• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.5
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• pp.297-302
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• 2014

$La_{0.5}Sr_{0.5}CoO_3$ (LSCO) electrode thin films with a resistivity of ~ 1,600 ${\mu}{\Omega}cm$ were grown on c-$Al_2O_3$ (0001) substrate. $ZnSnO_3$ (ZTO) thin films with different thicknesses were directly grown on LSCO/c-$Al_2O_3$ (0001) substrates at a substrate temperature that ranged from 550 to $750^{\circ}C$ using Pulsed Laser Deposition (PLD). The secondary phase $Zn_2SnO_4$ occurred during the growth of ZTO films and it became more significant with further increasing substrate temperature. Polarization-electric-field (P-E) hysteresis characteristics, with a remnant polarization and coercive field of 0.05 ${\mu}C/cm^2$ and 48 kV/cm, respectively, were obtained in the ZTO film grown at $700^{\circ}C$ in 200 mTorr.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.334-334
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• 2012

Transparent oxide semiconductors have recently attracted much attention as channel layer materials due to advantageous electrical and optical characteristics such as high mobility, high stability, and good transparency. In addition, transparent oxide semiconductor can be fabricated at low temperature with a low production cost and it permits highly uniform devices such as large area displays. A variety of thin film transistors (TFTs) have been studied including ZnO, InZnO, and InGaZnO as the channel layer. Recently, there are many studies for substitution of Ga in InGaZnO TFTs due to their problem, such as stability of devices. In this work, new quaternary compound materials, tantalum-indium-tin oxide (TaInSnO) thin films were fabricated by using co-sputtering and used for the active channel layer in thin film transistors (TFTs). We deposited TaInSnO films in a mixed gas (O2+Ar) atmosphere by co-sputtering from Ta and ITO targets, respectively. The electric characteristics of TaInSnO TFTs and thin films were investigated according to the RF power applied to the $Ta_2O_5$ target. The addition of Ta elements could suppress the formation of oxygen vacancies because of the stronger oxidation tendency of Ta relative to that of In or Sn. Therefore the free carrier density decreased with increasing RF power of $Ta_2O_5$ in TaInSnO thin film. The optimized characteristics of TaInSnO TFT showed an on/off current ratio of $1.4{\times}108$, a threshold voltage of 2.91 V, a field-effect mobility of 2.37 cm2/Vs, and a subthreshold swing of 0.48 V/dec.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.663-668
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• 2012

In order to reduce the indium contents in transparent conducting oxide(TCO) thin films of $In_{1.6{\sim}1.8}Zn_{0.2}Sn_{0.2{\sim}0.4}O_3$ (IZTO), $In_{1.6}Zn_{0.2}Sn_{0.2}O_{3-{\delta}}$(IZTO) was prepared by replacing indium with Zn and Sn. The TCO films were deposited via RF-magnetron sputtering of the IZTO target at various deposition temperatures and its film characteristics were investigated. When deposited in an Ar atmosphere at $400^{\circ}C$, the electrical resistivity of the film decreased to $6.34{\times}10^{-4}{\Omega}{\cdot}cm$ and the optical transmittance was 80%. As the deposition temperature increased, the crystallinity of the IZTO film was enhanced. As a result, the electrical conductivity and transmittance properties were improved. This demonstrates the possibility of replacing ITO TCO film with IZTO.

• Korean Journal of Metals and Materials
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• v.48 no.9
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• pp.861-866
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• 2010

Tetrapod-shaped ZnO crystals were synthesized through a simple oxidation of metallic Zn powder in air without the presence of any catalysts or substrates. X-ray diffraction data revealed that the ZnO crystals had wurtzite structure. It is supposed that the growth of the tetrapod proceeded in a vapor-solid growth mechanism. As the amount of the source powder increased, the size of the tetrapod decreased. The tip morphology of the tetrapod changed from a needle-like shape to a spherical shape with the oxidation time. ZnO crystals with rod shape were fabricated via the oxidation of Zn and Sn mixture. Sn played an important role in the formation of ZnO crystals with different morphology by affecting the growth mode of ZnO crystals. The cathodoluminescent properties were measured for the samples. The strongest green emission was observed for the rod-shaped ZnO crystals, suggesting that the crystals had the high density of oxygen vacancies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.79-79
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• 2009

Samples of Ta-doped in $In_2O_3-ZnO-SnO_2$(IZTO) with a doping level up to 4wt% were sintered at $1600^{\circ}C$ in $O_2$. The crystal phase of the samples was identified by an X-ray diffraction experiment. apparent density and porosity with sintered temperature from $1500^{\circ}C$ to $1640^{\circ}C$ are mesured by archimedes method. For each sample, the specific resistivity was determined. samples of sintered at $1600^{\circ}C$ had the highest density and lowest porousity and The Ta 0.25-wt%-doped IZTO ceramics had the lowest resistivity.

