In this study, two alignment methods were used to create a Fringe-Field Switching (FFS) mode liquid crystal device using an organic thin film (polyimide: PI) as an alignment layer. In addition, the electro-optical (EO) characteristics of the liquid crystal device manufactured in this way were investigated to evaluate the feasibility of mass production application of the technology. In general, the photo-alignment method using unpolarized ultraviolet rays can obtain a relatively low pretilt angle, so a liquid crystal device in FFS mode, which is a driving mode of the liquid crystal device that reflects the characteristics of liquid crystal alignment, was manufactured, and the liquid crystal has a high reactivity with the alignment film. Considering this, nematic liquid crystal (NLC) was used. In addition, in order to improve the misalignment, it was observed whether more stable orientation occurred by irradiating ultraviolet rays for an additional 1 to 3 hours in the aligned state. As a result of the experiment, it was found that NLC alignment occurs through a photodecomposition reaction caused by unpolarized UV irradiation oblique to the PI surface. In addition to the existing orientation method, UV irradiation was used to achieve a more stable orientation state and stable V-T curve and response characteristics. With liquid crystal alignment completed, more stable orientation characteristics and EO characteristics at the mass production level were obtained through additional UV irradiation for 3 hours. This method can further stabilize the orientation stability caused by existing UV irradiation through an additional process.

We investigated the cause of liquid crystal alignment when an ion beam is irradiated to the liquid crystal(LC) alignment film for liquid crystal alignment. We investigated liquid crystal alignment in response to changes in ion beam (IB) incident angle and electro-optical (EO) properties of twisted nematic (TN)-liquid crystal displays (LCDs) on polyimide (PI) surface. X-ray photoelectron spectroscopy(XPS) analysis showed that the C=O chemical bond strength decreased with changes in the IB incident angle, while the C-O chemical bond strength increased. Therefore, it was found that the dipole-dipole interaction between C-O chemical bonds and LC molecules has a chemical ordering effect. Good and uniform alignment of nematic LC was observed on the liquid crystal alignment layer surface by IB irradiation, and good EO properties of IB aligned TN-LCD were achieved on the liquid crystal alignment layer surface.

Using UV nanoimprint lithography(UV-NIL), 1-dimensional(1-D) pattern structures were fabricated on a hybrid mixture thin film of lanthanum oxide and a UV-curable resin. 1-D pattern on a wafer fabricated by the laser interference lithography was transferred to polydimethylsiloxane and this is used as a mold of UV-NIL process. Conducting an X-ray photoelectron spectroscopy, C 1s and La 3d spectra were analyzed, and it was confirmed that hybrid thin film was successfully deposited on glass substrate. Also, transferred pattern structure was observed by using an atomic force microscopy. Through this, it was revealed that agglomerations between 1-D pattern were increased as UV irradiation time increased and this phenomenon disrupted the quality of NIL process. Additionally, liquid crystal(LC) cells with patterned hybrid thin films were fabricated and LC alignment performances were investigated. Using the polarizing optical microscopy and the crystal rotation method, LC alignment state and pretilt angles were observed. Consequently, the uniform homogeneous LC alignment was achieved at UV irradiation time of 1min and 3min where high resolution pattern transfer was observed.

Using lanthanum zinc oxide (LZO) film with the ion-beam irradiation, uniform and homogeneous liquid crystal (LC) alignment was achieved. To fabricate the LZO thin film on glass substrate, solution process was conducted as a deposition method. Cross-polarized optical microscopy (POM) and the crystal rotation method reveal the state of LC alignment on the ion-beam irradiated LZO film. Between orthogonally placed polarizers, POM image showed constant black color with regular transmittance. Furthermore, collected incidence angle versus transmittance curve from the crystal rotation method revealed that the LC molecules on the ion-beam irradiated LZO film were aligned homogeneously. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were conducted to reveal the relationship between the ion-beam irradiation and the LC alignment. The ion-beam irradiation changed the LZO film surface to rougher than before by etching effect. Numerical roughness values from AFM analysis supported this phenomenon specifically. XPS analysis showed the chemical composition change due to the ion-beam irradiation by investigation of O 1s, La 3d and Zn 2p spectra. The ion-beam irradiation induced the breakage of chemical bonds in the LZO film surface and this occurred surface chemical anisotropic characteristics for uniform LC alignment.

