Preparation of smooth self-supporting Ni /Cu multilayer

Fengju Gao,Ruiting Zheng,Guoan Cheng,Jing Yu 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.-

[Ni(5 nm)/Cu(5 nm)]50 multilayer was deposited on SiN membranes by DC magnetron sputtering. Field emission scanning-electron microscopy (FESEM), atomic-force microscopy (AFM), and X-ray diffraction (XRD) were used to analyze the surface morphology and the microstructure. The surface of the multilayer is continuous and flat, with root-mean-square roughness (RMS) of 9.9 nm. The period of the multilayer is 10.7 nm, which is very close to the designed period of 10 nm. The multilayer was composed of multi-crystal. These results show that this experiment is a promising way to obtain flat self-supporting metal multilayer. [Ni(5 nm)/Cu(5 nm)]50 multilayer was deposited on SiN membranes by DC magnetron sputtering. Field emission scanning-electron microscopy (FESEM), atomic-force microscopy (AFM), and X-ray diffraction (XRD) were used to analyze the surface morphology and the microstructure. The surface of the multilayer is continuous and flat, with root-mean-square roughness (RMS) of 9.9 nm. The period of the multilayer is 10.7 nm, which is very close to the designed period of 10 nm. The multilayer was composed of multi-crystal. These results show that this experiment is a promising way to obtain flat self-supporting metal multilayer.

염화나트륨 흡착 및 방출에 따른 다층 다공질규소의 반사율 스펙트럼 변화

Horchhong CHENG,김영유,김한중 한국물리학회 2010 새물리 Vol.60 No.4

We investigated the reflectance spectrum when sodium chloride was absorbed into and when it was released from the porous silicon multilayer. The reflectance spectrum is decreased and shifted toward longer wavelengths when the sodium chloride was absorbed into the porous silicon multilayer. The air in the pores of porous silicon multilayer was replaced by sodium chloride when sodium chloride was absorbed. Accordingly, we can see a red-shift of the reflectance peak due to the average refractive index of the multilayer increased, which caused by the increased of the optical thickness of the porous silicon multilayer. After releasing the absorbed sodium chloride from porous silicon multilayer, the reflectance spectrum almost returned to the original spectrum with longer release time. In this work, we have shown that the reflectance spectrum of the porous silicon multilayer was affected by the presence of sodium chloride. This experimental results opened the possibility of biomedical applications based on the variation of the reflectance spectrum from porous silicon multilayer. 단결정규소기판을 양극산화시켜 다층구조의 다공질규소를 제작하고 그 표면에 염화나트륨을 흡착 및 방출시킬 때 나타나는 반사율 스펙트럼을 조사하였다. 그 결과 다층 다공질규소 표면에 염화나트륨을 흡착시키면 반사율은 감소하고, 최대봉우리는 장파장 쪽으로 이동하였다. 그리고 염화나트륨을 방출시키면 방출시간이 증가함에 따라 점차 본래의 스펙트럼으로 거의 회복되었다. 이와 같이 염화나트륨 흡착 및 방출에 따라 반사율 스펙트럼의 최대봉우리가 이동하는 현상은 다공질규소층의 미세공을 통해 내부로 들어간 염화나트륨에 의해 광학적 두께 및 굴절률이 변화되었기 때문으로 해석하였다.

Utilization of AZO/Au/AZO multilayer electrodes instead of FTO for perovskite solar cells

Dang, Tran-Van,Pammi, S.V.N.,Choi, Jihoon,Yoon, Soon-Gil Elsevier 2017 Solar energy materials and solar cells Vol.163 No.-

