• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.307-308
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.29-30
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• 2013

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.432-437
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• 2011

Recently, industry needs a new design of Czochralski(Cz) process for higher productivity with reasonable energy consumption. In this study, we carried out computational simulations for finding out a new optimal design of Cz process with variables which can be applied in real industry such as location of heater, shape of shield and crucible size. Objective process was Cz process which can be produced 8 inch diameter Si ingot for solar cell and we acquired an optimal design for higher productivity, low power consumption with stable production condition. For higher productivity we also change the crucible diameter from 22 inches to 24 inches with changing insulation thickness only because the process housing size could not be changed in industry.

• Current Photovoltaic Research
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• v.6 no.2
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• pp.49-55
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• 2018

Recently solar cell industry needs the optimal design of Czochralski process for low cost high quality silicon mono crystalline ingot. Because market needs both high efficient solar cell and similar cost with multi-crystalline Si ingot. For cost reduction in Czochralski process, first of all energy reduction should be completed because Czochralski process is high energy consumption process. For this purpose we studied optimal water-cooling tube design and simultaneously we also check the quality of ingot with Von mises stress and V(pull speed of ingot)/G(temperature gradient to the crystallization) values. At this research we used $CG-Sim^{(R)}$ S/W package and finally we got improved water-cooling tube design than normally used process in present industry. The optimal water-cooling tube length should be 200mm. The result will be adopted at real industry.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.775-780
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• 2016

Recently, photovoltaic industry needs a new design of Czochralski (Cz) process for higher productivity with reasonable energy consumption as well as solar cell's efficiency. If the process uses the large size reactor for increasing productivity, it is possible to produce a 12-inch, rather than the 8-inch. Also the continuous czochralski process method can be maximized to increase productivity. In this study, it was designed to improve the yield value of ingot with optimal condition which reduce consumption of electrical power. It has increased the productivity of the 12-inch ingot process condition by using CFD simulation. I have found optimal growth rate, by comparing each growth rate the interface shape, Temperature gradient, power consumption. As a result, the optimal process parameters of the growth furnace has been derived to improve for the productivity and to reduce energy. This study will contribute to the improvement of the productivity in the solar cell industry.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.125-130
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• 2014

This paper is research result for a development of solar cell silicon ingot glowing(SCSIG) PWM converter system for 120[kW] 3[kA]. The system include 3-phase AC-DC rectifier diode converter of input voltage AC 460[V] and 60[Hz], DC-AC single phase full bridge PWM inverter of high frequency, AC-DC single-phase full wave rectifier using center-tapped of transformer for low voltage 50[V] and large current 3,000[A], carbon resistor load 0.2 [$m{\Omega}$]. PWM switching frequency for IGBT inverter control set 15KHz. The suggested researching contents are designed data sheets of power converter system, PSIM simulation, operating characteristics and analysis results of developed SCSIG system.

• Korean Journal of Materials Research
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• v.22 no.9
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• pp.450-453
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• 2012

In crystalline solar cells, the substrate itself constitutes a large portion of the fabrication cost as it is derived from semiconductor ingots grown in costly high temperature processes. Thinner wafer substrates allow some cost saving as more wafers can be sliced from a given ingot, although technological limitations in slicing or sawing of wafers off an ingot, as well as the physical strength of the sliced wafers, put a lower limit on the substrate thickness. Complementary to these economical and techno-physical points of view, a device operation point of view of the substrate thickness would be useful. With this in mind, BC-BJ Si and GaAs solar cells are compared one to one by means of the Medici device simulation, with a particular emphasis on the substrate thickness. Under ideal conditions of 0.6 ${\mu}m$ photons entering the 10 ${\mu}m$-wide BC-BJ solar cells at the normal incident angle (${\theta}=90^{\circ}$), GaAs is about 2.3 times more efficient than Si in terms of peak cell power output: 42.3 $mW{\cdot}cm^{-2}$ vs. 18.2 $mW{\cdot}cm^{-2}$. This strong performance of GaAs, though only under ideal conditions, gives a strong indication that this material could stand competitively against Si, despite its known high material and process costs. Within the limitation of the minority carrier recombination lifetime value of $5{\times}10^{-5}$ sec used in the device simulation, the solar cell power is known to be only weakly dependent on the substrate thickness, particularly under about 100 ${\mu}m$, for both Si and GaAs. Though the optimum substrate thickness is about 100 ${\mu}m$ or less, the reduction in the power output is less than 10% from the peak values even when the substrate thickness is increased to 190 ${\mu}m$. Thus, for crystalline Si and GaAs with a relatively long recombination lifetime, extra efforts to be spent on thinning the substrate should be weighed against the expected actual gain in the solar cell output power.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.94-98
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• 2012

The behavior of ozone micro bubble cleaning system was investigated to evaluate the solution as a new method of solar cell wafer cleaning in comparison with former conventional RCA cleaning. We have developed the ozone dissolution system in the ozonated water for more efficient cleaning conditions. The optimized cleaning conditions for solar cell wafer process were 10 ppm of ozone concentration and 12 minutes in cleaning periods, respectively. We have confirmed the cleaning reliability and cell efficiencies after ozone micro bubble cleaning. Using this new cleaning technology, it was possible to obtain higher efficiency, higher productivity, and fast tact time for applying cleaning in the fields on bare ingot wafer, LED wafers as well as the solar cell wafer.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.299.2-299.2
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• 2013

We investigated the potassium remaining on a crystalline silicon solar cell after potassium hydroxide (KOH) etching and its effect on the lifetime of the solar cell. KOH etching is generally used to remove the saw damage caused by cutting a Si ingot; it can also be used to etch the rear side of a textured crystalline silicon solar cell before atomic layer-deposited Al2O3 growth. However, the potassium remaining after KOH etching is known to be detrimental to the efficiency of Si solar cells. In this study, we etched a crystalline silicon solar cell in three ways in order to determine the effect of the potassium remnant on the efficiency of Si solar cells. After KOH etching, KOH and tetramethylammonium hydroxide (TMAH) were used to etch the rear side of a crystalline silicon solar cell. To passivate the rear side, an Al2O3 layer was deposited by atomic layer deposition (ALD). After ALD Al2O3 growth on the KOH-etched Si surface, we measured the lifetime of the solar cell by quasi steady-state photoconductance (QSSPC, Sinton WCT-120) to analyze how effectively the Al2O3 layer passivated the interface of the Al2O3 layer and the Si surface. Secondary ion mass spectroscopy (SIMS) was also used to measure how much potassium remained on the surface of the Si wafer and at the interface of the Al2O3 layer and the Si surface after KOH etching and wet cleaning.

• Journal of the Korean Solar Energy Society
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• v.33 no.5
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• pp.24-33
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• 2013

Renewable energy industries, including sola cell plants, has been ever increasing ones for reducing fossil fuel consumption and strengthening national energy policy. In this paper we tried to identify occupational health hazards in solar cell-related industries operated in Korea. Poly silicon, silicon ingot and wafer, solar cell and module are major processes for producing solar cells. Poly silicon operations may cause hazards to workers from metal silicon, silanes, silicon, hydro fluoric acid and nitric acid. Solar cells could not be constructed without using metals such as aluminum and silver, acids such as hydrofluoric acid and nitric acid, bases such as sodium hydroxide and potassium hydroxide, and solvent and phosphorus chloride oxide. Workers in module assembly process may exposed to isopropanol, flux, solders that contain lead, tin and/or copper. To prevent occupational exposure to these hazards, it is essential to identify the hazards in each process and educate workers in industries with proper engineering and administrative control measures.