• Korean Journal of Materials Research
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• v.16 no.6
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• pp.360-366
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• 2006

A series of ZnO thin films were grown by radio-frequency (RF) magnetron sputtering with various RF powers on $SiO_2/Si$(100) substrates at $500^{\circ}C$. Thicknesses of the investigated ZnO films were fixed to about 250nm by changing the growth time based on the changes of growth rates with RF powers. All the ZnO thin films were grown with <0001> preferred orientation. Average grain sizes of about 250nm-thick ZnO films evaluated by FE-SEM, AFM, and TEM were increased by decreasing the RF power. Structural properties addressed by FWHM values of XRD (0002) omega rocking curves and their intensities were better for the smaller grain sized ZnO films grown with high RF powers, which implies small values of tilt for smaller grain sized ZnO films. However, optical properties addressed by intensities of band edge emissions from room temperature and low temperature photoluminescence were better for the larger grain sized ZnO films with low RF power, which implies grain boundaries acted as nonradiation recombination centers.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.2
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• pp.55-58
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• 2013

ITO thin films deposited on glass substrate with RF magnetron sputtering were vacuum annealed at 100, 200 and $300^{\circ}C$ for 30 minutes and then effect of annealing temperature on the structural, electrical and optical properties of ITO films were investigated. The structural properties are strongly related to annealing temperature. The annealed films above $100^{\circ}C$ are grown as a hexagonal wurtzite phase and the largest grain size is observed in the films annealed at $300^{\circ}C$. The electrical resistivity also decreases as low as $4.65{\times}10^{-4}{\Omega}cm$ with a increase in annealing temperature and ITO film annealed at $300^{\circ}C$ shows the lowest sheet resistance of $43.6{\Omega}/{\Box}$. The optical transmittance in a visible wavelength region also depends on the annealing temperature. The films annealed at $300^{\circ}C$ show higher transmittance of 80.6% than those of the films prepared in this study.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.28.1-28.1
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• 2009

The superior properties of ZnO such as high exciton binding energy, high thermal and chemical stability, low growth temperature and possibility of wet etching process in ZnO have great interest for applications ranging from optoelectronics to chemical sensor. Particularly, vertically well-aligned ZnO nanorods on large areas with good optical and structural properties are of special interest for the fabrication of electronic and optical nanodevices. Currently, low-dimensional ZnO is synthesized by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), thermal evaporation, and sol.gel growth. Recently, our group has been reported about achievement the growth of Ga-doped ZnO nanorods using ZnO seed layer on p-type Si substrate by RF magnetron sputtering system at high rf power and high growth temperature. However, the crystallinity of nanorods deteriorates due to lattice mismatch between nanorods and Si substrate. Also, in the growth of oxide using sputtering, the oxygen flow ratio relative to argon gas flow is an important growth parameter and significantly affects the structural properties. In this study, Phosphorus (P) doped ZnO nanorods were grown on c-sapphire substrates without seed layer by radio frequency magnetron sputtering with various argon/oxygen gas ratios. The layer change films into nanorods with decreasing oxygen partial pressure. The diameter and length of vertically well-aligned on the c-sapphire substrate are in the range of 51-103 nm and about 725 nm, respectively. The photoluminescence spectra of the nanorods are dominated by intense near band-edge emission with weak deep-level emission.

• Korean Journal of Materials Research
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• v.14 no.7
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• pp.494-499
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• 2004

The structural, electrical and optical properties of GaN epilayers grown on various ion-implanted sapphire(0001) substrates by MOCVD were investigated. Sapphire substrates have been widely adopted to grow high quality GaN epilayer despite the large differences of lattice constant and thermal expansion coefficient between them. So, GaN or AlN buffer layer and pre-treatment was indispensably introduced before the GaN epilayer growth. The ion-implanted substrate's surface had decreased internal free energies during the growth of the ions implanted sapphire(0001) substrates. The crystal and optical properties of GaN epilayers grown in ions implanted sapphire(0001) substrate were improved. Also, excessively roughened and modified surface by ions degraded the GaN epilyers. Not only the ionic radius but also the chemical species of implanted sapphire(0001) substrates could improve the properties of GaN epilayers grown by MOCVD. This result implies that higher quality of GaN epilayers was achieved by using ion-implanted sapphire(0001) substrate with various ions.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.170-171
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• 2000

최근 광 응용기술, 레이저 및 광통신 기술이 빠르게 발전함에 따라 고부가 가치 광학박막의 규격이 높아지고 있으며, 덩어리와 같은 광학적, 기계적 특성을 갖는 광학박막이 요구되고 있다. 일반적으로 이러한 성능을 만족하는 광학박막을 제작하기 위해 전자빔으로 증발되어 기판에 증착되는 박막에 직접 산소 이온을 이온총을 이용하여 기판에 쏘아줌으로써 양질의 산화박막을 제작하는 이온빔 보조 증착법이 가장 많이 적용되고 있다. 여기서 이온빔은 증착되는 박막의 기둥구조를 파괴시켜 원래의 덩어리(bulk)에 가까운 성질을 갖는 조밀한 박막을 제작하는데 이용된다. 좀더 조밀한 박막을 만들어 덩어리에 가까운 성질을 갖도록 하기 위해서는 박막을 형성하는 이온들의 이온에너지를 높여주어야 하는데, 그 방법으로 이온빔 스퍼터링이나 RF 또는 DC 마그네트론 스퍼터링 방법 등이 있으며, 최근에는 medium frequency에 의한 twin-마그네트론 스퍼터링 기술을 이용하기도 한다$^{(1 4)}$ . (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.266-267
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• 2001

