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MgZnO/ZnO 이중 구조의 성장을 위한 사파이어 기판에서의 InZnO 버퍼층 연구
염아람,김홍승,안형수,장낙원 한국물리학회 2019 새물리 Vol.69 No.1
The replacement of Zn by Mg increases the bandgap of ZnO from 3.37 eV to 7.8 eV. The quantum-well structure of MgZnO/ZnO can be utilized as an active layer for ultra violet light-emitting diode (UV-LED) and high-mobility field effect transistor (HEMT). However, forming a high-quality MgZnO/ZnO heterostructure is difficult because of the lattice mismatch and surface roughness of the ZnO layer on a sapphire substrate. This study was carried out to introduce an InZnO buffer layer for the formation of a good-quality ZnMgO/ZnO quantum-well structure. Pulsed laser deposition (PLD) was used for this purpose, and X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to evaluate the structural properties. Atomic force microscopy (AFM) was also performed to observe surface changes. The addition of only a small amount of In improved the surface roughness of the buffer layers. This revealed that a buffer layer of InZnO is favorable for growing ZnMgO/ZnO thin films of high quality. Mg에 의한 Zn의 치환은 ZnO의 밴드 갭을 3.37 eV에서 7.8 eV로 증가시킨다. 이를 이용하여 ZnMgO/ZnO의 양자우물 구조 형성 시 UV-LED (ultra violet light-emitting diode) 및 ZnO 기반 고이동도 전계효과 트랜지스터의 활성층으로 활용할 수 있다. 하지만 양질의 ZnMgO/ZnO 구조를 사파이어 기판위에 형성 시 격자 불일치 및 ZnO 층의 표면 거칠기 등으로 양질의 이중 구조 박막의 형성이 어려운 실정이다. 본 연구는 양질의 ZnMgO/ZnO 양자우물 구조 형성을 위하여 InZnO 버퍼층을 도입하여 박막 표면의 변화를 관찰하고자 진행하였다. 이를 위하여 펄스 레이저 증착법을 이용하였고 형성된 InZnO의 구조적 특성 평가를 위하여 X-선 회절법 및 투과 전자현미경 분석을 행하였다. 또한 표면 변화 관찰을 위하여 원자력 현미경 분석도 실시하였다. 소량의 In 첨가로 InZnO 버퍼층은 ZnO 층에 비해 표면 거칠기가 급격히 감소하여 양질의 ZnMgO/ZnO 박막을 성장하기 위한 유리한 조건을 갖추었다.
졸-겔법으로 성장시킨 Mg<sub>0.3</sub>Zn<sub>0.7</sub>O 박막의 Mg 전구체의 종류에 따른 광학적·구조적 특성에 관한 연구
염아람,김홍승,장낙원,윤영,안형수,Yeom, Ahram,Kim, Hong Seung,Jang, Nak Won,Yun, Young,Ahn, Hyung Soo 한국전기전자재료학회 2020 전기전자재료학회논문지 Vol.33 No.3
In this study, Mg<sub>x</sub>Zn<sub>1-x</sub>O thin films, which can be applied not only to active layers of light-emitting devices (LEDs), such as UV-LEDs, but also to solar cells, high mobility field-effect transistors, and power semiconductor devices, are fabricated using the sol-gel method. ZnO and Mg<sub>0.3</sub>Zn<sub>0.7</sub>O solution synthesized by the sol-gel method and the thin film were grown by spin coating on a Si (100) substrate and sapphire substrate. The solutions are synthesized by dissolving precursor materials in 2-methoxyethanol (2-ME) solvent, and then monoethanolamine (MEA) was added to the mixed solution as a sol stabilizer. Zinc acetate dihydrate is used as a ZnO precursor, while Mg nitrate hexahydrate and Mg acetate tetrahydrate are used as an MgO precursor. Then, the optical and structural characteristics of the fabricated thin films are compared. The molar concentration of the Zn precursor in the solvent is fixed at 0.3 M, and the amount of the Mg precursor is 30% of Mg<sup>2+</sup>/Zn<sup>2+</sup>. The optical characteristics are measured using an UV-vis spectrophotometer, and the transmittance of each wavelength is measured. Structural characteristics are measured using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Composition analyses are performed using energy dispersive X-ray spectroscopy (EDS). The Mg<sub>0.3</sub>Zn<sub>0.7</sub>O thin film was well formed at the ratio of the Mg precursor added regardless of the type of Mg precursor, and the c-axis of the thin film was decreased, while the band gap was increased to 3.56 eV.
Sputum Processing Method for Lateral Flow Immunochromatographic Assays to Detect Coronaviruses
강아람,염민주,김혜권,윤선우,정대균,문형준,류광수,나운성,송대섭 대한면역학회 2021 Immune Network Vol.21 No.1
Coronavirus causes an infectious disease in various species and crosses the species barriers leading to the outbreak of zoonotic diseases. Due to the respiratory diseases are mainly caused in humans and viruses are replicated and excreted through the respiratory tract, the nasal fluid and sputum are mainly used for diagnosis. Early diagnosis of coronavirus plays an important role in preventing its spread and is essential for quarantine policies. For rapid decision and prompt triage of infected host, the immunochromatographic assay (ICA) has been widely used for point of care testing. However, when the ICA is applied to an expectorated sputum in which antigens are present, the viscosity of sputum interferes with the migration of the antigens on the test strip. To overcome this limitation, it is necessary to use a mucolytic agent without affecting the antigens. In this study, we combined known mucolytic agents to lower the viscosity of sputum and applied that to alpha and beta coronavirus, porcine epidemic diarrhea virus (PEDV) and Middle East respiratory syndrome coronavirus (MERS-CoV), respectively, spiked in sputum to find optimal pretreatment conditions. The pretreatment method using tris(2-carboxyethyl)phosphine (TCEP) and BSA was suitable for ICA diagnosis of sputum samples spiked with PEDV and MERS-CoV. This sensitive assay for the detection of coronavirus in sputum provides an useful information for the diagnosis of pathogen in low respiratory tract.