• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.220-225
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• 2020

Gallium oxide nano-powder, the key starting material for IGZO target, is fabricated by gas phase synthesis using a new apparatus consist of reaction, transportation, and collection parts. As a result of gallium metal evaporation above 1150℃, Ga2O3 nano-powders, are successfully synthesized. The SEM images of the synthesized powders displace the spherical shaped powders without severe agglomeration. X-ray diffraction and PSA analysis show that the higher temperature at the reaction part results in the better crystallinity and larger powder size of the synthesized Ga2O3. To see the applicability to IGZO target, Ga2O3 nano-powders synthesized at 1250℃ are mixed with indium oxide and zinc oxide (In2O3 : Ga2O3 : ZnO = 1 : 1 : 1), and then sintered at 1400~1500℃. The highest sintered density of 5.83 g/㎤ (= 91 % of relative density) is achieved when sintered at 1450℃, showing better sinterability compared to the commercially available Ga2O3 powder, which has 5.61 g/㎤ of sintered density at the same condition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.4
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• pp.400-406
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• 2024

Next-generation wide-bandgap semiconductors such as SiC, GaN, and Ga2O3 are being considered as potential replacements for current silicon-based power devices due to their high mobility, larger size, and production of high-quality wafers at a moderate cost. In this study, we investigate the gradual modulation of chemical composition in multi-stacked metal oxide semiconductor thin films to enhance the performance and bias stability of thin-film transistors (TFTs). It demonstrates that adjusting the Ga ratio in the indium gallium oxide (IGO) semiconductor allows for precise control over the threshold voltage and enhances device stability. Moreover, employing multiple deposition techniques addresses the inherent limitations of solution-processed amorphous oxide semiconductor TFTs by mitigating porosity induced by solvent evaporation. It is anticipated that solution-processed indium gallium oxide (IGO) semiconductors, with a Ga ratio exceeding 50%, can be utilized in the production of oxide semiconductors with wide band gaps. These materials hold promise for power electronic applications necessitating high voltage and current capabilities.

• Transactions on Electrical and Electronic Materials
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• v.17 no.2
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• pp.109-112
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• 2016

We demonstrated an alternative electrically controlled birefringence liquid crystal (ECB-LC) system with ion beam (IB)-irradiated yttrium gallium oxide (YGaO) alignment films using a sol-gel process. The surface roughness of the films was dependent on the annealing temperature; aggregated particles on surface were observed at lower annealing temperatures, whereas a smooth surface could be obtained with higher annealing temperatures. Higher transmittance in the visible region was observed at higher annealing temperatures. The film had an amorphous crystallographic state irrespective of the annealing temperature. Furthermore, ECB-LC cell with our IB-irradiated YGaO film yielded faster response time when compared to ECB-LC cell with rubbed polyimide. Considering the fast response time and high transmittance, the IB-irradiated YGaO-base LC system is a powerful alternative application for the liquid crystal display industry.

• Journal of Sensor Science and Technology
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• v.24 no.4
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• pp.219-223
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• 2015

Indium free consisting of three alternating layers GTO/Ag/GTO has been fabricated by radio-frequency (RF) sputtering for the applications as transparent conducting electrodes and the structural, electrical and optical properties of the gallium tin oxide (GTO) films were carefully studied. The gallium tin oxide thin films deposited at room temperature are found to have an amorphous structure. Hall Effect measurements show a strong influence on the conductivity type where it changed from n-type to p-type at $700^{\circ}C$. GTO/Ag/GTO multilayer structured electrode with a few nm of Ag layer embedded is fabricated and show the optical transmittance of 86.48% in the visible range (${\lambda}$ = 380~770 nm) and quite low electrical resistivity of ${\sim}10^{-5}{\Omega}cm$. The resultant power conversion efficiency of 2.60% of the multilayer based OPV (GAG) is lower than that of the reference commercial ITO. GTO/Ag/GTO multilayer is a promising transparent conducting electrode material due to its low resistivity, high transmittance, low temperature deposition and low cost components.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.307.1-307.1
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• 2016

Amorphous zinc tin oxide (ZTO) thin films are being widely studied for a variety electronic applications such as the transparent conducting oxide (TCO) in the field of photoelectric elements and thin film transistors (TFTs). Thin film transistors (TFTs) with transparent amorphous oxide semiconductors (TAOS) represent a major advance in the field of thin film electronics. Examples of TAOS materials include zinc tin oxide (ZTO), indium gallium zinc oxide (IGZO), indium zinc oxide, and indium zinc tin oxide. Among them, ZTO has good optical and electrical properties (high transmittance and larger than 3eV band gap energy). Furthermore ZTO does not contain indium or gallium and is relatively inexpensive and non-toxic. In this study, ZTO thin films were formed by UHV RF magnetron co-sputter deposition on silicon substrates and sapphires. The films were deposited from ZnO and SnO2 target in an RF argon and oxygen plasma. The deposition condition of ZTO thin films were controlled by RF power and post anneal temperature using rapid thermal annealing (RTA). The deposited and annealed films were characterized by X-ray diffraction (XRD), atomic force microscope (AFM), ultraviolet and visible light (UV-VIS) spectrophotometer.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.6-11
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• 2019

