• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.73.1-73.1
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• 2010

태양광 시장은 세계적인 금융 위기 속에서도 점점 그 규모가 확대되고 있다. 시장의 규모가 확대되고 있음에도 불구하고 금융 위기를 겪으면서 생산자 중심의 시장에서 수요자 중심의 시장으로 바뀌게 되었다. 이에 따라 더 적은 비용으로 높은 출력의 제품만이 경쟁력을 가지게 됨으로써 효율이 더욱 이슈화되었다. 여러 태양전지 중 가장 점유율이 높은 결정질 태양전지는 일반적인 양산 공정만으로 효율을 높이는데 한계가 있으므로 selective emitter, back contact, light induced plating 등의 새로운 공정을 도입하여 효율을 높이려는 경향이 나타나고 있다. 본 연구에서는, ALD 장치를 사용하여 결정질 태양전지의 후면을 passivation 함으로써 효율을 높이는 방법을 모색하였다. 부동화 층으로는 $Al_2O_3$를 사용하였으며 셀을 제조하여 평가하였다. 실험방법은 p-type의 웨이퍼를 이용하여 습식으로 texturing 후 $POCl_3$ 용액으로 p-n junction을 형성하였고 anti-reflection 막인 SiNx는 PECVD를 사용하여 R.I 2.05, 80nm 두께로 증착하였다. 그런 다음 후면의 n+ layer를 제거하기 위하여 SiNx에 영향을 미치지 않는 용액을 사용하여 후면을 식각하였다. BSF 층은 screen printer로 Al paste를 printing하여 형성하였고 Al etching용액으로 여분의 Al제거한 후 ALD 장치를 이용하여 $Al_2O_3$를 증착하였다. 마지막으로 전극을 형성한 후 laser로 isolation하여 효율을 평가하였다.

• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.142-150
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• 2012

In this Study, Mo back electrode were deposited as the functions of various working pressure, deposition time and plasma per-treatment on sodalime glass (SLG) for application to CIGS thin film solar cell using by DC sputtering method, and were analyzed Mo change to $MoSe_2$ layer through selenization processes. And finally Mo back electrode characteristics were evaluated as application to CIGS device after Al/AZO/ZnO/CdS/CIGS/Mo/SLG fabrication. Mo films fabricated as a function of the working pressure from 1.3 to 4.9mTorr are that physical thickness changed to increase from 1.24 to 1.27 ${\mu}m$ and electrical characteristics of sheet resistance changed to increase from 0.195 to 0.242 ${\Omega}/sq$ as according to the higher working pressure. We could find out that Mo film have more dense in lower working pressure because positive Ar ions have higher energy in lower pressure when ions impact to Mo target, and have dominated (100) columnar structure without working pressure. Also Mo films fabricated as a function of the deposition time are that physical thickness changed to increase from 0.15 to 1.24 ${\mu}m$ and electrical characteristics of sheet resistance changed to decrease from 2.75 to 0.195 ${\Omega}/sq$ as according to the increasing of deposition time. This is reasonable because more thick metal film have better electrical characteristics. We investigated Mo change to $MoSe_2$ layer through selenization processes after Se/Mo/SLG fabrication as a function of the selenization time from 5 to 40 minutes. $MoSe_2$ thickness were changed to increase as according to the increasing of selenization time. We could find out that we have to control $MoSe_2$ thickness to get ohmic contact characteristics as controlling of proper selenization time. And we fabricated and evaluated CIGS thin film solar cell device as Al/AZO/ZnO/CdS/CIGS/Mo/SLG structures depend on Mo thickness 1.2 ${\mu}m$ and 0.6 ${\mu}m$. The efficiency of CIGS device with 0.6 ${\mu}m$ Mo thickness is batter as 9.46% because Na ion of SLG can move to CIGS layer more faster through thin Mo layer. The adhesion characteristics of Mo back electrode on SLG were improved better as plasma pre-treatment on SLG substrate before Mo deposition. And we could expect better efficiency of CIGS thin film solar cell as controlling of Mo thickness and $MoSe_2$ thickness depend on Na effect and selenization time.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.79-85
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• 2004

