박막에서의 상형성 및 상전이의 예측

곽준섭(Joon Seop Kwak),최정동(Jeong Dong Choi),지응준(Eung Joon Chi),백홍구(Hong Koo Baik) 대한금속재료학회 1993 大韓金屬學會會報 Vol.6 No.2

무분극 a-plane 질화물계 발광다이오드에서 SiO₂ 전류 제한 층을 통한 발광 효율 증가

황성주,곽준섭,Hwang, Seong Joo,Kwak, Joon Seop 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.3

In this study, we investigate the $SiO_2$ current blocking layer (CBL) to improve light output power efficiency in nonpolar a-plane (11-20) GaN LEDs on a r-plane sapphire substrate. The $SiO_2$ CBL was produced under the p-pad layer using plasma enhanced chemical vapor deposition (PECVD). The results show that nonpolar GaN LED light output power with the $SiO_2$ CBL is considerably enhanced compared without the $SiO_2$ CBL. This can be attributed to reduced light absorption at the p-pad due to current blocking to the active layer by the $SiO_2$ CBL.

Light Intensity 및 명암비 향상을 위한 마이크로 LED의 사파이어 기판 형상 변화 연구

차유정,곽준섭,Cha, Yu-Jung,Kwak, Joon Seop 한국전기전자재료학회 2021 전기전자재료학회논문지 Vol.34 No.1

Micro-LEDs can be applied to various parts of a product. However, it has disadvantages compared to general LEDs in large displays such as low efficiency, intensity, and contrast ratio, among others, owing to their short history of study. The simulations were carried out using ray-tracing software to investigate the change in light intensity and light distribution according to pattern shapes on the sapphire substrate of the flip-chip micro-LED (FC μ-LED) array. Three patterns-concave square patterns, convex square patterns, and Ag coated convex patterns-which existed on the opposite side of FC μ-LEDs (115 ㎛ × 115 ㎛) array, were applied. The intensity of FC μ-LEDs on the center of the receivers depends on the pattern depth with shape. The concave square patterns having FC μ-LEDs arrays show that decreasing intensity as the patterns depth. On the contrary, the convex square patterns having FC μ-LEDs arrays shows that increasing intensity as the patterns depth. In addition, the highest intensity shows that FC μ-LEDs having Ag-coated convex patterns on the opposite side of sapphire lead to a reduction in light crosstalk owing to the Ag film.

Erratum to : 청색 마이크로 LED의 광 추출 효율에 미치는 칩 크기 의존성 연구

박현정,차유정,곽준섭,Park, Hyun Jung,Cha, Yu-Jung,Kwak, Joon Seop 한국전기전자재료학회 2020 전기전자재료학회논문지 Vol.33 No.2

HDU를 이용한 적외선 LED CCTV의 LED 수명 향상을 위한 방열설계에 관한 연구

이동규,김형진,곽준섭,Lee, Dong Kyu,Kim, Hyeong Jin,Kwak, Joon Seop 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.10

In this paper, thermal analysis of HDU (Heat Dissipation Unit) for infrared CCTV is performed by using SolidWorks Simulation (Thermal analysis) package, in order to change the part materials and HDU shape is optimized. Furthermore, HDU disperses the aggregated heat around the LED inside the housing. The junction temperature of infrared LED checked by HDU check was $65.83^{\circ}C$, $42.02^{\circ}C$, respectively. In addition, the Thermoelement by changing the shape of the HDU was possibly designed and equipped with. Comparison with simulation and prototype measurement results, without HDU model was $65.83^{\circ}C$, $61.99^{\circ}C$, respectively. In addition to with HDU model was $42.02^{\circ}C$, $39.01^{\circ}C$, respectively. Only HDU mounted into infrared CCTV is usable in the ordinary house or outdoors. Also HDU with thermal element, fan mounted into infrared CCTV is usable in a blast furnace workplace or high temperature workplace.

