• 한국재료학회지
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• 제28권4호
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• pp.235-240
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• 2018

We propose a speedy two-step deposit process to form an Au electrode on hole transport layer(HTL) without any damage using a general thermal evaporator in a perovskite solar cell(PSC). An Au electrode with a thickness of 70 nm was prepared with one-step and two-step processes using a general thermal evaporator with a 30 cm source-substrate distance and $6.0{\times}10^{-6}$ torr vacuum. The one-step process deposits the Au film with the desirable thickness through a source power of 60 and 100 W at a time. The two-step process deposits a 7 nm-thick buffer layer with source power of 60, 70, and 80 W, and then deposits the remaining film thickness at higher source power of 80, 90, and 100 W. The photovoltaic properties and microstructure of these PSC devices with a glass/FTO/$TiO_2$/perovskite/HTL/Au electrode were measured by a solar simulator and field emission scanning electron microscope. The one-step process showed a low depo-temperature of $88.5^{\circ}C$ with a long deposition time of 90 minutes at 60 W. It showed a high depo-temperature of $135.4^{\circ}C$ with a short deposition time of 8 minutes at 100 W. All the samples showed an ECE lower than 2.8 % due to damage on the HTL. The two-step process offered an ECE higher than 6.25 % without HTL damage through a deposition temperature lower than $88^{\circ}C$ and a short deposition time within 20 minutes in general. Therefore, the proposed two-step process is favorable to produce an Au electrode layer for the PSC device with a general thermal evaporator.

• 한국결정성장학회지
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• 제23권1호
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• pp.8-13
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• 2013

다른 형태의 ZnO는 형태에 따라 각각의 활용분야에 사용할 수 있다. 다양한 형태의 ZnO 구조체(structures)는 촉매를 사용하지 않는 열 기화법(thermal evaporation process)으로 합성되었다. ZnO 구조체의 형태들은 같은 실험 공정에서 기판과 소스간의 거리에 의존하였으며, 그 결과 합성물의 형태는 hollow, cage, star 이었다. ZnO 구조체의 형상과 결정성을 주사전자현미경(SEM)과 X선 회절분석(XRD)으로 각기 평가했다. 본 연구에서는 어떤 종류의 성장 요소가 최종 구조체의 형태에 관여하는지를 입증한다.

• 한국전기전자재료학회논문지
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• 제20권6호
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• pp.546-549
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• 2007

As a rule, high temperature superconducting coated conductors have multi-layered buffers consisting of seed, diffusion barrier and cap layers. Multi-buffer layer deposition requires longer fabrication time. This is one of main reasons which increases fabrication cost. Thus, single buffer layer deposition seems to be important for practical coated conductor process. In this study, a single layered buffer deposition of $CeO_2$ for low cost coated conductors has been tried using thermal evaporation technique. 100 nm-thick $CeO_2$ layers deposited by thermal evaporation were found to act as a diffusion layer. $1\;{\mu}m-thick$ SmBCO superconducting layers were deposited by thermal co-evaporation on the $CeO_2$ buffered Ni-5%W substrate. Critical current of 90 A/cm was obtained for the SmBCO coated conductors.

• 전기학회논문지P
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• 제58권3호
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• pp.310-315
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• 2009

This investigation was performed to study the characteristics of electricity and heat transfer that occur in the cylinder of electrode type humidifier during the process of water evaporation. Measurements were made to obtain the amount of water evaporation, the consumption of electric power, electrical conductivity, etc according to the materials and shapes of electrode. When the humidifier was in non-drain controlled mode, the number and amplitude of current cycle per minute increased gradually with the lapse of time, whereas for drain controlled mode, it decreased about 40[%] after draining water. It was found that for non-drain controlled mode, the thermal efficiency of humidifier which used SS400, STS316 and wire net electrode type was about 95~96[%] and it was 2~4[%] higher than that of drain controlled mode. Also, it was shown that the thermal efficiency of humidifier which used neighboring six-phase electrode balanced electrically was 4[%] higher than that of existing six-phase type.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.335-340
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• 2005

Nonlinear and forced oscillations of supported viscous droplet were focused in the present study. The droplet has a free contact line with solid plate and inviscid fluid. Natural frequencies of a pendant droplet have been investigated experimentally by imposing the acoustic wave while the frequency is being increased at a fixed amplitude. The evaporation was observed at atmosphere pressure. The droplet was recorded throughout the entire evaporation process and transient variations of the volume was measured. The evaporation process of oscillating droplet with thermofoil has been also observed to investigate analyzing the resonance effect on the thermal characteristics of droplet. It is found that a pendant droplet shows the resonant behaviors at each mode similar to the theoretical analysis. During imposing the acoustic wave, the pendant droplet makes a rotating motion in its longitudinal axis which is a new shape oscillation mode. The evaporation rate of a pendant droplet at resonant frequency is significantly enhanced.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권3호
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• pp.239-243
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• 2008

In this study, Bi-Sb thin film structure was prepared by thermal evaporation method. The electrical, optical transmission and structural characteristics of the prepared samples were introduced before and after thermal annealing process. At temperature of $500^{\circ}C$, the absorption of the structure was improved to reach 97% at near-infrared region. As well, the thermal annealing caused to reduce the bulk resistance of the Bi-Sb thin film structure. The morphology of Bi-Sb structure was also improved by thermal annealing as characteristic islands of the structure appear clearly in form hexagonal areas distinct from each other. This study is aiming to examine such structures if they are employed as photonic devices such as photodetectors, LED's and optical switches.