<P><B>Abstract</B></P> <P>Aluminum (3at%)-doped ZnO (AZO)/Au/AZO multilayer films with low resistivity and high transmittance are in situ deposited at room temperature via facing-target sputtering for AZO and direct current (DC) sputtering for Au. The optical and electrical properties of multilayer films are compared with conventionally (<I>on</I>-axis) sputtered and facing-target sputtered (FTS) AZO films. The FTS samples show better crystallinity than that of <I>on</I>-axis sputtered samples, and the lowest value for resistivity is 7.9×10<SUP>−5</SUP> Ω-cm at an Au layer thickness of 8nm, which is compared with that of a conventional FTO electrode. The photo-conversion efficiencies (PCE) of the perovskite solar cells based on the AZO multilayer electrodes deposited via FTS and <I>on</I>-axis sputtering are 9.5% and 8.2%, respectively. Although the PCE of AZO multilayer-based-solar cells exhibit a lower efficiency than that of the FTO based-devices (~12.3%), the perovskite solar cell performance based on the FTS AZO multilayer electrodes is very attractive for applications to flexible planar-structured solar cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Utilization of the AZO/Au/AZO multilayer electrodes for perovskite solar cells. </LI> <LI> Low resistivity and high transmittance of AZO/Au/AZO deposited at room temperature via FTS. </LI> <LI> Damage-free FTS method from the plasma for multilayer electrodes. </LI> <LI> Achievement of high photo-conversion efficiency (~9.5%) using multilayer electrodes deposited via FTS. </LI> </UL> </P>

NdFeB 영구자석에의 Al/Al₂O₃ 다층막 코팅 및 부식 특성

정재인(J. I. Jeong),양지훈(J. H. Yang) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.2

Various types of multilayer coatings including Al/Al₂O₃ structure have been prepared on Nd-Fe-B permanent magnet to modify the morphology of the coating and to enhance the corrosion resistance of the magnet. Magnetron sputtering has been employed to make the multilayer coatings. Al₂O₃ sputtering conditions were optimized in reactive sputtering by varying the deposition parameters. The formation of Al₂O₃ film was confirmed from the binding energy shift measured by electron spectroscopy for chemical analysis. 3 types of coating structures were designed and prepared by magnetron sputtering. The coating structures consist of (1) single Al coating, (2) modified coatings having oxide or plasma treated layer in the middle of coating structure, and (3) Al/Al₂O₃ multilayer coatings. Surface and cross-sectional morphologies showed that Al/Al₂O₃ multilayer grew as a layered structure, and that very compact Zone 3 like structure were formed. Xray diffraction peak showed that the crystal orientations of multilayer coatings were similar to that of the bulk powder pattern. Hardness increased drastically when the Al thickness was around 1im in the Al/Al₂O₃ multilayer. From the salt spray test and pressure cooker test, it has been shown that the multilayer coatings showed good corrosion resistance compared to Al single or modified layer coatings.

Bonding Strength of Conductive Inner-Electrode Layers in Piezoelectric Multilayer Ceramics

Wang, Yiping,Yang, Ying,Zheng, Bingjin,Chen, Jing,Yao, Jinyi,Sheng, Yun The Korean Institute of Electrical and Electronic 2017 Transactions on Electrical and Electronic Material Vol.18 No.4

Multilayer ceramics in which piezoelectric layers of $0.90Pb(Zr_{0.48}Ti_{0.52})O_3-0.05Pb(Mn_{1/3}Sb_{2/3})O_3-0.05Pb(Zn_{1/3}Nb_{2/3})O_3$ (0.90PZT-0.05PMS-0.05PZN) stack alternately with silver electrode layers were prepared by an advanced low-temperature co-fired ceramic (LTCC) method. The electrical properties and bonding strength of the multilayers were associated with the interface morphologies between the piezoelectric and silver-electrode layers. Usually, the inner silver electrodes are fabricated by sintering silver paste in multi-layer stacks. To improve the interface bonding strength, piezoelectric powders of 0.90PZT-0.05PMS-0.05PZN with an average particle size of $23{\mu}m$ were added to silver paste to form a gradient interface. SEM observation indicated clear interfaces in multilayer ceramics without powder addition. With the increase of piezoelectric powder addition in the silver paste, gradient interfaces were successfully obtained. The multilayer ceramics with gradient interfaces present greater bonding strength as well as excellent piezoelectric properties for 30~40 wt% of added powder. On the other hand, over addition greatly increased the resistance of the inner silver electrodes, leading to a piezoelectric behavior like that of bulk ceramics in multilayers.

