Growth and Characterization of Conducting ZnO Thin Films by Atomic Layer Deposition

민요셉,안정진,김성근,정재원,황철성 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.9

ZnO thin films were grown on Si or SiO2/Si substrates, at growth temperatures ranging from 150 to 400 oC, by atomic layer deposition (ALD) using diethylzinc and water. Despite the large band gap of 3.3 eV, the ALD ZnO films show high n-type conductivity, i.e. low resistivity in the order of 10‒3 Ωcm. In order to understand the high conductivity of ALD ZnO films, the films were characterized with X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, elastic recoil detection, Rutherford backscattering, Photoluminescence, and Raman spectroscopy. In addition, the various analytical data of the ZnO films were compared with those of ZnO single crystal. According to our analytical data, metallic zinc plays an important role for the high conductivity in ALD ZnO films. Therefore when the metallic zinc was additionally oxidized with ozone by a modified ALD sequence, the resistivity of ZnO films could be adjusted in a range of 3.8 × 10‒3 ~ 19.0 Ωcm depending on the exposure time of ozone.

실리콘 태양전지의 금속전극 특성

조은철,김동섭,민요셉,조영현,이수홍,Cho, Eun-Chel,Kim, Dong-Seop,Min, Yo-Sep,Cho, Young-Hyun,Ebong, A.U.,Lee, Soo-Hong 한국태양에너지학회 1997 한국태양에너지학회 논문집 Vol.17 No.2

개방전압과 단락전류와 같은 태양전지 출력변수들은 접합깊이, 도핑농도, 금속접합 및 태양전지구조에 의한 변수들이다. 태양전지 설계의 중요한 요소로서 인이 도핑된 에미터와 금속사이의 금속접합은 일함수 차이가 작아 낮은 직렬저항을 가져야 한다. PESC 태양전지는 금속 접합장벽 전극으로 티타늄을 사용한다. 새로운 접합장벽 전극물질로 티타늄과 일함수가 비슷하지만 전기전도도가 우수한 크롬은 금속 접합장벽 전극으로 유망한 금속이다. 티타늄은 일함수 차가 작지만, 접합장벽으로 크롬은 태양전지 제조시 티타늄보다 우수한 전기적 특성들을 갖는다. 본 논문에서는 실리콘 태양전지의 접합장벽 금속전극의 특성을 비교 분석하였다. The solar cell electrical output parameters such as the open circuit voltage($V_{oc}$) and short circuit current density($V_{sc}$) are intrinsic characteristics depending on junction depth, doping concentration, metal contacts barriers and cell structure. As a role of thumb for solar cell design, the metal contact barriers for phosphorus doped emitter should have lower work function in order to provide lower series resistance. The fabrication of PESC(passivated emitter solar cell) structure usually involves the use of titanium as a metal contact barrier. Chromium, which work function is similar to titanium but conductance is higher than titanium is being investigated as the new metal contact barrier. Although titanium has lower work function difference than chromium, the electric performances of chromium as contact barrier are higher than titanium. This better performance is attributed to the lower resistivity from chromium. This paper, therefore, compares the attributes of metal barrier contacts using titanium and chromium.

태양광 발전의 최근 업계 동향

이수홍,조은철,김동섭,조영현,민요셉,A. U. Ebong 한국결정성장학회 1997 한국결정성장학회지 Vol.7 No.1

태양전지를 이용한 태양광 발전은 조용하고 안전하게 무한한 에너지원인 태양에너지를 이용하여 전기에너지를 얻는 청정에너지 발생법이다. 1995년 태양전지의 출하량은 약 84.8 MW로, 매년 20% 이상의 시장성장이 예상된다. 본 논문에서는 태양광 발전의 원리, 특징, 종류, 주변기자재 등을 조사하였고, 최신의 태양전지 업계의 동향을 살펴보았다. A solar cell is a device which converts solar energy into electricity without any polluting by-product. Solar cells are useful when they are connected together to form modules. Total production of PV modules worldwide jumped 20 % in 1995 to reach a new record 84.8 MW. In this paper, the recent market trends in photovoltaic industries, principles and characteristics of solar cells and photovoltaic systems are reviewed.

