• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.226-226
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• 2010

Boron Nitride (BN) doped GeSbTe films were grown by the ion beam sputtering deposition (IBSD). The in-situ sheet resistance data and the x-ray diffraction patterns showed the crystallization is suppressed due to the BN incorporation. The phase change speed in BN doped GeSbTe films were investigated using the static tester equipped with nanosecond pulsed laser. The phase change speed for BN doped GST films become faster than the corresponding values for an undoped GST film. The Johnson-Mehl-Avrami(JMA) plot and Avrami coefficient for laser crystallization showed that the change in growth mode during the laser crystallization is a most important factor for the phase change speed in the BN doped GST films. The JMA results and the atomic force microscopy (AFM) images indicate that the origin of the change in the crystalline growth mode is due to an increase in the number of initial nucleation sites which is produced by the incorporated BN. In addition, the retension properties for the laser writing/erasing are remarkably improved in BN doped GeSbTe films owing to the stability of the incorporated BN.

• Journal of Surface Science and Engineering
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• v.29 no.6
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• pp.788-796
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• 1996

$TiO_2$ films prepared by RF magnetron sputtering, electron beam evaporation, ion assisted deposition (IAD) and sol-gel method are prepared on c-Si substrate and vitreous silica substrate respectively. From the transmission spectra of $TiO_2$ films on vitreous silica substrate in the spectral region from 190 nm to 900 nm, k($\lambda$) of $TiO_2$ is obtained. Using k($\lambda$) in the interband transition region the coefficients of the quantum mechanical dispersion relation of an amorphous $TiO_2$ and hence n($\lambda$) including the optically opaque region of above fundamental transition energy are obtained. The spectroscopic ellipsometry spectra of $TiO_2$ films in the spectral region of 1.5-5.0eV are model analyzed to get the film packing density variation versus i) substrate material, ii) film thickness and iii) film growth technique. The complex refractive index change of these $TiO_2$ films versus water condensation is also studied. Film micro-structures by SE modelling results are compared with those by atomic force microscopy images and X-ray diffraction data.

• Tribology and Lubricants
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• v.18 no.1
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• pp.1-8
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• 2002

Nano adhesion and friction between a $Si_{3}N_{4}$ AFM(atomic force microscope) tip and thin silver films were experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM and LFM(lateral force microscope) modes in various range of normal loads. Thin silver films deposited by IBAD (ion beam assisted deposition) on Si-wafer (100) and other Si-wafers of different surface roughness were used. Results showed that nano adhesion and friction decreased with the surface roughness. When the Si surfaces were coated by pure silver, the adhesion and friction decreased. But the adhesion and friction were not affected by the thickness of IBAD silver coating. As the normal force increased, the adhesion forces of bare Si-wafer and IBAD silver coating film remained constant, but the friction forces increased linearly. Test results suggested that the friction was mainly governed by the adhesion as long as the load was low.

• Korean Journal of Materials Research
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• v.5 no.3
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• pp.297-309
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• 1995

본 연구에서는 이온선보조증착법에 의해 Si(100)기판위에 정합성장된 $Si_{0.5}$Ge_{0.5}$층의 핵성성과 성장을 고찰하였다. 성장층에 대한 AFM(Atomic Force Microscopy), RHEED(Reflection High Energy Electron diffraction) 등의 분석결과 Si(100)기판위에 이온선보조증착에 의하여 성장된 $Si_{0.5}$Ge_{0.5}$층은 Stranski-Kranstanov(SK)기구로 성장되며, 300eV, 10 $\mu$A/$cm^{2}$의 Ar이온선을 조사시키는 경우 결정성이 향상되었고, SK 성장 방식의 임계두께가 증가하였다. Ar 이온선 조사에 의해 MBE에 의한 정합성장온도(55$0^{\circ}C$-$600^{\circ}C$)보다 훨씬 낮은 20$0^{\circ}C$에서 정합성장이 가능하였으며, $x_{mn}$값은 10.5%로 MBE에 의한 정합성장시 보고된 $x_{mn}$ 값보다 낮았다. 이온충돌에 의해 발생한 3차원 island의 분해와 표면확산의 증가가 $Si_{0.5}$Ge_{0.5}$층의 성장에 현저한 영향을 미쳤으며, 이온충돌의 영향은 3차원 island의 생성보다 3차원 island의 분해가 더 안정한 낮은 증착온도에서만 관찰되었다.