Multilayer-structured, SiO₂/sulfonated poly(phenylsulfone) composite membranes for proton exchange membrane fuel cells

Lee, J.R.,Won, J.H.,Yoon, K.S.,Hong, Y.T.,Lee, S.Y. Pergamon Press ; Elsevier Science Ltd 2012 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.37 No.7

In an effort to improve the dimensional change and proton conductivity of sulfonated poly(phenylsulfone) (SPPSU) membranes and facilitate their application to proton exchange membrane fuel cells (PEMFC), we develop a new composite membrane featured with a multilayer structure. The multilayer structure consists of a SPPSU-impregnated SiO<SUB>2</SUB> ceramic layer and a SPPSU layer. In contrast to a bulk composite membrane containing randomly dispersed SiO<SUB>2</SUB> nanoparticles, this unusual multilayer-structured composite membrane has an independent ceramic layer comprising close-packed SiO<SUB>2</SUB> nanoparticles and polyetherimide (PEI) binders. On the basis of structural characterization of the composite membranes, the effects of the multilayer structure on the membrane properties are investigated. The introduction of the SiO<SUB>2</SUB> ceramic layer is found to be effective in not only suppressing dimensional change but also enhancing proton conductivity of the multilayered composite membrane. Another intriguing finding is that the decrease of proton conductivity at a low humidity condition encountered in conventional water-swollen membranes is retarded in the multilayered composite membrane. These improvements in the proton conductivity of the multilayered composite membrane are discussed by considering the morphological uniqueness and the water retention capability of hygroscopic SiO<SUB>2</SUB> nanoparticles.

Multilayer-Structured Poly-Vanadium Acid/Polyaniline Composite: Synthesis and Properties for Humidity Sensing

Li Li,Yanan Guo,Chao Zhao,Liyuan Song 한국고분자학회 2018 Macromolecular Research Vol.26 No.7

A high-performance humidity sensor based on multilayer-structured poly-vanadium acid/polyaniline (V/PANI) composite was reported in this paper. Two-layer-structured V/PANI composite was fabricated by dip-coating poly-vanadium acid and electrochemically polymerizing PANI onto the interdigitated gold electrode in sequence, and then the process could be repeated to prepare the second two-layer-structured V/PANI composite. The crystalline phase properties and structural characteristics of the poly-vanadium acid, PANI, and V/PANI composite were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and UV-visible spectroscopy, respectively. The morphological characteristics of the first two-layer-structured V/PANI composite and multilayer-structured V/PANI composite were characterized by scanning electron microscopy. Additionally, sensors based on the multilayer-structured V/PANI composite showed good humidity sensing properties. For instance, its impedance changed linearly for approximately four orders of magnitude in a wide range of 11-97% RH. Furthermore, it displayed small hysteresis (∼5%RH), fast response (t90% of 8 s and 12 s for adsorption and desorption processes, respectively), good stability. The possible sensing mechanism was analyzed by considering the special multilayer structure and using complex impedance spectra and the corresponding equivalent circuit of the sensor. The measurement results highlight the multilayer-structured V/PANI composite film is a candidate material for constructing humidity sensors.

Bonding Strength of Conductive Inner-Electrode Layers in Piezoelectric Multilayer Ceramics

Yiping Wang,Ying Yang,Bingjin Zheng,Jing Chen,Jinyi Yao,Yun Sheng 한국전기전자재료학회 2017 Transactions on Electrical and Electronic Material Vol.18 No.4

Multilayer ceramics in which piezoelectric layers of 0.90 Pb(Zr0.48Ti0.52)O3 -0.05 Pb(Mn1/3Sb2/3)O3 -0.05 Pb(Zn1/3Nb2/3)O3(0.90PZT-0.05PMS-0.05PZN) stack alternately with silver electrode layers were prepared by an advanced low-temperatureco-fired ceramic (LTCC) method. The electrical properties and bonding strength of the multilayers were associated with theinterface morphologies between the piezoelectric and silver-electrode layers. Usually, the inner silver electrodes are fabricatedby sintering silver paste in multi-layer stacks. To improve the interface bonding strength, piezoelectric powders of0.90PZT-0.05PMS-0.05PZN with an average particle size of 23 μm were added to silver paste to form a gradient interface. SEMobservation indicated clear interfaces in multilayer ceramics without powder addition. With the increase of piezoelectricpowder addition in the silver paste, gradient interfaces were successfully obtained. The multilayer ceramics with gradientinterfaces present greater bonding strength as well as excellent piezoelectric properties for 30~40 wt% of added powder. Onthe other hand, over addition greatly increased the resistance of the inner silver electrodes, leading to a piezoelectric behaviorlike that of bulk ceramics in multilayers.

