• Clean Technology
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• v.18 no.1
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• pp.43-50
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• 2012

Cleaning procedure of solar silicon wafer, following ingot sawing process in solar cell production is studied. Types of solar silicon wafer can be divided into monocrystalline or multicrystalline, and slurry sawn wafer or diamond sawn wafer according to the ingot growing methods and the sawing methods, respectively. Wafer surface and contaminants can vary with these methods. The characterisitics of contaminants and wafer surface are investigated for each cleaning substrate, and appropriate cleaning agents are developed. Physical properties and cleaning ability of the cleaning agents are evaluated in order to verify the application in the industry. The wafers cleaned with the cleaning agents do not show any residual contaminants when analyzed by XPS and regular patterns are formed after texturization. Furthermore, the cleaning agents are applied in the production industry, which shows superior cleaning results compared to the existing cleaning agents.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.3
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• pp.119-123
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• 2013

Most of the world's solar cells in photovoltaic industry are currently fabricated using crystalline silicon. Czochralski-grown silicon crystals are more expensive than multicrystalline silicon crystals. The future of solar-grade Czochralski-grown silicon crystals crucially depends on whether it is usable for the mass-production of high-efficiency solar cells or not. It is generally believed that the main obstacle for making solar-grade Czochralski-grown silicon crystals a perfect high-efficiency solar cell material is presently light-induced degradation problem. In this work, the substitution of boron with gallium in p-type silicon single crystal is studied as an alternative to reduce the extent of lifetime degradation. The diamond-wire sawing technology is employed to slice the silicon ingot. In this paper, the quality of the diamond wire-sawn gallium-doped silicon wafers is studied from the chemical, electrical and structural points of view. It is found that the characteristic of gallium-doped silicon wafers including texturing behavior and surface metallic impurities are same as that of conventional boron-doped Czochralski crystals.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.295-298
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• 2015

Ozone micro-bubble cleaning system was designed, and made to develop a unique technique to clean wafers by using ozone micro-bubbles. The ozone micro-bubble cleaning system consisted of loading, cleaning, rinsing, drying and un-loading zones, respectively. In case of the cleaning the silicon wafers of a solar cell, more than 99 % of cleaning efficiency was obtained by dipping the wafers at 10 ppm of ozone for 10 minutes. Both of long cleaning time and high ozone concentration in the wet-solution with ozone micro-bubbles reduced cleaning efficiency because of the re-sorption of debris. The cleaning technique by ozone micro-bubbles can be also applied to various wafers for an ingot and LED as an eco-friendly method.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.111.1-111.1
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• 2011

The solar energy is dramatically increasing as the alternative energy source and the silicon(Si) solar cell are used the most. In this study, the improved process and equipment for the metallurgical refinement of multicrystalline Si were evaluated for the inexpensive solar cell. The planar plane and columnar dendrite aheadof the liquid-solid interface position caused the superior segregation of impurities from the Si. The solidification rate and thermal gradient determined the shape of dendrite in solidified Si matrix solidified by the directional solidification(DS) method. To simulate this equipment, the commercial software, PROCAST, was used to solve the solidification rate and thermal gradient. Si was vertically solidified by the DS system with Stober process and up-graded metallurgical grade or metallurgical grade Si was used as the feedstock. The inductively coupled plasma mass spectrometry (ICP) was used to measure the concentration of impurities in the refined Si ingot. According to the result of ICP and simulation, the high thermal gradient between the two phases wasable to increase the solidification rate under the identical level of refinement. Also, the separating heating zone equipped with the melting and solidification zone was effective to maintain the high thermal gradient during the solidification.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.2
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• pp.47-53
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• 2014

Three kinds of crystalline silicon have been used for the solar cell grade. First of all, single crystalline silicon is the main subject to enhance the production yield. Most of the efforts are focused on the control of the melt-crystal interface shape affected by the crystal-crucible rotation rate. The main subject in the multi-crystalline silicon ingot is the contamination control. Faster Ar gas flow above the melt surface will lower the carbon contamination in the crystal. And also, twin boundary electrically inactive is found to be more effective than grain boundary for the improvement of the MCLT. In the case of mono-like silicon material, propagation of the multi-crystalline silicon growing from the inner side crucible is the problem lowering the portion of the single crystalline part at the center of the ingot. Crystal growing apparatus giving higher cooling rate at the bottom and lower cooling rate at the side crucible was suggested as the optimum solution obtaining higher quality of the mono-like silicon ingot. Proper application of the seeds at the bottom of the crucible would be one of the solutions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.5
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• pp.195-199
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• 2008

