• Journal of the Korean Vacuum Society
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• v.18 no.3
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• pp.186-196
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• 2009

Since it is difficult to extract a high flux ion beam directly at an energy of hyperthermal range ($1{\sim}100\;eV$), especially, lower than 50 eV, the ions should be neutralized into neutral particles and extracted as a neutral beam. A plasma source required to generate and efficiently transport high flux hyperthermal neutral beams should be easily scaled up and produce a high ion density (${\ge}10^{11}\;cm^{-3}$) even at a low working pressure (${\le}$ 0.3 mTorr). It is suggested that the required plasma source can be realized by Electron Cyclotron Resonance (ECR) plasmas with diverse magnetic field configurations of permanent magnets such as a planar ECR plasma source with magnetron field configuration and cylindrical one with axial magnetic fields produced by permanent magnet arrays around chamber wall. In both case of the ECR sources, the electron confinement is based on the simple mirror field structure and efficiently enhanced by electron drifts for producing the high density plasma even at the low pressure.

• Journal of the Korean Vacuum Society
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• v.11 no.2
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• pp.108-112
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• 2002

We investigated the secondary electron emission characteristics of MgO layer used as the protecting material in a.c. plasma display panel(a.c.-PDPs) using a pulsed ion beam technique, where the surface charging can be effectively suppressed during the measurement. The measurement of the secondary electron emission coefficients ($\gamma$) on the surface of $SiO_2$ was carried out and then, it was found that the yields were dependent on incident ion energies. In addition, it was clearly demonstrated that the sputtering on MgO surface leads to lower yields, which suggests that the surface plays a key role on the operating conditions, such as life time, fast response, and etc.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.196-196
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• 2013

가시광 영역에서의 높은 투과도와 낮은 전기 비저항을 갖는 ITO (Indium Tin Oxide) 박막은 현재 Display, Solar Cell, LED, Smart Phone 등 최첨단 IT산업에서 가장 많이 사용되고 있는 투명전극소재이다. IBD (Ion Beam Deposition)방법은 박막의 증착 방법 중 Plasma에서 독립적으로 이온만을 빔의 형태로 조사하여 박막을 증착하는 방법으로 기존 RF 또는 DC 스퍼터방법에 비해서 상대적으로 높은 진공도(low 10E-04 torr)와 비교적 높은 스퍼터 된 입자의 에너지를 가지는 등의 장점으로 증착 된 박막의 밀도, 거칠기가 향상되고 상대적으로 적은 결함을 가지는 박막의 제작에 사용되고 있는 기술이다. (주)인포비온에서는 IBD 기술과 더불어 표면만을 선택적으로 가열할 수 있는 EBA Technology를 사용하여 박막에 Energy를 전달하고, 이를 바탕으로 ITO 박막의 전기적, 광학적, 구조적인 특성의 변화를 관찰 연구했다 [1]. 본 연구에서는 기존의 Sputter 방법과 IBD 방법으로 증착 된 ITO 박막의 전기적, 광학적, 구조적인 특성 변화를 비교 관찰하였고, EBA 후처리로 ITO 박막을 상온에서 처리하여, 박막의 투과도, 면 저항, 미세구조의 변화를 관찰하였다. 각 특성의 변화는 UV-VIS, 4Point-Probe, TEM을 사용하여 분석하였고, 처리 전, 후의 박막의 결합에너지는 XPS로, 박막의 조성변화는 SIMS를 이용하여 각각 분석하였다.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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• pp.704-723
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• 2000

