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비정질 하프늄인듐징크옥사이드 산화물 반도체의 공정 파워에 따른 트랜지스터의 전기적 특성 연구
유동윤,정유진,김도형,주병권,이상렬,Yoo, Dong-Youn,Chong, Eu-Gene,Kim, Do-Hyung,Ju, Byeong-Kwon,Lee, Sang-Yeol 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.8
The dependency of sputtering power on the electrical performances in amorphous HIZO-TFT (hafnium-indium-zinc-oxide thin film transistors) has been investigated. The HIZO channel layers were prepared by using radio frequency (RF) magnetron sputtering method with different sputtering power at room temperature. TOF-SIMS (time of flight secondary ion mass spectrometry) was performed to confirm doping of hafnium atom in IZO film. The field effect mobility (${\mu}FE$) increased and threshold voltage ($V_{th}$) shifted to negative direction with increasing sputtering power. This result can be attributed to the high energy particles knocking-out oxygen atoms. As a result, oxygen vacancies generated in HIZO channel layer with increasing sputtering power resulted in negative shift in Vth and increase in on-current.
레이저 멀티 펄스 중첩과 회절광학소자를 이용한 숨쉬는 필름 고속 가공 기술
유동윤,최훈국,손익부,노영철,이용탁,김영재,김영한,강호민,노지환,Yoo, Dongyoon,Choi, Hun-Kook,Sohn, Ik-Bu,Noh, Young-Chul,Lee, Yong-Tak,Kim, Young-Jae,Kim, Young-Han,Kang, Ho-Min,Noh, Jihwan 한국레이저가공학회 2014 한국레이저가공학회지 Vol.17 No.3
In this paper, we studied a machining method using a diffractive beam splitter (DBS) and multi- pulse repeated radiation for breathable film. We fabricated micro-grooves on polypropylene (PP) films using multi-pulse radiation and one-shot radiation (radiating pulses at once) and a DBS. In the result, width and depth of the PP film using multi-pulse repeated radiation were more precisely controllable. Therefore, this method can be applicable to in manufacturing breathable film precisely at a high speed.
CO<sub>2</sub> 레이저를 이용한 음각 원뿔 구조 광섬유 팁 가공 최적화 연구
유동윤,최훈국,손익부,노영철,정덕,김영섭,이호,김창환,Yoo, Dongyoon,Choi, Hun-Kook,Sohn, Ik-Bu,Noh, Young-Chul,Jung, Deok,Kim, Young-Sup,Lee, Ho,Kim, Chang-Hwan 한국레이저가공학회 2015 한국레이저가공학회지 Vol.18 No.3
A helical fabricating method using $CO_2$ laser was utilized for producing cone-shaped structure on a silica substrate. Output power and the number of scanning radiation were modified in order to control the structure. The experiment shows that the depth and width of cone-shape were increased with higher output power of the laser and the number of scanning. We demonstrate fabrication of multidirectional side-firing optical fiber with diameter of 440 um using the $CO_2$ laser fabrication technique.
유동윤,최훈국,손익부,노영철,신중원,Yoo, Dongyoon,Choi, Hun-Kook,Sohn, Ik-Bu,Noh, Young-Chul,Shin, Jung-Won 한국레이저가공학회 2015 한국레이저가공학회지 Vol.18 No.1
In this paper, controlling shape of optical fiber tip for endoscope was investigated for eliminating blind spot. The blind spot of endoscope is generated by divergence angle of optical fiber, so it is easy to generate blind spot when tightly focusing. In order to eliminate this region, fiber tip is necessary to be controlled as convex or concave. Illumination simulation of convex and concave type of fiber tip in the endoscope was in progress, so the distance of non- blind region was investigated in each case. As well as the simulation, the tip was fabricated as concave shape by UV laser machining. Then the beam radiation was measured to observe the blind region. The result showed that controlling the fiber tip as convex or concave shape makes the narrow blind region of illumination in endoscope.
Ultraprecision Machining-based Micro-Hybrid Lens Design for Micro Scanning Devices
유동윤,이선규,이동호 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.4
This paper presents design of a refractive-diffractive hybrid lens for use in micro optical scanning systems. To achieve the target focallength with minimized aberration, the refractive lens was optimally designed with consideration of reducing transverse ray aberration. The diffractive efficiency was calculated in terms of depth and period of the Fresnel pattern via rigorous coupled wave-analysis(RCWA). The geometry of the V-shaped diamond tools limits the depth of Fresnel edge of the diffractive lens due to the interference,which eventually determines the whole size of the lens. In this study, two types of hybrid lenses for micro scanning system werecompared and designed in consideration of optical performance and machining limit. Therefore, the designed diffractive lens wasoptimized for 300 μm focal length with minimum aberration. The depth of Fresnel edge and the diameter was determined to be 0.94μm and 423.4 μm within the machining limit, respectively. The lens base mold was fabricated using a 5-axis ultraprecision machine,and the lens was imprinted through a hot embossing process. The measured focal length and the calculated NA are 336 μm and 0.63respectively. Lastly, Imaging tests and diffractive efficiency are measured to evaluate the optical performance of the micro-hybrid lens.