AZO/Cu/AZO thin films were deposited on glass by RF magnetron sputtering. The specimens showed the preferred orientation of (0002) AZO and (111) Cu. The Cu crystal sizes increased from about 3.7 nm to about 8.5 nm with increasing Cu thickness, and from about 6.3 nm to about 9.5 nm with increasing heat treatment temperatures. The sizes of AZO crystals were almost independent of the Cu thickness, and increased slightly with heat treatment temperature. The residual stress of AZO after heat treatment also increased compressively from -4.6 GPa to -5.6 GPa with increasing heat treatment temperature. The increase in crystal size resulted from grain growth, and the increase in stress resulted from the decrease in defects that accompanied grain growth, and the thermal stress during cooling from heat treatment temperature to room temperature. From the PL spectra, the decrease in defects during heat treatment resulted in the increased intensity. The electrical resistivities of the 4 nm Cu film were 5.9 × 10-4 Ω ‧ cm and about 1.0 × 10-4 Ω ‧ cm for thicker Cu films. The resistivity decreased as the temperature of heat treatment increased. As the Cu thickness increased, an increase in carrier concentration resulted, as the fraction of AZO/Cu/AZO metal film increased. And the increase in carrier concentration with increasing heat treatment temperature might result from the diffusion of Cu ions into AZO. Transmittance decreased with increasing Cu thicknesses, and reached a maximum near the 500 nm wavelength after being heat treated at 200 °C.

Amorphous In-Ga-Zn-O (a-IGZO) thin film transistors, because of their relatively low mobility, have limits in attempts to fulfill high-end specifications for display backplanes. In-Zn-O (IZO) is a promising semiconductor material for high mobility device applications with excellent transparency to visible light region and low temperature process capability. In this paper, the effects of working pressure on the physical and electrical properties of IZO films and thin film transistors are investigated. The working pressure is modulated from 2 mTorr to 5 mTorr, whereas the other process conditions are fixed. As the working pressure increases, the extracted optical band gap of IZO films gradually decreases. Absorption coefficient spectra indicate that subgap states increase at high working pressure. Furthermore, IZO film fabricated at low working pressure shows smoother surface morphology. As a result, IZO thin film transistors with optimum conditions exhibit excellent switching characteristics with high mobility (≥ 30cm2/Vs) and large on/off ratio.

The effects of fast neutron irradiation on the electrical and optical properties of Li (3 at%) doped ZnSnO (ZTO) thin films fabricated using a sol-gel process are investigated. From the results of Li-ZTO TFT characteristics according to change of neutron irradiation time, the saturation mobility is found to increase and threshold voltage values shift to a negative direction from 1,000 s neutron irradiation time. X-ray photoelectron spectroscopy analysis of the O 1s core level shows that the relative area of oxygen vacancies is almost unchanged with different irradiation times. From the results of band alignment, it is confirmed that, due to the increase of electron carrier concentration, the Fermi level (EF) of the sample irradiated for 1,000 s is located at the position closest to the conduction band minimum. The increase in electron concentration is considered by looking at the shallow band edge state under the conduction band edge formed by fast neutron irradiation of more than 1,000 s.

The effects of electron beam(EB) irradiation on the electrical and optical properties of InGaZnO(IGZO) thin films fabricated using a sol-gel process were investigated. As the EB dose increased, the electrical characteristic of the IGZO TFTs changed from semiconductor to conductor, and the threshold voltage values shifted to the negative direction. X-ray photoelectron spectroscopy analysis of the O 1s core level showed that the relative area of oxygen vacancies increased from 14.68 to 19.08 % as the EB dose increased from 0 to 1.5 × 1016 electrons/cm2. In addition, spectroscopic ellipsometer analysis showed that the optical band gap varied from 3.39 to 3.46 eV with increasing EB dose. From the result of band alignment, it was confirmed that the Fermi level(EF) of the sample irradiated with 1.5 × 1016 electrons/cm2 was located at the closest position to the conduction band minimum(CBM) due to the increase of electron carrier concentration

