Chemical Solution Deposition 방법을 이용한 BiFeO₃/Pb(Zr<SUB>0.52</SUB>Ti<SUB>0.48</SUB>)O₃ 다층박막의 전기적 특성에 대한 연구

차정옥(J. O. Cha),안정선(J. S. Ahn),이광배(K. B. Lee) 한국진공학회(ASCT) 2010 Applied Science and Convergence Technology Vol.19 No.1

BiFeO₃(BFO)/Pb(Zr0.52Ti0.48)O₃(PZT) bilayer와 multilayer의 다층구조를 만들어 전기적 특성을 측정하여 같은 두께의 BFO 단층박막과 비교해 보았다. BFO와 PZT 용액을 이용하였으며 chemical solution deposition 방법으로 Pt/Ti/SiO₂/Si(100) 기판위에 각 박막을 증착하였다. X-ray diffraction 분석을 통해 모든 박막이 다배향(multi-orientation) 페로브스카이트(perovskite) 구조를 가졌음을 확인하였다. BFO/PZT Bilayer와 multilayer 박막들은 BFO 단층박막의 비해 누설전류 값이 500 ㎸/㎝에서 약 4, 5차수 정도 감소했으며, 이로 인해 BFO/PZT 다층박막의 강유전체 특성이 크게 향상되었다. BFO/PZT multilayer 다층구조 박막의 경우 안정된 이력곡선(hysteresis loop)을 나타냈으며, 잔류 분극(remanent polarization)의 값은 44.3μC/㎠이었으며, 항전계(2Ec) 값은 681.4 ㎸/㎝였다. BiFeO₃/Pb(Zr0.52Ti0.48)O₃(BFO/PZT) multilayer thin films have been prepared on a Pt/Ti/SiO₂/Si(100) substrate by chemical solution deposition. BFO single layer, BFO/PZT bilayer and multilayer thin films were studied for comparison. X-ray diffraction analysis showed that the crystal structure of all films was multi-orientated perovskite phase without amorphous and impurity phase. The leakage current density at 500 ㎸/㎝ was reduced by approximately four and five orders of magnitude by bilayer and multilayer structure films, compared with BFO single layer film. The low leakage current density leads to saturated P-E hysteresis loops of bilayer and multilayer films. In BFO/PZT multlayer film, saturated remanent polarization of 44.3μC/㎠ was obtained at room temperature at 1 ㎑ with the coercive field(2Ec) of 681.4 ㎸/㎝.

Non-Classical Crystallization of Bulk Crystals in Solution and of Thin Films in the Gas Phase by Chemical Vapor Deposition

Jae-Ho Suk,Nong-Moon Hwang 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.1

Although non-classical crystallization is a relatively revolutionary concept, where a building block for crystallization is neither an atom nor an ion but a nanoparticle, it has become so much established now that numerous papers as well as several books were published and its tutorial and technical sessions were included in international conferences. The purpose of this paper is to review how non-classical crystallization was developed in solution and in the gas phase synthesis of films by chemical vapor deposition (CVD). Findings made in the study of non-classical crystallization in solution turn out to be very useful in understanding of non-classical crystallization of thin films by CVD. Similarly, findings made in the study of non-classical crystallization of thin films by CVD would be useful in understanding of non-classical crystallization of bulk crystals in solution. Therefore, it is synergistic to review non-classical crystallization both in solution and in the gas phase. For example, the presence of charge in nanoparticles is hardly mentioned in non-classical crystallization in solution whereas it is clearly revealed by the current measurement in the gas phase synthesis of thin films by CVD. The building block in non-classical crystallization is not simply a nanoparticle but a charged nanoparticle (CNP). Many evidences indicate that charged nanoparticles (CNPs) should be liquid-like or superplastic and this property changes abruptly with their charging state and size.