We report on a transmittance controlled photomask with phase patterns on the back quartz surface. Theoretical analysis for changes in illumination pupil shape with respect to the variation of size and density of backside phase patterns and experimental results for improvement of critical dimension uniformity on a wafer by using the transmittance controlled photomask are presented. As phase patterns for controlling transmittance of the photomask we used etched contact-hole type patterns with 180" rotative phase with respect to the unetched region. It is shown that pattern size on the backside of the photomask must be made as small as possible in order to keep the illumination pupil shape as close as possible to the original pupil shape and to achieve as large an illumination intensity drop as possible at a same pattern density. The distribution of illumination intensity drop suitable for correcting critical dimension error was realized by controlling pattern density of the contact-hole type phase patterns. We applied this transmittance controlled photomask to a critical layer of DRAM (Dynamic Random Access Memory) having a 140nm design rule and could achieve improvement of the critical dimension uniformity value from 24.0 nm to 10.7 nm in 3$\sigma$.TEX>.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.105-110
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• 2011

The doping procedure in crystalline silicon solar cell fabrication usually contains oxygen injection during drive-in process and removal of phosphorous silicate glass(PSG). In this paper, we studied the effect of oxygen injection and PSG on conversion efficiency of solar cell. The mono crystalline silicon wafers with $156{\times}156mm^2$, $200{\mu}m$, $0.5-3.0{\Omega}{\cdot}cm$ and p-type were used. After etching $7{\mu}m$ of the surface to form the pyramidal structure, the P(phosphorous) was injected into silicon wafer using diffusion furnace to make the emitter layer. After then, the silicon nitride was deposited by the PECVD with 80 nm thickness and 2.1 refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were formed by screen-printing method, followed by firing in 400-425-450-550-$880^{\circ}C$ five-zone temperature conditions to make the ohmic contact. Solar cells with four different types were fabricated with/without oxygen injection and PSG removal. Solar cell that injected oxygen during the drive-in process and removed PSG after doping process showed the 17.9 % conversion efficiency which is best in this study. This solar cells showed $35.5mA/cm^2$ of the current density, 632 mV of the open circuit voltage and 79.5 % of the fill factor.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1518-1520
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• 2001

Bi-layer Mo films were deposited on sodalime glass substrates using DC magnetron sputtering. As the gas pressure and power density, the resistivity varied from $1.5{\times}10^{-5}$ to $4.97{\times}10^{-4}{\Omega}{\cdot}cm$. Furthermore, stress direction yielded compressive-to-tensile transition stress curves. The microstructure of the compressive stress films which had poor adhesion consists of tightly packed columns, but of the tensile-stressed films had less dense structure. Under all gas pressure conditions, Mo films exhibited distinctly increasing optical reflection with decreasing gas pressure. The expansion of (110) peak width with the gas pressure meant the worse crystalline growth. Also, The highest efficiency was 15.2% on 0.2 $cm^2$. The fill factor, open circuit voltage and short circuit current were 63 %, 570 mV and 42.6 mA/$cm^2$ respectively.

• Macromolecular Research
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• v.17 no.1
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• pp.31-36
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• 2009

Highly transparent, thin polythiophene (PT) films were successfully synthesized by the plasma polymerization of thiophene. These films were doped with $O_2$ plasma by in-situ doping technique. The plasma polymerized PT films were deposited at about 50 to 340 nm/min, depending on the temperature and plasma power. A resultant transparency as high as 85% was achieved. The plasma polymerized PT films exhibited the characteristics of an insulator or semiconductor ($10^{10{\sim}12}{\Omega}/{\Box}$, $10^{-7}S/cm$). The conductivity was immediately increased up to $10{\Omega}/{\Box}$ and $10^{-2}S/cm$, when doped with $O_2$ plasma. The plasma-doped PT films exhibited an increased surface roughness resulting in a decreased contact angle. However, the thickness of the PT layer was partially decomposed and/or etched with increasing voltage above 40 W.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.9
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• pp.36-45
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• 1992

