• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.9
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• pp.681-684
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• 2010

The $TiO_2$/ZnS/Ag/ZnS/$TiO_2$ multilayered structure for the transparent electrodes in plasma display panel was designed by essential macleod program (EMP) and the multilayered film was deposited on a glass substrate by direct-current (DC)/radio-frequency (RF) magnetron sputtering system. During film deposition process, the Ag layer in $TiO_2$/Ag/$TiO_2$ structure became oxidized and the filter characteristic was degraded easily. In this study, ZnS layer was adopted as a diffusion blocking layer between $TiO_2$ and Ag to prevent the oxidation of Ag layer efficiently in $TiO_2$/ZnS/Ag/ZnS/$TiO_2$ structure. Based on the AES depth profiling analysis, the Ag layer was effectively protected by the ZnS layer as compared with the $TiO_2$/Ag/$TiO_2$ multilayered films without ZnS as an antioxidant layer. The 3 times stacked $TiO_2$/ZnS/Ag/ZnS/$TiO_2$ films have low sheet resistance of $1.22{\Omega}/{\square}$ and luminous transmittance was as high as 62% in the visible ranges.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1370-1374
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• 2018

A heterojunction $SnS_2/p-Si$ photodetector was fabricated by RF magnetron sputtering system. $SnS_2$ was formed with 2-inch $SnS_2$ target. Al was applied as the front and the back metal contacts. Rapid thermal process was conducted at $500^{\circ}C$ to enhance the contact quality. 2D material such as $SnS_2$, MoS2 is very attractive in various fields such as field effect transistors (FET), photovoltaic fields such as photovoltaic devices, optical sensors and gas sensors. 2D material can play a significant role in the development of high performance sensors, especially due to the advantages of large surface area, nanoscale thickness and easy surface treatment. Especially, $SnS_2$ has a indirect bandgap in the single and bulk states and its value is 2 eV-2.6 eV which is considerably larger than that of the other 2D material. The large bandgap of $SnS_2$ offers the advantage for the large on-off current ratio and low leakage current. The $SnS_2/p-Si$ photodetector clearly shows the current rectification when the thickness of $SnS_2$ is 80 nm compared to when it is 135 nm. The highest photocurrent is $19.73{\mu}A$ at the wavelength of 740 nm with $SnS_2$ thickness of 80 nm. The combination of 2D materials with Si may enhance the Si photoelectric device performance with controlling the thickness of 2D layer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1393-1398
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• 2015

In this study, the electrical and optical properties of GZO (Ga-doped ZnO) thin films prepared on PES substrates by RF magnetron sputtering method with various working pressures (5 to 20 mTorr) were investigated. All GZO thin films exhibited c-axis preferential growth regardless of working pressure, the GZO thin film deposited at 5 mTorr showed the most excellent crystallinity having 0.44˚ of FWHM. In AFM observations, surface roughness exhibited the lowest value of 0.20 nm in a thin film produced by the working pressure 5 mTorr. Figure of merits of GZO thin film deposited at 5 mTorr showed the highest value of 6652, in this case resistivity and average transmittance in the visible light region were 6.93×10^-4Ω-cm and 81.4%, respectively. We could observed the Burstein-Moss effect that carrier concentration decrease with the increase of working pressure and thus the energy band gap is narrowed.

• Transactions on Electrical and Electronic Materials
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• v.14 no.6
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• pp.321-323
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• 2013

100 nm thick Ga doped ZnO (GZO) thin films were deposited with DC and RF magnetron sputtering at room temperature on glass substrate and Al coated glass substrate, respectively. and the effect of the Al underlayer on the optical and electrical properties of the GZO films was investigated. As-deposited GZO single layer films had an optical transmittance of 80% in the visible wavelength region, and sheet resistance of 1,516 ${\Omega}/{\Box}$, while the optical and electrical properties of GZO/Al bi-layered films were influenced by the thickness of the Al buffer layer. GZO films with 2 nm thick Al film show a lower sheet resistance of 990 ${\Omega}/{\Box}$, and an optical transmittance of 78%. Based on the figure of merit (FOM), it can be concluded that the thin Al buffer layer effectively increases the performance of GZO films as a transparent and conducting electrode without intentional substrate heating or a post deposition annealing process.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.125.1-125.1
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• 2011

