전자오븐을 이용한 간편하고 연속적인 마이크로파 발생 장치 개발

권기청(Gi-Chung Kwon),김재현(Jayhyun Kim),김정희(Junghee Kim),이효석(Hyo-Suk Yi),전상진(Sang-Jean Jeon),허승희(Songwhe Huh),최원호(W. Choe) 한국진공학회(ASCT) 2000 Applied Science and Convergence Technology Vol.9 No.3

KAIST-TOKAMAK에서 재현성이 좋은 저항가열 플라즈마를 발생시키는데 필요한 전이온화(pre-ionization)에 응용하기 위해 2.45 ㎓ 마그네트론을 사용하여 간편한 마이크로파 발생장치를 개발하였다. 장치에 사용한 마그네트론은 출력 500 W, 주파수 2.45 ㎓이며, 일반적인 가정용 전자오븐(microwave oven)에 사용된다. 기존의 가정용 마그네트론은 음극(cathode)과 양극(anode)사이에 걸리는 고전압이 60 ㎐의 주기를 갖기 때문에 약 16 ㎳ 마다 약 8 ㎳ 동안만 주기적으로 마이크로파를 발생한다. 이 마그네트론을 사용하여 토카막 전이온화에 충분할 정도로 연속적으로 발생되는 마이크로파를 얻기 위해서 음극과 양극사이에 개량된 회로로 리플전압이 작은 DC 고전압(5㎸, 1 A)을 인가하였다. 본 논문에서는 주기적으로 생성ㆍ소멸하는 ECH 플라즈마와 연속적인 ECH 플라즈마를 발생시켜 랑뮈어탐침과 광증배관(PMT)을 이용한 이온 포화전류와 H_α 방출(emission)을 측정하여 마이크로파 발생장치의 특정을 조사하였다. In order to utilize as a pre-ionization means for reproducible ohmic plasma on KAIST-TOKAMAK, a simple, safe, economical and continuous microwave source has been developed using a home kitchen microwave oven. The magnetron used in the study can provide 500 W of power at 2.45 ㎓. A conventional magnetron in a home kitchen microwave oven generates microwave for 8 ㎳ at every 16 ms periodically due to the periodic (60 ㎐) high voltage applied to the magnetron cathote. In order to generate continuous microwave which is suitable for tokamak pre-ionization, the magnetron operation circuit has been modified using a DC high voltage (5 ㎸, 1 A) power supply. It provides high-voltage with small ripple for magnetron cathode bias. Using the developed magnetron system, electron cyclotron resonace heated (ECH) plasmas were produced and the characteristics of the system were studied by diagnosing the ECH plasma using Langmuir probe and H_α emission diagnostics.

전하밀도파 이론으로 결정질 태양전지의 입사각에 따른 단락전류밀도 변화 연구

서일원,구제환,윤명수,조태훈,이원영,조광섭,권기청,Seo, Il Won,Koo, Je Huan,Yun, Myoung Soo,Jo, Tae Hoon,Lee, Won Young,Cho, Guang Sup,Kwon, Gi Chung 한국진공학회 2013 Applied Science and Convergence Technology Vol.22 No.4

광 입사각에 따른 태양전지의 양자효율을 전류의 출력으로 변환시켜 측정하였다. 기존의 태양전지의 원리는 태양전지가 태양광을 받았을 때 전자와 전공으로 분리되어 전류가 흐르게 된다는 것이었다. 그렇지만 저자들 중에 일부가 얼마 전에 태양전지원리를 새롭게 주장한 바 있다. 그 이론은 전하밀도파(charge density wave)들이 고정(pinning) 되었을 때, 이 고정 전위벽(pinning potential barrier)을 태양 광에 의해 넘을 수 있어서 전자 덩어리에 의한 전류 즉 단락전류($I_{SC}$)가 가능하다는 것이었다. 본 실험에서는 태양광의 입사각에 따른 태양전지의 단락전류밀도 ($J_{SC}$)를 측정하여 비교해본 결과 측정값들과 전하밀도파 이론과 매우 일치함을 보인다. We measure solar currents transformed from quantum efficiency as a function of incident angles of solar lights. According to conventional models for solar cells, solar currents can be induced when electrons are separated into electrons and holes in the presence of incident solar lights. On the contrary, solar currents can be possible at the time when pinned charge density waves go beyond the pinning potential barrier under the influence of incident solar beams suggested by some authors. In this experiment, measured solar currents and our theory are in good correspondence to confirm the angle dependence of solar lights.