This study was undertaken to evaluate the tensile bond strength of In-Ceram alumina core treat-ed by ion assisted reaction(IAR). Ion assisted reaction is a prospective surface modification technique without damage by a keV low energy ion beam irradiation in reactive gas environments or reactive ion itself. 120 In-Ceram specimens were fabricated according to manufacturer's directions and divided into six groups by surface treatment methods of In-Ceram alumina core. SD group(control group): sandblasting SL group: sandblasting + silane treatment SC group: sandblasting + Siloc treatment IAR I group: sandblasting + Ion assisted reaction with argon ion and oxygen gas IAR II group: sandblasting + Ion assisted reaction with oxygen ion and oxygen gas IAR III group: sandblasting + Ion assisted reaction with oxygen ion only For measuring of tensile bond strength, pairs of specimens within a group were bonded with Panavia 21 resin cement using special device secured that the film thickness was $80{\mu}m$. The results of tensile strength were statistically analyzed with the SPSS release version 8.0 programs. Physical change like surface roughness of In-Ceram alumina core treated by ion assistad reaction was evaluated by Contact Angle Measurement, Scanning Electron Microscopy, Atomic Force Microscopy; chemical surface change was evaluated by X-ray Photoelectron Spectroscopy. The results as follows: 1. In tensile bond strength, there were no statistically significant differences with SC group, IAR groups and SL group except control group(P<0.05). 2. Contact angle measurement showed that wettability of In-Ceram alumina core was enhanced after IAR treatment. 3. SEM and AFM showed that surface roughness of In-Ceram alumina core was not changed after IAR treatment. 4. XPS showed that IAR treatment of In-Ceram alumina core was enabled to create a new functional layer. A keV IAR treatment of In-Ceram alumina core could enhanced tensile bond strength with resin cement. In the future, this ion assisted reaction may be used effectively in various dental materials as well as in In-Ceram to promote the bond strength to natural tooth structure.

• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.384-389
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• 2009

ZnO, a wurtzite lattice structure, has attracted much attention as a promising material for light-emitting diodes (LEDs) due to highly efficient UV emission resulting from its large band gap of 3.37 eV, large exciton binding energy of 60 meV, and low power threshold for optical pumping at room temperature. For the realization of LEDs, both n-type ZnO and p-type ZnO are required. Now, n-type ZnO for practical applications is available; however, p-type ZnO still has many drawbacks. In this study, ZnO films were grown on glass substrates by using atomic layer deposition (ALD) and the ZnO films were irradiated by nitrogen ion beams (20 keV, $10^{13}{\sim}10^{15}ions/cm^2$). The effects of nitrogen-beam irradiation on the ZnO structure as well as the electrical property were investigated by using fieldemission scanning electron microscopy (FESEM) and Hall-effect measurement.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.79-90
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• 2007

Prototype of $800{\ell}$ vacuum web coater (Vic Mama) consisting of ion source with low energy less than 250 eV for high speed surface modification and 4 magnetron sputter cathodes was designed and constructed. Its performance was evaluated through fabricating the adhesiveless flexible copper clad laminate (FCCL). Pumping speed was monitored in both upper noncoating zone pumped down by 2 turbo pumps with 2000 l/sec pumping speed and lower surface modification and sputter zone vacuumed by turbo pumps with 450 1/sec and 1300 1/sec pumping speed respectively. Ion current density, plasma density, and uniformity of ion beam current were measured using Faraday cup and the distribution of magnetic field and erosion efficiency of sputter target were also investigated. With the irradiation of ion beams on polyimide (Kapton-E, $38{\mu}m$) at different fluences, the change of wetting angle of the deionized water to polyimide surface and those of surface chemical bonding were analyzed by wetting anglometer and x-ray photoelectron spectroscopy. After investigating the deposition rate of Ni-Cr tie layer and Cu layer was investigated with the variations of roll speed and input power to sputter cathode. FCCL fabricated by sputter and electrodeposition method and characterized in terms of the peel strength, thermal and chemical stability.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.36.2-36.2
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• 2009

In this work, the high power CW Nd:YAG laser has been used for thermal treatment of inkjet printed Ag films-involving eliminating organic additives (dispersant, binder, and organic solvent) of Ag ink and annealing Ag nanoparticles. By optimizing laser parameters, such as laser power and defocusing value, the laser energy can totally be converted to heat energy, which is used to thermal treatment of inkjet printed Ag films. This results in controlling the microstructures and the resistivity of films. We investigated the thermal diffusion mechanisms during laser annealing and the resulting microstructures. The impact of high power laser annealing on microstructures and electrical characteristic of inkjet printed Ag films is compared to those of the films annealed by a conventional furnace annealing. Focused ion beam (FIB) channeling image shows that the laser annealed Ag films have large columnar grains and dense structure (void free), while furnace annealed films have tiny grains and exhibit void formation. Due to these microstructural characteristics of laser annealed films, it has better electrical property (low resistivity) compared to furnace annealed samples.

