• 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.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.47.2-47.2
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• 2010

For reducing outer reflection in mono-crystalline silicon solar cell, wet texturing process has been adapted for long period of time. Nowadays mixed solution with potassium hydroxide and isopropyl alcohol is used in silicon surface texturing by most manufacturers. In the process of silicon texturing, etch rate is very critical for effective texturing. Several parameters influence the result of texturing. Most of all, temperature, process time and concentration of potassium hydroxide can be classified as important factors. In this paper, temperature, process time and concentration of potassium hydroxide were set as major parameters and 3-level test matrix was created by using robust design for the optimized condition. The process optimization in terms of lowest reflection and stable etch rate can be traced by using robust design method.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.335.2-335.2
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• 2016

The fixed negative charge of the Al2O3 passivation layer gives excellent passivation performance for both n-type and p-type silicon wafers. For the best passivation quality, annealing is known to be a prerequisite step and a lot of studies concerning annealing effect on the passivation characteristics have been performed. Meanwhile, for manufacturing a crystalline silicon solar cell, firing process is applied to the Al2O3 passivation layer. Therefore, study on not only annealing effect but also on firing effect is necessary. In this work, Al2O3 passivation performance (minority carrier lifetime) for p-type silicon wafer was evaluated with Quasi-Steady-State Photoconductance(QSSPC) measurement after annealing at different temperatures. For the samples which showed different aspects, C-V measurement was performed for the cause - whether it is due to the chemical effect or field-effect. The change in Al2O3 passivation property after firing processes was investigated and the mechanism for the change could be estimated.

• Journal of the Semiconductor & Display Technology
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• v.12 no.3
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• pp.41-46
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• 2013

Efficient and inexpensive solar cells are necessary for photo-voltaic to be widely adopted for mainstream electricity generation. For this to occur, the recombination losses of charge carriers (i.e. electrons or holes) must be minimized using a surface passivation technique suitable for manufacturing. Recently it has been shown that aluminum oxide thin films are negatively charged dielectrics that provide excellent surface passivation of silicon solar cells to attract positive-charged holes. Especially aluminum oxide thin film is a quite suitable passivation on the rear side of p-type silicon solar cells. This paper, it demonstrate the interfacial microstructure and electrical properties of mono-crystalline silicon surface passivated by $Al_2O_3$ films during firing process as applied for screen-printed solar cells. The first task is a comparison of the interfacial microstructure and chemical bonds of PECVD $Al_2O_3$ and of PEALD $Al_2O_3$ films for the surface passivation of silicon. The second is to study electrical properties of double-stacked layers of PEALD $Al_2O_3$/PECVD SiN films after firing process in the temperature range of $650{\sim}950^{\circ}C$.

• Current Photovoltaic Research
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• v.12 no.1
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• pp.6-16
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• 2024

The efficiency of silicon solar cells is approaching a theoretical limit referred to as 'the state of the art'. Consequently, maintaining efficiency is more productive than pursuing improvements the last room for limiting efficiency. One of the primary considerations in silicon module conservation is the occurrence of failures and degradation. Degradation can be mitigated during the cell manufacturing stage, unlike physical and spontaneous failure. It is mostly because the chemical reaction is triggered by the carrier generation of thermal and light injection, an inherent aspect of the solar cell environment. Therefore, numerous researchers and cell manufacturers are engaged in implementing mitigation strategies based on the physical degradation mechanism.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.143-146
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• 2009

One of the most important issues of crystalline silicon solar cell is minimizing reflectance at the surface. Laser texturing is an isotropic process that will sculpt the surface of a silicon wafer, regardless of its crystallographic orientation. We investigated surface texturing process using Nd-YAG laser ($\lambda$=1064 nm) on multi-crystalline silicon wafer. Removal of slag formed after the laser process was performed using acid solution (HF : $HNO_3$ : $CH_3COOH$ : DI water). The reflectance and carrier lifetime of the samples were measured and analyzed using UV-Vis spectrophotometer and carrier lifetime tester. It was found that the minimum reflectance of the samples was 16.39% and maximum carrier life time was $21.8\;{\mu}s$.

• Current Photovoltaic Research
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• v.5 no.1
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• pp.25-27
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• 2017

Nanoscale textured black silicon has attracted intensive attention due to its great potential as applications in multicrystalline silicon-based solar cells. It absorbs sunlight over a broad range of wavelengths but introduces large recombination centers, non-uniform doping into cell. In this study, we present a metal-assisted chemical etching technique plus alkaline etching process to fabricate nanoscale pyramid structures with optimized condition. To make the structures, silver nanoparticles-loaded mc-Si wafer was submerged into $H_2O_2/HF$ solution first for nanohole texturing the wafer and textured wafer etched again with KOH solution for making nanoscale pyramid structures. The average reflectivity (350-1050 nm) is about 8.42% with anti-reflection coating.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.140-143
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• 2013

Lowering surface reflectance of silicon wafer by texturization is one of the most important processes to improve the efficiency of silicon solar cells. Generally, the texturing of crystalline silicon was carried out using alkaline solution. The average reflectance of this method was 11% at the wavelength between 400 and 1,000 nm. In this study, the wafers were first texturing by NaOH solution at $80^{\circ}C$ for 35 min. Then the wafers were texturing by $SF_6$ and $O_2$ plasma in RIE (Reactive Ion Etching). The average reflectance of two step texturing was reduced to below 5% at the wavelength between 400 and 1,000 nm.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.65-69
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• 2017

This paper presents a Technology-CAD (TCAD) simulation of the characteristics of crystalline Si pillar array solar cells. The junction depth and the surface concentration of the solar cells were optimized to obtain the targeted sheet resistance of the emitter region. The diffusion model was determined by calibrating the emitter doping profile of the microscale silicon pillars. The dimension parameters determining the pillar shape, such as width, height, and spacing were varied within a simulation window from ${\sim}2{\mu}m$ to $5{\mu}m$. The simulation showed that increasing pillar width (or diameter) and spacing resulted in the decrease of current density due to surface area loss, light trapping loss, and high reflectance. Although increasing pillar height might improve the chances of light trapping, the recombination loss due to the increase in the carrier's transfer length canceled out the positive effect to the photo-generation component of the current. The silicon pillars were experimentally formed by photoresist patterning and electroless etching. The laboratory results of a fabricated Si pillar solar cell showed the efficiency and the fill factor to be close to the simulation results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.209-216
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• 2014

The screen printed technique is one of the electrode forming technologies for crystalline silicon solar cell. It has the advantage that can raise the production efficiency due to simple process. The electrode technology is the core process because the electrode feature is given a substantial factor (for solar cell efficiency). In this paper, we tried to change conditions such as squeegee angle $55{\sim}75^{\circ}$, snap off 0.5~1.75 mm, printing pressure 0.6~0.3 MPa and 1.6~2.0 mm finger spacing. As a result, the screen printing process showed an improved performance with an increased height higher finger height. Optimization of fabrication process has achieved 17.48% efficiency at screen mesh of 1.6 mm finger spacing.