광 입사각이 BIPV에 적용되는 단결정 또는 비정질 실리콘 태양전지의 양자효율에 미치는 영향

강정욱,손찬희,조광섭,유진혁,김정식,박창균,차성덕,권기청,Kang, Jeong-Wook,Son, Chan-Hee,Cho, Guang-Sup,Yoo, Jin-Hyuk,Kim, Joung-Sik,Park, Chang-Kyun,Cha, Sung-Duk,Kwon, Gi-Chung 한국진공학회 2012 Applied Science and Convergence Technology Vol.21 No.1

건재 일체형 태양광발전(BIPV) 응용을 위해 광 입사각에 따른 태양전지의 변환 효율은 중요하다. 양자효율은 태양전지의 파장별 전자 수집효율을 말하며, 입사각별 양자효율 측정으로 입사각에 따른 태양전지 출력 변화 요인을 분석할 수 있다. 이러한 입사각별 양자효율은 태양전지 종류에 따라 차이를 보인다. 본 연구에서는 가장 많이 쓰이는 벌크형 단결정 실리콘 태양전지와 박막형 비정질 실리콘 태양전지의 입사각별 양자효율을 비교하였다. 그 결과, 단결정 실리콘 태양전지에서는 광 입사각이 증가함에 따라 전 파장영역에서 양자효율이 감소했다. 반면, 비정질 박막 실리콘 태양전지에서는 단파장 영역에서는 결정질 실리콘과 동일하게 감소하였으나, 그 이후의 흡수 영역에서 약 $40^{\circ}$의 입사각까지 증가 또는 일정한 양자효율을 보이다가 이후에 급격히 감소하는 결과를 얻었다. 이는 비정질 박막 실리콘 태양전지에서 입사각이 증가함에 따라 특정 파장 영역에서 산란과 박막 구조의 영향으로 예상된다. 따라서, 태양전지의 구조 및 광학 구조 최적화 등으로 BIPV 적용에 유리한 구조 태양전지 제작이 가능할 것으로 보인다. The conversion efficiency of solar cells depending on incident angle of light is important for building-integrated photovoltaics (BIPV) applications. The quantum efficiency is the ratio of the number of charge carriers collected by the solar cell to the number of photons of a given energy shining on the solar cell. The analysis of angle dependence of quantum efficiencies give more information upon the variation of power output of a solar cell by the incident angle of light. The variations in power output of solar cells with increasing angle of incidence is different for the type of cell structures. In this study we present the results of the quantum efficiency measurement of single-crystalline silicon solar cells and a-Si:H thin-film solar cells with the angle of incidence of light. As a result, as the angle of incidence increases in single-crystalline silicon solar cells, quantum efficiency at all wavelength (300~1,100 nm) of light were reduced. But in case of a-Si:H thin-film solar cells, quantum efficiency was increased or maintained at the angle of incidence from 0 degree to about 40 degrees and dramatically decrease at more than 40 degrees in the range of visible light. This results of quantum efficiency with increasing incident angle were caused by haze and interference effects in thin-film structure. Thus, the structural optimization considering incident angle dependence of solar cells is expected to benefit BIPV.