TiO$_2$와 SiO$_2$는 일반적으로 가시광 영역에서부터 근적외선까지의 넓은 파장영역의 광학박막을 제작하기 위한 물질로서 사용되어져 오고 있다. 이 두 물질은 비교적 큰 굴절률 차이를 지니고 있어 이들을 이용한 다층박막 또는 혼합박막에 대한 연구가 이루어져왔다. TiO$_2$-SiO$_2$ 혼합박막을 제작하기 위해 e-beam evaporation, CVD, flame hydrolysis, sol-gel 등 다양한 방법이 연구되고 있다. 특히 sol-gel법은 혼합물질의 조성이 용이하고 최종 물질의 광학적 특성이 우수하다. (중략)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.154-157
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• 2003

$TiO_2$ thin films were fabricated by RF magnetron sputtering system at by controlling deposition times, ratios of $Ar:O_2$ partial presser ratio and substrate conditions. And the surface, cross-section morphology, microstructure, and composition ratio of the films were analyzed by FE-SEM, TEM and XPS. Besides, the optical absorption and transmittance of the $TiO_2$ films were measured by a UV-VIS-NIR Spectrophotometer, and photocatalytic properties were studied by G${\cdot}$C Analyzer & Data Analysis system. As the result, when $TiO_2$ thin film was made at deposition time of 120[min] and $Ar:O_2$ ratio of 60:40, the best structural and optical properties among many thin films could be accepted. The best results of properties were as follows: thickness; 360~370[nm), grain size; 40[nm], gap between two peak binding energy; $5.8{\pm}0.05[eV]$ ($2_{p3/2}$ peak and $2_{p1/2}$ peak of Ti was show at $458.3{\pm}0.05[eV]$ and $464.1{\pm}0.05[eV]$ respectively), binding energy; $530{\pm}0.05[eV]$, optical energy band gap; 3.4[eV].

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.12
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• pp.961-965
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• 2010

In this study, we investigated the optical, electrical, and structural properties of the IGZO($In_2O_3:Ga_2O_3:ZnO$=1:9:90 wt.%) thin films prepared by RF-magnetron sputtering system under various substrate temperatures. All of the IGZO thin films shows an average transmittance of over the 80% in visible range. Most of all, deposited IGZO thin film at $100^{\circ}C$ substrate temperature have ZnO (002) of main growth peak and 17.02 nm of increased grains. And also IGZO thin film have low resistivity($1.35{\times}10^{-3}\;\Omega{\cdot}cm$), high carrier concentration($6.62{\times}10^{20} cm^{-3}$) and mobility($80.1 cm^2$/Vsec). IGZO thin film have 2.08 mV at surface potential of electric force microscopy(EFM). We suggest that pre-annealing at $100^{\circ}C$ can be applied for improving optical, electrical and structural properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.6
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• pp.392-397
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• 2018

In this paper, the ZnS nanoparticles were synthesized according to the process conditions of hydrothermal synthesis. When the molar ratio of Zn to S was 1:1.2, it was confirmed that it had a cubic single phase and a high crystal phase. After the molar ratio is fixed, hydrothermal synthesis was conducted at $180^{\circ}C$ for 24, 36, 72 and 96 h in order to confirm the structural change with the change of hydrothermal synthesis times. As the hydrothermal synthesis times increased, the particle size increased. The hydrothermal synthesized particle size for 72 h was considered to be suitable for sintering. The ZnS ceramic had a density of 99.7% and an excellent transmittance of ~70% in the long-wavelength region.

• Korean Journal of Materials Research
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• v.24 no.10
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• pp.543-549
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• 2014

A zinc oxide (ZnO) hybrid structure was successfully fabricated on a glass substrate by metal organic chemical vapor deposition (MOCVD). In-situ growth of a multi-dimensional ZnO hybrid structure was achieved by adjusting the growth temperature to determine the morphologies of either film or nanorods without any catalysts such as Au, Cu, Co, or Sn. The ZnO hybrid structure was composed of one-dimensional (1D) nanorods grown continuously on the two-dimensional (2D) ZnO film. The ZnO film of 2D mode was grown at a relatively low temperature, whereas the ZnO nanorods of 1D mode were grown at a higher temperature. The change of the morphologies of these materials led to improvements of the electrical and optical properties. The ZnO hybrid structure was characterized using various analytical tools. Scanning electron microscopy (SEM) was used to determine the surface morphology of the nanorods, which had grown well on the thin film. The structural characteristics of the polycrystalline ZnO hybrid grown on amorphous glass substrate were investigated by X-ray diffraction (XRD). Hall-effect measurement and a four-point probe were used to characterize the electrical properties. The hybrid structure was shown to be very effective at improving the electrical and the optical properties, decreasing the sheet resistance and the reflectance, and increasing the transmittance via refractive index (RI) engineering. The ZnO hybrid structure grown by MOCVD is very promising for opto-electronic devices as Photoconductive UV Detectors, anti-reflection coatings (ARC), and transparent conductive oxides (TCO).