• Clean Technology
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• v.20 no.4
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• pp.449-456
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• 2014

There has been increasing concerns for the problems of water security in countries, caused by the frequent occurrence of localized drought due to the climate change and uncertainty of water balance. The importance of fresh water is emphasized as considerable amount of usable fresh water is utilized for power generation sector producing electricity. PV power system, the source of renewable energy, consumes water for the every steps of life cycle: manufacturing, installation, and operation. However, it uses relatively less water than the traditional energy sources such as thermal power and nuclear power sources. In this study, to find out the use of water for the entire process of PV power system from extracting raw materials to operating the system, the footprint of water in the whole process is measured to be analyzed. Measuring the result, the PV water footprint of value chain was $0.989m^3/MWh$ and the water footprint appeared higher specially in poly-Si and solar cell process. The following two reasons explain it: poly-Si process is energy-intensive process and it consumes lots of cooling water. In solar cell process, deionized water is used considerably for washing a high-efficiency crystalline silicon. It is identified that PV system is the source using less water than traditional ones, which has a critical value in saving water. In discussing the future energy policy, it is vital to introduce the concept of water footprint as a supplementary value of renewable energy.

• Resources Recycling
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• v.26 no.1
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• pp.16-21
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• 2017

This paper relates to the synthesis of a source powder for SiC crystal growth. ${\beta}-SiC$ powders are synthesized at high temperatures (>$1400^{\circ}C$) by a reaction between silicon powder and carbon powder. The reaction is carried out in a graphite crucible operating in a vacuum ambient (or Ar gas) over a period of time sufficient to cause the Si+C mixture to react and form poly-crystalline SiC powder. End-product characterizations are pursued with X-ray diffraction analysis, SEM/EDS, particle size analyzer and ICP-OES. The purity of the end-product was analyzed with the Korean Standard KS L 1612.

• Analytical Science and Technology
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• v.20 no.5
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• pp.413-418
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• 2007

Poly(vinylpyrrolidone) stabilized cadmium sulfide (CdS) nanoparticles were loaded onto the surface of silica ($SiO_2$) nanoparticles by using ${\gamma}$-irradiation. TEM micrograph reveals the presence of ~20nm sized CdS nanoparticles on the surface of $SiO_2$ nanoparticles. XRD patterns confirm the crystalline. PL spectra of the simple PVP-stabilized CdS nanoparticle and $SiO_2$@CdS composite confirm the differences in the emission characteristics between them. Two prominent emission peaks were noted around 550 nm and 600 nm for PVP-stabilized CdS nanoparticles). The emission peaks noted for the PVP-stabilized CdS nanoparticles were found to be blue shifted for $SiO_2$@CdS composites. Besides, an additional emission peak around 450 nm was noticed for the $SiO_2$@CdS composite. The presence of CdS nanoparticles influence the emission characteristics and induce quantum confinement effect.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.2 s.39
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• pp.15-19
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• 2006

The resistance switching characteristics of amorphous $SiO_2$ and poly-crystalline $TiO_2$ were investigated. Both films exhibit well defined switching characteristics with low and high resistance states. From I-V curve analyses, it was found that the low resistance states of both films obey an ohmic conduction mechanism and the high resistance states show generation of a Schottky potential barrier. Regarding the mechanism for resistance switching of the binary oxide, it is suggested that the generation and annihilation of potential barriers accounts for the changes to the high resistance state and low resistance state, respectively. The device operation characteristic parameters such as reset and set voltages of $TiO_2$ are distinctly smaller than those of $SiO_2$, indicating that the values are related to the dielectric constant.

• Korean Journal of Metals and Materials
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• v.46 no.3
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• pp.159-168
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• 2008

Thermally-evaporated 10 nm-Ni/1 nm-Ru/(30 nm or 70 nm-poly)Si structures were fabricated in order to investigate the thermal stability of Ru-inserted nickel monosilicide. The silicide samples underwent rapid thermal anne aling at $300{\sim}1,100^{\circ}C$ for 40 seconds. Silicides suitable for the salicide process were formed on the top of the single crystal and polycrystalline silicon substrates mimicking actives and gates. The sheet resistance was measured using a four-point probe. High resolution X-ray diffraction and Auger depth profiling were used for phase and chemical composition analysis, respectively. Transmission electron microscope and scanning probe microscope(SPM) were used to determine the cross-sectional structure and surface roughness. The silicide, which formed on single crystal silicon and 30 nm polysilicon substrate, could defer the transformation of $Ni_2Si $i and $NiSi_2 $, and was stable at temperatures up to $1,100^{\circ}C$ and $1,100^{\circ}C$, respectively. Regarding microstructure, the nano-size NiSi preferred phase was observed on single crystalline Si substrate, and agglomerate phase was shown on 30 nm-thick polycrystalline Si substrate, respectively. The silicide, formed on 70 nm polysilicon substrate, showed high resistance at temperatures >$700^{\circ}C$ caused by mixed microstructure. Through SPM analysis, we confirmed that the surface roughness increased abruptly on single crystal Si substrate while not changed on polycrystalline substrate. The Ru-inserted nickel monosilicide could maintain a low resistance in wide temperature range and is considered suitable for the nano-thick silicide process.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1221_1222
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• 2009