잔류가스분석기 및 발광 분광 분석법을 통한 중간압력의 NF₃ 플라즈마 실리콘 식각 공정

권희태,김우재,신기원,이환희,이태현,권기청,Kwon, Hee Tae,Kim, Woo Jae,Shin, Gi Won,Lee, Hwan Hee,Lee, Tae Hyun,Kwon, Gi-Chung 한국반도체디스플레이기술학회 2018 반도체디스플레이기술학회지 Vol.17 No.4

$NF_3$ Plasma etching of silicon was conducted by injecting only $NF_3$ gas into reactive ion etching. $NF_3$ Plasma etching was done in intermediate pressure. Silicon etching by $NF_3$ plasma in reactive ion etching was diagnosed through residual gas analyzer and optical emission spectroscopy. In plasma etching, optical emission spectroscopy is generally used to know what kinds of species in plasma. Also, residual gas analyzer is mainly to know the byproducts of etching process. Through experiments, the results of optical emission spectroscopy during silicon etching by $NF_3$ plasma was analyzed with connecting the results of etch rate of silicon and residual gas analyzer. It was confirmed that $NF_3$ plasma etching of silicon in reactive ion etching accords with the characteristic of reactive ion etching.

RIE 표면 텍스쳐링 모양에 따른 결정질 실리콘 태양전지의 영향

박인규,윤명수,현덕환,진법종,최종용,김정식,강형동,권기청,Park, In-Gyu,Yun, Myoung-Soo,Hyun, Deoc-Hwan,Jin, Beop-Jong,Choi, Jong-Yong,Kim, Joung-Sik,Kang, Hyoung-Dong,Kwon, Gi-Chung 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.4

다결정 실리콘 웨이퍼 표면에 대면적 reactive ion etching (RIE) 장비로 표면 텍스쳐를 형성한 뒤 태양전지를 제작하였다. 웨이퍼 표면에 텍스쳐를 형성하는 것은 광학적 손실을 줄이기 위해 일반적으로 사용되는 방법으로 alkaline etching이 사용된다. 그러나 다결정 실리콘 태양전지의 경우 재료의 결정 방향에 따라 식각되는 alkaline etching은 텍스쳐링의 모양을 제어할 수 없어 효과적이지 못하다. 이와 달리 플라즈마 식각방법을 사용하면 표면 텍스쳐의 모양을 효과적으로 제어하여 조금 더 낮은 반사율을 얻을 수 있다. 하지만 텍스쳐 모양 조절로 얻은 낮은 반사율이 항상 높은 변환효율을 얻을 수 있는 것은 아니다. 본 연구에서는 대면적 RIE 공정 조건별로 얻은 태양전지 표면 텍스쳐의 모양에 따라 각각의 반사율과 양자효율 및 변환효율이 미치는 영향을 살펴보았다. We fabricated a plasma texturing for multi-crystalline silicon cells using reactive ion etching (RIE). Multi-crystalline Si cells have not benefited from the cost-effective wet-chemical texturing processes that reduce front surface reflectance on single-crystal wafers. Elimination of plasma damage has been achieved while keeping front reflectance to extremely low levels. We will discuss reflectance, quantum efficiency and conversion efficiency for multi-crystalline Si solar cell by each RIE process conditions.

임피던스 변화를 이용한 실시간 기판 변형 측정

김우재,신기원,권희태,온범수,박연수,김지환,방인영,권기청,Kim, Woo Jae,Shin, Gi Won,Kwon, Hee Tae,On, Bum Soo,Park, Yeon Su,Kim, Ji Hwan,Bang, In Young,Kwon, Gi-Chung 한국반도체디스플레이기술학회 2021 반도체디스플레이기술학회지 Vol.20 No.1

The number of processes in the manufacture of semiconductors, displays and solar cells is increasing. And as the processes is performed, multiple layers of films and various patterns are formed on the wafer. At this time, substrate warpage occurs due to the difference in stress between each film and pattern formed on the wafer. the substrate warping phenomenon occurs due to the difference in stress between each film and pattern formed on the wafer. We developed a new warpage measurement method to measure wafer warpage during real-time processing. We performed an experiment to measure the presence and degree of warpage of the substrate in real time during the process by adding only measurement equipment for applying additional electrical signals to the existing ESC and detecting the change of the additional electric signal. The additional electrical measurement signal applied at this time is very small compared to the direct current (DC) power applied to the electrostatic chuck whit a frequency that is not generally used in the process can be selectively used. It was confirmed that the measurement of substrate warpage can be easily separated from other power sources without affecting.

