• 한국자기학회지
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• 제5권5호
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• pp.465-469
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• 1995

We have investigated the effects of deposition angle on structural and magnetic properties of e-beam evaporated ${(4-{\AA}\;Co/9.2-{\AA}\;Pt)}_{23}$ multilayer thin films prepared on tilted substrates. It was found that the [111] crystallographic orientations of the multilayer thin films were not aligned with colummar growth orientations and they were remained to be normal to the substrate planes even though the deposition angle was severely oblique up to $60^{\circ}$. The analysis of the torque curve reveal that the intrinsic anisotropy energy was monotonically decreased with the deposition angle but the easy axis orientation parallel to the substrate normal was not much influenced by deposition angle.

• 한국광학회:학술대회논문집
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• 한국광학회 2007년도 하계학술발표회 논문집
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• pp.21-22
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• 2007

The periodic multilayer is considered as the X-ray reflection mirror. High X-ray reflectivity from the incident angle greater than the grazing critical angle can be obtained by the periodic multilayer structure. The Optical constants are investigated in order to determine the material for X-ray reflection mirror. The X-ray reflection mirror is designed for W, Si using computer simulation. The reflectivity is calculated for various incident angles and ratio of thickness.

• 한국방사선학회논문지
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• 제12권1호
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• pp.17-22
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• 2018

다층박막거울은 규소나 게르마늄과 같은 단결정 회절소자를 대체할 수 있는 광학소자로 수 나노미터 두께의 인공적인 회절 평면을 갖는다. 작은 두께 주기를 갖는 W/Si 다층박막거울에서 박막의 두께 변화에 따른 첫 번째 브래그 각도 및 반사율 저하를 조사하였다. 작은 두께 주기를 갖는 W/Si 다층박막거울은 $0.55^{\circ}$ 및 17.5 keV에서 최대 반사율을 나타내도록 설계되었고 72.67%의 반사율을 보였다. 텅스텐 및 규소의 박막 두께가 동일하게 변화되었을 때 첫 번째 브래그 각도의 변화 및 반사율 저하가 관찰되었다. 다층박막거울에서 텅스텐 박막중 하나의 층에서만 두께 변화가 있을 때는 반사율의 변화는 없지만 포락선의 요철이 관찰되었다. 무작위적인 가우시안 두께 변화에서도 반사율 저하가 관찰되었다. 작은 두께 주기를 갖는 W/Si 다층박막거울에서 두께 변화에 따른 반사율의 저하를 통해 제작되는 다층박막거울의 공차를 예측할 수 있을 것이다.

• 한국표면공학회지
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• 제45권3호
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• pp.111-116
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• 2012

Oblique angle deposition (OAD) is a physical vapor deposition method which utilizes non-normal angles between the substrate and the vaporizing source. It has been known that tilting the substrate changes the properties of the film deposited on it, which was thought to be a result of morphological change of the film. In this study, OAD has been applied to prepare single and multilayer Al films by magnetron sputtering. The magnetron sputtering source of 4 inch diameter was used to deposit the films. Al films have been deposited on Si wafers and cold-rolled steel sheets. The multilayer films were prepared by changing the tilting angle upside down at each layer interval, which means that when the first layer was deposited at an angle of $+45^{\circ}$, the second layer was deposited at an angle of $-45^{\circ}$, and vice versa. The microstructure, surface roughness and reflectance of the films were investigated using a scanning electron microscope, a surface profiler and a spectrophotometer, respectively. The corrosion resistance was measured and compared using the salt spray test. The single layer film prepared at an oblique angle of $60^{\circ}$ prepared at other angles. However, for the multilayer films, the film prepared at an oblique angle of $45^{\circ}$ showed the most compact and featureless structure. The multilayer films were found to exhibit higher corrosion resistance than the single layer films.

• ETRI Journal
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• 제45권4호
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• pp.557-569
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• 2023

Traditional deterministic channel modeling is accurate in prediction, but due to its complexity, improving computational efficiency remains a challenge. In an alternative approach, we investigated a multilayer artificial neural network (ANN) to predict large-scale and small-scale channel characteristics in metro tunnels. Simulated high-precision training datasets were obtained by combining measurement campaign with a ray tracing (RT) method in a metro tunnel. Performance on the training data was used to determine the number of hidden layers and neurons of the multilayer ANN. The proposed multilayer ANN performed efficiently (10 s for training; 0.19 ms for prediction), and accurately, with better approximation of the RT data than the single-layer ANN. The root mean square errors (RMSE) of path loss (2.82 dB), root mean square delay spread (0.61 ns), azimuth angle spread (3.06°), and elevation angle spread (1.22°) were impressive. These results demonstrate the superior computing efficiency and model complexity of ANNs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.367-367
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• 2013