• Radiation Oncology Journal
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• v.11 no.2
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• pp.449-454
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• 1993

The skin sparing effect associated with high energy x-ray or gamma ray beams may be reduce or lost under certain conditions of treatment. Current trends in using large fields. Shield carrying trays, compensating filters, and isocentric methods of treatment have posed problems of increased skin dose which sometimes become a limiting factor in giving adquate tumor doses. We used the shallow ion chamber to measure the phantom surface dose and the physical treatment variables for Co-60 gamma ray, 4MV and 10 MV x-ray beam. The dependence of percent surface dose on field sizes, atomic number of the shielding tray materials and its distance from the surface for 4, 10MV x-rays and Co-60 gamma ray is qualitatively similar. The use of 2 mm thick tin filter is recommended for situations where a low atomic number tray is introduced into the beam at distances less than 15 cm from the surface and with the large field sized for 4 MV x-ray beam. In case of Co-60 gamma ray, the lead glass tray is suitable for enhancement of skin sparing. Also, the filter distance should be as large as possible to achieve substantial skin sparing.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.99-101
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• 1998

1. Introduction : The conventional grafting polymerization technique requires chemically reactive groups on the surface as well as on the polymer chains. For this reason, a series of prefunctionalization steps are necessary for covalent grafting. The surface prefunctionalizational technique for grafting can be used to ionization radiation, UV, plasma, ion beam or chemical initiators. Of these techniques, radiation method is one of the useful methods because of uniform and rapid creation of active radical sites without catalytic contamination in grafted samples. If the diffusion of monomer into polymer is large enough to come to the inside of polymer substrate, a homogeneous and uniform grafting reaction can be carried out throughout the whole polymer substrate. Radiation-induced grafting method may attach specific functional moieties to a polymeric substrate, such as preirradiation and simultaneous irradiation. The former is irradiated at backbone polymer in vacuum or nitrogen gas and air, and then subsequent monomer grafting by trapped or peroxy radicals, while the latter is irradiated at backbone polymer in the presence of the monomer. Therefore, radiation-induced polymerization can be used to modification of the chemical and physical properties of the polymeric materials and has attracted considerable interest because it imparts desirable properties such as blood compatibility. membrane quality, ion excahnge, dyeability, protein adsorption, and immobilization of bioactive materials. Synthesizing biocompatible materials by radiation method such as preirradiation or simultaneous irradiation has often used $\gamma$-rays to graft hydrophilic monomers onto hydrophobic polymer substrates. In this work, in attempt to produce surfaces that show low levels of anti-fouling of bovine serum albumin(BSA) solutions, hydroxyethyl methacrylate(HEMA) was grafted polypropylene membrane surfaces by preirradiation technique. The anti-fouling effect of the polypropylene membrane after grafting was examined by permeation BSA solution.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.335-335
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• 2011

Instability of a thin film attached to a compliant substrate often leads to emergence of exquisite wrinkle patterns with length scales that depend on the system geometry and applied stresses. However, the patterns that are created using the current techniques in polymer surface engineering, generally have low aspect ratio of undulation amplitude to wavelength, thus, limiting their application. Here, we present a novel and effective method that enables us to create wrinkles with a desired wavelength and high aspect ratio of amplitude over wavelength as large as to 2.5:1. First, we create buckle patterns with high aspect ratio of amplitude to wavelength by deposition of an amorphous carbon film on a surface of a soft polymer poly(dimethylsiloxane) (PDMS). Amorphous carbon films are used as a protective layer in structural systems and biomedical components, due to their low friction coefficient, strong wear resistance against, and high elastic modulus and hardness. The deposited carbon layer is generally under high residual compressive stresses (~1 GPa), making it susceptible to buckle delamination on a hard substrate (e.g. silicon or glass) and to wrinkle on a flexible or soft substrate. Then, we employ glancing angle deposition (GLAD) for deposition of a high aspect ratio patterns with amorphous carbon coating on a PDMS surface. Using this method, pattern amplitudes of several nm to submicron size can be achieved by varying the carbon deposition time, allowing us to harness patterned polymers substrates for variety of application. Specifically, we demonstrate a potential application of the high aspect wrinkles for changing the surface structures with low surface energy materials of amorphous carbon coatings, increasing the water wettability.