• 한국응용과학기술학회지
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• 제20권2호
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• pp.177-181
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• 2003

Ultra-thin films of amphiphillic squarylium dye were prepared on the hydrophillic substrate by Langmuir-Blodgett(LB) technique. In this study, the photoelectric properties of a amphiphillic squarylium dye LB film was investigated. The visible light(${\lambda}$ = 684nm ) of xenon lamp was illuminated on the amphiphillic squarylium dye LB films and light absorptivity and photoconductivity were observed. The photoconductivity was nearly constant regardless of nominal layer number. The photoelectric properties of the amphiphillic squarylium dye LB films with bottom electrode showed better than that top electrode.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.353-353
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• 2008

Carbon nanotubes (CNTs) are attractive for field emitter because of their outstanding electrical, mechanical, and chemical properties. Several applications using CNTs as field emitters have been demonstrated such as field emission display (FED), backlight unit (BLU), and X-ray source. In this study, we fabricated a CNT cathode using transparent ultra-thin CNT film. First, CNT aqueous solution was prepared by ultrasonically dispersing purified single-walled carbon nanotubes (SWCNTs) in deionized water with sodium dodecyl sulfate (SDS). To obtain the CNT film, the CNT solution in a milliliter or even several tens of micro-litters was deposited onto a porous alumina membrane through vacuum filtration process. Thereafter, the alumina membrane was solvated by the 3 M NaOH solution and the floating CNT film was easily transferred to an indium-tin-oxide (ITO) glass substrate of $0.5\times0.5cm^2$ with a film mask. The transmittance of as-prepared ultra-thin CNT films measured by UV-Vis spectrophotometer was 68~97%, depending on the amount of CNTs dispersed in an aqueous solution. Roller activation, which is a essential process to improve the field emission characteristics of CNT films, increased the UV-Vis transmittance up to 93~98%. This study presents SEM morphology of CNT emitters and their field emission properties according to the concentration of CNTs in an aqueous solutions. Since the ultra-thin CNT emitters prepared from the solutions show a high peak current density of field emission comparable to that of the paste-base CNT emitters and do not contain outgassing sources such as organic binders, they are considered to be very promising for small-size-but-high-end applications including X-ray sources and microwave power amplifiers.

• Structural Engineering and Mechanics
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• 제44권4호
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• pp.431-448
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• 2012

In this paper, the first-order shear deformation theory (FSDT) (Mindlin) for continuum incorporating surface energy is exploited to study the static behavior of ultra-thin functionally graded (FG) plates. The size-dependent mechanical response is very important while the plate thickness reduces to micro/nano scales. Bulk stresses on the surfaces are required to satisfy the surface balance conditions involving surface stresses. Unlike the classical continuum plate models, the bulk transverse normal stress is preserved here. By incorporating the surface energies into the principle of minimum potential energy, a series of continuum governing differential equations which include intrinsic length scales are derived. The modifications over the classical continuum stiffness are also obtained. To illustrate the application of the theory, simply supported micro/nano scaled rectangular films subjected to a transverse mechanical load are investigated. Numerical examples are presented to present the effects of surface energies on the behavior of functionally graded (FG) film, whose effective elastic moduli of its bulk material are represented by the simple power law. The proposed model is then used for a comparison between the continuum analysis of FG ultra-thin plates with and without incorporating surface effects. Also, the transverse shear strain effect is studied by a comparison between the FG plate behavior based on Kirchhoff and Mindlin assumptions. In our analysis the residual surface tension under unstrained conditions and the surface Lame constants are expected to be the same for the upper and lower surfaces of the FG plate. The proposed model is verified by previous work.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.761-763
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• 2001

Dendrimers represent a new class of synthetic macromolecules characterized by a regularly branched treelike structure. Dendrimer can be made with high regularity and controlled molecular weight. Peculiar features of the dendritic geometry are the large number of end groups as well as the shape persistence in higher generations, approaching spherical geometry. One of the most peculiar characteristics of dendritic macromolecules is their controlled molecular structure and orientation, which means that they have a practical application in achieving a highly organized molecular arrangement. We attempted to fabricate a G4-48PyA dendrimer LB films containing 48 pyridinealdoxime functional end group that could form a complex structure with metal ions. Also, we investigated the surface activity of dendrimer films at air-water interface. And we have studied the electrical properties of the ultra-thin dendrimer LB films. The electrical properties of the ultra-thin dendrimer LB films were investigated by studying the current-voltage(I-V) characteristics of metal/dendrimer LB films/metal (MIM) structure. And rectifying behavior of the devices was occurred in applied field.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
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• pp.248-251
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• 1996

Langmuir-Biodgett(LB) method is known as a unique method for preparing organic thin films, which can control thickness of the films in molecular level, and many kinds of ultra thin films of functional molecules have been prepared using this method. In this study, The organization of phospholipid monolayers on a water surface was investigated by means of displacement current measurement technique.

