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유도결합 플라즈마 조건에 따른 Nylon/spandex 혼방섬유의 표면손상 및 실리콘 오일 제거 영향
정탁,신중욱,지영연,김상식,Jeong, Tak,Sin, Jung-Uk,Ji, Young-Yeon,Kim, Sang-Sik 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.5
Plasma treatment has been increasingly used for surface cleaning and polymerization in many industries. In this study, inductively coupled plasma (ICP) treatment is used to remove organic residuals, mainly silicon oils from nylon66/spandex fabrics. The removed silicone oils from the fabrics are characterized using scanning electron microscopy. EDX and XPS are also used for determination of the change in elements on the fiber surface. It is shown that lower energy plasma treatment with longer plasma operating time Performs the best in removal of the silicon oils from the fabrics. On the contrary, increasing the energy input enhances the ion damage and yields high heat loads on the fiber surface. Meanwhile, ICP treatment for removing silicon oils is almost same as wet chemical cleaning method in terms of efficiency.
Via-hole 구조의 n-접합을 갖는 수직형 발광 다이오드 전극 설계에 관한 연구
박준범,박형조,정탁,강성주,하준석,임시종,Park, Jun-Beom,Park, Hyung-Jo,Jeong, Tak,Kang, Sung-Ju,Ha, Jun-Seok,Leem, See-Jong 한국마이크로전자및패키징학회 2015 마이크로전자 및 패키징학회지 Vol.22 No.4
Recently, light emitting diodes (LEDs) have been studied to improve their efficiencies for the uses in various fields. Particularly in the aspect of chip structure, via hole type vertical LED chip is developed for improvement of light output power, and heat dissipations. However, current vertical type LEDs have still drawback, which is current concentration around the n-contact holes. In this research, to solve this phenomenon, we introduced isolation layer under n-contact electrodes. With this sub-electrode, even though the active area was decreased by about 2.7% compared with conventional via-hole type vertical LED, we could decrease the forward voltage by 0.2 V and wall-plug efficiency was improved approximately 4.2%. This is owing to uniform current flow through the area of n-contact. 최근 Light Emitting Diode (LED)의 효율을 높이기 위한 연구가 활발히 진행 되고 있다. 특히 소자 측면에서는 수평형 LED, 수직형 LED, via-hole 구조의 수직형 LED 등의 다양한 구조가 제시되었다. 본 논문에서는 시뮬레이션을 통해 via-hole 구조의 수직형 LED의 새로운 전극 디자인을 제시하였다. 기존 Via-hole 구조의 수직형 LED의 n-contact hole 주변에 전류가 밀집되는 문제점을 해결하면서 유효 발광면적을 극대화 시켜 소자 전체에 균일한 전류를 주입할 수 있는 소자 디자인에 대해 평가하였다. 시뮬레이션 결과를 바탕으로 최적의 전극 디자인을 실제 디바이스로 제작하여 기존의 via-hole 구조의 수직형 LED와 비교 분석하였다. 최적화된 디자인이 적용된 via hole type 수직형 LED의 경우 기존 디자인에 비해 350 mA 주입시 약 0.2 V의 Forward Voltage 감소하였지만 광 출력은 비슷하여 최종적으로 4.2%의 WPE (Wall plug efficiency)가 향상됨을 보였다.
자외선 수직형 LED 제작을 위한 Indium Tin Oxide 기반 반사전극
정기창,이인우,정탁,백종협,하준석,Jung, Ki-Chang,Lee, Inwoo,Jeong, Tak,Baek, Jong Hyeob,Ha, Jun-Seok 한국재료학회 2013 한국재료학회지 Vol.23 No.3
In this paper, we studied a p-type reflector based on indium tin oxide (ITO) for vertical-type ultraviolet light-emitting diodes (UV LEDs). We investigated the reflectance properties with different deposition methods. An ITO layer with a thickness of 50 nm was deposited by two different methods, sputtering and e-beam evaporation. From the measurement of the optical reflection, we obtained 70% reflectance at a wavelength of 382 nm by means of sputtering, while only 30% reflectance resulted when using the e-beam evaporation method. Also, the light output power of a $1mm{\times}1mm$ vertical chip created with the sputtering method recorded a twofold increase over a chip created with e-beam evaporation method. From the measurement of the root mean square (RMS), we obtained a RMS value 1.3 nm for the ITO layer using the sputtering method, while this value was 5.6 nm for the ITO layer when using the e-beam evaporation method. These decreases in the reflectance and light output power when using the e-beam evaporation method are thought to stem from the rough surface morphology of the ITO layer, which leads to diffused reflection and the absorption of light. However, the turn-on voltage and operation voltage of the two samples showed identical results of 2.42 V and 3.5 V, respectively. Given these results, we conclude that the two ITO layers created by different deposition methods showed no differences in the electric properties of the ohmic contact and series resistance.