Production of the silicon feedstock for the semiconductor industry cannot meet the requirement for the solar cell industry because the production volume is too small and production cost is too high. This situation stimulates the solar cell industry to try the lower grade silicon feedstock like UMG (Upgraded Metallurgical Grade) silicon of 5$\sim$6 N in purity. However, this material contains around 1 ppma of dopant atoms like boron or phosphorous. Calculation of the composition profile of these impurities using segregation coefficient during crystal growth makes us expect the change of the type from p to n : boron rich area in the early solidified part and phosphorous rich area in the later solidified part of the silicon ingot. It was expected that the change of the growth speed during the silicon crystal growth is effective in controlling the amount of the metal impurities but not effective in reducing the amount of dopants.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.369-380
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• 2020

Most mono-crystalline silicon ingots are manufactured by the Czochralski (Cz) process. But If there are oxygen impurities, These Si-ingot tends to show low-efficiency when it is processed to be solar cell substrate. For making single-crystal Si- ingot, We need Czochralski (Cz) process which melts molten Si and then crystallizing it with seed of single-crystal Si. For melts poly Si-chunk and forming of single-crystalline Si-ingot, the heat transfer plays a main role in the structure of Cz-process. In this study to obtain high-quality Si ingot, the Cz-process was modified with the process design. The crystal growth simulation was employed with pulling rate and rotation speed optimization. Studies for modified Cz-process and the corresponding results have been discussed. The results revealed that using crystal growth simulation, we optimized the oxygen concentration of single crystal silicon by the optimal design of the pulling rate, rotation speed and melt charge level of Cz-process.

• Ceramist
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• v.22 no.4
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• pp.452-463
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• 2019

A quartz glass crucible is the essential material for manufacturing silicon ingots such as semiconductors and solar cells. Quartz glass crucibles for semiconductors and solar cells are made similar, but differ in surface purity, structure and durability. Recently, ultra high purity synthetic glass crucibles for semiconductors have become more important due to foreign problems. In Korea, it has succeeded in producing 28-inch quartz glass crucibles through the past 10 years. However, 32-inch synthetic quartz glass for the production of silicon ingots for semiconductors is not up to the level of advanced technology, and the technology gap is expected to be 2 to 3 years. In order to overcome these technological gaps and localize synthetic quartz glass ware, close cooperation between production companies and demand companies and localization of synthetic quartz glass powder must also be made. In addition, if government support can be added, faster results can be expected.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.237-238
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• 2012

본 연구는 태양전지용 실리콘 결정 성장용으로 개발된 150[KW] 3,000[A]의 PWM 컨버터 시스템을 개발한 결과이다. 시스템의 구성은 3상 AC-DC 정류변환기, DC-AC 고주파 변환 단상 전파 브리지 PWM 인버터, AC-DC 변압기 중성점을 이용한 단상 전파정류기로 구성되어 있다. 입력 전압은 3상 460[V]이며, 출력은 직류 60[V], 3000[A]로 카본 저항 $2[m{\Omega}]$의 부하에 인버터의 고주파 변압기를 사용하여 스위칭 주파수가 15[KHz]로 PWM제어 방식에 의하여 전력을 제어한다.

• The Journal of Information Technology
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• v.12 no.4
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• pp.19-24
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• 2009

Recently, for the efforts of low-carbon deduction and to solve the problems of global warming, many industrial nations in world have been strengthening positively their competitive power into the research, development and industrialization of new renewable sources of energy and clean energy. In the most promising source of photovoltaic, it is essential that the government take an initiative role to develop and industrialize the materials, ingot or wafer, solar cell, power conditioning system and photovoltaic system, and need to establish both short-term and long-term technical development of goal setting and forward plan in the direction of the technical development strategy and forward industrialization for the strengthening of world market. This paper analyze new technology, policies and the market trend of photovoltaic field which are currently strategically and actively enhancing the research, development and practical-industralization by Korea and other nations.