Commercial applications of indium tin oxide (ITO) can be separated into two useful areas. As it is perceived to bear electrical properties and optical transparency at once, its chance to apply to promising fields, usually for an optical device, gets greater in the passing time. ITO is one of the transparent conducting oxides (TCO), and required to carry the relative resistance less than $10^{-3}{\Omega}$/cm and transmittances over 80 % in the visible wavelength of light. Because ITO has considerable refractive index, there exist applications for anti-reflection coatings. Anti-reflection properties require gradual change in refractive index from films to air. Such changes are obtained from film density or nano-clustered fractional void. Glancing angle deposition (GLAD) method is a well known process for adjusting nanostructure of the films. From its shadowing effects, GLAD helps to deposit well-controlled porous films effectively. In this study, we are comparing the reference sample to samples coated with controlled ITO multilayer accumulated by an e-beam evaporation system. At first, the single ITO layer samples are prepared to decide refractive index with ellipsometry. Afterwards, ITO multilayer samples are fabricated and fitted by multilayer ellipsometric model based on single layer data. The structural properties were measured by using atomic force microscopy (AFM), and by scanning X-ray diffraction (XRD) measurements. The ellipsometry was used to determine refractive indices and extinction coefficient. The optical transmittance of the film was investigated by using an ultraviolet-visible (UV-Vis) spectrophotometer.

• Journal of Magnetics
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• 제3권1호
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• pp.21-30
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• 1998

An artificially modulated magnetic Co/Pd multilayer is one of the promising candidates for high density magneto-optic (MO) recording media, due to large Kerr rotation angle in the wavelength of a blue laser beam. however, since multilayer structure, as well as amorphous structure, is a non-equilibrium state in terms of free energy and MO recording is a kind of thermal recording which is conducted aound Curie temperature (Tc) of the recording media, when the multilayer is used for the MO recording media, changes in the multilayer structure are occurred as the amorphous structure do. Therefore, the assessment of the structural stability in the Co/Pd multilayer is crucially important both for basic research and applications. As the parameter of the structural stability in this research, modulation amplitude and particle size of the Co/Pd multilayer are measured in terms of Ar sputtering pressure and heat treatment temperature. From the results of the research, we find out that the magnetic exchange energy in the structural changes of a magnetic multilayer structure and suggest the operating temperature range for MO recording in the Co/Pd multilayer for the basic research and applications, respectively.

• 한국방사선학회논문지
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• 제12권1호
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• pp.101-106
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• 2018

다층박막거울은 높은 반사 효율로 엑스선을 단색화 하는데 많이 사용되고 있다. 반사되는 엑스선의 파장은 두께주기와 입사각도에 의해 결정되고, 반사율은 층수와 표면 거칠기에 크게 의존하게 된다. 다층박막거울은 중원소와 경원소가 번갈아 적층되어 있는 구조로 되어 있으며 각 계면에서의 거칠기를 고려해야 한다. 본 논문에서는 두께 변화 W/Si 다층박막거울에서 계면 거칠기와 상호확산을 동시에 고려하여 반사율을 조사하였다. 두께 변화 다층박막거울은 균일한 다층박막거울에 비해 반사율은 감소하나 각도 및 에너지 반치폭이 넓은 특징을 보였으며, 상호확산에 따른 반사율의 저하가 크게 증가하였다. 이론적인 설계값에 가까운 반사율을 획득하기 위해서는 다층박막거울을 제작 할 때 나타나는 상호확산의 효과를 고려하여 설계함으로써 목적에 부합하는 최적의 다층박막거울을 설계하고 제작할 수 있을 것이다.

• 한국자기학회지
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• 제4권4호
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• pp.313-318
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• 1994

전자빔 증착 Co/Pt 다층박막에서 증발원자의 입사방향이 자기 및 자기광학적 성질에 미치는 영향을 조사하였다. 조성변조 Co/Pt 다층박막을 증발원자의 입사방향이 $0^{\circ},\;15^{\circ},\;30^{\circ},\;45^{\circ},\;60^{\circ}$이 되도록 하여 전자빔 증착법으로 제조한 후 x-ray 회절실험, 주사전자현미경으로 구조분석을 하였고, VSM, torque magnetometer, Kerr loop tracer를 사용하여 자기 및 자기광학적 성질을 조사하였다. x-ray 회절실험을 통해 모든 시료가 조성변조 다층박막 구조로 만들어졌음을 확인하였고, 입사각이 증가함에 따라 주상구조의 성장방향은 기판 수직선에서 벗어나지만 <111> 결정방향은 기판 수직선 가까이에 존재함이 관찰되었다. 포화자화값 $M_{s}$, Kerr회전각 ${\theta}k$는 입사각이 증가하면 줄어들었는데 이는 박막의 밀도 감소 때문이다. 자기이방성 또한 입사각의 증가에 따라 줄어들었다.

• 마이크로전자및패키징학회지
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• 제8권2호
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• pp.15-18
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• 2001

Magnetron sputtering 장비를 이용하여 극자외선 노광 공정용 Mo/Si 다층 박막을 증착하였다. 증착 파워로는 Mo의 경우 DC파워를, Si의 경우 RF파워를 이용하였다. 각각의 target에 인가되는 DC 또는 RF 파워의 시간 및 파워 조절을 통해서 원하는 구조인자를 가진 다층박막을 증착하였다. 증착된 다층박막을 단면 TEM, low/high angle XRD 등을 이용하여 박막의 미세구조와 interfacial layer의 거동을 살펴 보았으며, low angle XRD로부터 다층박막을 간접적으로 평가할 수 있었으며, 단면 TEM으로부터 Si위에 형성되는 Mo의 interfacial layer가 Mo위에 형성되는 경우보다 두꺼운 것을 알 수 있었다.