빛 에너지를 전기에너지로 변환하는 발전소자인 태양전지는 청정 재생 에너지원으로 최근 Si 박막 태양전지의 고 효율화를 위해 여러 기술적인 면에서 개발되어지고 있다. 현재 박막형 태양전지는 실리콘계가 주류를 이루고 있으며, 유리 혹은 유연성기판(금속 or 고분자)에 비정질 실리콘 박막을 형성시킨 태양전지와 실리콘웨이퍼의 양면에 태양전지를 형성함으로써 효율을 극대화시킨 이종접합태양전지 등이 연구되고 있다. 특히 flexible 태양전지는 hard 기판에 비해 비교적 저가인 플라스틱 필름과 금속 foil을 기판으로 이용함으로서 저가화가 용이하며, 가볍고 유연성을 갖추고 있어 휴대와 시공에 있어 매우 우수한 장점을 가지고 있다. 본 연구에서는 flexible 기판(stainless steel)을 이용하여 태양전지 내 반사막 층이 미치는 영향을 알아보기 위하여 AZO/Ag 이중구조 박막의 특성을 연구하였다. RF magnetron sputtering system을 이용하였으며, 상온에서 Ag/AZO 이중구조 박막을 제조하였다. stainless steel 기판 위에 Ag층을 25nm 두께로 증착하였으며 연속공정으로 AZO 박막을 100~500nm의 두께경사를 가지도록 성장시켰다. 이 때의 AZO/Ag 이중구조 박막의 표면 morphology는 AFM 분석결과 7nm~3nm의 값을 나타내었으며, AZO 박막의 두께가 증가할수록 rms 값이 감소하는 경향을 보여주었다. 본 발표에서는 flexible 기판 상에 성장된 AZO/Ag 이중구조 박막의 전기적, 광학적 특성 등에 관하여 추가적으로 토론한 후 태양전지 효율 중 흡수층 내 반사막 층이 미치는 역할을 알아보겠다.

• Journal of the Korean Society for Heat Treatment
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• v.25 no.6
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• pp.279-282
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• 2012

$SnO_2$ thin films were prepared on the Si substrate by radio frequency (RF) magnetron sputtering and then surface of the films were irradiated with intense Ar ion beam to investigate the effect of Ar ion irradiation on the properties and hydrogen gas sensitivity of the films. From atomic force microscope observation, it is supposed that intense Ar bombardments promote rough surface and increase gas sensitivity of $SnO_2$ films for hydrogen gas. The films that Ar ion beam irradiated at 6 keV show the higher sensitivity than the films were irradiated at 3 keV and 9 keV. These results suggest that the $SnO_2$ thin films irradiated with optimized Ar ion beam are promising for practical high-performance hydrogen gas sensors.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.494-498
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• 2000

RuO$_2$ thin films are prepared by RF magnetron reactive sputtering and their characteristics of crystallization, microstructure, surface roughness and resistivity are studied with various $O_2$/ (Ar+O$_2$) ratios and substrate temperatures. As $O_2$/(Ar+O$_2$) ratio decreases and substrate temperature increases, the preferred growing plane of RuO$_2$ thin films are changed from (110) to (101) plane. With increase of the $O_2$/(Ar+O$_2$) ratio from 20% to 50%, the surface roughness and the resistivity of RuO$_2$ thin films increase from 2.38nm to 7.81 nm, and from 103.6 $\mu$$\Omega$-cm to 227 $\mu$$\Omega$-cm, respectively, but the deposition rate decreases from 47 nm/min to 17 nm/min. On the other hand, as the substrate temperature increases from room temperature to 500 $^{\circ}C$, resistivity decreases from 210.5 $\mu$$\Omega$-cm to 93.7 $\mu$$\Omega$-cm. RuO$_2$ thin film deposited at 300 $^{\circ}C$ shows a excellent surface roughness of 2.38 nm. As the annealing temperature increases in the range between 400 $^{\circ}C$ and 650 $^{\circ}C$, the resistivity decreases because of the improvement of crystallinity. We find that RuO$_2$ thin film deposited at 20% of $O_2$/(Ar+O$_2$) ratio and 300 t of substrate temperature shows excellent combination of surface smoothness and low resistivity so that it is well Qualified for bottom electrodes for ferroelectric thin films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.869-873
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• 2002