• Journal of Mechanical Science and Technology
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• 제18권12호
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• pp.2104-2113
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• 2004

Surface degreasing method with premixed flame is proposed as the removal method of adherent impurities on materials. Effects of adherent molecular thickness and surface potential energy on evaporation rate of adherent molecules and molecular evaporation mechanism were investigated and discussed in the present study. Evaporation processes of adherent molecules on surface molecules were simulated by the molecular dynamics method to understand thermal phenomena on evaporation processes of adherent molecules by using high temperature gas like burnt gas. The calculation system was composed of a high temperature gas region, an adherent molecular region and a surface molecular region. Both the thickness of adherent molecules and potential parameters affceted the evaporation rate of adherent molecules and evaporation mechanism in molecular scale.

• 한국재료학회지
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• 제28권10호
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• pp.578-582
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• 2018

ZnO crystals with different morphologies are synthesized through thermal evaporation of the mixture of Zn and Cu powder in air at atmospheric pressure. ZnO crystals with wire shape are synthesized when the process is performed at $1,000^{\circ}C$, while tetrapod-shaped ZnO crystals begin to form at $1,100^{\circ}C$. The wire-shaped ZnO crystals form even at $1,000^{\circ}C$, indicating that Cu acts as a reducing agent. As the temperature increases to $1,200^{\circ}C$, a large quantity of tetrapod-shaped ZnO crystals form and their size also increases. In addition to the tetrapods, rod-shaped ZnO crystals are observed. The atomic ratio of Zn and O in the ZnO crystals is approximately 1:1 with an increasing process temperature from $1,000^{\circ}C$ to $1,200^{\circ}C$. For the ZnO crystals synthesized at $1,000^{\circ}C$, no luminescence spectrum is observed. A weak visible luminescence is detected for the ZnO crystals prepared at $1,100^{\circ}C$. Ultraviolet and visible luminescence peaks with strong intensities are observed in the luminescence spectrum of the ZnO crystals formed at $1,200^{\circ}C$.

• 한국재료학회지
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• 제30권7호
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• pp.338-342
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• 2020

Tin oxide (SnO₂) nanocrystals are synthesized by a thermal evaporation method using a mixture of SnO₂ and Mg powders. The synthesis process is performed in air at atmospheric pressure, which makes the process very simple. Nanocrystals with a belt shape start to form at 900 ℃ lower than the melting point of SnO₂. As the synthesis temperature increases to 1,100 ℃, the quantity of nanocrystals increases. The size of the nanocrystals did not change with increasing temperature. When SnO₂ powder without Mg powder is used as the source material, no nanocrystals are synthesized even at 1,100 ℃, indicating that Mg plays an important role in the formation of the SnO₂ nanocrystals at temperatures as low as 900 ℃. X-ray diffraction analysis shows that the SnO₂ nanocrystals have a rutile crystal structure. The belt-shaped SnO₂ nanocrystals have a width of 300~800 nm, a thickness of 50 nm, and a length of several tens of micrometers. A strong blue emission peak centered at 410 nm is observed in the cathodoluminescence spectra of the belt-shaped SnO₂ nanocrystals.

• 한국재료학회지
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• 제33권7호
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• pp.279-284
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• 2023

One-dimensional MgO nanostructures with various morphologies were synthesized by a thermal evaporation method. The synthesis process was carried out in air at atmospheric pressure, which made the process very simple. A mixed powder of magnesium and active carbon was used as the source powder. The morphologies of the MgO nanostructures were changed by varying the growth temperature. When the growth temperature was 700 ℃, untapered nanowires with smooth surfaces were grown. As the temperature increased to 850 ℃, 1,000 ℃ and 1,100 ℃, tapered nanobelts, tapered nanowires and then knotted nanowires were sequentially observed. X-ray diffraction analysis revealed that the MgO nanostructures had a cubic crystallographic structure. Energy dispersive X-ray analysis showed that the nanostructures were composed of Mg and O elements, indicating high purity MgO nanostructures. Fourier transform infrared spectra peaks showed the characteristic absorption of MgO. No catalyst particles were observed at the tips of the one-dimensional nanostructures, which suggested that the one-dimensional nanostructures were grown in a vapor-solid growth mechanism.