• Applied Microscopy
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• v.41 no.2
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• pp.89-98
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• 2011

Atom Probe Tomography (APT) can provide 3-dimensional information such as position and chemical composition with atomic resolution. Despite the ability of this technique, APT could not be applied for poor conductive materials such as semiconductor. Recently APT has dramatically developed by applying the laser pulsing and combining with Focused Ion Beam (FIB). The invention and combination of these techniques make possible site-specific sample preparation and permit the investigation of various materials including insulators. In this paper, we introduced the recently achieved state of the art applications of APT focusing on Si based FET devices, LED devices, low dimensional materials.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.11
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• pp.821-825
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• 2013

Effect of multi-stacked layer (MSL), 0.1 mol (M) and 0.3 mol (M) hafnium oxide ($HfO_2$) alignment layers were fabricated via a solution-process for LCs orientation. The solutions were spin-coated and annealed in a furnace. MSL consists of three sub-layers using 0.1 M solution, mono-layer (ML) is composed of 0.3 M $HfO_2$ solution. Then ion-beam irradiation was treated with 1.8 keV for 2 min. $HfO_2$-based LC cells were investigated through photographs, pre-tilt angle using crystal rotation method, X-ray photoelectron spectroscopy (XPS) measurement, and surface roughness using atomic force microscopy(AFM) for their characteristic research. Good LC orientation characteristics were observed on MSL $HfO_2$ surface. The LC alignment mechanism on MSL $HfO_2$ and ML $HfO_2$ surfaces was attributed to van der Waals (VDW) interaction between the LC molecular and substrate surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.503-504
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• 2007

$Bi_2Sr_2Ca_{n-1}Cu_nO_x$(n=0, 1, 2)superconducting thin films have been fabricated by atomic layer-by-layer deposition at an ultra low growth rate using IBS(Ion Beam Sputtering) method. During the deposition, 90 mol% ozone gas of typical pressure of $1{\sim}9{\times}10^{-5}$ Torr are supplied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal out that a buffer layer with some different compositions is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1287-1299
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• 2023

A new Monte-Carlo-based computer program (RDS-BASIC) is developed to simulate the transport of energetic ions in pure matter. This computer program is utilizing an algorithm that uses detailed numerical solutions for the classical scattering integral for evaluating the outcomes of the binary collision processes. This approach is adopted by several prominent similar simulation programs and is known to provide results with higher accuracy compared to other approaches that use approximations to shorten the simulation time. Furthermore, RDS-BASIC simulation program contains special methods to reduce the displacement energy threshold of surface atoms. This implementation is found essential for accurate simulation results for sputtering yield in the case of very low energy ions irradiation (near sputtering energy threshold) and also successfully solve the problem of simultaneously obtaining an acceptable number of atomic displacements per incident ions. Results of our simulation for several irradiation systems are presented and compared with their respective TRIM (SRIM-2013) and the state-of-the-art SDTrimSP simulation results. Our sputtering simulation results were also compared with available experimental data. The simulation execution time for these different simulation programs has also been compared.

• 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.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.89-93
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• 2015

Ion-beam irradiation(IB) on $HfO_2$ surface induced high-performance liquidcrystal(LC) driving at a 1-V threshold with vertical alignment of liquid crystals(LC). The high-k materials Atomic layer deposition was used to obtain LC orientation on ultrathin and high-quality films of $HfO_2$ layers. To analyze surface morphological transition of $HfO_2$ which can act as physical alignment effect of LC, atomic force microscopy images are employed with various IB intensities. The contact angle was measured to elucidate the mechanism of vertical alignment of LC on $HfO_2$ with IB irradiation. Contact angle measurement show the surface energy changes via IB intensity increasing.