Fluorine-doped SnO2 (FTO) thin film/Ag nanowire (NW) double layers were fabricated by means of spin coating and ultrasonic spray pyrolysis. To investigate the optimum thickness of the FTO thin films when used as protection layer for Ag NWs, the deposition time of the ultrasonic spray pyrolysis process was varied at 0, 1, 3, 5, or 10 min. The structural, chemical, morphological, electrical, and optical properties of the double layers were examined using X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, the Hall effect measurement system, and UV-Vis spectrophotometry. Although pure Ag NWs formed isolated droplet-shaped Ag particles at an annealing temperature of 300 oC, Ag NWs covered by FTO thin films maintained their high-aspect-ratio morphology. As the deposition time of the FTO thin films increased, the electrical and optical properties of the double layers degraded gradually. Therefore, the double layer fabricated with FTO thin films deposited for 1 min exhibited superb sheet resistance (~14.9Ω/□), high optical transmittance (~88.6 %), the best FOM (~19.9 × 10−3 Ω−1), and excellent thermal stability at an annealing temperature of 300 oC owing to the good morphology maintenance of the Ag NWs covered by FTO thin films.

This paper presents new type magnetostrictive optical systems. The suggested wireless optical systems are developed by using two types of magnetostrictive thin film actuators. The first is a seesaw type wireless-controlled compact optical switch, and another is a comb type TbDyFeNi thin film actuator by silicon micromachining techniques with DC magnetron sputtering. In the seesaw type, TbDyFe films are selectively deposited on the micromachined switch matrix. For the optical switching operation, switch is arranged in a 1×2 array (mirror size of 5mm × 800μm × 50μm) and has different length from the supporting point. Mirrors are also actuated by externally applied magnetic fields up to 0.5T. In the comb type, the effect of Ni content on the magneto-mechanical properties of the Tb0.24Dy0.76Fe2 system is investigated with the effect of deposited film thickness of TbDyFeNi on silicon substrate for wireless microactuator. As results, magneto-mechanical characteristics are investigated. using magnetization and deflected angle variation

Vanadium dioxide (VO2) is an attractive material for smart window applications where the transmittance of light can be automatically modulated from a transparent state to an opaque state at the critical temperature of ~68˚C. Meanwhile, F : SnO2 (F-doped SnO2, FTO) glass is a transparent conductive oxide material that is widely used in solar-energy-related applications because of its excellent optical and electrical properties. Relatively high transmittance and low emissivity have been obtained for FTO-coated glasses. Tunable transmittance corresponding to ambient temperature and low emissivity can be expected from VO2 films deposited onto FTO glasses. In this study, FTO glasses were applied for the deposition of VO2 thin films by pulsed DC magnetron sputtering. VO2 thin films were also deposited on a Pyrex substrate for comparison. To decrease the phase transition temperature of VO2, tungsten-doped VO2 films were also deposited onto FTO glasses. The visible transmittance of VO2/FTO was higher than that of VO2/pyrex due to the increased crystallinity of the VO2 thin film deposited on FTO and decreased interface reflection. Although the solar transmittance modulation of VO2/FTO was lower than that of VO2/pyrex, room temperature solar transmittance of VO2/FTO was lower than that of VO2/pyrex, which is advantageous for reflecting solar heat energy in summer.

본 연구에서는 말단기에 diene 기와 dithiol 기를 갖는 두 가지 새로운 액정 단량체의 합성을 보고하며, 이를 배향 후 광경화하여 광학 위상지연 필름을 제조하는 방법에 대해 논의하였다. 특히 합성된 두 가지액정단량체의 구조를 확인하였으며, 이들의 액정특성을 연구하였다. 또한 이들을 광개시제와 혼합하여광경화형 액정조성물을 제조하고 이를 러빙 배향막이 코팅된 표면 위에서배향시킨 후 광조사하여 thiol-ene 중합에 의해 경화함으로써 광학 위상지연 필름을 제조하였다.

In this study, we analyzed the effect of silicon oxynitride matrix on the optical properties of Au nanoparticles dispersed on composite film and explored the effectiveness of the silicon in fine tuning the refractive index of the composite film for applications in optical waveguide devices. The atomic fraction of nitrogen in SiOxNy films was controlled by varying the relative flow ratio of nitrogen gas in reactive sputtering and was evaluated optically using an effective medium theory with Bruggeman geometry consisting of a random mixture between SiO2 and Si3N4. The Au nanoparticles were embedded in the SiOxNy matrix by employing the alternating deposition technique and clearly showed an absorption peak due to the excitation of surface plasmon. With increasing nitrogen atomic fraction in the matrix, the surface plasmon resonance wavelength shifted to a longer wavelength (a red-shift) with an enhanced resonance absorption. These characteristics were interpreted using the Maxwell-Garnett effective medium theory. The formation of a guided mode in a slab waveguide consisting of 3 μm thick Au:SiOxNy nanocomposite film was confirmed at the telecommunication wavelength of 1550 nm by prism coupler method and compared with the case of using SiO2 matrix. The use of SiOxNy matrix provides an effective way of controlling the mode confinement while maintaining or even enhancing the surface plasmon resonance properties.

