• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2207-2212
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• 2012

Dimethylaluminum isopropoxide (DMAI, $(CH_3)_2AlO^iPr$) as a single precursor, which contains one aluminum and one oxygen atom, has been adopted to deposit non-stoichiometric aluminum oxide ($AlO_x$) films by low pressure metal organic chemical vapor deposition without an additional oxygen source. The atomic concentration of Al and O in the deposited $AlO_x$ film was measured to be Al:O = ~1:1.1 and any serious interfacial oxide layer between the film and Si substrate was not observed. Gaseous by-products monitored by quadruple mass spectrometry show that ${\beta}$-hydrogen elimination mechanism is mainly contributed to the $AlO_x$ CVD process of DMAI precursor. The current-voltage characteristics of the $AlO_x$ film in Au/$AlO_x$/Ir metalinsulator-metal (MIM) capacitor structure show high ON/OFF ratio larger than ${\sim}10^6$ with SET and RESET voltages of 2.7 and 0.8 V, respectively. Impedance spectra indicate that the switching and memory phenomena are based on the bulk-based origins, presumably the formation and rupture of filaments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.208-213
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• 2020

Four types of BaTiO₃ powders are prepared and successfully deposited on glass and Pt/Si substrates using the aerosol deposition process. Particles with sizes of 0.45 ㎛ and 0.3 ㎛ are selected as the starting powder, while those powders are treated using a different milling method. The jet-milled and ball-milled powders not only showed a smaller particle-size distribution, but compared with the non-milled powder, it also had a higher deposition rate using the uniformly generated aerosol. Although the films deposited using particles with size 0.45 ㎛ exhibited some craters on the surface, significantly flat film surfaces were obtained. However, particles with size 0.3 ㎛ create a slightly rough film surface, but the dielectric constant was greater than in the case involving particles with size 0.45 ㎛. Consequently, a suitably large particle size significantly influences the deposition rate and improvement in the surface roughness, and a uniform particle size distribution appears to contribute to an improved dielectric constant. Therefore, it is believed that the dielectric properties along with the growth characteristics can be enhanced by limiting particle size and shape.

• Korean Journal of Metals and Materials
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• v.46 no.7
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• pp.458-463
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• 2008

High purity Fe thin films were prepared by the ion beam deposition method with $^{56}Fe^{+}$ions on the Si substrate at the room temperature. The Fe thin films were deposited at the ion energy of 50 eV and 100 eV. Microstructural properties were investigated on the atomic scale using high-resolution transmission electron microscopy (HRTEM). It was found that the Fe thin film obtained with the energy of 50 eV having an excellent corrosion resistance consists of the amorphous layer of ~15 nm in thickness and the bcc crystalline layer of about 30 nm in grain size, while the thin film obtained with the energy of 100 eV having a poor corrosion resistance consists of little amorphous layer and the defective crystalline layer. Furthermore the crystal structures and arrangements of the oxide layers formed on the Fe thin films were analyzed by processing of the HRTEM images. It was concluded that the corrosion behavior of Fe thin films relates to the surface morphology and the crystalline structure as well as the degree of purification.

• Journal of Sensor Science and Technology
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• v.29 no.5
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• pp.354-359
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• 2020

The high vacuum hermetic sealing technique ensures excellent performance of MEMS resonators. For the high vacuum hermetic sealing, the customization of anodic bonding equipment was conducted for the glass/Si/glass triple-stack anodic bonding process. Figure 1 presents the schematic of the MEMS resonator with triple-stack high-vacuum anodic bonding. The anodic bonding process for vacuum sealing was performed with the chamber pressure lower than 5 × 10^-6 mbar, the piston pressure of 5 kN, and the applied voltage was 1 kV. The process temperature during anodic bonding was 400 ℃. To maintain the vacuum condition of the glass cavity, a getter material, such as a titanium thin film, was deposited. The getter materials was active at the 400 ℃ during the anodic bonding process. To read out the electrical signals from the Si resonator, a vertical feed-through was applied by using through glass via (TGV) which is formed by sandblasting technique of cap glass wafer. The aluminum electrodes was conformally deposited on the via-hole structure of cap glass. The TGV process provides reliable electrical interconnection between Si resonator and aluminum electrodes on the cap glass without leakage or electrical disconnection through the TGV. The fabricated MEMS resonator with proposed vacuum packaging using three-layer anodic bonding process has resonance frequency and quality factor of about 16 kHz and more than 40,000, respectively.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.221-225
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• 2003

The MFIS-FET(Field Effect Transistor) devices using $BLT/Y_2O_3$ buffer layer on p-Si(100) substrates were fabricated by the Sol-Gel method and conventional memory processes. The crystal structure, morphologies and electrical properties of prepared devices were investigated by using various measuring techniques. From the C-V(capacitance-voltage) data at 5V, the memory window voltage of the $Pt/BLT/Y_2O_3/si$ structure decreased from 1.4V to 0.6V with increasing the annealing temperature from $700^{\circ}C\;to\;750^{\circ}C$. The drain current (Ic) as a function of gate voltages $(V_G)$ for the $MFIS(Pt/BLT/Y_2O_3/Si(100))-FET$ devices at gate voltages $(V_G)$ of 3V, 4V and 5V, the memory window voltages increased from 0.3V to 0.8V as $V_G$ increased from 3V to 5V.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.138-143
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• 2022

We analyzed the influence of post-annealing on Ga₂O₃/n-type 4H-SiC heterojunction diode. Gallium oxide (Ga₂O₃) thin films were deposited by radio frequency (RF) sputtering. Post-deposition annealing at 950℃ in an Oxygen atmosphere was performed. The material properties of Ga₂O₃ and the electrical properties of the diodes were investigated. Atomic Force Microscopy (AFM), X-Ray Diffraction and Scanning Electron Microscope (SEM) images show a significant increase in the roughness and crystallinity of the O₂-annealed films. After Oxygen annealing X-ray Photoelectron Spectroscopy (XPS) shows that the atomic ratio of oxygen increases which is related to a decrease in oxygen vacancy within the Ga₂O₃ film. The O₂-annealed diodes exhibited higher on-current and lower leakage current. Moreover, the ideality factor, barrier height, and thermal activation energy were derived from the current-voltage curve by increasing the temperature from 298 - 434K.

