Academic literature on the topic 'Cu poor layer'
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Journal articles on the topic "Cu poor layer"
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Li, Zhang, Xue Yu-Ming, Xu Chuan-Ming, He Qing, Liu Fang Fang, Li Chang-Jian, and Sun Yun. "Microstructural characterization of Cu-poor Cu (In, Ga)Se2 surface layer." Thin Solid Films 520, no. 7 (January 2012): 2873–77. http://dx.doi.org/10.1016/j.tsf.2011.11.077.
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Nishimura, Takahito, Yoshiaki Hirai, Yasuyoshi Kurokawa, and Akira Yamada. "Theoretical and experimental investigation of the recombination reduction at surface and grain boundaries in Cu(In,Ga)Se2 solar cells by valence band control." MRS Proceedings 1771 (2015): 125–31. http://dx.doi.org/10.1557/opl.2015.387.
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ABSTRACTWe carried out theoretical calculation for Cu(In,Ga)Se2 (CIGS) solar cells with energy bandgap of 1.4 eV assuming formation of a Cu-poor layer on the surface of CIGS films. This calculation result revealed that formation of a thinner Cu-poor layer such as a few nanometers leads to improvement of the solar cells performance. This is because interfacial recombination was suppressed due to repelling holes from the interface by valence band offset (ΔEV). Next, we investigated composition distribution in the cross section of CIGS solar cells with Ga contents of 30% and 70% by transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). It was revealed that the Cu-poor layer was formed on the surface and at the grain boundary (GB) in the case of conversion efficiency (η) of 17.3%, although it was not formed in the case of lower η of 13.8% for a Ga content of 30%. These results indicate that formation of the Cu-poor layer contributed to improvement of cell performance by suppression of carrier recombination. Moreover, it was also confirmed that although the Cu-poor layer was observed on the surface, it was not observed at the GB in the case of CIGS solar cells with a Ga content of 70% which had η of 12.7%. It is thought that the effect of repelling holes by ΔEV is not obtained at the GB and the solar cell performance in the Ga content of 70% is lower than that in the Ga content of 30%. Thus, we suggest importance of the Cu-poor layer at the GB for high efficiency of CIGS solar cells with high Ga contents.
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Zhang, Man, Yue Bin Lin, Jian Qiang Lv, and Hai Lin Jiang. "Effect of Al on Zn-Al Filler Metal Wettability on Pure Copper Surface." Advanced Materials Research 538-541 (June 2012): 196–99. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.196.
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Zn-Al filler metal wettability tests were performed. With the match of CsF-AlF3 flux, Zn-Al filler metal wettability is poor on pure copper surface. The Cu-Al-Zn intermetallic compound interface layer exits between Zn-Al filler metal and Cu base metal. When Al content is low in Zn-Al filler metal, the filler metal wettability is poor and the filler metal melting point is low. In the wettability test course, the time is long in which Cu base metal interacts with liquid Zn-Al filler metal. And the Cu-Al-Zn intermetallic compound interface layer grows thick between filler metal and base metal. With the increase of Al content in Zn-Al filler metal, the interaction strengthens between Zn-Al filler metal and Cu base metal. In the wettability test course, the time beocome short in which Cu base metal interacts with liquid Zn-Al filler metal. The Cu-Al-Zn intermetallic compound interface layer gets thin between filler metal and base metal. Meanwhile, Zn-Al filler metal wettability improves on pure copper surface. But the improvement is not remarkable. Its wettablility is still poor on pure copper surface.
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Sung, Po-Hsien, and Tei-Chen Chen. "Performance of Cu–Ag Thin Films as Diffusion Barrier Layer." Coatings 10, no. 11 (November 13, 2020): 1087. http://dx.doi.org/10.3390/coatings10111087.
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It is well-known that Cu–Sn intermetallic compounds are easily produced during reflow process and result in poor reliability of solder bump. Recently, amorphous metallic films have been considered to be the most effective barrier layer because of the absence of grain boundaries and immiscibility with copper. Since Cu–Ag alloys are characterized by their lower electrical resistivity and superior glass-forming ability, they are appropriate to be used as the diffusion barrier layers. In this study, molecular dynamics simulation was performed to investigate the effects of composition ratio and quenching rate on the internal microstructure, diffusion properties, and the strength of the interface between polycrystalline Cu and Cu–Ag barrier layers. The results showed that Cu40Ag60 and Cu60Ag40 present more than 95% of the amorphous at quenching rate between 0.25 and 25 K/ps, indicating a good glass-forming ability. Diffusion simulation showed that a better barrier performance can be achieved with higher amorphous ratio. For the sample of Cu20Ag80 with quenching rate of 25 K/ps, a void is initially generated in amorphous Cu–Ag layer during the tensile test. This indicates the strength of amorphous Cu–Ag is weaker than Cu–Ag/Cu interface and the polycrystalline Cu layer.
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Terajima, Takeshi. "Development of Cu-Clad Metallic Glass for Soldering." Materials Science Forum 706-709 (January 2012): 1343–47. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.1343.