화학 용액 증착법으로 제조한 Bi0.9A0.1Fe0.975Zn0.025O3-δ (A=Eu, Dy) 박막의 구조와 전기적 특성

김윤장,김진원,장성근 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.4

Pure BiFeO3 (BFO) and codoped Bi0.9A0.1Fe0.975Zn0.025O3-δ (A=Eu, Dy) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by chemical solution deposition. The remnant polarizations (2Pr) of the Bi0.9Eu0.1Fe0.975Zn0.025O3-δ(BEFZO) and Bi0.9Dy0.1Fe0.975Zn0.025O3-δ (BDFZO) thin films were about 36 and 26 μC/cm2 at the maximum electric fieldsof 900 and 917 kV/cm, respectively, at 1 kHz. The codoped BEFZO and BDFZO thin films showed improved electricalproperties, and leakage current densities of 3.68 and 1.21×10–6 A/cm2, respectively, which were three orders of magnitudelower than that of the pure BFO film, at 100 kV/cm.

Eu와 V 동시 도핑에 의한 BiFeO3 박막의 구조와 전기적 특성

장성근,김윤장 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.3

Pure BiFeO3 (BFO) and (Eu, V) co-doped Bi0.9Eu0.1Fe0.975V0.025O3+δ (BEFVO) thin films were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by chemical solution deposition. The effects of co-doping were observed by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The electrical properties of the BEFVO thin film were improved as compared to those of the pure BFO thin film. The remnant polarization (2Pr) of the BEFVO thinfilm was approximately 26 μC/cm2 at a maximum electric field of 1,190 kV/cm with a frequency of 1 kHz. The leakage current density of the co-doped BEFVO thin film (4.81×10–5 A/cm2 at 100 kV/cm) was two orders of magnitude lower than of that of the pure BFO thin film. Pt (111) / Ti / SiO2 / Si (100) 기판 상에 순수 BiFeO3 (BFO) 및 유로퓸을 동시 도핑한 Bi0.9Eu 0.1Fe0.975V0.025O3 + δ(BEFVO) 박막을 화학 물질 용액 증착법으로 형성하였다. X 선 회절, 라만 분광법 및 주사 전자 현미경을 사용하여 동시 도핑의 영향을 관찰하였다. 순수한 BFO 박막과 비교하여 BEFVO 박막의 전기적 특성이 향상됨을 확인했습니다. BEFVO 박막의 잔류 분극 (2Pr)은 1 kHz의 주파수에서 1190 kV/cm의 최대 전기장에서 약 26 μC/cm2을 보였고. 동시 도핑 된 BEFVO의 누설 전류 밀도는 100 kV/cm에서 순수한 BFO 박막의 누설 전류 밀도보다 100배 낮은 4.8 x 10-5 A/cm2 을 보였다.

Eu와 V 동시 도핑에 의한 BiFeO₃ 박막의 구조와 전기적 특성

장성근,김윤장,Chang, Sung-Keun,Kim, Youn-Jang 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.3

Pure $BiFeO_3$ (BFO) and (Eu, V) co-doped $Bi_{0.9}Eu_{0.1}Fe_{0.975}V_{0.025}O_{3+{\delta}}$ (BEFVO) thin films were deposited on $Pt(111)/Ti/SiO_2/Si(100)$ substrates by chemical solution deposition. The effects of co-doping were observed by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The electrical properties of the BEFVO thin film were improved as compared to those of the pure BFO thin film. The remnant polarization ($2P_r$) of the BEFVO thin film was approximately $26{\mu}C/cm^2$ at a maximum electric field of 1,190 kV/cm with a frequency of 1 kHz. The leakage current density of the co-doped BEFVO thin film ($4.81{\times}10^{-5}A/cm^2$ at 100 kV/cm) was two orders of magnitude lower than of that of the pure BFO thin film.

화학 용액 증착법으로 제조한 Bi_0.9A_0.1Fe_0.975Zn_0.025O_3-_δ (A=Eu, Dy) 박막의 구조와 전기적 특성

김윤장,김진원,장성근,Kim, Youn-Jang,Kim, Jin-Won,Chang, Sung-Keun 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.4

Pure $BiFeO_3$ (BFO) and codoped $Bi_{0.9}A_{0.1}Fe_{0.975}Zn_{0.025}O_{3-{\delta}}$ (A=Eu, Dy) thin films were prepared on Pt(111)/Ti/$SiO_2$/Si(100) substrates by chemical solution deposition. The remnant polarizations (2Pr) of the $Bi_{0.9}Eu_{0.1}Fe_{0.975}Zn_{0.025}O_{3-{\delta}}$ (BEFZO) and $Bi_{0.9}Dy_{0.1}Fe_{0.975}Zn_{0.025}O_{3-{\delta}}$ (BDFZO) thin films were about 36 and $26{\mu}C/cm^2$ at the maximum electric fields of 900 and 917 kV/cm, respectively, at 1 kHz. The codoped BEFZO and BDFZO thin films showed improved electrical properties, and leakage current densities of 3.68 and $1.21{\times}10^{-6}A/cm^2$, respectively, which were three orders of magnitude lower than that of the pure BFO film, at 100 kV/cm.