Layer-by-Layer 흡착을 통한 MWNT를 갖는 다층 고분자전해질에 관한 연구

이헌(Hun Lee),강미선(Misun Kang) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.7

본 연구에서는 고분자전해질의 다층흡착을 통하여 카본나노튜브(CNT)를 함유하는 multilayer를 형성하였다. 다층흡착 기법은 정전기적 인력을 이용하여 간단하면서도 효과적으로 다층 구조의 물질을 만들수 있는 방법이다. 양이온성과 음이온성 고분자전해질로 Polyallylamine hydrochloride(PAH)와 polystyrene sulfonate sodium salt(PSS)를 사용하였으며, 산처리된 multiwalled carbon nanotube(MWNT)를 도입하였다. 다층흡착으로 얻어진 시료의 두께와 층 수를 분석하였으며, 그 표면의 특징을 살펴보았다. 시료의 층 수가 증가할수록 적층된 고분자전해질의 양이 증가하여 전체 두께가 증가함을 보였다. 적층이 진행될수록 표면의 구조와 거칠기가 달라짐에 따라 접촉각 특성이 변하였다. 고분자전해질의 적층 시간은 표면의 거칠기를 빠르게 최대치에 도달하게 만드는 반면에 MWNT의 노출 시간은 적층 두께에 영향이 없었다. 최종 층에 MWNT의 도입에 있어 표면의 거칠기가 최대인 지점까지 고분자전해질의 적층이 이루어지는 것이 유리하였다. 이에 따라 표면 특성의 효과를 고려하여 적층된 MWNT가 최대일 때 형성된 multilayer의 전기적인 특성이 가장 높게 나타났다. Polyelectrolyte multilayers with multiwalled carbon nanotubes (MWNT) were prepared by layer-by-layer (LbL) self-assembly, which is a simple and effective method for fabricating thin multilayers. Polyallylamine hydrochloride (PAH) and polystyrene sulfonate sodium salt (PSS) were used as the cationic polymer and anionic polymer, respectively. The PAH and PSS polymer layers were deposited alternately on a silicon wafer via electrostatic self-assembly. The MWNTs functionalized with carboxylic acid were deposited on top of the cationic surface. The thickness of the multilayer increased linearly with increasing number of deposition layers. When the number of layers increased, the contact angle increased until the critical point due to surface roughness. The dipping time of the polyelectrolyte solution influenced the contact angle of the surface, but the thickness of the MWNT layer had no effect on the deposition time. The polyelectrolyte multilayer obtained at the optimal point for introducing MWNTs exhibited electrical properties suitable for various applications. This study demonstrates that a polyelectrolyte multilayer with MWNTs was developed using LbL self-assembly.

Hardness and Oxidation Resistance of Ti_0.33Al_0.67N/CrN Nano-multilayered Superlattice Coatings

Ahn, Seung-Su,Oh, Kyung-Sik,Chung, Tai-Joo,Park, Jong-Keuk The Korean Ceramic Society 2019 한국세라믹학회지 Vol.56 No.1

$Ti_{0.33}Al_{0.67}N/CrN$ nano-multilayers, which are known to have excellent wear resistance, were prepared using an unbalanced magnetron sputter to have various periods of 2-5 nm. $Ti_{0.33}Al_{0.67}N$ had a hexagonal structure in a single layer, but converted to a cubic structure by forming a multilayer with CrN, which has a cubic structure. Thus, $Ti_{0.33}Al_{0.67}N$ formed a superlattice in the multilayer. The $Ti_{0.33}Al_{0.67}/CrN$ multilayer with a period of 2.5 nm greatly exceeded the hardness of the $Ti_{0.33}Al_{0.67}N$ and the CrN single layer, reaching 39 GPa. According to the low angle X-ray diffraction results, the $Ti_{0.33}Al_{0.67}N/CrN$ multilayer maintained its as-coated structure to a temperature as high as $700^{\circ}C$ and exhibited hardness of 30 GPa. The thickness of the oxide layer of the $Ti_{0.33}Al_{0.67}N/CrN$ multilayered coating was less than one-tenth of those of the single layers. Thus, $Ti_{0.33}Al_{0.67}N/CrN$ multilayered coating had hardness and oxidation resistance far superior to those of its constituent single layers.