고효율 단결정 실리콘 태양전지

김동섭,조은철,조영현,민요셉,이수홍,Kim, D.S.,Cho, E.C.,Cho, Y.H.,Ebong, A.U.,Min, Y.S.,Lee, S.H. 한국태양에너지학회 1997 한국태양에너지학회 논문집 Vol.17 No.2

단결정 실리콘 태양전지는 PESC(Passivated Emitter Solar Cell), PERC(Passivated Emitter and Rear Cell), Point Contact Cell, PERL(Passivated Emitter and Rear Locally-Diffused Cell) 형태로 기술적인 발전을 해왔다. BCSC(Buried Contact Solar Cell)는 낮은 제조 단가로 높은 효율을 얻을 목적으로 개발되었으며 개량된 형태인 DSBC(Double Sided Buried Contact Cell)는 양면으로 빛을 흡수할 수 있는 장점이 있다. Since PESC(passivated emitter solar cell) was developed in 1985, high efficiency silicon solar cell technology based on planar technology has been improved in the order of PERC, Point Contact Solar Cell, PERL. BCSC and DSBC, which do not require photolithography, are expected to replace commercial screen printed cells because of its potential for low cost and high efficiency. In this paper, history and characteristics of each type of cells are reviewed.

Transparent 3 nm-thick MoS2 counter electrodes for bifacial dye-sensitized solar cells

정태희,함소연,구본기,이필립,민요셉,김재엽,고민재 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

Molybdenum disulfide (MoS2) counter electrode (CE) is considered one of the most viable alternatives toPt CE in dye-sensitized solar cells (DSSCs) owing to its abundance, low cost, and superior electrocatalyticactivity. However, mostly, MoS2 CEs for DSSCs are prepared by conventional chemical reactions andannealing at a high temperature. By these conventional processes, deposition of sufficiently thin andtransparent MoS2 layers is challenging; therefore, bifacial DSSCs employing transparent MoS2 CEs havenot been studied. Here, we report transparent few-nanometer-thick MoS2 CEs prepared by atomic layerdeposition at a relatively low temperature (98 C) for bifacial DSSC applications. MoS2 nanofilms withprecisely controlled thicknesses of 3–16 nm are conformally coated on transparent conducting oxideglass substrates. With increase in the MoS2 nanofilm thickness, the MoS2 CE electrocatalytic activity forthe iodide/triiodide redox couple enhances, but its transparency decreases. Notably, the application of athinner MoS2 nanofilm in a bifacial DSSC leads to lower conversion efficiency under front-illumination,but higher conversion efficiency under back-illumination. In particular, only the 3 nm-thick MoS2nanofilm shows reasonable photovoltaic performances under both front- and back-illuminationconditions.

Band structure of amorphous zinc tin oxide thin films deposited by atomic layer deposition

이선영,김성준,신석희,Zhenyu Jin,민요셉 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.58 No.-

Recently, zinc tin oxide (ZTO) has attracted attention as an alternative buffer layer to replace CdS for photovoltaic cells. ZTO thin films were grown by atomic layer deposition from diethylzinc, tetrakis(dimethylamido)tin, and water. Compositional, structural and optical properties were characterized to construct band diagram of the ZTO films depending on Sn content. The ZTO films exhibit optical bandgaps of 2.95–3.07 eV which are wider than that of CdS. Furthermore, their work function is also observed to vary in a wide range of 4.32–5.16 eV. It is attributed to incorporation of Sn into ZTO which strongly influences formation of oxygen vacancies.

A Novel Chemical Route to Atomic Layer Deposition of ZnS Thin Film from Diethylzinc and 1,5-Pentanedithiol

고동현,김성준,Zhenyu Jin,신석희,이선영,민요셉 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.7

This study describes a novel chemical route to grow ZnS thin films via atomic layer deposition (ALD). By using diethylzinc and 1,5-pentanedithiol as precursors of Zn and S, respectively, ZnS films are grown on substrates with an atomic precision by repeating self-limiting chemisorption of each precursor. The growth-per-cycle of the ALD process is around 0.1 Å per cycle at 150°C, and the as-grown films are characterized to be amorphous ZnS by X-ray diffraction and X-ray photoelectron spectroscopy.

