Uniform Liquid Crystal Alignment Properties on Ion-Beam Irradiated Indium Zinc Oxide Films with Stable Electro-Optical Performances

오병윤 대한전기학회 2019 전기학회논문지 P Vol.68 No.3

The uniform liquid crystal (LC) molecules alignment was successfully achieved by using ion-beam irradiated indium zinc oxide (IZO) films. Conducting the solution process as a film deposition method, the IZO film was deposited on the glass substrate and ion-beam with various energy was irradiated on the IZO film. To verify the LC alignment properties, anti-parallel cell was fabricated and polarizing optical microscope was used. Field emission scanning electron microscope was adopted to observe the surface morphology of the IZO Film. Furthermore, X-ray photoelectron spectroscopy was used to investigate the chemical composition change as ion-beam energy increased. The strong ion-beam irradiation induced the breakage of metal oxide bonds on the surface and this increased the surface anisotropic characteristics which greatly affected on the LC alignment. Finally, electro-optical performance of the twisted-nematic cell was measured.

Solution-Derived Hafnium Lanthanum Oxide Films Prepared Using Ion-Beam Irradiation and Their Applications as Alignment Layers for Twisted-Nematic Liquid Crystal Displays

오병윤 한국전기전자재료학회 2016 Transactions on Electrical and Electronic Material Vol.17 No.6

We present the alignment characteristics of LC (liquid crystal) molecules on solution-derived HLO (hafniumlanthanum oxide) films fabricated using IB (ion-beam) irradiation. We then demonstrated that LC molecules can behomogeneously and uniformly aligned on the HLO film irradiated at an IB incident energy of 1.2 keV. Physicochemicalanalysis methods such as atomic force microscopy and X-ray photoelectron spectroscopy were used to verify theLC alignment mechanism on the IB-irradiated HLO film. In addition, the electro-optical performance of a TN(twisted-nematic) cell fabricated using the IB-irradiated HLO film exhibited characteristics superior to those of theconventional TN cell fabricated using a rubbed polyimide layer.

Fabrication of Aligned Nano Patterns on HfZnO based on the Imprinting Method for Liquid Crystal Display

오병윤 한국기계기술학회 2019 한국기계기술학회지 Vol.21 No.3

We demonstrate convenient alignment technologies using imprinting lithography with sol-gel process. The aligned nano pattern is fabricated on a silicon wafer by laser interference lithography. For conformal imprinting process, aligned nano pattern was transferred onto the polydimethylsiloxane (PDMS). Using a PDMS sheet with aligned nano pattern, aligned nano pattern was created onto the sol-gel driven hafnium zinc oxide by imprinting lithography. The process was conducted at annealing temperatures of 150 °C. The obtained pattern on the HfZnO film acted as a guide for aligning liquid crystal (LC) molecules. The geometric restriction induced by aligned pattern leads to LC alignment along to the aligned nano pattern. The combination of imprint lithography and solution-processed inorganic materials proved good alternative of LC alignment technique.

투명전극용 Al - doped ZnO film의 전기적 특성

오병윤,명재민 한국진공학회 2004 한국진공학회 학술발표회초록집 Vol.- No.-

임프린팅법을 이용한 YSnO 박막의 표면 이방성 획득과 액정 배향 특성 연구

오병윤 한국전기전자재료학회 2020 전기전자재료학회논문지 Vol.33 No.1

We investigated a solution-driven Yttrium Tin Oxide (YSnO) film that was imprinted using a parallel nanostructure as a liquid crystal (LC) alignment layer. The imprinting process was conducted at the annealing temperature of 100℃. To evaluate the effect of this process, we conducted surface analyses including atomic force microscopy (AFM). During imprinting, the surface roughness was reduced, and anisotropic characteristics were observed. Planar LC alignment was observed at a pretilt angle of 0.22° on YSnO film. Surface anisotropy induced by imprinting method forces LC to align along the direction of the parallel nanostructure, which is an alternative to conventional polyimide treated using a rubbing process. 본 논문에서는 임프린팅 법을 이용하여 Yttrium Tin Oxide (YSnO) 박막 위 표면 이방성을 획득하고, 액정 배향 막으로 사용하여 액정 배향 특성을 연구하였다. 액정의 프리틸트 각은 0.22°의 수평배향 특성을 보여주었다. 표면 이방특성을 확인하기 위하여 Atomic force microscopy (AFM) 으로 YSnO 박막 표면의 형상을 관측하였다. 표면 이방성에 의하여 정렬된 액정 분자는 균일한 액정 배향특성을 보여주었다. 임프린팅 법과 용액 공정을 통하여 기존의 러빙법을 대체하는 대면적 공정이 가능한 배향 막을 제작 할 수 있었다.