Effects of Annealing Temperature on the Electrical Properties of Cr-Substituted BiFeO3 Thin Films

Kim, J. K.,Kim, S. S.,Park, M. H.,Kim, J. W.,Choi, E. J.,Ha, T. G.,Cho, H. K.,Guo, R.,Bhalla, A. S. Taylor Francis 2007 Ferroelectrics Vol.350 No.1

<P> Cr-substituted BiFeO3 (BFCr-3 mol%) thin films were deposited on Pt(200)/TiO2/SiO2/Si substrates by a chemical solution deposition. The coated films were annealed in the temperature range of 500°C∼ 600°C for 30 min under nitrogen atmosphere. The electrical properties of BFCr thin films were found to be sensitive to the annealing temperature. It was found that BFCr thin films exhibited good ferroelectric properties, such as an improved leakage-current density and P-E hysteresis characteristics. The BFCr thin film annealed at 525°C exhibits a low leakage current density of 9.2 × 10- 7 A/cm2 at an applied electric field of 100 kV/cm. The films exhibited a well-saturated hysteresis loop with a remanent polarization (Pr) of 47 μC/cm2 at room temperature. The reason for the improved leakage current and ferroelectric properties in BFCr thin films can be attributed to the effects of increased grain size and oxygen vacancies reduced by Cr doping.</P>

Study on Growth Parameters for Monolayer MoS₂ Synthesized by CVD Using Solution-based Metal Precursors

Seon Kyeong Kang,Hyun Seok Lee 한국진공학회(ASCT) 2019 Applied Science and Convergence Technology Vol.28 No.5

Two-dimensional (2D) materials have received a considerable amount of attention owing to their unique properties compared with those of bulk materials, such as ultralow thickness with no dangling bonds and direct bandgap for monolayers. Monolayer MoS₂ with a direct bandgap of ~1.8 eV is representative of 2D semiconductors, which can facilitate a high on/off ratio in field-effect transistors and can have various optoelectronic applications in the visible range. Large area MoS₂ monolayers are generally synthesized using chemical vapor deposition (CVD) methods, where various types of metal precursors are utilized. Here, we report the effects of process parameters on the growth mode of MoS₂ monolayers prepared by CVD using solution-based metal precursors. We investigated various growth modes of MoS₂ flakes depending on the growth temperature and time, Mo-precursor concentration in precursor solutions, and carrier gas amount. The synthesized MoS₂ monolayers revealed typical n-type semiconductor behaviors, which were investigated by optical microscopy, confocal photoluminescence and Raman spectroscopy, atomic force microscopy, and I–V characterization of field-effect transistors. The n-doping effect was reduced by removing unreacted precursors after transferring the MoS₂ layer on new SiO₂/Si substrates.

