• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.458.2-458.2
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• 2014

We have demonstrated that simple brush-painted Ti-doped $In_2O_3$(TIO) films can be used as a cost effective transparent anodes for organic solar cells (OSCs). We examined the RTA effects on the electrical, optical, and structural properties of the brush painted TIO electrodes. By the direct brushing of TIO nanoparticle ink and rapid thermal annealing (RTA), we can simply obtain TIO electrodes with a low sheet resistance of 28.25 Ohm/square and a high optical transmittance of 85.48% under atmospheric ambient conditions. Furthermore, improvements in the connectivity of the TIO nano-particles in the top region during the RTA process play an important role in reducing the resistivity of the brush-painted TIO anode. In particular, the brush painted TIO films showed a much higher mobility ($33.4cm^2/V-s$) than that of previously reported solution-process transparent oxide films ($1{\sim}5cm^2/V-s$) due to the effects of the Ti dopant with higher Lewis acid strength (3.06) and the reduced contact resistance of TIO nanoparticles. The OSCs fabricated on the brush-painted TIO films exhibited cell-performance with an open circuit voltage (Voc) of 0.61 V, shot circuit current (Jsc) of $7.90mA/cm^2$, fill factor (FF) of 61%, and power conversion efficiency (PCE) of 2.94%. This indicates that brush-painted TIO film is a promising cost-effective transparent electrode for printing-based OSCs with its simple process and high performance.

• 한국분무공학회지
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• 제5권3호
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• pp.17-26
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• 2000

The main parameter commonly used to evaluate spray distribution is spray angle. Spray angle is important because it influences the axial and radial distribution of the fuel. Spray angles were measured and compared for the two non-air assisted injectors such as 2hole-2stream 4hole-1stream injectors used for port fuel injection gasoline engines with n-heptane as a fuel by three different measuring techniques, i.e., digital image processing, shadowgraphy, and spray patternator, respectively. Fuel was injected with the injection pressures of 0.2-0.35 MPa into the room temperature and atmospheric pressure environment. In digital image processing approach, the selection of the transmittance level is critical to obtain the edge of spray and hence to measure the spray angle. From the measurement results by the shadowgraphy technique, it is dear that the spray angle is varied during the spray injection period. The measurement results from spray patternator show that the different spray angles exist in different region. Spray angle increases with the increase in the injection pressure. it is suggested that the spray angle and stream separated angle should be specified when spray is characterized for 2hole-2stream injector, because spray angle is much different though stream separated angle is same. It was also considerably affected by the measurement techniques introduced in this experimental work. However, the optimal axial distance for measuring the spray angle seems to be at least 60-80 mm from the injector tip for two non-air assisted injectors.

• 한국결정성장학회지
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• 제10권1호
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• pp.5-12
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• 2000

Silicon carbide(SiC)는 뛰어난 전기적, 열적, 물리적 특성 때문에 내환경 전자소자용 반도체 재료로 널리 연구되고 있다. 본 연구에서는 화학기상증착법으로 단결정 6H-SiC 동종박막을 성장시키고 이의 성장 특성을 조사하였다. 특히, 몰리브덴 (Mo)-plate를 이용하여 SiC를 코팅하지 않은 graphite susceptor를 사용한 6H-SiC 동종박막 성장조건을 성공적으로 얻었다. 대기압 상태의 RF-유도가열식 챔버에서 CVD성장을 수행하였고, <1120> 방향으로 $3.5^{\circ}$off-axis된 기판을 사용하였다. 성장 박막의 결정성을 평가하기 위하여 Nomarski 관찰, 투과율 측정 , 라만 분광, XRD, 광발광(PL) 분광, 투과전자현미경(TEM) 측 정 등의 방법을 이용하였다. 이상과 같은 실험을 통하여, 본 연구에서는 성장온도 $1500^{\circ}C$, C/Si flow ratio ($C_3H_8$ 0.2 sccm, $SiH_4$ 0.3 sccm)인 성장조건에서 결정성이 가장 좋은 6H-SiC 동종박막을 얻을 수 있었다.

• 반도체디스플레이기술학회지
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• 제21권3호
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• pp.101-104
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• 2022

Mist-CVD is known to have advantages of low cost and high productivity compared to ALD and PECVD methods. It is capable of reacting to the substrate by misting an aqueous solution using ultrasonic waves under vacuum-free conditions of atmospheric pressure. In particular, Ga₂O₃ is regarded as advanced power semiconductor material because of its high quality of transmittance, and excellent electrical conductivity through N-type doping. In this study, Computational Fluid Dynamics were used to predict the uniformity of the thin film on a large-area substrate. And also the deposition pattern and uniformity were analyzed using the flow velocity and particle tracking method. The uniformity was confirmed by quantifying the deposition cross section with an FIB-SEM, and the consistency of the uniformity prediction was secured through the analysis of the CFD distribution. With the analysis and experimental results, the match rate of deposition area was 80.14% and the match rate of deposition thickness was 55.32%. As the experimental and analysis results were consistent, it was confirmed that it is possible to predict the deposition thickness uniformity of Mist-CVD.

• 한국재료학회지
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• 제32권12호
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• pp.560-564
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• 2022

In this study, lanthanum boron silicate glasses were prepared with a composition of x Li₂O-(60-x)B₂O₃-5CaO-5BaO-7ZnO-10SiO₂-10La₂O₃-3Y₂O₃ where x = 1,3,5,7, and 9 mol%. Each composition was melted in a platinum crucible under atmospheric conditions at 1,400 ℃ for 2 h. Clear glasses with a transmittance exceeding 85 % were fabricated. Their optical, thermal, and physical properties, such as refractive index, Abbe number, density, glass transition (T_g) and Knoop hardness were studied. The results demonstrated that refractive index was between 1.6859 and 1.6953 at 589.3 nm. The Abbe number was calculated using an equation for 589.3 nm (nd), 656.3 nm (nf) and 486.1 nm (nc) and was observed to be in the range from 57.5 to 62.6. As the Li₂O content increased, the glass transition temperature of the optical glass decreased from 608 ℃ to 564 ℃. If glass mold pressing is performed using a material with a low transition temperature and high mechanical strength, then the optical glasses developed in this study can be completely commercialized.

• 공업화학
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• 제25권1호
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• pp.41-46
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• 2014

폴리카보네이트의 표면에 무기계 $SiO_2$ 박막을 바인더로 코팅한 후 광촉매 특성을 갖는 $TiO_2$ 박막을 추가로 형성하여 모재의 특성을 향상시키는 연구가 수행되었다. 바인더로 사용되는 $SiO_2$ 박막은 광투과 특성이 우수하며, 상압플라즈마처리를 통한 친수성의 증가로 $TiO_2$ 함유 수용액의 도포성을 향상시켜 균일한 박막을 형성시킬 수 있었다. 약 200 nm이상으로 코팅된 $TiO_2$ 박막은 180~400 nm의 자외선을 차단하여 폴리카보네이트의 황변현상을 억제하고 내열성을 크게 향상하는데 기여하였다. 최외층에 형성된 $TiO_2$ 박막은 자외선의 흡수로 활성화되는 표면산화특성으로 유기 오염물의 분해반응 촉진과 표면의 친수성의 증가에 따른 자기세정특성을 나타내었다. $TiO_2$ 박막과 폴리카보네이트 기재 사이에 $SiO_2$ 박막의 적용은 기재의 부식에 의한 코팅된 $TiO_2$ 층의 박리를 억제하여 구조 안정성을 유지할 수 있었다.