• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.617-620
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• 1999

In this study, the polarization e(fecal and the birefringence effect of amorphous germanium (a-Ge) thin films were investigated by using linearly polarized He-Ne laser beam. The a-7e thin films were deposited on the quarts substrate by plasma enhanced chemical vapor deposition (PECVD) and thermal vacuum evaporation In order to obtain the optimum grating arrays, inorganci resists such as Si$_3$N$_4$ and a-Se$_{75}$ Ge$_{25}$ , were prepared with the optimized thickness by Monte Carlo (MC) simulation. As the results of MC simulation, the thickness ofa-Se$_{75}$ Ge$_{25}$ resist was determined with Z$_{min}$ of 360$\AA$ . The resists were exposed to Ga$^{+}$-FIB with accelerating energies of 50 keV, developed by wet etching, and a-Ge thin film was etched by reactive ion-etching (RIE). Finally, we were obtained grating arrays which grating width and linewidth are 0.8${\mu}{\textrm}{m}$, respectively and we studied the polarization and birefringence effect in transmission grating array made of high refractive amorphous material, and the applicability as waveplates and polarizers in optical device.e.e.

• 한국산학기술학회논문지
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• 제16권12호
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• pp.8679-8683
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• 2015

세라믹은 고온에서 뛰어난 내마모성, 내부식성을 가지기 때문에 산업적 응용에 있어서 널리 사용된다. 세라믹은 금속과 비교해서 고온에서 더 큰 강도를 가지고 있고, 더 낮은 열전도도 및 열팽창 계수를 가진다. 그러나, 세라믹이 가진 취성의 성질은 전기전자산업과 고온에서의 구조적 적용에의 넓은 적용을 제한한다. Ti 활성금속과 STS304를 IBAD 기술을 이용해서 동시에 증착시켜 STS304 스테인레스강에 $Al_2O_3$(알루미나)의 브레이징 접합강도에 어떤 영향을 미치는지 알아보았으며, 시험편들은 Ti 타겟과 Ti+ STS304 타겟 두 종류를 이용하여 두께를 변화시켜가며 증착하였다. 브레이징 접합을 위한 삽입금속으로는 일반적으로 사용되는 Ag-Cu 공정조성의 합금이 사용되었다. 브레이징 접합품의 강도는 Ag-Cu 삽입금속과 알루미나 사이의 반응층의 두께와 반응 생성물 조직에 의해 결정되며, 본 실험에서는 계면 반응의 메커니즘을 보다 구체화하고 계면 반응에 의한 경사기능성의 접합계면을 더욱 향상시키는 결과를 얻고자 한다.

• 한국결정성장학회지
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• 제9권5호
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• pp.459-462
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• 1999

Recent advances in NLO Borate Crystals for UV Generation are reviewed with the particular emphasis on the technique to improve the life time of UV optics. The laser-damage resistance of CLBO and fused silica surfaces was successfully improved after removing polishing compound by ion beam etching. The polishing compound embedded in the CLBO and fused silica surfaces were to a depth of less than 100nm. We were able to remove polishing compound without degrading the surface condition when the applied ion beam voltage was less than 200 V. The laser-induced surface damage threshold of CLBO was improved up to 15J/$\textrm{cm}^2$(wavelength: 355 nm, pulse width: 0.85 ns)as compared with that of the as-polished surface (11 J/$\textrm{cm}^2$). The laser-induced surface damage of fused silica also increased from 7.5J/$\textrm{cm}^2$ to 15J/$\textrm{cm}^2$. For the irradiation of a 266 nm high-intensity and high-repetition laser light, the surface lifetime of CLBO and fused silica could be more doubled compared with that of the as-polished surface.

• Nuclear Engineering and Technology
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• 제40권3호
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• pp.233-238
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• 2008

This study investigates the surface modification of a Hastelloy X plate and diffusion bonding in the assembly of surface modified plates. These types of plates are involved in the key processes in the fabrication of a process heat exchanger (PHE) for a $SO_3$ decomposer. Strong adhesion of a SiC film deposited onto Hastelloy X can be achieved by a thin SiC film deposition and a subsequent N ion beam bombardment followed by an additional deposition of a thicker film that prevents the Hastelloy X surface from becoming exposed to a corrosive environment through the pores. This process not only produces higher corrosion resistance as proved by electrolytic etching but also exhibits higher endurance against thermal stress above 9$900^{\circ}C$. A process for a good bonding between Hastelloy X sheets, which is essential for a good heat exchanger, was developed by diffusion bonding. The diffusion bonding was done by mechanically clamping the sheets under a heat treatment at $900^{\circ}C$. When the clamping jig consisted of materials with a thermal expansion coefficient that was equal to or less than that of the Hastelloy X, sound bonding was achieved.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.360-363
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• 2005

