• Current Photovoltaic Research
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• v.2 no.3
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• pp.88-94
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• 2014

The structural, optical and electrical properties of sputter-deposited CIGS films were directly influenced by the sputtering process parameters such as substrate temperature, working pressure, RF power and distance between target and substrate. CIGS thin films deposited by using a quaternary target revealed to be Se deficient due to Se low vapor pressure. This Se deficiency affected the overall stoichiometry of the films, causing the films to be Cu-rich. Current tends to pass through the Cu-Se channels which act as the shunting path increasing the film conductivity. The crystal structure of CIGS thin films depends on the substrate orientation due to the influence of surface morphology, grain size and stress of Mo substrate. The excess of Cu was removed from the CIGS films by KCN treatment, achieving a suitable Cu concentration (referred as Cu-poor) for the fabrication of solar cell. Due to high Cu concentrations on the CIGS film surface induced by Cu-Se phases after CIGS film deposition, KCN treatment proved to be necessary for the fabrication of high efficiency solar cells. Also during KCN treatment, dislocation density and lattice parameter decreased as excess Cu was removed, resulting in increase of bandgap and the decrease of conductivity of CIGS films. It was revealed that Cu-Se secondary phase could be removed by KCN wet etching of CIGS films, allowing the fabrication of high efficiency absorber layer.

• Journal of the Korean Vacuum Society
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• v.20 no.3
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• pp.200-204
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• 2011

In this paper, we deposited the tungsten carbon nitride (W-C-N; nitrogen gas flow of 2 sccm) and tungsten carbon (W-C) thin film on silicon substrate using rf magnetron sputter. Then the thin films annealed at $800^{\circ}C$ during 30 minute ($N_2$ gas ambient) for thermal damage. Nano-indenter was executed 16 points on thin film surface to measure the thermal stability, and we also propose the elastic modulus and the Weibull distribution, respectively. This nanotribology method provides statistically reliable information. From these results, the W-C-N thin film included nitrogen gas flow is more stable for film uniformities, physical properties and crystallinities than that of not included nitrogen gas flow.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1088-1092
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• 1995

In this paper, we evaluated the sputter-deposited Cr/Cu thin film fuses on $Al_2O_3$ substrates by the adhesive, breaking and repetitive over-current test as a function of temperature on them. Each Cr and Cu was deposited $1700{\pm}300{\AA},\;3700{\pm}300{\AA}$ using RF sputtering unit. The electroplated Cu of $25{\mu}m$ thickness was added in order to make sensitive thin film fuse of the normal current 15[A]. The adhesive strength and the number of repetition were Increasing and then decreasing with the temperature. The maximum adhesive strength of over $9kgf/9mm^2$ was obtained at $400^{\circ}C$. In the breaking test, the post-arc time characteristic was better than any other factor.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1433-1435
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• 1997

ZnO shows the properties of wide conductivity variation, high optical transmittance, and excellent piezoelectricity. Using these properties of ZnO, the material applications were extended to sensors, SAW filters, solar cells, and display devices. This paper investigated transmittance influencing factors for thin film ZnO grown by RF magnetron sputtering. The growth rate and structural investigation were carried out in conjunction with optical transmittance characteristics of thin film ZnO. The glass substrate temperature of $175^{\circ}C$ exhibited a preferential crystallization along (002) orientation. Transmittance of ZnO film deposited at the substrate temperature of $175^{\circ}C$ showed higher than 92%. An active sputter gas was investigated with a variation of $O_2$ partial pressure from 0 to 10% in an Ar atmosphere. ZnO film grown in 100% Ar gas shows that a reduced transmittance of 82% at the short wavelengths and decreased resistivity value. As the partial pressure of $O_2$ gas increased, the optical transmittance was increased above 90% at the short wavelengths, however, resistivity was drastically increased to higher than $10^4{\Omega}$-cm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.280-281
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• 2006

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of a Titanium dioxide ($TiO_2$) thin film by rf magnetron sputtering system for 15min under various rf power. A very low pretilt angle by ion beam exposure on the $TiO_2$ thin film was measured. A good LC alignment by the ion beam alignment method on the $TiO_2$ thin film surface was observed at annealing temperature of $200^{\circ}C$, and the alignment defect of the NLC was observed above annealing temperature of $250^{\circ}C$. Consequently, the low NLC pretilt angle and the good thermal stability of LC alignment by the ion beam alignment method on the $TiO_2$ thin film by sputter method as various rf power condition can be achieved.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.103-103
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• 2011

The epitaxial Cu-doped ZnO and pure ZnO thin films were grown on Al2O3 (0001) substrates by RF sputtering method. The structures and crystallographic orientations were investigated using X-ray diffraction (XRD) and X-ray absorption spectroscopy. From the XRD pattern, it is observed that peak positions shift towards higher $2{\theta}$ value with Cu doping. The ${\omega}$-scan measurements at the (0002) diffraction peak for these samples reveal that the full-widths at half-maxima (FWHMs) are about $0.017-0.019^{\circ}$, which indicate a good c-axis orientation of the Zn1-xCuxO films. From phi-scan, all of the Zn1-xCuxO films were epitaxially grown. EXAFS measurements also demonstrated that Cu incorporated into a Zn-atom position substitutionally. All the results confirmed that copper ion were well incorporated into the ZnO lattices by substituting Zn sites without changing the wurtzite structure and no secondary phase existed in Cu-doped ZnO thin films.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.190-190
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• 2011