Solution-Derived Amorphous Yttrium Gallium Oxide Thin Films for Liquid Crystal Alignment Layers

오병윤 한국전기전자재료학회 2016 Transactions on Electrical and Electronic Material Vol.17 No.2

We demonstrated an alternative electrically controlled birefringence liquid crystal (ECB-LC) system with ion beam (IB)-irradiated yttrium gallium oxide (YGaO) alignment films using a sol-gel process. The surface roughness of the films was dependent on the annealing temperature; aggregated particles on surface were observed at lower annealing temperatures, whereas a smooth surface could be obtained with higher annealing temperatures. Higher transmittance in the visible region was observed at higher annealing temperatures. The film had an amorphous crystallographic state irrespective of the annealing temperature. Furthermore, ECB-LC cell with our IB-irradiated YGaO film yielded faster response time when compared to ECB-LC cell with rubbed polyimide. Considering the fast response time and high transmittance, the IB-irradiated YGaO-base LC system is a powerful alternative application for the liquid crystal display industry.

Transparent conductive ZnO:Al films grown by atomic layer deposition for Si-wire-based solar cells

오병윤,김정환,한진우,서대식,장환수,최호진,백성호,김재현,허기석,김태원,김광영 한국물리학회 2012 Current Applied Physics Vol.12 No.1

Structural, electrical, and optical properties of atomic layer-controlled Al-doped ZnO (ZnO:Al) films grown by atomic layer deposition (ALD) on glass substrates were characterized at various growth temperatures for use as transparent electrodes. The Al atomic content in ZnO:Al films increased due to the reduced ZnO film growth rate with increasing temperature. The preferred orientation of ZnO:Al films was changed, and the optimum condition for best crystallinity was identified by varying the growth temperature. Furthermore, the carrier concentration of free electron was increased by substituting the Zn sites with Al atoms in the crystal, resulting from monolayer growth based on alternate self-limiting surface chemical reactions. The electrical resistivity of ZnO:Al film grown by ALD at 225 ℃ reached the lowest value of 8.45 ×10-4 U cm, with a carrier mobility of 9.00 cm2 V-1 s-1 and optical transmittance of w93%. This result demonstrates that ZnO:Al films grown by ALD possess excellent potential for applications in electronic devices and displays as transparent electrodes and surface passivation layers. Structural, electrical, and optical properties of atomic layer-controlled Al-doped ZnO (ZnO:Al) films grown by atomic layer deposition (ALD) on glass substrates were characterized at various growth temperatures for use as transparent electrodes. The Al atomic content in ZnO:Al films increased due to the reduced ZnO film growth rate with increasing temperature. The preferred orientation of ZnO:Al films was changed, and the optimum condition for best crystallinity was identified by varying the growth temperature. Furthermore, the carrier concentration of free electron was increased by substituting the Zn sites with Al atoms in the crystal, resulting from monolayer growth based on alternate self-limiting surface chemical reactions. The electrical resistivity of ZnO:Al film grown by ALD at 225 ℃ reached the lowest value of 8.45 ×10-4 U cm, with a carrier mobility of 9.00 cm2 V-1 s-1 and optical transmittance of w93%. This result demonstrates that ZnO:Al films grown by ALD possess excellent potential for applications in electronic devices and displays as transparent electrodes and surface passivation layers.

[취임사] “주민자치가 실현되도록 함께 뛰겠다”

오병윤 한국자치학회 2015 월간 주민자치 Vol.39 No.-

무기막 NiOx의 정렬 패턴 전사를 이용한 액정의 배향 특성 연구

오병윤,Oh, Byeong-Yun 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.5

We demonstrate an alignment technology using an imprinting process on an inorganic NiOx film. The aligned nanopattern was fabricated on a silicon wafer by laser interference lithography. The aligned nano pattern was then imprinted onto the sol-gel driven NiOx film using an imprinting process at an annealing temperature of $150^{\circ}C$. After the imprinting process, parallel grooves had been formed on the NiOx film. Atomic force microscopy and water contact angle measurements were performed to confirm the parallel groove on the NiOx film. The grooves caused liquid crystal alignment through geometric restriction, similar to grooves formed by the rubbing process on polyimide. The liquid crystal cell exhibited a pretilt angle of $0.2^{\circ}$, which demonstrated homogeneous alignment.

이온빔 조사된 용액 공정 기반 LaZnO 박막 위 액정 분자의 수평 배향 특성

오병윤,Oh, Byeong-Yun 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.5

The alignment characteristics of liquid crystal (LC) molecules on a solution-derived lanthanum zinc oxide (LZO) film under ion-beam irradiation were demonstrated. Using the solution process, an LZO film was fabricated on the glass substrate and cured at $100^{\circ}C$. Afterwards, ion-beam irradiation was performed following the LC alignment method. Using this film, an LC cell was fabricated and the characteristics of the LC alignment were verified. Cross polarizing microscopy and the crystal rotation method were used to investigate the alignment state of the LC molecules on the LZO films. Furthermore, field emission scanning electron microscopy and X-ray photoelectron spectroscopy were used to explore the effect of the ion-beam irradiation on the LZO film. Through these, it was confirmed that the ion-beam irradiation induced surface modification, which demonstrated anisotropic physical and chemical surface characteristics. Due to this, uniform LC alignment was achieved. Finally, the residual DC and anchoring energy of the LC cell based on the LZO films were measured using a capacitance-voltage curve.