• 한국재료학회지
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• 제9권6호
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• pp.595-598
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• 1999

Ultra-thin films of amphiphilic Squarylium dye were prepared on the hydrophilic glass substrate by Langumuir-Blodgett(LB) technique. From the measurement of the surface pressure-area($\pi$-A) isotherm at air-water interface, it was found that amphiphilic Squarylium dye can form the stable monolayers. Using the LB technique, the Z-type monolayer assembly can be obtained. The amphiphilic Squarylium dye LB films exhibit λ\ulcorner at 684nm. The absorption is significantly red-shifted from solution of amphiphilic Squarylium dye(637nm in chloroform), suggesting that the Squarylim chromophores form J-aggregate in the LB film.

• 한국응용과학기술학회지
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• 제18권1호
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• pp.49-54
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• 2001

Ultra-thin films of organic charge transfer complex were prepared on a hydrophilic substrate by Langmuir-Blodgett(LB) technique. In this study, the photoelectric properties of a LB film consisting of (N-docosyl quinolinium)-TCNQ(1:2) complex was investigated. The visible light(${\lambda}$ : 700 nm) of xenon lamp was illuminated on the LB films and light absorptivity and photoconductivity were observed. The photocurrent increased linearly and was saturated at the light intensity of 23 ${\mu}W/cm^{2}$.

• 센서학회지
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• 제15권2호
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• pp.84-89
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• 2006

Highly concentrated p-type ZnO thin films can be obtained by doping of N, P and As elements. In this study, undoped ZnO buffer layers were prepared on a (0001) sapphire substrate by a ultra high vaccum pulsed laser deposition(UHV-PLD) method. ZnO buffer layers were deposited with various deposition temperature($400{\sim}700^{\circ}C$) at 350 mtorr of oxygen working pressure. Arsenic doped(1 wt%) ZnO thin films were deposited on the ZnO buffer layers by UHV-PLD. Crystallinity of the samples were evaluated by X-ray diffractometer and scanning electron microscopy. Optical, electrical properties of the ZnO thin films were estimated by photoluminescence(PL) and Hall measurements. The optimal condition of the undoped ZnO buffer layer for the deposition of As-doped ZnO thin films was at $600^{\circ}C$ of deposition temperature.

• 한국전기전자재료학회논문지
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• 제13권11호
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• pp.963-968
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• 2000

Magnetic properties and microstructures of Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films were investigated as a function of addition of element Ag, (X$\_$Ag/=0 to 6 at.%) and annealing temperature, T$\_$a/=300$\^{C}$ to 600$\^{C}$. In the case of adding Ag, magnetic properties of Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films were improved than those of Ag-free Fe$\_$93/Zr$_3$B$_4$thin films. The prominent soft magnetic properties with coercivity of 1.1 Oe, saturation magnetization of 2.2 T and permeability of 5400 at 50㎒ were obtained from Fe$\_$88/Zr$_3$B$_4$Ag$\_$5/ thin film annealed was lower than that of Fe-base or Co-base thin films reported previously. Such enhanced magnetic properties are presumably attributed to the format in ultra fine grains. Also, the reduced eddy current loss in the annealed sample is due to refined micro magnetic domains with increasing the amount of Ag in Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films.

• 한국전기전자재료학회논문지
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• 제13권6호
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• pp.459-466
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• 2000

For the applications in the ultra-large-scale-integration (ULSI) metallization processing copper thin films have been prepared by metal organic chemical vapor deposition (MOCVD) technology on TiN/Si substrates. The films have been deposited with varying the experimental conditions of substrate temperatures and copper source vapor pressures. The films were then annealed in a vacuum condition after the deposition and the annealing effect to the electrical conductivity of the films was measured. The grain size and the crystallinity of the films were observed to be increased by the post annealing and the electrical conductivity was also increased. The best electrical property of the copper film was obtained by in-situ annealing treatment at above 40$0^{\circ}C$ for the sample prepared at 18$0^{\circ}C$ of the substrate temperature.