$Cu_2ZnSnS_4$ (CZTS) thin film is one of the candidate materials for the solar cell. It has an excellent optical absorption coefficient as well as appropriate 1.4~1.5eV band gap. The purpose of this study is replacing a half of high-cost Indium(In) atoms with low-cost Zinc(Zn) atoms and the other half with low-cost Tin(Sn) atoms in the lattice of CIS. In annealing process of thin films deposited with mixture target, the thin films were appeared the peeling. The resistivity was decreased. Thin films were deposited on ITO glass substrates using a compound target which were made by $CU_2S$, ZnS, $SnS_2$ powder were sintered in the atmosphere of Al at room temperature by rf magnetron sputtering We investigated potentialities of a low-cost material for the solar cell by measuring of thin film composition, the structure and optical properties. We could get an appropriate $Cu_2ZnSnS_4$ composition A (112) preferred orientation was appeared without annealing temperature as shown in the diffraction peaks of the CIS cells and was available for photovoltaic thin film materials. The band gap increased from 1.4 to 1.7eV as the composition ratio of Zn/Sn.. The optical absorption coefficient of the thin film was above $10^4cm^{-1}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05b
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• pp.79-83
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• 2001

In order to compare the barrier properties of Ta-N/Si(001) with those of Ta-N/Ta/Si(001), we studied structural properties of films grown by RF magnetron sputtering with various $Ar/N_2$ ratios. To evaluate the barrier properties, the samples were annealed in a vacuum chamber. Ex-situ x-ray scattering measurements were done using an in-house x-ray system. With increasing nitrogen ratio in Ta-N/Si(001), the barrier property of Ta-N/Si(001) was enhanced, finally failed at $750^{\circ}C$ due to the crystallization and silicide formation. Compared with Ta-N/Si(001), Ta-N/Ta/Si(001) forms silicides at $650^{\circ}C$. However it does not crystallize even at $750^{\circ}C$. With increasing nitrogen composition in Ta-N/Ta/Si(001), the formation of tantalum silicide was reduced and the surface roughness was improved. To observe the surface morphology of Ta-N/Ta/Si(001) during annealing, we performed an in-situ x-ray scattering experiment using synchrotron radiation of the 5C2 at Pohang Light Source(PLS). Addition of Ta layer between Ta-N and Si(001) improved the surface morphology and reduced the surface degradation at high temperatures. In addition, increasing $N_2/Ar$ flow ratio reduced the formation of tantalum silicide and enhanced the barrier properties.

• Korean Journal of Materials Research
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• v.20 no.9
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• pp.483-487
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• 2010

To fabricate $TiO_2$ nanoparticle-based dye sensitized solar cells (DSSCs) at a low-temperature, DSSCs were fabricated using hydropolymer and ZnO nanoparticles composites for the electron transport layer around a low-temperature ($200^{\circ}C$). ZnO nanoparticle with 20 nm and 60 nm diameter were used and Pt was deposited as a counter electrode on ITO/glass using an RF magnetron sputtering. We investigate the effect of ZnO nanoparticle concentration in hydropolymer and ZnO nanoparticle solution on the photoconversion performance of the low temperature fabricated ($200^{\circ}C$) DSSCs. Using cis-bis(isothiocyanato)bis(2,20 bipyridy1-4,40 dicarboxylato) ruthenium (II) bis-tetrabutylammonium (N719) dye as a sensitizer, the corresponding device performance and photo-physical characteristics are investigated through conventional physical characterization techniques. The effect of thickness of the ZnO photoelectrode and the morphology of the ZnO nanoparticles with the variations of hydropolymer to ZnO ratio on the photoconversion performance are also investigated. The morphology of the ZnO layer after sintering was examined using a field emission scanning electron microscope (FE-SEM). 60 nm ZnO nanoparticle DSSCs showed an incident photon-to-current conversion efficiency (IPCE) value of about 7% higher than that of 20 nm ZnO nanoparticle DSSCs. The maximum parameters of the short circuit current density ($J_{sc}$), the open circuit potential ($V_{oc}$), fill factor (ff), and efficiency ($\eta$) in the 60 nm ZnO nanoparticle-based DSSC devices were 4.93 mA/$cm^2$, 0.56V, 0.40, and 1.12%, respectively.