공정가스와 RF 주파수에 따른 웨이퍼 표면 텍스쳐 처리 공정에서 저반사율에 관한 연구

윤명수,현덕환,진법종,최종용,김정식,강형동,이준신,권기청,Yun, Myoung-Soo,Hyun, Deoc-Hwan,Jin, Beop-Jong,Choi, Jong-Young,Kim, Joung-Sik,Kang, Hyoung-Dong,Yi, Jun-Sin,Kwon, Gi-Chung 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.2

Conventional surface texturing in crystalline silicon solar cell have been use wet texturing by Alkali or Acid solution. But conventional wet texturing has the serious issue of wafer breakage by large consumption of wafer in wet solution and can not obtain the reflectance below 10% in multi crystalline silicon. Therefore it is focusing on RIE texturing, one method of dry etching. We developed large scale plasma RIE (Reactive Ion Etching) equipment which can accommodate 144 wafers (125 mm) in tray in order to provide surface texturing on the silicon wafer surface. Reflectance was controllable from 3% to 20% in crystalline silicon depending on the texture shape and height. We have achieved excellent reflectance below 4% on the weighted average (300~1,100 nm) in multi crystalline silicon using plasma texturing with gas mixture ratio such as $SF_6$, $Cl_2$, and $O_2$. The texture shape and height on the silicon wafer surface have an effect on gas chemistry, etching time, RF frequency, and so on. Excellent conversion efficiency of 16.1% is obtained in multi crystalline silicon by RIE process. In order to know the influence of RF frequency with 2 MHz and 13.56 MHz, texturing shape and conversion efficiency are compared and discussed mutually using RIE technology. 일반적으로 결정질 실리콘 태양전지에서 표면에 텍스쳐링(texturing)하는 것은 알칼리 또는 산성 같은 화학용액을 사용하고 있다. 그러나 실리콘 부족으로 실리콘의 양의 감소로 인하여 웨이퍼 두께가 감소하고 있는 추세에 일반적으로 사용하고 있는 습식 텍스쳐링 방법에서 화학용액에 의한 많은 양의 실리콘이 소모되고 있어 웨이퍼의 파손이 심각한 문제에 직면하고 있다. 그리하여 습식 텍스쳐링 방법보다는 플라즈마로 텍스쳐링할 수 있는 건식 텍스쳐링 방법인 RIE (reactive ion etching) 기법이 대두되고 있다. 그리고 습식 텍스쳐링으로는 결정질 실리콘 태양전지의 반사율을 10% 이하로는 낮출 수가 없다. 다결정 실리콘 웨이퍼 표면에 텍스쳐링을 하기 위하여 125 mm 웨이퍼 144개를 수용할 수 있는 대규모 플라즈마 RIE 장비를 개발하였다. 반사율을 4% 이하로 낮추기 위하여 공정가스는 $Cl_2$, $SF_6$, $O_2$를 기반으로 RIE 텍스쳐링을 하였고 텍스쳐링의 모양은 공정가스, 공정시간, RF 주파수 등에 의해 조절이 가능하였다. 본 연구에서 RIE 공정을 통하여 16.1%의 변환효율을 얻었으며, RF 주파수가 텍스쳐링의 모양에 미치는 영향을 살펴보았다.

