• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.474-477
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• 1996

The solid state cesium ion beam sputter deposition system has been developed for negative carbon ion beam deposition. The negative carbon ion beams are effectively produced by cesium ion bombardment. The C-ion beam current and deposition energy can be independently controlled for the deposition of a-D films. This system is very compact, reliable and high flux without any gas discharge or plasma and has been successfully used in the studies of the ion beam deposited amorphous diamond(a-D)

• Transactions on Electrical and Electronic Materials
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• v.13 no.1
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• pp.6-9
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• 2012

In this study, we carried out an investigation of the etching characteristics (etch rate, selectivity to $SiO_2$) of ZnO thin films in $N_2/Cl_2$/Ar inductivity coupled plasma. A maximum etch rate and selectivity of 108.8 nm/min and, 3.21, respectively, was obtained for ZnO thin film at a $N_2/Cl_2$/Ar gas mixing ratio of 15:16:4 sccm. The plasmas were characterized by optical emission spectroscopy. The x-ray photoelectron spectroscopy analysis showed the efficient destruction of oxide bonds by ion bombardment. An accumulation of low volatile reaction products on the etched surface was also shown. Based on this data, an ion-assisted chemical reaction is proposed as the main etch mechanism for plasmas containing $Cl_2$.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.163-169
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• 1995

Ion beam assisted deposition(IBAD) technique was used to synthesize hard coatings including diamond-like carbon(DLC), carbon nitride(CN) and metal-ceramic multilayered films. It was found that DLC films formed at low energy ion bombardment possess more $Sp^3$ bonds and much higher hardness. The films exhibited an excellent wear resistance. Nanometer multialyered Fe/TiC films was deposited by ion beam sputtering. The structure and properties were strongly dependent on the thickness of the individual layers and modulation wave length. It was disclosed that both hardness and toughness of the films could be enhanced by adjusting the deposition parameters. The CN films synthesized by IBAD method consisted of tiny crystallites dispersed in amorphous matrix, which were identified by electron diffraction pattern to be $\beta -C_3N_4$.

• Applied Science and Convergence Technology
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• v.25 no.5
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• pp.98-102
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• 2016

The level set method has recently become popular in the simulation of semiconductor processes such as etching, deposition and photolithography, as it is a highly robust and accurate computational technique for tracking moving interfaces. In this research, full three-dimensional level set simulation has been developed for the investigation of focused ion beam processing. Especially, focused ion beam induced nanodot formation was investigated with the consideration of three-dimensional distribution of redeposition particles which were obtained by Monte-Carlo simulation. Experimental validations were carried out with the nanodots that were fabricated using focused $Ga^+$ beams on Silicon substrate. Detailed description of level set simulation and characteristics of nanodot formation will be discussed in detail as well as surface propagation under focused ion beam bombardment.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.157-158
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• 2007

Tin oxide films were successfully crystallized without additional heating by inductively coupled plasma assisted chemical vapor deposition (ICP-CVD). The degree of crystallization was affected by the ICP power, hydrogen flow and ion bombardment induced by negative substrate bias. The substrate temperature was increased only up to $150^{\sim}180^{\circ}C$ by plasma heating, which suggests that the formation of $SnO_2$ crystalswas caused by enhanced reactivity of precursors in high density plasma. The hardness of deposited tin oxide films ranged from 5.5 to 11GPa at different hydrogen flow rates.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.139-140
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• 2007

본 연구에서는 ion bombardment에 의한 폴리머 기판의 손상을 줄이기 위해 FTS (Facing Target Sputtering) 장치를 이용하여 투명 전극용 ITO 박막을 합성하였다. 산소와 헬륨의 혼합비율을 변수로 하여 박막을 합성한 결과, 투명전극에 적합한 낮은 비저항과 80% 이상의 투과도를 갖는 박막을 합성할 수 있었다.

• Bulletin of the Korean Chemical Society
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• v.17 no.11
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• pp.1036-1039
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• 1996

Synthetic lipoidal peptides based on viral protein sequences have been prepared. These peptides contain an N-palmitoyl group at the N-terminal residue, which is a modified cysteine, containing a S-[2,3-bis(acyloxy)-(2-R,S)-propyl] moiety. When this residue (Pam3Cys) is at the N-terminus of a synthetic peptide, it acts as potent immunoadjuvant to enhance both IgM and IgG antibody responses to the attached peptide. Conventional analytical procedures (e.g., Edman degradation and amino acid analysis) are either not applicable due to the N-terminal modification, or do not provide confirmation of the intact structure. Chromatographic analysis is also hindered by the tendency of these lipoidal Pam3Cys peptides to form large aggregates, and in some cases to be permanently adsorbed on reversed phase columns. We have applied several mass spectrometric techniques, including fast atom bombardment (FAB), electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) to characterize the intact structures of a number of different Pam3Cys synthetic peptides. The MALDI-MS has been found to be the most sensitive for the analysis of the structure of Pam3Cys peptides.

• Archives of Pharmacal Research
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• v.22 no.3
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• pp.237-242
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• 1999

A proteinacious inhibitor with a molecular weight of 1,600 Da which inhibits S-adenosyl-L-methionine-dependent transmethylation reactions was purified from porcine liver to homogeneity by procedures including boiling, Sephadex G-25 column chromatography and repeated HPLC. Employing both Nuclear Magnetic Resonance (NMR) and Fast Atom Bombardment-Mass (FAB-Mass) spectroscopy, S-adenosylhomocysteine was conclusively identified as an integral part of the inhibitor. The purified S-adenosylhomocysteine was competitive with S-adenosyl-L-methionine with Ki value of $6.3{\times}10^{-6}$ M towards protein methylase II.

• Applied Microscopy
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• v.48 no.4
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• pp.122-125
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• 2018

The focused ion beam (FIB) method is widely used to prepare specimens for observation by transmission electron microscopy (TEM), which offers a wide variety of imaging and analytical techniques. TEM has played a significant role in material investigation. However, the FIB method induces amorphization due to bombardment with the high-energy gallium ($Ga^+$) ion beam. To solve this problem, electron beam induced deposition (EBID) is used to form a protective layer to prevent damage to the specimen surface. In this study, we introduce an optimized TEM specimen preparation procedure by comparing the EBID of carbon and tungsten as protective layers in FIB. The selection of appropriate EBID conditions for preparing specimens for TEM analysis is described in detail.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1939-1941
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• 2021

The sputtering yield of tungsten pellets composed of different particle sizes of <1, 12, 44-74, and 149-297 ㎛ was systematically investigated by bombardment with Ar⁺ ions accelerated at 2.0 keV in an ultra-high vacuum chamber. We found that the tungsten sample fabricated from larger particles had a higher surface roughness, based on the surface profile results. Using the data of the surface roughness for the four types of tungsten pellets, we confirmed that the sputtering yield for a tungsten pellet with the highest surface roughness was 7 times lower than that of the lowest surface roughness. This could be due to the redeposition of sputtered tungsten particles onto neighboring asperities.