For a wider application of laser direct patterning, selective laser ablation of indium tin oxide (ITO) film on transparent oxide semiconductor (TOS) thin film was carried out using a diode-pumped Q-switched Nd:YVO₄ laser at a wavelength of 1064 nm. In case of the laser ablation of ITO on indium gallium zinc oxide (IGZO) film, both of ITO and IGZO films were fully etched for all the conditions of the laser beams even though IGZO monolayer was not ablated at the same laser beam condition. On the contrary, in case of the laser ablation of ITO on zinc oxide (ZnO) film, it was possible to etch ITO selectively with a slight damage on ZnO layer. The selective laser ablation is expected to be due to the different coefficient of thermal expansion (CTE) between ITO and ZnO.

• Resources Recycling
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• v.23 no.6
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• pp.63-67
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• 2014

Gallium is an important material and is used by industry of oxide semi-conductor and LED chip. However, the most of the gallium-containing waste resources became outflow abroad and the most of which is imported from oversea by following technical problem and low circulation rate. In this research, the recovery of high purity Gallium metal from Gallium scrap, which containing about 30% of Gallium, was investigated by using hydro-metallurgical process. As pretreatment, the Gallium scrap was pulverized and leached by strong acid such as hydro chloric acid. At the leached solution, Indium was separated as an Indium sponge by substitution reaction and then Gallium and Zinc hydroxide separated and filtrated using strong alkaline solution such as sodium hydroxide by precipitation method. Also, Gallium metal and Zinc metal was recovered by electrowinning method. To make an electrolytic solution, Gallium and Zinc hydroxide was leached by strong alkaline solution. Finally, High purity Gallium metal was recovered by vacuum refining process to remove the Zinc impurity.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1586-1589
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• 2009

We investigated the influence of chemical compositions of gallium and indium cations on the performance of solgel derived amorphous gallium indium zinc oxide (a-GIZO) based thin-film transistors (TFTs). Systematical composition study allows us to understand the solutionprocessed a-GIZO TFTs. Understanding of the compositional influence can be utilized for tailoring the solution processed amorphous oxide TFTs for the specific applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.256-256
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• 2012

Oxide semiconductors such as zinc tin oxide (ZTO) or indium gallium zinc oxide (IGZO) have attracted a lot of research interest owing to their high potential for application as thin film transistors (TFTs) [1,2]. However, the instability of oxide TFTs remains as an obstacle to overcome for practical applications to electronic devices. Several studies have reported that the electrical characteristics of ZnO-based transistors are very sensitive to oxygen, hydrogen, and water [3,4,5]. To improve the reliability issue for the amorphous InGaZnO (a-IGZO) thin-film transistor, back channel passivation layer is essential for the long term bias stability. In this study, we investigated the instability of amorphous indium-gallium-zinc-oxide (IGZO) thin film transistors (TFTs) by the back channel contaminations. The effect of back channel contaminations (humidity or oxygen) on oxide transistor is of importance because it might affect the transistor performance. To remove this environmental condition, we performed vacuum seasoning before the deposition of hybrid passivation layer and acquired improved stability. It was found that vacuum seasoning can remove the back channel contamination if a-IGZO film. Therefore, to achieve highly stable oxide TFTs we suggest that adsorbed chemical gas molecules have to be eliminated from the back-channel prior to forming the passivation layers.

• Transactions on Electrical and Electronic Materials
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• v.14 no.2
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• pp.59-62
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• 2013

At an infra-red (IR) wavelength of 1,064 nm, a diode-pumped Q-switched $Nd:YVO_4$ laser was used for the direct patterning of various transparent conductive oxide (TCO) thin films on glass substrate. With various laser beam conditions, the laser ablation results showed that the indium tin oxide (ITO) film was removed completely. In contrast, zinc oxide (ZnO) film was not etched for any laser beam conditions and indium gallium zinc oxide (IGZO) was only ablated with a low scanning speed. The difference in laser ablation is thought to be due to the crystal structures and the coefficient of thermal expansion (CTE) of ITO, IGZO, and ZnO. The width of the laser-patterned grooves was dependent on the film materials, the repetition rate, and the scanning speed of the laser beam.