Eung-Ryul Kim

Highly Transparent Tin Oxide Films Prepared by DC Magnetron Sputtering and Its Liquid Crystal Display Application

A thin film of tin oxide (SnO2) was prepared on a plastic substrate by DC magnetron roll sputtering. The deposition thickness of SnO2 rapidly decreased with the increase of O2 gas flow rate, even though the refractive index remained almost constant at the level of 2.0 after the flow rate exceeded 40 sccm. The SnO2 thin film was applied as the oxide layer of the inner side of the multilayer conductive electrode having the sandwich structure of the oxide/metal/oxide system for flat panel display (FPD). The SnO2 layer in the sandwich structure (SnO2/Ag/ In2O3–SnO2; ITO) serves as a nucleation modification layer of the metal layer while preventing the diffusion of materials from the metal layer (Ag) to the barrier layer (SiO2). In particular, the transmittance in the 600–700 nm range is about 10% higher than that measured for the ITO/Ag/ITO structured electrode. This multilayered conductor also has approximately 5–8 Ω/square electrical resistance and 85% optical transmission at 550 nm.

Light-emitting diodes based on poly 3-(2-(5-chlorobenzotriazolo)ethyl) thiophene Langmuir-Blodgett films

A multilayer polymer thin film electroluminescence (EL) device has been prepared by fully using the LB film method. We synthesized a novel polythiophene derivative poly-3-(2-(5-chlorobenzotriazole)ethyl)thiophene (PCBET) and studied the EL effect of LB LEDs PCBET as the emitting materials. The PL spectra of polymer shows a peak at around 605 nm, which is about 65 nm blue shifted compared with poly 3-decylthiophene results from the benzotrizole group.

Preparation of Self-Assembled Fullerene-Diaminododecane Multilayer Films on (MeO)Si(CH3)2(CH2)4NH2-Modified Oxide Surfaces

Abstract Self-assembled fullerene-diaminoaodecane multilayer films were prepared on planar silicon wafer and quartz plate and on nonplanar fumed silica surfaces, and the growth of each layer and its uniformity was charackrized by using FTIR, UV, contact angle measurement and ellipsometric measurement. It is suggested that fullerene-diaminododecane layers are not completely packed on oxide surfaces, but the growrh of each layer was confirmed.

Electrical characterization of InAs/InP self-assembled quantum dots by deep level transient spectroscopy

In this paper, electrical characterization of InAs/InP self-assembled quantum dots is studied. The PL signals shown a peak at 0.67 eV with a full-width at half-maximum of about 50 meV.

Synthesis and Characterization of X-azo Dyes (X˭Ni, Cu, Zn) for Digital Versatile Disc-Recordable (DVD-R)

Abstract We have synthesized 5-(diethylamino)-2-[(E)-2-(methoxy-1, 3-benzo thiazole)-1-diazenyl] phenol (DMBTA) azo and DMBTA complexed with Ni, Cu, and Zn for DVD-R fabrication. The structures of the products were characterized by 1H-NMR and FT-IR. The properties of the compounds required for DVD-R fabrication were elucidated by UV-VIS and TGA. From the UV-VIS data, Zn-DMBTA exhibited the best response with 635 nm generally used in a DVD player. Based on the analysis of TGA data, it showed high thermal stability. Accordingly, Zn-DMBTA is the best compound as a recording material for DVD-R fabrication.

Synthesis and Characterization of Polythiophene Derivatives Containing Electron Transporting and Hole Transporting Moieties

Abstract Novel luminescent copolymers, poly(3-(2-benzotriazoloethyl)thiophene-co-octylcarbazolylene) ([(BET)m-OcCz2]n) that contain both electron transporting benzotriazole and hole transporting octylcarbazole moiety were synthesized by oxidation of ferric chloride with changing the composition ratio of BET and OcCz. The absorption peak of UV-VIS was blue-shifted from λmax=440 nm in poly(3-(2-benzotriazoloethyl)thiophene) (PBET) to λmax= 412 nm in [(BET)4-OcCz2]n. The photolumine scence (PL) and electroluminescence (EL) intensities of the polymers were decreased with presence of carbazole moieties in the copolymer.

Surface coverage of self-assembed zirconium perylene phosphonate derivative films on quartz and crystal growth of zirconium perylene phosphonate derivative

Abstract The N,N′-bis(benzyl phosphonic acid)-3,4,9,10-perylene (dicarboximide) (BPPI) has been known as a photoconducting material in xerography and its layer-by-layer growth with Zr4+ ion as a self-assembled multilayer film has been studied. We describe a method for measuring the relative surface coverage of self-assembled zirconium-BPPI monolayer on quartz substrate using UV-Vis spectrophotometry. The crystalline Zr-BPPI was grown at the controlled pH and temperature and its morphology was flat-flake shape.

Synthesis of Silicon-Containing Photoresists for ArF Excimer Laser Lithography

Two new positive-type photoresists which are terpolymers of methyl methacrylate (MMA), 1,3-bis(trimethylsilyl)isopropyl methacrylate (BPMA) and either methacrylic acid (MAA) or maleic anhydride (MA) have been synthesized for ArF excimer laser lithography. Terpolymers have a silicon containing acid labile protecting group which can be deprotected by photo acid generator (PAG). Terpolymers have a good thermal stability up to 140°C and the glass transition temperature (Tg) of poly(MMAx-BPMAy-MAz) was 119°C. The minimum feature resolution with 0.17 µm L/S pattern was achieved with poly(MMA5.9-BPMA2.1-MAA2.0) by using an ArF exposure system with 17 mJ/cm2 energy dose.

Preparation and Characterization of Conductive Polymer Nano-Films

We investigate the electrically conductive polypyrrole(PPy)and poly(3,4-ethylenedioxythiophene, PEDOT)nano-films prepared in a continuous roll-to-roll process by vapor-phase polymerization method. Thin films of ferric chloride doped conductive PPy and PEDOT on plastic substrates, in which neither matrix polymers nor binders are used for the film forming process, are obtained at nano-level thickness. PPy and PEDOT film thickness was varying depend on reaction time and reaction temperature. The surface resistance change with time of exposure to monomer vapors, and the value was in the range of 103 ∼ 105 Ω/sq. at 20–60 nm thick films and showed up to 600Ω/sq. for the > 600 nm thick films. These thin films had a very highly ordered surface morphology. Especially, in the case of PEDOT film, the growth of highly ordered conductive PEDOT crystalline microstructure, which high anisotropy, parallel to the substrate film was fabricated, was observed by AFM.

Role of inserting layer controlling wavelength in InGaAs quantum dots

Emission wavelength from the self-assembled In(Ga)As QDs on GaAs is typically around 1.0 /spl mu/m. In order to be applied to optical fiber communication, the extension of its optical emission wavelength to 1.3 /spl mu/m and further is necessary. Several groups have demonstrated GaAs-based InGaAs QDs with 1.3 /spl mu/m photoluminescence (PL). During the formation of such ternary dots, the variation of composition and dot size make it difficult to reproducibly achieve long wavelength emission. Long emission wavelength up to 1.3 /spl mu/m at room temperature cannot be realized until the In(Ga)As dots are placed in or below and InGaAs matrix. Among the proposed origins of achieving long wavelength emission from InAs quantum dots, we believe that the residual strain in quantum dots plays a key role. In this study, we have investigated the role of inserting layers tuning emission wavelength in InGaAs quantum dots.