• 한국재료학회지
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• 제23권3호
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• pp.177-182
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• 2013

Nanosphere lithography is an inexpensive, simple, high-throughput nanofabrication process. NSL can be done in different ways, such as drop coating, spin coating or by means of tilted evaporation. Nitride-based light-emitting diodes (LEDs) are applied in different places, such as liquid crystal displays and traffic signals. The characteristics of gallium nitride (GaN)-based LEDs can be enhanced by fabricating nanopatterns on the top surface of the LEDs. In this work, we created differently sized (420, 320 and 140 nm) nanopatterns on the upper surfaces of GaN-based LEDs using a modified nanosphere lithography technique. This technique is quite different from conventional NSL. The characterization of the patterned GaN-based LEDs revealed a dependence on the size of the holes in the pattern created on the LED surface. The depths of the patterns were 80 nm as confirmed by AFM. Both the photoluminescence and electroluminescence intensities of the patterned LEDs were found to increase with an increase in the size of holes in the pattern. The light output power of the 420-nm hole-patterned LED was 1.16 times higher than that of a conventional LED. Moreover, the current-voltage characteristics were improved with the fabrication of differently sized patterns over the LED surface using the proposed nanosphere lithography method.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.346.2-346.2
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• 2014

To use the GaN based light-emitting diodes (LEDs) as solid state lighting sources, the improvement of light extraction and internal quantum efficiency is essential factors for high brightness LEDs. In this study, we suggested the new materials system of a zinc tin oxide (ZTO) layer formed on blue LED epi-structures to improve the light extraction. ZTO is a representative n-type oxide material consisted of ZnO and SnO system. Moreover, ZTO is one of the promising oxide semiconductor material. Even though ZTO has higher chemical stability than IGZO owing to its SnO2 content this has high mobility and high reliability. After formation of ZTO layer on p-GaN layer by using the spin coating method, structural and optical properties are investigated. The x-ray diffraction (XRD) measurement results show the successful formation of ZTO. The photoluminescence (PL) and absorption spectrum shows that it has 3.6-4.1eV band gap. Finally, the light extraction properties of ZTO/LED chip using electroluminescence (EL) measurement were investigated. The experimental and theoretical analyses were simultaneously conducted.

• 한국결정성장학회지
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• 제31권5호
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• pp.212-217
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• 2021

Silica sol에 YAG 형광체를 첨가량별로 spin 코팅 후, 코팅막의 blue LED에서 백색광이 발현되는 정도와 표면 및 곡면 코팅용 binder로써, 적용가능성을 확인하였다. SEM, PSA를 통해YAG의 입자 크기는 D₅₀: 9~10 ㎛ 내외이며, XRD를 통해 YAG의 결정구조가 garnet(Y₃Al₅O₁₂), cubic인 것을 확인하였다. 코팅막은 crack이 없고 동시에 silica sol이YAG 형광체를 균질하게 도포된 형상을 보였으며, 첨가량 증가와 비례하게 코팅막 내에서 YAG 첨가량과 두께는 최대 40 ㎛까지 증가하는 추세를 보였다. 그리고 YAG 첨가량이 증가할수록 PL emission intensity 증가와 chromatic locus 곡선 끝 방향으로 색좌표 이동을 확인하였다. Soda-lime 유리기판 표면에 코팅 후, crack이 없으며 YAG 형광체가 균질하게 도포된 코팅성과 코팅막의 백색광 발현특성을 확인할 수 있었고 이는 직접적으로 LED에 다양한 형태의 형광 형상의 구현이 가능하다는 것을 의미한다.

• 대한화학회지
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• 제45권2호
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• pp.156-161
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• 2001

여러 가지 산화상태의 폴리아닐린을 화학적으로 합성하여 FT-IR, UV-Vis, GPC, TG-DTA로 측성 분석하였다. ITO 기관위에 다양한 산화상태의 LEB-PAN/NMP 용액으로 스핀코팅하고, AI 전극을 진공증착하여 단일층 발광다이오드를 제작하고 I-V 특성과 EL 스팩트럼에서 완전환원형인 LEB 함량이 증가할수록 ${\pi}$-${\pi}$* 전이의 장파장이동과 분자 엑시톤 전이 세기가 감소하고 PL과 EL 세기가 증가하는 것을 확인하였다. ITO/LEB/AI 구조의 LED에서 작동 전압은 5V 이었다. 백색광은 단지 폴리아닐린의 환원형 구조에서만 발광하는 것을 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.451-451
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• 2012

Instead of a highly toxic CdSe and ZnScore-shell,InP/ZnSecore-shell quantum dots [1,2] were investigated as an active material for quantum dot light emitting diode (QD-LED). In this paper, aquantum dot light-emitting diode (QDLED), consisting of a InP/ZnS core-shell type materials, with the device structure of glass/indium-tin-oxide (ITO)/PEDOT:PSS/Poly-TPD/InP-ZnS core-shell quantum dot/Cesium carbonate(CsCO3)/Al was fabricated through a simple spin coating technique. The resulting InP/ZnS core-shell QDs, emitting near blue green wavelength, were more efficient than the above CdSe QDs, and their luminescent properties were comparable to those of CdSe QDs.Thebrightness ofInP/ZnS QDLED was maximumof 179cd/m2.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.918-925
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• 1996

The effect of structured water by dissolution of xenon was examined from the view point of the suppression of both browning and respiratory metabolism of broccoli. The structured water is formed duet to hydrophobic interaction when xenon gas dissolves into water. NMR measurements were carried out to determine proton spin-spin relaxation time, T2, for water. There was a difference in proton T2 between distilled water and structured water. This can be interpreted as the change of water structure. Fro the broccoli cut in half stored for 16 days at 279K, the section color did not change appreciably for the sample whose water was structured by dissolution of xenon whose initial partial pressure was 0.39MPa. In contrast to this, the browning of section surface was observed for the sample stored under the condition of nitrogen gas at the same partial pressure as xenon and for the sample stored under atmospheric condition . These results led to the conclusion that the suppression of b owning by oxidation was due to structured water but not to applied pressure. Adding to this, the water structured by xenon has resulted in suppression of respiratory metabolism of broccoli.

