• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.183-186
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• 2009

The crystalline silicon solar cell was one of the first to be developed and it is still the most widely used type. The photovoltaic cells will exhibit long-term degradation if the temperature exceed a certain limit. The purpose of this study is to investigate the possible of improving the performance of a photovoltaic cooling system. According to the results of the experiment, the thermal degradation of 44.63degrees was observed by cooling on the surface of photovoltaic cells. It is a decrease of 22.215percent of generating power. It is shown that photovoltaic cooling system is effected on improving the effectiveness of a photovoltaic out of power.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.3
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• pp.120-125
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• 2002

The aim of the present work is to optimized the annealing parameter in both front and back screen printed contacts realization on p-type multicrystalline silicon and with phosphorus diffused. The RTA treatments were carried out at various temperatures from 600 to 850$\^{C}$ and annealing time ranging from 3 min to 5 min in air, O$_2$and N$_2$ ambiance. The contacts parameters are obtained according to Transmission Line Model measurements. A good RTA cycle is obtained with a temperature plateau of 700$\^{C}$-750$\^{C}$ and annealing ambiance of air. Several processing parameters required for good cell efficiency are discussed with an emphasis placed on the critical role of the glass frit in the aluminum paste. A anamolus behaviour of Aluminum n-doping on p-type Si wafer, contact at high temperature have also been studied.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.488.2-488.2
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• 2014

Carbon-based materials such as carbon nanotubes and graphene have emerged as promising building blocks in applications for nanoelectronics and energy devices due to electrical property, ease of processability, and relatively inert electrochemistry. In recent years, there has been considerable interest in core-shell nanomaterials, in which inorganic nanowires are surrounded by inorganic or organic layers. Especially, carbon encapsulated semiconductor nanowires have been actively investigated by researchers in lithium ion batteries. We report a method to synthesize silicon nanowire (SiNW) core/carbon shell structures by chemical vapor deposition (CVD), using methane (CH4) as a precursor at growth temperature of $1000{\sim}1100^{\circ}C$. Unlike carbon-based materials synthesized via conventional routes, this method is of advantage of metal-catalyst free growth. We characterized these materials with FE-SEM, FE-TEM, and Raman spectroscopy. This would allow us to use these materials for applications ranging from optoelectronics to energy devices such as solar cells and lithium ion batteries.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1277-1279
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• 1993

As a highly information-oriented society developes, various kinds of amorphous semiconductor devices, such as solar cells, electrographic printers, image sensors, and flat-panel televisions, have been developed as man/machine interfaces. This paper proposed the laser CVD techniques to deposit hydrogenated amorphous silicon thin film on glass or dielectric substrate at low temperatures. Varying the deposition conditions, we examined optical and electrical charateristics of a-Si:H film deposited by Laser CVD.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.75.2-75.2
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• 2010

We studied the fabrication of polycrystalline silicon (pc-Si) films as seed layers for application of pc-Si thin film solar cells, in which amorphous silicon (a-Si) films in a structure of glass/Al/$Al_2O_3$/a-Si are crystallized by the aluminum-induced layer exchange (ALILE) process. The properties of pc-Si films formed by the ALILE process are strongly determined by the oxide layer as well as the various process parameters like annealing temperature, time, etc. In this study, the effects of the oxide film thickness on the crystallization of a-Si in the ALILE process, where the thickness of $Al_2O_3$ layer was varied from 4 to 50 nm. For preparation of the experimental film structure, aluminum (~300 nm thickness) and a-Si (~300 nm thickness) layers were deposited using DC sputtering and PECVD method, respectively, and $Al_2O_3$ layer with the various thicknesses by RF sputtering. The crystallization of a-Si was then carried out by the thermal annealing process using a furnace with the in-situ microscope. The characteristics of the produced pc-Si films were analyzed by optical microscope (OM), scanning electron microscope (SEM), Raman spectrometer, and X-ray diffractometer (XRD). As results, the crystallinity was exponentially decayed with the increase of $Al_2O_3$ thickness and the grain size showed the similar tendency. The maximum pc-Si grain size fabricated by ALILE process was about $45{\mu}m$ at the $Al_2O_3$ layer thickness of 4 nm. The preferential crystal orientation was <111> and more dominant with the thinner $Al_2O_3$ layer. In summary, we obtained a pc-Si film not only with ${\sim}45{\mu}m$ grain size but also with the crystallinity of about 75% at 4 nm $Al_2O_3$ layer thickness by ALILE process with the structure of a glass/Al/$Al_2O_3$/a-Si.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.114-120
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• 2010