투명전자소자를 위한 HfO₂계 투명 MIM 커패시터 특성연구

조영제,이지면,곽준섭,Jo, Young-Je,Lee, Ji-Myon,Kwak, Joon-Seop 한국진공학회 2009 Applied Science and Convergence Technology Vol.18 No.1

The effects of $HfO_2$ film thickness on electrical, optical, and structural properties were investigated. We fabricated ITO/$HfO_2$/ITO metal-insulator- metal (MIM) capacitor using transparent conducting oxide. When $HfO_2$ film thickness increase from 50 nm to 300 nm, dielectric constant of $HfO_2$ was decreased from 20.87 to 9.72. The transparent capacitor shows an overall high performance, such as a dielectric constant about 21 by measuring the ITO/$HfO_2$/ITO capacitor structures and a low leakage current of $2.75{\times}10^{-12}\;A/cm^2$ at +5 V. Transmittance above 80% was observed in visible region. 투명 전자소자의 고유전 $HfO_2$ 절연막을 개발하기 위하여, ITO/$HfO_2$/ITO 금속-절연체-금속 (Metal-Insulator-Metal, MIM) 커패시터 구조를 형성한후 $HfO_2$ 박막의 두께에 따른 전기적, 광학적, 구조적 특성의 변화를 연구하였다. $HfO_2$ 박막의 두께가 50 nm에서 300 nm로 증가함에 따라 유전상수는 20에서 10이하로 감소하였으나, $HfO_2$ 두께가 증가함에 따라 누설전류는 감소하여 200 nm 이상의 두께에서는 $2.7{\times}10^{-12}\;A/cm^2$ 이하의 낮은 누설전류 특성을 나타내었다. ITO/$HfO_2$/ITO MIM 커패시터의 $HfO_2$ 박막의 두께가 50 nm에서 300 nm로 증가함에 따라 투과율은 감소하였으나 300 nm 두께에서도 가시광선 영역에서 80% 이상의 투과율을 나타내어 우수한 투과도 특성을 나타내었다.

두 가지 배광을 갖는 LED 횡단보도 조명장치에 관한 연구

김형진,이동규,곽준섭,Kim, Hyeong Jin,Lee, Dong Kyu,Kwak, Joon Seop 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.9

Recently, LED lighting fixtures for crosswalk become popular in order to recognize the pedestrians at crosswalk, which can enhance the safety of the pedestrian at crosswalk. However, there are several problems related to the LED lighting fixtures for crosswalk, such as a lot of energy consumption due to a constant illumination during night and glaring of pedestrians at the opposite side of crosswalk. In this study, in order to overcome these problems, we have investigated a novel LED lighting fixture for crosswalk, which has two modules with different angles ($60^{\circ}$, $120^{\circ}$). Illuminance of min and max at four-line city street crosswalk shown 50 Lux, 125 Lux, respectively. Illuminance of min and max at eight-line city street crosswalk shown 150 Lux, 200 Lux, respectively. Simulation investigation was optimized design using optical program. Prototype was verified measurement by goniometer system.

광학 시뮬레이션을 이용한 Patterned Sapphire Substrate에 따른 Flip Chip LED의 광 추출 효율 변화에 대한 연구

박현정,이동규,곽준섭,Park, Hyun Jung,Lee, Dong Kyu,Kwak, Joon Seop 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.10

Recently many studies being carried out to increase the light efficiency of LED. The external quantum efficiency of LED, generally the light efficiency, is determined by the internal quantum efficiency and the light extraction efficiency. The internal quantum efficiency of LED was already reached to more than 90%, but the light extraction efficiency is still insufficient compared with the internal quantum efficiency because the total internal reflection is generated in the interface between the LED chip and air. Thus, we studied about flip chip LED with PSS and performed the optical simulation which find more optimized PSS for flip chip LED to increase the light extraction efficiency. Decreasing of the total internal reflection and effect of diffused reflection according to PSS improved the light extraction efficiency. To get more higher the efficiency, we simulated flip chip with PSS that the parameters are arrangement, edge spacing, radius, height and shape of PSS.

