO) as a channel layer of an oxide TFT have been attracted by advantages such as high mobility, good uniformity, and high transparency. In order to apply such an amorphous oxide TFTs to a display, the stability in various environments must be ensured. In the InGaZnO which has been studied in the past, Ga elements act as a suppressor of oxygen vacancy and result in a decreased mobility at the same time. Previous studies have been showed that the InZnO, which does not contain Ga, can achieve high mobility, but has relatively poor stability under various instability environments. In this study, the TFTs using $IZO/Al_2O_3$ double layer structure were studied. The introduction of an $Al_2O_3$ interlayer between source/drain and channel causes superior electrical characteristics and electrical stability as well as reduced contact resistance with optimally perfect ohmic contact. For the IZO and $Al_2O_3$ bilayer structures, the IZO 30nm IZO channels were prepared at $Ar:O_2=30:1$ by sputtering and the $Al_2O_3$ interlayer were depostied with various thickness by ALD at $150^{\circ}C$. The optimal sample exhibits considerably good TFT performance with $V_{th}$ of -3.3V and field effect mobility of $19.25cm^2/Vs$, and reduced $V_{th}$ shift under positive bias stress stability, compared to conventional IZO TFT. The enhanced TFT performances are closely related to the nice ohmic contact properties coming from the defect passivation of the IZO surface inducing charge traps, and we will provide the detail mechanism and model via electrical analysis and transmission line method.

• Journal of the Korean institute of surface engineering
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• v.55 no.5
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• pp.284-291
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• 2022

Herein, we studied ultrathin Cu-layer-based transparent heaters embedded between a ZnO underlayer and an Al₂O₃ overlayer. The anti-reflecting functions for the ZnO and Al₂O₃ layers by independently varying the layer thicknesses, with the Cu layer thickness fixed at 8.5 nm. The smallest visible light transmittance of 11.1% was achieved when the overlayer and underlayer thicknesses were 90 and 30 nm, respectively. We conducted electrically driven Joule heating test for the Cu layers having thicknesses of 8.5 nm (R_s: 14.7 Ohm/sq.) and 19 nm (R_s: 3.4 Ohm/sq.). External voltages were increased with an interval of 2 V until irreversible failures occurred at temperatures of ~390 ℃ and 550 ℃, respectively. At each voltage increase before heater failures, the heater exhibited superior thermal response with the heater temperatures reaching over 90% of the final temperatures. The heaters also showed excellent reproducibility when turning on and off the heater repeatedly.

• Transactions on Electrical and Electronic Materials
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• v.9 no.3
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• pp.96-100
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• 2008

The microstructure, voltage-current, and capacitance-voltage relations ofP CCYA doped ZnO-based varistors were investigated for different amounts of $Al_2O_3$. As the $Al_2O_3$ amount increased, the average grain size (d) increased from d=4.3 to $d=5.5{\mu}m$ and the sintered density $({\rho})$ increased from ${\rho}=5.63$ to ${\rho}=5.67g/cm^3$. As the $Al_2O_3$ amount increased, the breakdown voltage $(V_B)$ increased from $V_B=633$ to $V_B=71$ V/mm and the non-ohmic coefficient $({\alpha})$ increased from ${\alpha}=47$ to ${\alpha}=4$. $Al_2O_3$ served as a donor due to the donor density $(N_d)$, which increases in the range of $N_d=0.77-1.85{\times}10^{18}/cm^3$ with increasing amount of $Al_2O_3$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.525-528
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• 2001

ZnO:Al thin film can be used as a transparent conducting oxide(TCO) which has low electric resistivity and high optical transmittance for the front electrode of amorphous silicon solar cells and display devices. This study of electrical, crystallographic and optical properties of Al doped ZnO thin films prepared by Facing Targets Sputtering(FTS), where strong internal magnets were contained in target holders to confine the plasma between the targets, is described. Optimal transmittance and resistivity was obtained by controlling flow rate of $O_2$ gas and substrate temperature. When the $O_2$ gas rate of 0.3 and substrate temperature $200^{\circ}C$, ZnO:Al thin film had strongly oriented c-axis and lower resistivity( < $10^{-4}{\Omega}-cm$ ).

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.177-179
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• 2009

In order to investigate the possible application of ZnO films as a transparent conducting oxide (TCO) electrode, ZnO:Al films were prepared by RF magnetron sputtering method. The effects of surface treatment and doping concentration on the structural and electrical properties of ZnO films were mainly studied experimentally. Five-inch PDP cells using either a ZnO:Al or indium tin oxide (ITO) electrode were also fabricated separately under the same manufacturing conditions. The luminous properties of both the transparent conducting oxide electrode were measured and compared with each other. By doping the ZnO target with 2 wt% of Al2O3, the film deposited at a chemical surface treatment resulted in the minimum resistivity of 8.5 _ 10_4 U-cm and a transmittance of 91.7%. And DBD surface treatment resulted in the minimum resistivity of 8.5 _ 10_4 U-cm and a transmittance of 91.7%. Although the luminance and luminous efficiency of the transparent conducting oxide electrode using ZnO:AI are lower than those of the cell with the ITO electrode by about 10%, these values are sufficient enough to be considered for the normal operation of TCO.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.46.1-46.1
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• 2007

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.466-467
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• 2005

Al doped zinc oxide films (ZnO:Al) were deposited on glass substrate by RF magnetron sputtering from a ZnO target mixed with 2 wt% $Al_2O_3$. The as-deposited ZnO:Al films were rapid-thermal annealed. Electrical properties and structural evolution of the films, as annealed by rapid thermal process (RTP), were studied and compared with the films annealed by conventional annealing process. RTP, the (002) peak intensity increases and the electrical resistivity decreases by 20%, after RT annealing. The effects of RT annealing on the structural evolution and electrical properties of RF sputtered films were further discussed and compared also with the films deposited by DC magnetron sputtering.

• ETRI Journal
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• v.28 no.6
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• pp.787-789
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• 2006

In this letter, we report that vertically well-aligned ZnO nanowires were grown on GaN epilayers and c-plane sapphire via a vapor-liquid-solid process by introducing a 3 nm Au thin film as a catalyst. In our experiments, epitaxially grown ZnO nanowires on Au-coated GaN were vertically well-aligned, while nanowires normally tilted from the surface when grown on Au-coated c-$Al_2O_3$ substrates. However, pre-growth annealing of the Au thin layer on c-$Al_2O_3$ resulted in the growth of well-aligned nanowires in a normal surface direction. High-resolution transmission electron microscopy measurements showed that the grown nanowires have a hexagonal c-axis orientation with a single-crystalline structure.