화학용액 증착법으로 제조한 바나듐이 첨가된 Na0.5Bi4.5Ti₄O15 박막의 전기적 성질

김진원,도달현,김상수 한국물리학회 2010 새물리 Vol.60 No.5

Ferroelectric thin films have been extensively investigated for integrated device applications, such as nonvolatile ferroelectric random access memories, microelectromechanical systems, tunable mi-crowave devices, integrated optical modulators, and infrared sensors. Bismuth-layer-structured fer-roelectrics belonging to the Aurivillus family, denoted by (Bi₂O₂)²+(Am−₁BmO3m+₁)²−, where m=1, 2, 3, 4, 5, etc., have been considered to be promising materials. The ferroelectric Na0.5Bi4.5Ti₄O15 (NaBTi) thin film, an Aurivillius family with m=4, is not fully understood yet. Especially, there are almost no reports regarding the properties of NaBTi thin films. Pure Na0.5Bi4.5Ti₄O15 (NaBTi) and V-doped Na0.5Bi4.5−x/3Ti4−xVxO15 (NaBTiV-x, x=0.01, 0.03 and 0.05) thin films were prepared by using a chemical solution deposition. For all samples, a layered perovskite structure with a single phase and with a good crystalline structure was observed in the X-ray diffraction (XRD) patterns, and the surface was composed of fine grains without cracks in the SEM results. The NaBTiV-0.01 thin film exhibited a better saturated hysteresis loop than the NaBTi thin film. For the NaBTiV-0.01 thin film, the remnant polarization (2Pr) was 61㎛/㎠ at room temperature, and the leakage current density measured at room temperature was 2.4×10−7 A/㎠ at an external electric field of 100 kV/㎝. There results show that V-doping is an effective method for improving the ferroelectric properties of the NaBTi thin film. 순수한 Na0.5Bi4.5Ti₄O15 (NaBTi) 박막과 바나듐이 첨가된 Na0.5Bi4.5−x/3Ti4−xVxO15 (NaBTiV-x, x=0.01, 0.03 그리고 0.05) 박막을 화학 용액 증착법으로 Pt(111)/Ti/SiO₂/Si(100) 기판 위에 성장시켜 바나듐 첨가량에 따른 박막의 미세구조와 전기적 특성을 측정, 비교 분석하였다. 성장된 NaBTi 및 NaBTiV-x 박막들은 결정화를 위해 750℃의 산소 분위기에서 RTA법으로 열처리하였으며 박막의 결정화 상태와 미세구조는 XRD, SEM 측정 결과로부터 알아 보았다. 바나듐이 첨가된 박막이 큰 잔류 분극과 작은 항전기장 및 누설 전류, 좋은 피로 특성을 보였는데 바나듐이 x=0.01 첨가된 NaBTiV-0.01 박막은 외부 전기장 648 kV/cm 일 때 잔류 분극(2Pr)과 항전기장(2Ec)은 각각 61㎛/㎠, 311 kV/㎝이었고 외부 전기장 100 kV/㎝일 때 누설전류 밀도는 2.4×10−7A/㎠이었으며 4.44×108까지 피로 현상을 보이지 않았다. 이러한 특성 향상은 바나듐울 첨가하였을 때 박막 내 산소 빈자리의 수가 감소하고 산소 빈자리의 이동도가 약화된 것에 기인한 것으로 판단된다.

화학적인 용액 코팅방법에 의한 박막형 고온초전도체에 사용되는 SUS310 금속모재의 평탄화 연구

이종범,이현준,김병주,권병국,김선진,이종수,이철영,문승현,이희균,홍계원,Lee, J.B.,Lee, H.J.,Kim, B.J.,Kwon, B.K.,Kim, S.J.,Lee, J.S.,Lee, C.Y.,Moon, S.H.,Lee, H.G.,Hong, G.W. 한국초전도학회 2011 Progress in superconductivity Vol.12 No.2

The properties of $2^{nd}$ generation high temperature superconducting wire, coated conductor strongly depend on the quality of superconducting oxide layer and property of metal substrate is one of the most important factors affecting the quality of coated conductor. Good mechanical and chemical stability at high temperature are required to maintain the initial integrity during the various process steps required to deposit several layers consisting coated conductor. And substrate need to be nonmagnetic to reduce magnetization loss for ac application. Hastelloy and stainless steel are the most suitable alloys for metal substrate. One of the obstacles in using stainless steel as substrate for coated conductor is its difficulties in making smooth surface inevitable for depositing good IBAD layer. Conventional method involves several steps such as electro polishing, deposition of $Al_2O_3$ and $Y_2O_3$ before IBAD process. Chemical solution deposition method can simplify those steps into one step process having uniformity in large area. In this research, we tried to improve the surface roughness of stainless steel(SUS310). The precursor coating solution was synthesized by using yttrium complex. The viscosity of coating solution and heat treatment condition were optimized for smooth surface. A smooth amorphous $Y_2O_3$ thin film suitable for IBAD process was coated on SUS310 tape. The surface roughness was improved from 40nm to 1.8 nm by 4 coatings. The IBAD-MgO layer deposited on prepared substrate showed good in plane alignment(${\Delta}{\phi}$) of $6.2^{\circ}$.