Modified Shrinking Core Model for Atomic Layer Deposition of TiO2 on Porous Alumina with Ultrahigh Aspect Ratio

Inhye Park,Jina Leem,Hoo-Yong Lee,민요셉 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.2

When atomic layer deposition (ALD) is performed on a porous material by using an organometallic precursor, minimum exposure time of the precursor for complete coverage becomes much longer since the ALD is limited by Knudsen diffusion in the pores. In the previous report by Min et al. (Ref. 23), shrinking core model (SCM) was proposed to predict the minimum exposure time of diethylzinc for ZnO ALD on a porous cylindrical alumina monolith. According to the SCM, the minimum exposure time of the precursor is influenced by volumetric density of adsorption sites, effective diffusion coefficient, precursor concentration in gas phase and size of the porous monolith. Here we modify the SCM in order to consider undesirable adsorption of byproduct molecules. TiO2 ALD was performed on the cylindrical alumina monolith by using titanium tetrachloride (TiCl4) and water. We observed that the byproduct (i.e., HCl) of TiO2 ALD can chemically adsorb on adsorption sites, unlike the behavior of the byproduct (i.e., ethane) of ZnO ALD. Consequently, the minimum exposure time of TiCl4 (~16 min) was significantly much shorter than that (~ 71 min) of DEZ. The predicted minimum exposure time by the modified SCM well agrees with the observed time. In addition, the modified SCM gives an effective diffusion coefficient of TiCl4 of ~1.78 × 10−2 cm2/s in the porous alumina monolith.

원자층증착법으로 성장시킨 MoS₂ 박막을 다른 기판으로 이전하기

김진우(Zhenyu Jin),김성준(Sungjoon Kim),민요셉(Yo-Sep Min) 한국기계가공학회 2017 한국기계가공학회 춘추계학술대회 논문집 Vol.2017 No.4

실리콘 태양전지의 금속전극 특성

조은철(Eun-Chel Cho),김동섭(Dong-Seop Kim),민요셉(Yo-Sep Min),조영현(Young-Hyun Cho),A.U.Ebong,이수홍(Soo-Hong Lee) 한국태양에너지학회 1997 한국태양에너지학회 논문집 Vol.17 No.1

개방전압과 단락전류와 같은 태양전지 출력변수들은 접합깊이, 도핑농도, 금속접합 및 태양전지 구조에 의한 변수들이다. 태양전지 설계의 중요한 요소로서 인이 도핑된 에미터와 금속사이의 금속접합은 일함수 차이가 작아 낮은 직렬저항을 가져야 한다. PESC 태양전지는 금속 접합장벽 전극으로 티타늄을 사용한다. 새로운 접합장벽 전극물질로 티타늄과 일함수가 비슷하지만 전기전도도가 우수한 크롬은 금속 접합장벽 전극으로 유망한 금속이다. 티타늄은 일함수 차가 작지만, 접합장벽으로 크롬은 태양전지 제조시 티타늄보다 우수한 전기적 특성들을 갖는다. 본 논문에서는 실리콘 태양전지의 접합장벽 금속전극의 특성을 비교 분석하였다. The solar cell electrical output parameters such as the open circuit voltage (Voc) and short circuit current density (J_sc) are intrinsic characteristics depending on junction depth, doping concentration, metal contacts barriers and cell structure. As a rule of thumb for solar cell design, the metal contact barriers for phosphorus doped emitter should have lower work function in order to provide lower series resistance. The fabrication of PESC (passivated emitter solar cell) structure usually involves the use of titanium as a metal contact barrier. Chromium, which work function is similar to titanium but conductance is higher than titanium is being investigated as the new metal contact barrier. Although titanium has lower work function difference than chromium, the electric performances of chromium as contact barrier are higher than titanium. This better performance is attributed to the lower resistivity from chromium. This paper, therefore, compares the attributes of metal barrier contacts using titanium and chromium.