루미나리에(Luminarie)용 고출력 LED패키지 배광분포 모델링 및 광학적 특성 분석

조재문,김병일,곽준섭,윤동주,유진열,Cho, Jae-Moon,Kim, Byung-Il,Kwak, Joon-Seop,Yoon, Dong-Joo,Yu, Jin-Yeul 한국광학회 2007 한국광학회지 Vol.18 No.4

기존 필라멘트 방식의 루미나리에용 조명의 단점을 극복하기 위해 필라멘트를 LED로 바꾸기 위한 연구가 활발하게 진행 중이다. 본 연구는 루미나리에용에 적합한 LED패키지 구조를 만들기 위해 ray tracing simulator를 이용해 다양한 구조를 모델링하고 시뮬레이션을 통해 각 구조에서의 배광분포를 측정하였다. 시뮬레이션 결과, LED 패키지의 내부 반사경의 각을 증가시킬수록 배광분포가 두 개의 피크로 갈라지면서 피크간의 각이 점점 커졌다. 또한 외부 반사경 각이 증가함에 따라 양쪽 피크간의 각이 점점 줄어들다가 $50^{\circ}$를 기준으로 다시 증가하였다. 이러한 결과는 LED에서 발생한 빛이 두 개의 반사경에 의하여 반사되는 각도가 달라짐에 의하여 발생함을 알 수 있었다. Ray tracing simulator를 이용하여 구한 LED 패키지 구조의 조건을 적용하여 루미나리에용 LED패키지를 제작하였고 배광분포 측정기를 이용해 광 특성을 측정하였으며 시뮬레이션의 결과와 유사한 특성을 얻었다. Today's research has been focused on changing the light source from filament to LED for luminarie illumination to overcome the shortcoming of a filament. The purpose of this research is to make an appropriate high power LED package structure for luminarie. We simulated radiation patterns of the various structures by the ray tracing simulator (Light Tools), and also analyzed the radiation patterns using an LED test system (OL770). As we increased an inner reflector angle, the radiation pattern split into two peaks and the angle between two peaks became larger. In addition, when we increased an outer reflector angle, the angle between side peaks gradually decreased, while it increased again when the angle reach $50^{\circ}$. These results could be understood from the ray tracing of the light reflected from two reflectors. We made the high power LED package for luminarie on the condition of the optimized structure which was made by ray tracing simulation results, and we measured the radiation patterns by using an LED test system, and these results were well matched to the simulation results.

Ion Beam Mixing에 의한 Co / Si계의 상 형성 및 전이에 관한 연구

최정동(Jeong-Dong Choi),곽준섭(Joon-Seop Kwak),백홍구(Hong-Koo Baik),황정남(Chung-Nam Whang) 한국진공학회(ASCT) 1995 Applied Science and Convergence Technology Vol.4 No.1

본 연구에서는 Co/Si계에 대한 이온선 혼합실험을 온도와 이온선량을 변수로 하여 실시하였고, Co/Si계에 대한 상형성 과정을 금속/Si계에 대한 이온선 혼합시의 비정질상 및 결정상 형성예측 모델(ADF Model)과 초기 결정상 예측 모델(PDF Model)을 이용하여 해석하였다. 이온선 혼합은 80 KeV 가속기를 이용하여 상온~400℃의 온도 범위에서 1.0×10^(15)Ar^+㎠~2.0×10^(16)Ar^+/㎠의 이온선량을 변화시키면서 실험하였으며 상 분석은 투과전자현미경(TEM)과 X선 회절 분석을 이용하였다. Co/Si계에서 이온선 혼합시 형성되는 초기 결정상은 Co₂Si이며 이온선량의 증가에 따라 CoSi로 상전이 하였다. 이러한 실험 결과는 비정질상 및 결정상 형성 예측 모델(ADF model)과 초기 결정상 예측 모델(PDF model)의 예측 결과와 매우 잘 일치하고 있다. 이상의 연구 결과로부터 ADF 모델과 PDF 모델을 이용하여 박막에서 형성되는 상을 보다 정확히 예측할 수 있음을 알 수 있었다. In present study, ion beam mixing was carried out at various temperatures with different doses in Co/Si system and the phase evolution induced by ion beam mixing was interpreted with amorphization determination factor(ADF) model and phase determination factor(PDF) model. Ion beam mixing was performed in R.T.~400℃ range using 80KeV accelerator with 1.0×10^(15)Ar^+/㎠~2.0×10^(16)Ar^+/㎠ and the phase characterization was analyzed by transmission electron microscopy and glancing incidence X-ray diffraction. The first phase during ion beam mixing was Co₂Si in Co/Si system and it transformed to CoSi with increasing ion dose. These experimental results fairly well corresponded to the predictions of ADF and PDF models. In conclusion, it can be well applied of ADF and PDF models to predict amorphization reaction and first phase formation in binary thin films.