일반적으로 TiO2와 WO3는 광촉매 작용으로 인하여 살균력을 보이며, 친수성으로 인해 자가 세정 능력을 가져 유리 및 건축자재의 표면처리, 전자제품의 마감처리 용도로 많이 사용하고 있다. 현재 Sol-gel, CVD, Sputter, Spin-coating 방법 등으로 많은 연구가 진행되어 오고 있다. 이에 본 실험에서는 박막의 두께를 균일하게 만들 수 있는 RF-magnetron sputtering 방법을 이용하여 표면 경도와 부착력이 우수한 TiO2에 열적 특성과 화학적 특성이 안정한 WO3를 Double Layer 방식으로 증착하여 박막을 제작하였다. 광학적 특성을 알아 본 결과 가시광 영역에서 TiO2 / WO3 Double Layer 박막이 80% 이상의 높은 투과율을 나타내었으며, 박막의 표면을 확인 한 결과 TiO2 / WO3 Double Layer 박막이 더 조밀한 표면을 보였다. 또한 접촉각을 측정을 통하여 TiO2박막보다 TiO2 / WO3 double layer박막이 낮은 접촉각을 나타내었다. 이는 TiO2 표면은 소수성이나 WO3로 인해 광촉매 기능이 향상되어 공기 중의 물 분자가 해리 흡착되면서 친수성이 향상되는 것으로 사료된다. 이러한 박막은 건물의 외벽이나 자동차의 내 외장재 전자기기용 광학 필름에 자가세정, 내반사 코팅소재로 활용 가치가 높을 것으로 예상된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.367-367
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• 2012

TTFT에 투명반도체로 사용되고 있는 IGZO 박막의 특성을 조사하였다. IGZO박막은 비정질임에도 불구하고 높은 이동도를 가지는 것으로 알려져 있다. 본 실험에서는 RF magnetron sputtering법을 이용하여 Ar Gas 유량 변화에 따른 IGZO 박막을 유리 기판 위에 제작 하였고 투명반도체의 구조적, 광학적, 전기적 특성을 조사하였다. 소결된 타겟 으로는 In:Ga:ZnO를 각각 1:1:2mol%의 조성비로 혼합하여 이용하였으며, $30{\times}30mm$의 XG Glass 유리기판에 Sputtering 방식으로 증착하였다. 공정 조건으로는 초기합력은 $2.0{\times}10^{-6}Torr$이하로 하였으며, 증착 압력은 $2.0{\times}10^{-2}Torr$로 하였다. Rf power를 75 W로 고정시켰다. 실험 변수로는 Ar Gas를 25, 50, 75, 100 sccm으로 변화를 주어 실험을 진행하였으며, 증착온도는 실온으로 고정하였다. 분석 결과로는 Ar Gas가 75 sccm일 때 XRD분석결과 $34^{\circ}$ 부근에서 (002) c-축 방향성 구조임을 확인할 수 있었으며, AFM분석결과 0.3 nm이하의 Roughness를 가졌다. UV-Visible-NIR 측정결과 가시광선 영역에서 85%이상의 투과도를 만족 시켰으며, Hall 측정결과 Carrier concentration $8.3{\times}101^{19}cm-^{-3}$, Mobility $12.3cm^2/v-s$이며, Resistivity $0.6{\times}10^{-2}{\Omega}-cm$, 투명반도체로 사용 가능함을 확인 할 수 있었다.

• Journal of the Korean institute of surface engineering
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• v.50 no.4
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• pp.237-243
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• 2017

We demonstrated the thin film deposition of sodium phosphorous oxynitride (NaPON) via RF magnetron sputtering of $Na_3PO_4$, as a solid-state Na-ion conductor similar to lithium phosphorous oxynitride (LiPON), which is a commonly used solid electrolyte. The deposited NaPON thin film was characterized by scanning electron microscopy, X-ray diffractometry, and electrochemical impedance spectroscopy, to investigate the feasibility of the solid-state electrolyte in several different cell configurations. The key properties of a solidstate electrolyte, i.e., ionic conductivity and activation energy, were estimated from the complex non-linear least square fitting of the measured impedance spectra at various temperatures in the range of $27-90^{\circ}C$. The ionic conductivity of the NaPON film was measured to be $8.73{\times}10^{-6}S\;cm^{-1}$ at $27^{\circ}C$, which was comparable to that of the LiPON film. The activation energy was estimated to be 0.164 eV, which was lower than that of the LiPON film (0.672 eV). The obtained values encourage the use of a NaPON thin film in the future as a reasonable solid-state electrolyte.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.24-25
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• 2006

In this paper, ZnO thin films were prepared on p-Si(100) by RF magnetron sputtering. Before the depostion, the substrates were pre-heated to 500, 400, 300, $200^{\circ}C$ or not. During the deposition, the substrates were cooled down naturally or kept and then the films were investigated by XRD(X-ray diffraction) and SEM (scanning micro scope). It is showed the most outstanding result that the film was prepared on the substrate were cooled from $400^{\circ}C$. When the substrate was cooled from a certain temperature during deposition, it could be improve the c-axis orientation and useful for application of SAW(surface acoustic wave) filter and FBAR(film bulk acoustic wave resonator) device.