The ion-beam irradiated lanthanum zinc oxide (LZO) films were conducted as liquid crystal (LC) alignment layer to achieve uniform and homogeneous alignment of LC molecules. Polarized optical microscopy and the pre-tilt angle measurements revealed the alignment characteristics of LC molecules on the LZO film surface. Physical characteristics of the LZO film surface were analyzed by field emission scanning electron microscope and atomic force microscopy. The strong ion-beam irradiation on the LZO film changed surface rougher than before and induced physical anisotropic characteristics. Chemical composition of the LZO film was investigated by X-ray photoelectron spectroscopy and it was revealed that the ion-beam irradiation induced the breakage of the metal-oxide bonds. Due to this, anisotropic dipole moment which related with van der Waals force between LC molecules and alignment layer was induced. Because of this, LC molecules were anchored to the LZO film surface to achieve uniform LC alignment. Collecting the capacitance-voltage curve, residual DC of the LC cell with the LZO films was measured and it was verified that the LC cell with the LZO film had a nearly zero residual DC. Therefore, the ion-beam irradiated LZO film is an efficient method as an LC alignment layer

In this study, we studied the alignment characteristics of liquid crystal on polyimide substrate when irradiated with ion beam in oblique direction on uniformly coated polyimide substrate. The inclined irradiation angle of the ion beam was set to 30 degree, 45 degree and 60 degree and the characteristics were observed for 1 minute and 2 minutes at an ion beam irradiation intensity of 600 to 3,000 eV for each angle. The Alignment of the liquid crystals were observed using a polarized microscope after preparing antiparallel specimens. The pretilt angle of the liquid crystal using the crystal rotation method was measured, and the applicability to actual products was evaluated. Experimental results showed that uniformly aligned liquid crystals could be obtained in samples irradiated at 1 and 2 minutes with an ion beam intensity of 1200 eV or higher when irradiated with 30 degree and 45 degree tilted ion beams. And, at 60 tilted degree, It shows that uniformly aligned liquid crystals could be obtained in samples irradiated at 1 and 2 minutes with an ion beam intensity of 2400 eV or higher. The pretilt angle of the liquid crystal showed the best characteristics when irradiated with ion beam inclined at 45 degrees, and it was confirmed that the pretilt angle was 0.2 to 1.3 degrees, which is usable for horizontally oriented LCD.

In this study, the ion beam irradiation method on organic (polyamic acid and epoxy resin compound) overcoat layer was investigated. The use of ion beam on overcoat organic layer has the potential to replace conventional rubbing process. The traditional alignment layer is made by coating process and 2 times heat treatment on polyamic acid liquid. It requires many times and process steps. However, it is very economic and convenient process substitute polyimide alignment layer for organic overcoat. In order to characterize the LC alignment the polarized microscope image and pretilt angle measurement were investigated. The good LC aligning capabilities treated on the organic overcoat thin film surfaces with ion beam exposure of 45° at above ion beam energy density of 1200 eV were achieved.

Homogeneous liquid crystal (LC) alignment on hafnium strontium oxide (HfSrO) films prepared by sol-gel process via ion-beam (IB) bombardment was investigated. Uniform LC alignment was achieved on the IB-irradiated HfSrO films at IB intensity of 1.8 keV. We confirmed the effect of surface morphology on LC alignment using field-emission scanning electron microscope (FE-SEM). In addition, we observed electro-optical characteristics of the twisted-nematic (TN)-LC cells based on HfSrO films to verify the possibility of LC display (LCD) application.

We present the structural, optical, and electrical properties of amorphous silicon suboxide (a-SiOx) films grown on indium tin oxide glass substrates with a radio frequency magnetron technique from a polycrystalline silicon oxide target using ambient Ar. For different substrate-target distances (d = 8 cm and 10 cm), the deposition temperature effects were systematically studied. For d = 8cm, oxygen content in a-SiOx decreased with dissociation of oxygen onto the silicon oxide matrix; temperature increased due to enlargement of kinetic energy. For d = 10 cm, however, the oxygen content had a minimum between 150˚ and 200˚. Using simple optical measurements, we can predict a preferred orientation of liquid crystal molecules on a-SiOx thin film. At higher oxygen content (x > 1.6), liquid crystal molecules on an inorganic liquid crystal alignment layer of a-SiOx showed homogeneous alignment; however, in the lower case (x< 1.6), liquid crystals showed homeotropic alignment.

강유전성 액정 분자 배향을 위해 열방성 고분자 액정물질을 배향막으로 사용하고 그표면 morphology를 AFM(Atomic Forced Microscope)으로 관찰한 결과 잘 배향된 sample cell에서도 microgroove 구조가 나타나지 않았음을 관찰하였다. 잘 배향된 sample cell 23:1의 contrast ratio를 보이면서 memory 효과를 나타내었다. 또한 20V의 AC field로 안정화시키자 전형적인 stripe-shaped 무늬가 나타났다.