Conventional surface texturing in crystalline silicon solar cell have been use wet texturing by Alkali or Acid solution. But conventional wet texturing has the serious issue of wafer breakage by large consumption of wafer in wet solution and can not obtain the reflectance below 10% in multi crystalline silicon. Therefore it is focusing on RIE texturing, one method of dry etching. We developed large scale plasma RIE (Reactive Ion Etching) equipment which can accommodate 144 wafers (125 mm) in tray in order to provide surface texturing on the silicon wafer surface. Reflectance was controllable from 3% to 20% in crystalline silicon depending on the texture shape and height. We have achieved excellent reflectance below 4% on the weighted average (300~1,100 nm) in multi crystalline silicon using plasma texturing with gas mixture ratio such as $SF_6$, $Cl_2$, and $O_2$. The texture shape and height on the silicon wafer surface have an effect on gas chemistry, etching time, RF frequency, and so on. Excellent conversion efficiency of 16.1% is obtained in multi crystalline silicon by RIE process. In order to know the influence of RF frequency with 2 MHz and 13.56 MHz, texturing shape and conversion efficiency are compared and discussed mutually using RIE technology.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.211-211
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• 2012

The electrical loss of the photo-generated carriers is dominated by the recombination at the metal- semiconductor interface. In order to enhance the performance of the solar cells, many studies have been performed on the surface treatment with passivation layer like SiN, SiO2, Al2O3, and a-Si:H. In this work, Al2O3 thin films were investigated to reduce recombination at surface. The Al2O3 thin films have two advantages, such as good passivation properties and back surface field (BSF) effect at rear surface. It is usually deposited by atomic layer deposition (ALD) technique. However, ALD process is a very expensive process and it has rather low deposition rate. In this study, the ICP-assisted reactive magnetron sputtering method was used to deposit Al2O3 thin films. For optimization of the properties of the Al2O3 thin film, various fabrication conditions were controlled, such as ICP RF power, substrate bias voltage and deposition temperature, and argon to oxygen ratio. Chemical states and atomic concentration ratio were analyzed by x-ray photoelectron spectroscopy (XPS). In order to investigate the electrical properties, Al/(Al2O3 or SiO2,/Al2O3)/Si (MIS) devices were fabricated and characterized using the C-V measurement technique (HP 4284A). The detailed characteristics of the Al2O3 passivation thin films manufactured by ICP-assisted reactive magnetron sputtering technique will be shown and discussed.

• Korean Journal of Materials Research
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• v.19 no.5
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• pp.245-252
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• 2009

Changes in the surface morphology and light scattering of textured Al doped ZnO thin films on glass substrates prepared by rf magnetron sputtering were investigated. As-deposited ZnO:Al films show a high transmittance of above 80% in the visible range and a low electrical resistivity of $4.5{\times}10^{-4}{\Omega}{\cdot}cm$. The surface morphology of textured ZnO:Al films are closely dependent on the deposition parameters of heater temperature, working pressure, and etching time in the etching process. The optimized surface morphology with a crater shape is obtained at a heater temperature of $350^{\circ}C$, working pressure of 0.5 mtorr, and etching time of 45 seconds. The optical properties of light transmittance, haze, and angular distribution function (ADF) are significantly affected by the resulting surface morphologies of textured films. The film surfaces, having uniformly size-distributed craters, represent good light scattering properties of high haze and ADF values. Compared with commercial Asahi U ($SnO_2$:F) substrates, the suitability of textured ZnO:Al films as front electrode material for amorphous silicon thin film solar cells is also estimated with respect to electrical and optical properties.

• Korean Journal of Materials Research
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• v.25 no.7
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• pp.336-340
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• 2015

For rear metallization with Al paste, Al back contacts require good passivation, high reflectance, and a processing temperature window compatible with the front metal. In this paper, the effect of the firing ambient during the metallization process on the formation of Al rear metal was investigated. We chose three different gases as ambient gases during the firing process. Using SEM, we observed the formation of a back surface field in $N_2$, $O_2$, and Air ambients. To determine the effect of the ambient on Voc, the suns-Voc tool was used. In this study, we described the mechanism of burn-out of organic materials in Al paste during the firing process. The oxygen ambient plays an important role in the burn-out process. We calculated the efficiency with obtained the back surface recombination velocities using PC1D simulation. It was found that the presence of oxygen during the firing process influenced the uniform back surface field because the organic materials in the Al paste were efficiently burned out during heating. The optimized temperature with oxygen flow shows an absolute efficiency of 19.1% at PC1D simulation.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.114.1-114.1
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• 2011

Electrical sintering of the front electrode for crystalline silicon solar cells was performed applying a constant DC current to the printed lines. Conducting lines were printed on glass substrate by a drop-on-demand (DOD) inkjet printer and silver nanoparticle ink. Specific resistance and microstructure of sintered silver lines and were measured with varying DC current. To find the relation between temperature increase with changing applied current and specific resistance, temperature elevation was also calculated. Sintering process finished within a few milliseconds. Increasing applied DC current, specific resistance decreased and grain size increased after sintering. Achieved minimum specific resistance is approximately 1.7 times higher than specific resistance of the bulk silver.