• Journal of Radiation Industry
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• v.10 no.1
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• pp.1-5
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• 2016

In this study, the effect of high-energy proton irradiation on the optical properties of polyacrylonitrile (PAN) films was investigated. PAN thin films spin-coated on a substrate were irradiated 150 keV proton ions at various fluences. The changes in the chemical structure and optical properties were investigated by FT-IR and UV-vis spectroscopy. The results of the FT-IR analysis revealed that the cyclization reaction took place by proton irradiation and the degree of cyclization increased with an increasing fluence. Based on the UV-vis analysis, the optical band gap of PAN decreased from 2.84 to 2.52 eV with an increasing fluence due to the formation of carbon clusters by proton irradiation. In addition, the number of carbon atoms per carbon cluster and the number of carbon atoms per conjugation length were found to be increased with an increasing fluence.

• Journal of IKEEE
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• v.25 no.1
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• pp.64-68
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• 2021

We demonstrate an effect of annealing temperature on imprinting process of BiLaO thin film for liquid crystal alignment. BiLaO prepared sol-gel process was deposited by spin coating on a glass substrate, and then transferred to a pre-fabricated aligned pattern which is fabricated on a silicon wafer by laser interference lithography. Thin film was annealed at different temperature of 100, 150, 200, and 250 ℃. From the polarized optical microscopy analysis, the liquid crystal orientation was not uniform at the annealing temperature of 200 ℃ or lower and the uniform liquid crystal alignment characteristics were confirmed at the annealing temperature of 250 ℃. From atomic force microscopy, the pattern was not transferred at a temperature of 200 ℃ or lower. In contrast, the pattern was transferred at 250 ℃. Anisotropy of the thin film was obtained by the alignment pattern transferred at a temperature of 250 ℃, and the liquid crystal molecules could be evenly oriented on the thin film. Therefore, it was confirmed that the liquid crystal alignment process by the imprinting process of the BiLaO oxide film was affected by the annealing temperature.

• Journal of Adhesion and Interface
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• v.6 no.1
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• pp.7-10
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• 2005

Condensation control of nano-particles has become important in order to fabricate minute condensed structures. In this study, we focus our attention on condensation mechanism of polymer aggregates in a resist film. The polymer aggregate is structural component of a resist material which is used in lithography process. The condensation nature of polymer aggregates in the resist film surface is observed by using atomic force microscope (AFM). By using the AFM, the condensation of polymer aggregates can be observed clearly. The condensation of polymer aggregate strongly affects to precise fabrication of resist pattern below 100nm size. The interaction force among polymer aggregates can be analyzed based on Derjaguin approximation. We also discuss about condensation nature of polymer aggregates in the resist film surface with the help of micro sphere model.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.89-92
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• 2003

Nano-scratch tests were performed on PMMA thin films spin-coated on a Si substrate using an atomic force microscopy (AFM) with loads ranging from 10nN to 100nN. At low applied loads, a ridge pattern was formed on the PMMA surface. No wear particles were observed during the pattern-forming mild wear. At high applied loads, severe wear occurred accompanied by wear particles. The film with the highest hardness showed the highest wear resistance. Friction force generated during the Scratching was closely related with surface deformation of the film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.351-354
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• 2001

We fabricated organic electroluminescent(EL) devices with mixed emitting layer of poly (N- vinylcarbazole) ( PVK) , 2,5-bis (5-tert-butyl -2- benzoxaBoly) thiophene ( BBOT) , N,N-diphenyl-N,N- (3-methyphenyl) -1,1-biphenyl-4, 4-thiamine(TPD) and poly(3-hexylthiophene) (P3HT) deposited by LB(Langumuir-Boldgett) method. From the AFM(atomic force microscope) images, the monolayer containing 30% of AA(arachidic acid) showed a roughness value of 28$\AA$. In the voltage-current characteristics of ITO/Emitting layer/BBOT/LiF/A1 devices, current density much smaller than that of the spin-coated devices having a same thickness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.56-56
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• 2008

ZnO Oxide TFT with organic dielectric was prepared. ZnO thin film as active channel was prepared by plasma enhanced atomic deposition technique. Organic dielectric was spin coated on the gate metal. The structure of prepared TFT is bottom gate type and top contact structure. The characterization of oxide TFT was performed. We obtained the mobility of $0.7cm^2$/Vs, the threshold voltage of -14V, and the on-off ratio of $10^4$. We also obtained good output characterization with solid saturation.

• Transactions of Materials Processing
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• v.13 no.1
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• pp.59-64
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• 2004

Nano-scratch tests were performed on PMMA thin films spin-coated on a Si substrate using an atomic force microscopy (AFM) with loads ranging form 10nN to 100nN. At low loads, a ridge pattern was formed on the PMMA thin film surface. No wear particles were observed during the pattern-forming mild wear. At high loads, severe wear by plowing occurred, accompanied by wear particles. The film with the highest hardness showed the highest wear resistance. Friction force generated during the scratching was measured, which was closely related with surface deformation of the film. A simple empirical equation to deduce scratch hardness of the film from a linear fixed-distance scratch test was proposed, and scratching-speed dependency of the scratch hardness was displayed.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.56-56
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• 2010

Using first-principles density-functional theory calculations, we find dramatically different electronic states in the C chains generated on the H-terminated C(111) surface, depending on their length and parity. The infinitely long chain has $\pi$ electrons completely delocalized over the chain, yielding an equal C-C bond length. As the chain length becomes finite, such delocalized $\pi$ electrons are transformed into localized ones. As a result, even-numbered chains exhibit a strong charge-lattice coupling, leading to a bond-alternated structure, while odd-numbered chains show a ferrimagnetic spin ordering with a solitonlike structure. These geometric and electronic features of infinitely and finitely long chains are analogous to those of the closed (benzene) and open (polyacetylene) chains of hydrocarbons, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.175-179
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• 1996

Ferroelectric SrBi$_2$Ta$_2$$O_{9}$ thin films were fabricated by tole Sol-Gel method using a spin-on coating with MOD(Metal Organic Dccomposition) solution on Pt/Ti/SiO$_2$/Si(100) substratcs. The films were anncalcd at 80$0^{\circ}C$ for one hour in oxygen atmosphere. The effects of Bi/Ti mole ratios on crystalline orientations, surface morphologies, and subface composition SBT thin films with a Bi/Ta mole ratios from 1.1 to 1.3 were investigated using X-ray Diffractometry (XRD). Atomic Force (AFM), X-Ray Photoelectron Spectroscopy(XPS). Ferroelectric properties of these films were also measured.d.

• Journal of Magnetics
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• v.15 no.1
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• pp.17-20
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• 2010

The relationship between ferromagnet anisotropic magnetization and the antiferromagnet atomic spin configuration was investigated for various angles of the uniaxial deposition magnetic field of the FeMn layer in the Corning glass/Ta(5nm)/NiFe(7nm)/FeMn(25nm)/Ta(5nm) multilayer that was prepared by the ion beam sputter deposition. The exchange bias field ($H_{ex}$) obtained from the measurement of the easy-axis MR loop decreased to 40 Oe at the deposition field angle of $45^{\circ}$, and to 0 Oe at the angle of $90^{\circ}$. When the difference between the uniaxial axis between the ferromagnet NiFe and the antiferromagnet FeMn was $90^{\circ}$, the strong antiferromagnetic dipole moment of FeMn caused the weak ferromagnetic dipole moment of NiFe to rotate in the interface.