대기압 플라즈마를 이용한 결정질 태양전지 표면 식각 공정

황상혁,권희태,김우재,최진우,신기원,양창실,권기청,Hwang, Sang Hyuk,Kwon, Hee Tae,Kim, Woo Jae,Choi, Jin Woo,Shin, Gi-Won,Yang, Chang-Sil,Kwon, Gi-Chung 한국재료학회 2017 한국재료학회지 Vol.27 No.4

Reactive Ion Etching (RIE) and wet etching are employed in existing texturing processes to fabricate solar cells. Laser etching is used for particular purposes such as selective etching for grooves. However, such processes require a higher level of cost and longer processing time and those factors affect the unit cost of each process of fabricating solar cells. As a way to reduce the unit cost of this process of making solar cells, an atmospheric plasma source will be employed in this study for the texturing of crystalline silicon wafers. In this study, we produced the atmospheric plasma source and examined its basic properties. Then, using the prepared atmospheric plasma source, we performed the texturing process of crystalline silicon wafers. The results obtained from texturing processes employing the atmospheric plasma source and employing RIE were examined and compared with each other. The average reflectance of the specimens obtained from the atmospheric plasma texturing process was 7.88 %, while that of specimens obtained from the texturing process employing RIE was 8.04 %. Surface morphologies of textured wafers were examined and measured through Scanning Electron Microscopy (SEM) and similar shapes of reactive ion etched wafers were found. The Power Conversion Efficiencies (PCE) of the solar cells manufactured through each process were 16.97 % (atmospheric plasma texturing) and 16.29 % (RIE texturing).

새로운 대기압 플라즈마 소스를 이용한 결정질 실리콘 태양전지 인산 도핑 가능성에 관한 연구

조이현(I-Hyun Cho),윤명수(Myoung-Soo Yun),조태훈(Tae-Hoon Jo),권기청(Gi-Chung Kwon) 한국조명·전기설비학회 2013 조명·전기설비학회논문지 Vol.27 No.6

Furnace is currently the most important doping process using POCl₃ in solar cell. However furnace need an expensive equipment cost and it has to purge a poisonous gas. Moreover, furnace typically difficult appling for selective emitters. In this study, we developed a new atmospheric pressure plasma source, in this procedure, we research the atmospheric pressure plasma doping that dopant is phosphoric acid(H₃P0₄). Metal tube injected Ar gas was inputted 5 ㎸ of a low frequency(scores of ㎑) induced inverter, so plasma discharged at metal tube. We used the P type silicon wafer of solar cell. We regulated phosphoric acid(H₃P0₄) concentration on 10% and plasma treatment time is 90 s, 150 s, we experiment that plasma current is 70 ㎃. We check the doping depth that 287 ㎚ at 90 s and 621 ㎚ at 150 s. We analysis and measurement the doping profile by using SIMS(Secondary Ion Mass Spectroscopy). We calculate and grasp the sheet resistance using conventional sheet resistance formula, so there are 240 Ohm/sq at 90 s and 212 Ohm/sq at 150 s. We analysis oxygen and nitrogen profile of concentration compared with furnace to check the doped defect of atmosphere.

펄스변조의 듀티비 변경에 따른 DBD 대기압 플라즈마 특성 연구

박종인,황상혁,조태훈,윤명수,곽형신,진기남,전부일,최은하,권기청,Park, Jong-in,Hwang, Sang-hyuk,Jo, Tae Hoon,Yun, Myoung Soo,Kwak, Hyoung sin,Jin, Gi nam,Jeon, Buil,Choi, Eun Ha,Kwon, Gi-Chung 한국재료학회 2015 한국재료학회지 Vol.25 No.11

Atmospheric pressure plasma is used in the biological and medical fields. Miniaturization and safety are important in the application of apply atmospheric plasma to bio devices. In this study, we made a small, pocket-sized inverter for the discharge of atmospheric plasma. We used pulse power to control the neutral gas temperature at which the, when plasma was discharged. We used direct current of 5 V of bias(voltage). The output voltage is about 1 to 2 kilo volts the frequency is about 80 kilo hertz. We analyzsed the characteristics of the atmospheric plasma using OES(Optical emission spectroscopy) and the Current-Voltage characteristic of pulse power. By calculating of the current voltage characteristics, we were able to determine that, when the duty ratio increased, the power that actually effects the plasma discharge also increased. To apply atmospheric plasma to human organisms, the temperature is the most important factor, we were able to control the temperature by modulating the pulse power duty ratio. This means we can use atmospheric plasma on the human body or in other areas of the medical field.