• 한국추진공학회지
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• 제24권5호
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• pp.91-102
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• 2020

최근 민간이 우주개발을 주도하는 뉴스페이스 시대가 시작되었다. 뉴스페이스 시대는 소형위성 시장 및 소형발사체 시장의 규모가 확대됨에 따라 민간이 우주개발에 적극 참여하는 시대라고 할 수 있다. 우주개발 선진국에서는 소형발사체의 경쟁력을 확보하기 위해 개발/제작/운용비용의 감소시키는 노력을 하고 있다. 본 논문에서는 도전적인 우주개발을 위한 국외 소형발사체 개발 동향 및 소요 기술의 동향을 분석하고 요약하였다. 소요 기술 중 전기 펌프, 적층 제조 등 spin-on 기술을 우주개발기술에 활용하기 위한 연구 개발이 시급하게 필요하다.

• 한국자기학회지
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• 제8권5호
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• pp.317-332
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• 1998

소자화 랭동법은 전자 또는 핵의 자기 모벤트를 등온적으로 자화시킨 다음 단열상태에서 자화를 없앰으로써 온도를 내리는 방법이다. 전자의 소자화 냉동기는 교석 랭동기의 출현으로 거의 사용되지 않고 있으나 핵의 소자화 냉동기는 ${\mu}K$ 이하의 극저온을 얻을 수 있는 유일한 방법으로 극저온에서의 $^{3}He$액체 또는 $^{3}He$ 고체의 상전이, 극저온 초전도 현상, 핵의 자발질서 현상, 스핀 유리 상전이등의 연구에 많이 사용되고 있다. 핵의 소자화 냉동기는 대개 물체(시료) 전체의 온도를 내리는데 사용하나 빠른 소자화를 통해 핵만의 온도를 내리는데도 사용된다. 핵만의 온도를 내리는 냉동방법은 핵 자기 현상의 연구에 많이 이용되고 있다. 이러한 극저온을 얻기 위한 냉동법은 최첨단 기술이나 현재 국내에서는 극저온을 중점적로 연구하는 곳이 없는 실정이다. 본 논문에서는 소자화 냉동에 관한 현재의 취세를 소개하고 앞으로의 연구방향을 제시하고자 한다.

• 센서학회지
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• 제31권4호
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• pp.249-254
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• 2022

To achieve high-performance colloidal quantum dot light-emitting diodes (QD-LEDs), the use of a densely packed QD film is crucial to prevent the formation of leakage current pathways and increase in interface resistance. Spin coating is the most common method to deposit QDs; however, this method often produces pinholes that can act as short-circuit paths within devices. Since state-of-the-art QD-LEDs typically employ mono- or bi-layer QDs as an emissive layer because of their low conductivities, the use of a densely packed and pinhole-free QD film is essential. Herein, we introduce the Langmuir-Blodgett (LB) technique as a deposition method for the fabricate densely packed QD films in QD-LEDs. The LB technique successfully transfers a highly dense monolayer of QDs onto the substrate, and multilayer deposition is performed by repeating the transfer process. To validate the comparability of the LB technique with the standard QD-LED fabrication process, we fabricate and compare the performance of LB-based QD-LEDs to that of the spin-coating-based device. Owing to the non-destructiveness of the LB technique, the electroluminescence efficiency of the LB-based QD-LEDs is similar to that of the standard spin coating-based device. Thus, the LB technique is promising for use in optoelectronic applications.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.97-97
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• 2010

We demonstrate the hybrid polymer-quantum dot based multi-functional device (Organic bistable devices, Light-emitting diode, and Photovoltaic cell) with a single active-layer structure consisting of CdSe/ZnS semiconductor quantum-dots (QDs) dispersed in a poly N-vinylcarbazole (PVK) and 1,3,5-tirs- (N-phenylbenzimidazol-2-yl) benzene (TPBi) fabricated on indium-tin-oxide (ITO)/glass substrate by using a simple spin coating technique. The multi-functionality of the device as Organic bistable device (OBD), Light Emitting Diode (LED), and Photovoltaic cell can be successfully achieved by adding an electron transport layer (ETL) TPBi to OBD for attaining the functions of LED and Photovoltaic cell in which the lowest unoccupied molecular orbital (LUMO) level of TPBi is positioned at the energy level between the conduction band of CdSe/ZnS and LiF/Al electrode (band-gap engineering). Through transmission electron microscopy (TEM) study, the active layer of the device has a p-i-n structure of a consolidated core-shell structure in which semiconductor QDs are uniformly and isotropically adsorbed on the surface of a p-type polymer core and the n-type small molecular organic materials surround the semiconductor QDs.