• Journal of IKEEE
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• v.13 no.4
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• pp.37-42
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• 2009

In this study, nanopower ZnO and $SnO_2$ as sensing materials were prepared by hydrazine and hydrothermal routes, respectively, and were doped with Pd, Ru catalyst. The CO and $NO_2$ sensors were fabricated by coating of sensing materials on the MEMS-based structure with electrodes and heaters. The 0.1 wt% Pd doped $SnO_2$ sensor and Ru doped ZnO sensor showed the high sensor response to CO 30 ppm and $NO_2$ 1 ppm, respectively. The sensor signal was stable. This can be used for the detection of pollutant gases emitted from gasoline engine.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.451-457
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• 1997

The thick films of oxide semiconductors such as $WO_{3}$, $SnO_{2}$ and ZnO for the $NO_{2}$ detection of sub-ppm range have been prepared and their characteristics were investigated. It is showed that the optimum operating temperatures of the sensors are $300^{\circ}C$ and $220{\sim}260^{\circ}C$ for $WO_{3}$-based and $SnO_{2}$-based thick films, and ZnO-based thick films, respectively. Since the resistance of ZnO-based thick films are extremely high($>10^{6}{\Omega}$), the signal to noise ratio was comparatively low. In order to determine the selectivity, the films are exposed to the interfering gases such as ozone, ammonia, methane and the mixture of carbon monoxide and propane. $WO_{3}$-ZnO(3 wt.%) and $SnO_{2}-WO_{3}$(3 wt.%) thick film sensors show high sensitivity, good selectivity, excellent reproducibility and the linearity of $NO_{2}$ concentration versus sensor resistance. The preliminary results clearly demonstrated that the sensor can be successfully applied for the detection of $NO_{2}$ in sub-ppm range.

• Journal of Integrative Natural Science
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• v.9 no.4
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• pp.223-227
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• 2016

The Zn, Sn, and ZnSn thin films were deposited on Si(100) substrate using radio frequency (RF) magnetron co-sputtering method. A surface profiler and X-ray photoelectron spectroscopy (XPS) were used to investigate the Zn, Sn, and ZnSn thin films. Thickness of the thin films was measured by a surface profiler. The deposition rates of pure Zn and Sn thin films were calculated with thickness and sputtering time for optimization. From the survey XPS spectra, we could conclude that the thin films were successfully deposited on Si(100) substrate. The chemical environment of the Zn and Sn was monitored with high resolution XPS spectra in the binding energy regions of Zn 2p, Sn 3d, O 1s, and C 1s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.27-30
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• 2006

In this paper, the undoped and Co-doped $Zn_4SnSe_6$ single crystals grown by the chemical transporting reaction(CTR) method using iodine as a transporting agent are investigated. For the crystal growth, the temperature gradient of the CTR furnace was kept at $680^{\circ}C$ for the source zone and at $780^{\circ}C$ for the growth zone for 7days. It was found from the analysis of x-ray diffraction that the $Zn_4SnSe_6$ and $Zn_4SnSe_6Co^{2+}$ compounds have a monoclinic structure. The direct optical energy band gap of the $Zn_4SnSe_6$ and $Zn_4SnSe_6Co^{2+}$ single crystals at 300K were found to be 2.146eV and 2.042eV.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.1
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• pp.18-21
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• 2014

Because the Pb-based piezoelectric materials showed problems such as an environmental pollution. lead-free $O_3$ materials were studied in the present study. The $O_3$ thin films were deposited at $640^{\circ}C$ on $Pt/Ti/SiO_2$ substrate by pulsed laser deposition (PLD) and were annealed for 5 min at $750^{\circ}C$ using rapid thermal annealing (RTA) in nitrogen atmosphere. Samples annealed at $750^{\circ}C$ showed a smooth morphology and an improvement of the dielectric and leakage properties, as compared with as-grown samples. However, electrical properties of the $O_3$ thin films obtained in the present study should be improved for piezoelectric applications.