다결정질 실리콘 웨이퍼의 도핑깊이, 도핑농도, 전면 재결합 속도, 면저항은 태양전지의 효율을 결정하는데 중요한 요소이다. 태양전지의 높은 효율을 얻기 위해 PC1D를 이용하여 태양전지의 에미터 도핑 깊이와 농도, 에미터 면저항, 전면 재결합 속도를 조절해 보았다. 그 결과로 최적화된 요소들은 peak doping $10^{18}cm^{-3}$, depth factor $0.5{\mu}m$, front recombination velocity $10^2cm/s$, sheet resistance $50{\Omega}/{\square}$를 얻을 수 있었다. 최적화 과정을 통하여 우리는 peak doping과 면저항이 높은 효율을 얻기 위한 중요한 요소가 된다는 사실을 알 수 있었다. 본 논문에서는 더 자세한 시뮬레이션 요소값과 그들이 태양전지에 미치는 영향에 대해 알아보고자 한다.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1123-1126
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• 2005

For creation of low temperature polycrystallinesilicon (LTPS) the line beam excimer laser annealing (ELA) is a well known and established technique in mass production. With introduction of Sequential Lateral Solidification (SLS) some aspects such as crystalline quality, throughput and flexibility regarding the substrate size could be improved, but for OLED manufacturing still further process development is necessary. This paper discusses line beam ELA and SLS techniques that might enable process engineers to make polycrystalline-silicon (poly-Si) films with a high degree of uniformity and quality as required for system on glass (SOG) and active matrix organic light emitting displays (AMOLED). Equipment requirements are discussed and compared to previous standards. SEM images of process examples are shown in order to demonstrate the viability.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.2
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• pp.55-62
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• 1992

Polycrystalline silicon ingots were manufactured using the casting method for polycrystalline silicon solar cells. These ingots were cut into wafers and ten n$^{+}$p type solar cells were made through the following simple process` surface etching, n$^{+}$p junction formation, metalization and annealing. For the grain boundary passivation, the samples were oxidized in O$_2$ for 5 min. at 80$0^{\circ}C$ prior to diffusion in Ar for 100 min. at 95$0^{\circ}C$. The conversion efficiency of polycrystalline silicon solar cells made from these wafers showed about 70-80% of those of the single crystalline silicon solar cell and superior conversion efficiency, compared to those of commercial polycrystalline wafers of Wacker Chemie. The maximum conversion efficiency of our wafers was indicated about 8%(without AR coating) in spite of such a simple fabrication method.

• Journal of the Korean institute of surface engineering
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• v.37 no.3
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• pp.164-168
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• 2004

Polycrystalline silicon thin films were deposited by inductively coupled plasma (ICP) assisted magnetron sputtering using a gas mixture of Ar and $H_2$ on a glass substrate at $250^{\circ}C$. At constant Ar mass flow rate of 10 sccm, the working pressure was changed between 10mTorr and 70mTorr with changing $H_2$ flow rate. The effects of RF power applied to ICP coil and $Ar/H_2$ gas mixing ratio on the properties of the deposited Si films were investigated. The crystallinity was evaluated by both X-ray diffraction and Raman spectroscopy. From the results of Raman spectroscopy, the crystallinity was improved as hydrogen mixing ratio was increased up to$ Ar/H_2$=10/16 sccm; the maximum crystalline fraction was 74% at this condition. When RF power applied to ICP coil was increased, the crystallinity was also increased around 78%. In order to investigate the surface roughness of the deposited films, Atomic Force Microscopy was used.

• Korean Journal of Materials Research
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• v.22 no.4
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• pp.202-206
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• 2012

$CoSi_2$ was formed through annealing of atomic layer deposition Co thin films. Co ALD was carried out using bis(N,N'-diisopropylacetamidinato) cobalt ($Co(iPr-AMD)_2$) as a precursor and $NH_3$ as a reactant; this reaction produced a highly conformal Co film with low resistivity ($50\;{\mu}{\Omega}cm$). To prevent oxygen contamination, $ex-situ$ sputtered Ti and $in-situ$ ALD Ru were used as capping layers, and the silicide formation prepared by rapid thermal annealing (RTA) was used for comparison. Ru ALD was carried out with (Dimethylcyclopendienyl)(Ethylcyclopentadienyl) Ruthenium ((DMPD)(EtCp)Ru) and $O_2$ as a precursor and reactant, respectively; the resulting material has good conformality of as much as 90% in structure of high aspect ratio. X-ray diffraction showed that $CoSi_2$ was in a poly-crystalline state and formed at over $800^{\circ}C$ of annealing temperature for both cases. To investigate the as-deposited and annealed sample with each capping layer, high resolution scanning transmission electron microscopy (STEM) was employed with electron energy loss spectroscopy (EELS). After annealing, in the case of the Ti capping layer, $CoSi_2$ about 40 nm thick was formed while the $SiO_x$ interlayer, which is the native oxide, became thinner due to oxygen scavenging property of Ti. Although Si diffusion toward the outside occurred in the Ru capping layer case, and the Ru layer was not as good as the sputtered Ti layer, in terms of the lack of scavenging oxygen, the Ru layer prepared by the ALD process, with high conformality, acted as a capping layer, resulting in the prevention of oxidation and the formation of $CoSi_2$.