광출력 3W급 GaN 기반의 수직형 발광다이오드 단일 칩 N-전극 최적화를 위한 연구
최원식 ( Won Sik Choi ),정탁 ( Tak Jeong ),박형조 ( Hyung Jo Park ),임시종 ( See Jong Leem ) 대한금속재료학회(구 대한금속학회) 2015 대한금속·재료학회지 Vol.53 No.4
N-type electrode optimization of GaN-based vertical light-emitting diode (VLED) single chip with 3-W output power is reported. The various n-type electrode designs were proposed and simulated to optimize the output power and operating voltage. In addition, the LED chip with optimized n-type electrode design was fabricated in the form of a vertical-injection structure with chip dimensions of 2×2 mm2. Electrical and optical characteristics of the VLED were measured up to 3 A injection current under pulsed operation condition. Output power and forward voltage at 2.7 A were obtained to be 3.1 W and 3.67 V, respectively. (Received May 21, 2014)
전해 도금을 이용한 높은 접착 특성을 갖는 섬유 기반 웨어러블 디바이스 제작
김형구,노호균,차안나,이민정,박준범,정탁,하준석,Kim, Hyung Gu,Rho, Ho Kyun,Cha, Anna,Lee, Min Jung,Park, Jun-beom,Jeong, Tak,Ha, Jun-Seok 한국마이크로전자및패키징학회 2021 마이크로전자 및 패키징학회지 Vol.28 No.1
In order to produce wearable displays with high adhesion while maintaining flexible characteristics, the adhesive method using electro plating method was carried out. Laser lift-off (LLO) transcription was also used to remove sapphire substrates from LEDs bonded to fibers. Afterwards, the SEM and EDS data of the sample, which conducted the adhesion method using electro plating, confirmed that copper actually grows through the lattice of the fiber fabric to secure the light source and fiber. The adhesion characteristics of copper were checked using Universal testing machine (UTM). After plating adhesion, the characteristics of the LLO transcription process completed and the LED without the transcription process were compared using probe station. The electroluminescence (EL) according to the enhanced current was measured to check the characteristics of the light source after the process. As the current increases, the temperature rises and the bandgap decreases, so it was confirmed that the spectrum shifted. In addition, the change in the electrical characteristics of the samples according to the radius change is confirmed using probe station. The radius strain also had mechanical strength that copper could withstand bending stress, so the Vf variation was measured below 6%. Based on these results, it is expected that it will be applied to batteries, catalysts, and solar cells that require flexibility as well as wearable displays, contributing to the development of wearable devices. 유연한 특성을 유지하면서 높은 접착력을 가진 웨어러블 디스플레이를 제작하기 위하여 전해도금법을 이용한 접착법을 진행하였다. 또한 섬유에 접착된 LED의 사파이어 기판을 제거하기 위하여 LLO 전사법을 이용하였다. 그 후 전해도금을 이용한 접착법을 진행한 샘플의 SEM, EDS 데이터를 통하여 실제로 구리가 섬유직물의 격자사이를 관통하여 성장하며 광원과 섬유를 고정시켜주는 것을 확인하였다. 구리의 접착특성을 확인하기 위하여 Universal testing machine (UTM)을 이용하여 측정하였다. 도금 접착 후 laser lift-off (LLO) 전사공정을 완료한 샘플과 전사공정을 진행하지 않은 LED의 특성을 probe station을 이용하여 비교하였다. 공정 이후의 광원의 특성을 확인하기 위하여 인가 전류에 따른 electroluminescence (EL)을 측정하였다. 전류가 증가할수록 온도가 상승하여 Bandgap이 감소하기 때문에 spectrum이 천이하는 것을 확인하였다. 또한 radius 변화에 따른 샘플의 전기적 특성 변화를 probe station을 이용하여 확인하였다. Radius 변형에도 구리가 bending stress를 견딜 수 있는 기계적 강도를 가지고 있어 Vf 변화는 6% 이하로 측정되었다. 이러한 결과를 토대로 웨어러블 디스플레이 뿐만 아니라 유연성이 필요한 배터리, 촉매, 태양전지 등에 적용되어 웨어러블 디바이스의 발전에 기여할 수 있을 것으로 기대한다.