본 연구에서는 인듐 액체금속이온원을 제작하여 빔 특성에 대해 연구를 하였으며, 기존의 연구를 하였던 갈륨 액체금속 이온원의 빔특성과 비교분석 하였다. 빔특성 분석을 위해 빔 안정도, 전류-전압특성곡선, 에너지 퍼짐을 측정하였다. 액체금속이온원에 사용되는 액체금속 저장소 및 바늘전극(tip)은 $500{\mu}m$의 직경을 갖는 텅스텐을 사용하였으며, 국내에서 제작된 제품을 사용하였다. 액체금속 저장소의 구조는 이전에 구상하여 연구가 이루어진 6개의 pre-etching된 텅스텐와이어(wire)가 묶여진 형태를 사용하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.223-224
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• 2012

금속 표면에 마이크로 나노 구조물을 형성하고 그 위에 발수 특성을 가진 물질을 증착하여, 발수성을 가지는 금속 표면을 개발하였다. Sand blast 공정으로 마이크로 구조 형성, Linear Ion Source(LIS)를 적용한 Ion beam etching으로 나노 구조를 형성하였다. 그 결과 FE-SEM을 통해 수~수십 ${\mu}m$ 크기의 구조 위에 nm 크기의 구조가 형성 된 것을 확인하였다. 발수 특성은 매끈한 표면보다 거친(rough)표면과 낮은 표면에너지로 구현된다. 마이크로 나노 구조가 형성된 Al의 표면에너지를 낮추기 위해 Hexamethyldisiloxane(HMDSO)을 코팅하였다. 접촉각 측정 결과 $105^{\circ}$로 표면 형상을 제어함으로써 발수 특성이 나타나는 것을 확인하였다.

• Journal of Magnetics
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• 제10권3호
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• pp.99-102
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• 2005

Modification in exchange bias of a NiFe/FeMn/NiFe trilayer, on introduction of a nonmagnetic Al layer at the top FeMn/NiFe interface, is investigated in multilayers prepared by rf magnetron sputtering. The introduction of Al layer leads to vanishing of bias of the top NiFe layer. But the bias for the bottom NiFe layer increases steadily with increasing Al layer thickness and attains bias (230 Oe) which is greater than that of the trilayer without the Al layer (150 Oe). When the top NiFe layer thickness is varied, exchange bias has highest value at 12 nm thickness for 1 nm thicknes of Al layer. Ion beam etching of the top NiFe layer also leads to an enhancement in bias for the bottom NiFe layer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.77-78
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• 2006

We fabricated photonic crystals on GaAs and GaN substrates. After anodizing the aluminium thin film in electrochemical embient, the porous alumina was implemented to the mask for reactive ion beam etching process of GaAs wafer. And photonic crystals in GaN wafer were also fabricated using electron beam nano-lithography process. The coated PMMA thin film with 200 nm-thickness on GaN surface was patterned with triangular lattice and etched out the GaN surface by the inductively coupled plasma source. The fabricated GaAs and GaN photonic crystals provide the enhanced intensities of light emission for the wavelengths of 858 and 450 nm, respectively. We will present the detailed dimensions of photonic crystals from SEM and AFM measurements.

• Current Optics and Photonics
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• 제4권1호
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• pp.9-15
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• 2020

Fresnel zone plates have been widely used in many applications, such as x-ray telescopes, microfluorescence, and microimaging. To obtain an x-ray Fresnel zone plate, many fabrication methods, such as electron-beam etching, ion-beam etching and chemical etching, have been developed. Fresnel zone plates fabricated by these methods will inevitably lead to some nonideal factors, which have an impact on the focusing characteristics of the zone plate. In this paper, the influences of these nonideal factors on the focusing characteristics of the zone plate are studied systematically, by numerical simulations based on scalar diffraction theory. The influence of the thickness of a Fresnel zone plate on the absolute focusing efficiency is calculated for a given incident x-ray's wavelength. The diffraction efficiency and size of the focal spot are calculated for different incline angles of the groove. The simulations of zone plates without struts, with regular struts, and with random struts are carried out, to study the effects of struts on the focusing characteristics of a zone plate. When a Fresnel zone plate is used to focus an ultrashort x-ray pulse, the effect of zone-plate structure on the final pulse duration is also discussed.

• 한국레이저가공학회지
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• 제13권4호
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• pp.7-13
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• 2010

Today, the most common process for generating Through Silicon Vias (TSVs) for 3D ICs is Deep Reactive Ion Etching (DRIE), which allows for high aspect ratio blind holes with low surface roughness. However, the DRIE process requires a vacuum environment and the use of expensive masks. The advantage of using lasers for TSV drilling is the higher flexibility they allow during manufacturing, because neither vacuum nor lithography or masks arc required and because lasers can be applied even to metal and to dielectric layers other than silicon. However, conventional nanosecond lasers have the disadvantage of causing heat affection around the target area. By contrast, the use of a picosecond laser enables the precise generation of TSVs with less heat affected zone. In this study, we conducted a comparison of thermalization effects around laser-drilled holes when using a picosecond laser set for a high pulse energy range and a low pulse energy range. Notably, the low pulse energy picosecond laser process reduced the experimentally recast layer, surface debris and melts around the hole better than the high pulse energy process.