The Modified Multi-Quantum Well(MMQWAl) structures have been grown by Mental-Organic chemical Vapor Deposition(MOCVD) method and stripe type MMQW laser diodes have been investigated. In the case of GaAs/AlGaAs superlattice and quantum well growth by MOCVD, the periodicity, interface abruptess, Al compositional uniformity and layer thickness have been confirmed though the shallow angle lapping technique, double crystal x-ray diffractometry (DCXD) and photoluminescence (PL) measurement. stripe-type MMQW laser diodes have been fabricated using the process technology of photolithography, chemical etching, ohmic contact, back side removing and cleaving. As the result of the electrical and opticalmeasurement of these laser diodes, we have achieved the series resistance of $1[\Omega}~2{\Omega}$ by current-voltage measurements, the threshold current of 200-300mA by currnt-light measurements and the lasing wavelength of 8000-8400$\AA$ by lasing spectrum measurements.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.108-112
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• 2012

Crystalline silicon solar cell remains the major player in the photovoltaic marketplace with 90 % of the market, despite the development of a variety of thin film technologies. Silicon's excellent efficiency, stability, material abundance and low toxicity have helped to maintain its position of dominance. However, the cost of silicon photovoltaic remains a major barrier to reducing the cost of silicon photovoltaics. Using the crystalline silicon wafer with thinner thickness is the promising way for cost and material reduction in the solar cell production. However, the thinner thickness of silicon wafer is, the worse bow phenomenon is induced. The bow phenomenon is observed when two or more layers of materials of different temperature expansion coefficiencies are in contact, in this case silicon and aluminum. In this paper, the solar cells were fabricated with different thicknesses of Al layer in order to reduce the bow phenomenon. With lower paste applications, we observed that the bow could be reduced by up to 40% of the largest value with 130 micron thickness of the wafer even though the conversion efficiency decrease of 0.5 % occurred. Since the bowed wafers lead to unacceptable yield losses during the module construction, the reduction of bow is indispensable on thin crystalline silicon solar cell. In this work, we have studied on the counterbalance between the bow and conversion efficiency and also suggest the formation of enough back surface field (BSF) with thinner Al paste application.

• Journal of Environmental Science International
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• v.11 no.5
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• pp.419-436
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• 2002

The current paper reports on the enhancement of O$_3$, CO, NO$_2$, and aerosols during the Asian dust event that occurred over Korea on 1 May 1999. To confirm the origin and net flux of the O$_3$, CO, NO$_2$, and aerosols, the meteorological parameters of the weather conditions were investigated using Mesoscale Meteorological Model 5(MM5) and the TOMS total ozone and aerosol index, the back trajectory was identified using the Hybrid Single-Particle Lagrangian Integrated Trajectory Model(HYSPLIT), and the ozone and ozone precursor concentrations were determined using the Urban Ashed Model(UAM). In the presence of sufficiently large concentrations of NO$\sub$x/, the oxidation of CO led to O$_3$ formation with OH, HO$_2$, NO, and NO$_2$ acting as catalysts. The sudden enhancement of O$_3$, CO, NO$_2$ and aerosols was also found to be associated with a deepening cut-off low connected with a surface cyclone and surface anticyclone located to the south of Korea during the Asian dust event. The wave pattern of the upper trough/cut-off low and total ozone level remained stationary when they came into contact with a surface cyclone during the Asian dust event. A typical example of a stratosphere-troposphere exchange(STE) of ozone was demonstrated by tropopause folding due to the jet stream. As such, the secondary maxima of ozone above 80 ppbv that occurred at night in Busan, Korea on 1 May 2001 were considered to result from vertical mixing and advection from a free troposphere-boundary layer exchange in connection with an STE in the upper troposphere. Whereas the sudden enhancement of ozone above 100 ppbv during the day was explained by the catalytic reaction of ozone precursors and transport of ozone from a slow-moving anticyclone area that included a high level of ozone and its precursors coming from China to the south of Korea. The aerosols identified in the free troposphere over Busan, Korea on 1 May 1999 originated from the Taklamakan and Gobi deserts across the Yellow River. In particular, the 1000m profile indicated that the source of the air parcels was from an anticyclone located to the south of Korea. The net flux due to the first invasion of ozone between 0000 LST and 0600 LST on 1 May 1999 agreed with the observed ground-based background concentration of ozone. From 0600 LST to 1200 LST, the net flux of the second invasion of ozone was twice as much as the day before. In this case, a change in the horizontal wind direction may have been responsible for the ozone increase.

• 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.