Ultraviolet curable coating solution was prepared with poly(ethylene glycol) acrylate oligomer and various mono and multi-functional acrylate monomers. The optical properties of UV cured coating layer on PET film with acrylate coating solution containing metal oxides, such as fumed silica and alumina, were also investigated to reduce light reflection on films. Poly(ethylene glycol) diacrylate which has 575 of average molecular weight was used as oligomer acrylate, and pentaerythritol triacrylate and dipentaerythritolpenta-/hexa acrylate were used as multi-functional acrylate monomers. Also, butyl acrylate was used to improve the adhesion as well as to reduce glass transition temperature to give a better flexability. 1-hydroxy cyclohexyl phenyl ketone was used as photoinitiator. We found out the metal oxides in acrylate coating solution showed a homogeneous dispersion from energy dispersive spectroscopy data. Transmittance and light reflection of coated PET film was measured with UV/vis spectrometer and gloss meter, respectively. When 1.00 g of both metal oxides was added into coating solution, the transmittance and the glossiness were reduced from 90% to 30% and from 190 GU to 35 GU, respectively. However, adding up to 1.00 g of the metal oxide into coating solution did not affect on the hardness of coating layer and adhesion between coated layer and PET film. Conclusively, we can control transmittance and light reflection of coated film by adjusting the amounts of metal oxide in coating solution.

Field sequential 액정 디스플레이(FSLCD)는 컬러필터를 사용하지 않아 높은 투과율 특성을 보이고 광 원으로 LED를 사용함으로써 색재현성이 매우 우수하다. 하지만 FSLCD(60Hz 구동)를 실현하기 위해서는 액정의 응답속도가 5ms이하로 고속응답 특성을 보여야 한다. 따라서 본 논문에서는 고속응답 ECB(electrically controlled birefringence) 셀의 최적 구조를 연구하여 5ms 이하의 응답시간을 얻었다. 그리고 ECB 모드에서 높은 구동전압과 시야각을 개선하기 위해 필름 보상을 연구하였다. 판상형 액정필름(discotic film)과 TAC(triacetyl cellulose) 필름의 위상차 값을 최적화함으로써 구동전압을 5V로 낮추고 상하좌우에서 160° 이상(CR>10:1)의 시야각을 실현하였다.

Taguchi methodology has been applied to get an idea about the parameters related to the chemical vapour deposition technique, which influences the formation of semiconducting carbon thin film of a desired band gap. L9 orthogonal array was used for this purpose. The analysis based on Taguchi methodology suggests that amongst the parameters selected, the temperature of pyrolysis significantly controls the magnitude of band gap (46%). Sintering time has a small influence (30%) on the band gap formation and other factors have almost no influence on the band gap formation. Moreover this analysis suggests that lower temperature of pyrolysis (≤ 750℃) and lower time of sintering (≤ 1 h) should be preferred to get carbon thin film with the desired band gap of 1.2eV.

HVPE(hydride vapor phase epitaxy)법으로 (111) MgAl2O4기판 위에 10~240μm두께의 GaN를 성장하고, GaN의 두께에 따 광학적 성질을 조사하였다. MgAl2O4기판 위에 성장된 GaN의 PL 특성은 결정성장온도에서 기판으로부터 Mg이 out-diffusion하여 auto-doping 됨으로써 불순물이 첨가된 GaN의 PL 특성을 나타내었다. 10K의 온도데서 측정된 PL 스펙트럼은 자유여기자와 속박여기자의 재결합천이에 의한 피크들과 불순물과 관련된 도너-억셉터 쌍 사이의 재결합 및 이의 포논 복제에 의한 발광으로 구성되었으며, 깊은 준위로부터의 발광은 나타나지 않았다. 중성 도너에 속박된 여기자 발광 에너지와 라만 E2모드 주파수는 GaN의 두께가 증가함에 따라 지수 함수적으로 감소하였으며, GaN 내의 잔류 응력에 대하여 라만 E2 모드 주파수는δΩ=3.93σ(cm-1/GPa)의 관계로 변화하였다.