• Bulletin of the Korean Chemical Society
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• v.25 no.4
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• pp.475-479
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• 2004

$TiO_2$ thin films were grown on Si (100) substrates by atomic layer deposition using $[Ti(OPr^i )_2(dmae)_2]$ and water as precursors. The thickness, chemical composition, crystalline structure, and morphology of the deposited films were investigated by transmission electron microscopy, UV spectrometry, X-ray photoelectron pectroscopy, X-ray diffraction, and atomic force microscopy. The results show that $TiO_2$ ALD using $[Ti(OPr^i )_2(dmae)_2]$ as a precursor is self-controlled at temperatures of 100-300$^{\circ}C$. At the growth temperatures below 300$^{\circ}C$, the surface morphology of the $TiO_2$ films is smooth and uniform. The $TiO_2$ film was grown with a preferred orientation toward the [101] direction at 400$^{\circ}C$.

• Tribology and Lubricants
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• v.19 no.4
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• pp.203-210
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• 2003

In order to enhance the thermal stability of binder materials of bonded type solid lubricants, several metal-alkoxide based sol-gel materials such as methyltrimethoxysilane(MTMOS), titaniumisopropoxide (Ti(Opr$\^$i/)$_4$), zirconiumisopropoxide (Zr(Opr$\^$i/)$_4$) and aluminumbutoxide (Al(Obu$\^$t/)$_4$) were modified chemically by both epoxy and acrylic silane compounds. Friction and wear characteristics of the bonded solid lubricants, whose binders were of several hybrid ceramic materials, were tested with a reciprocating tribo-tester. Wear life was evaluated with respect to the heat-curing temperature, friction temperature, type of supplement lubricants, and ratio of binder materials. Test results showed that the Si-Zr hybrid ceramic materials modified by epoxy-silane compounds had a higher wear life compared to others. Sb$_2$O$_3$ was the most effective supplement lubricants in the high temperature, and BUS analyses revealed that it was caused mainly by a strong anti-oxidation effect to MoS$_2$ particles. The higher heat-curing temperature resulted in the higher wear life, and the higher friction temperature resulted in the lower wear life.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.287-287
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• 2010

We report a new direct patterning method, called liquid bridge-mediated nanotransfer molding (LB-nTM), for the formation of two- or three-dimensional structures with feature sizes between tens of nanometers and tens of micron over large areas. LB-nTM is based on the direct transfer of various materials from a mold to a substrate via a liquid bridge between them. This procedure can be adopted for automated direct printing machines that generate patterns of functional materials with a wide range of feature sizes on diverse substrates. Arrays of TIPS-PEN TFTs were fabricated on 4" polyethersulfone (PES) substrates by LB-nTM using PDMS molds. An inverted staggered structure was employed in the TFT device fabrication. A 150 nm-thick indium-tin oxide (ITO) gate electrode and a 200 nm-thick SiO2dielectric layer were formed on a PES substrate by sputter deposition. An array of TIPS-PEN patterns (thickness: 60 nm) as active channel layers was fabricated on the substrate by LB-nTM. The nominal channel length of the TIPS-PEN TFT was 10 mm, while the channel width was 135 mm. Finally, the source and drain electrodes of 200 nm-thick Ag were defined on the substrate by LB-nTM. The TIPS-PEN TFTs can endure strenuous bending and are also transparent in the visible range, and therefore potentially useful for flexible and invisible electronics.

• Journal of the Korean institute of surface engineering
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• v.31 no.6
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• pp.334-344
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• 1998

Yew coating pmccss t.o form a surface layer ol CrN phasc on mild steel (A81 1020!, AlSI Hi3, 1Cr-0.5Mo steel (ASTM A213 and Nickrl-base superalloy (Inconel 718) was developed. Surlaces of various alloys t,n.ateii by chromizing for the formation ol Cr diffusion layer was subsequently trcaled by plasma nitriding in order t.o form the hard CrS coating layer on the surfaces. This duplex plasma surface tri-atments of chromizing and plasma nitriding have induced a lormation of a duplex-lrcated surfacr hyer of approximat~ls 70-80 $\mu\textrm{m}$thickncss with a iargcly improved microiiardnrss up to approxiniateW 1500Hv(50gf). The main cause for the lage improvment in the surface hardncss is altribilted to [.he fact that CrN and $Fe_xN$ phases are created successfully by ccliromizins and plasma nilriding treatment. High tenipera1,urc wear resislance of the duplex-treated mild steel and HI3 steels at $600^{\circ}C$ was examined. Comparing the duplex-treated specimens with the specimens treated only by chromizing, the rcsults shovmi that, thc wear volume of the duplex-treated mild skcl and 1113 stcel aSt.er a wear test, at $600^{\circ}C$ were reduced hy a Iactor of 8 and 3, respectively. Characteristics of the CrS phase by duplrx treatment were compared with $CrN_x$,/TEX> film by ion plating and the wear behaviors of CrN film lormed by two different nroccsses arc nea.riy identical.