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Soldering is a potential technique for joining metallic glasses. It can be performed at far below the crystallization temperature of various metallic glasses; thus, there is no possibility of crystallization. However, Cu-Zr-based metallic glass displays poor wettability to Pb-free solder, because a strong native oxide film prevents direct contact between the solder and the glass. To overcome this problem, Cu-Zr-based metallic glass clad with a thin film of Cu has been developed. This was produced by casting the melt of a Cu36Zr48Al8Ag8 pre-alloy into a Cu mold cavity, inside which a thin film of Cu with a thickness of 2 μm was placed. Cu36Zr48Al8Ag8 metallic glass was successfully formed and welded to the Cu thin film. From microstructure analysis, it was found that a reaction layer was formed at the interface between the Cu and the Cu36Zr48Al8Ag8 metallic glass. However, no oxide layer was observed in the Cu-clad layer. It was found that the Cu cladding played an important role in preventing the formation of the surface oxide film. Consequently, solderability to the Cu-Zr-based metallic glass was drastically improved.
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Jiang, N., and J. Silcox. "On The Formation Of Diffusion Layer Between Cr Film And Glass." Microscopy and Microanalysis 5, S2 (August 1999): 166–67. http://dx.doi.org/10.1017/s143192760001415x.
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Chromium films are commonly used as a metal “glue” layer because of good adhesion to glass. It is believed that an intermediate oxide layer is formed during deposition, since Cr has a very strong affinity for oxygen. For example, a graded Cu/Cr/CrOx/SiO2 structure ensures excellent adhesion of Cu to glass, whereas Cu exhibits poor adhesion to most dielectrics. In our recent study, however, a diffusion layer, Cr2O3+SiOy, was observed between CrOx and SiO2 (glass) substrate. It is quite likely that this diffusion layer is responsible for the good adhesion of Cr film to glass.The relative compositions of the major components across the interface are shown in Fig 1. A Cr film was evaporated on Corning Code 1737 glass (Al2O3-B2O3-SiO2 with ˜67at.% Si02) substrate at room temperature (RT) and subsequently covered with about lOnm Cu. A 5nm'wide diffusion layer is seen. The corresponding regions are also indicated in Fig 2, an Annular Dark Field (ADF) image whose contrast is approximately proportional to the density if the thickness is assumed uniform.
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TING, WU, T. EGI, R. ITTI, K. KURODA, N. KOSHIZUKA, and S. TANAKA. "IDENTIFICATION OF THE NATURAL TERMINATION LAYER ON THE SURFACES OF As-PREPARED Nd1Ba2Cu3Oy SINGLE CRYSTALS AND SURFACE DEFECT STRUCTURES." Modern Physics Letters B 09, no. 20 (August 30, 1995): 1297–301. http://dx.doi.org/10.1142/s0217984995001273.
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The natural termination layer has been identified to be the CuO chain layer on the surfaces of as-prepared high quality Nd 1 Ba 2 Cu 3 O 7−y (Nd123) single crystals, employing an ultrahigh vacuum scanning tunneling microscope (UHV-STM) system. It is found that the oxygen atoms of the CuO chain layer are unstable in the environment of UHV (~10−8 Pa). Oxygen loss occurs in some areas of the surfaces of Nd123 single crystals, leading to some localized surface defect structures. Such defect structures may be responsible for the poor reproducibility of the superconducting gap structure observed on the surface of Y 1 Ba 2 Cu 3 O y from low temperature tunneling measurements.
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Liu, Chung Ping, Ming Wei Chang, Chuan Lung Chuang, and Nien Po Chen. "Synthesis of Cu-Poor Copper-Indium-Gallium-Diselenide Nanoparticles by Solvothermal Route for Solar Cell Applications." International Journal of Photoenergy 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/976030.
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Copper-indium-gallium-diselenide (CIGS) thin films were fabricated using precursor nanoparticle ink and sintering technology. The precursor was a Cu-poor quaternary compound with constituent ratios ofCu/(In+Ga)=0.603,Ga/(In+Ga)=0.674, andSe/(Cu+In+Ga)=1.036. Cu-poor CIGS nanoparticles of chalcopyrite for solar cells were successfully synthesized using a relatively simple and convenient elemental solvothermal route. After a fixed reaction time of 36 h at 180°C, CIGS nanocrystals with diameters in the range of 20–70 nm were observed. The nanoparticle ink was fabricated by mixing CIGS nanoparticles, a solvent, and an organic polymer. Analytical results reveal that the Cu-poor CIGS absorption layer prepared from a nanoparticle-ink polymer by sintering has a chalcopyrite structure and a favorable composition. For this kind of sample, its mole ratio of Cu : In : Ga : Se is equal to 0.617 : 0.410 : 0.510 : 2.464 and related ratios ofGa/(In+Ga)andCu/(In+Ga)are 0.554 and 0.671, respectively. Under the condition of standard air mass 1.5 global illumination, the conversion efficiency of the solar cell fabricated by this kind of sample is 4.05%.
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Ghanta, Sivaprasad, Nilanjan Roy, and Partha Pratim Jana. "Crystal structures of two very similar 2 × 2 × 2 superstructures of γ-brass-related phases in ternary Ir–Cd–Cu system." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 76, no. 1 (January 15, 2020): 47–55. http://dx.doi.org/10.1107/s2052520619015488.
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A binary phase Ir8Cd41 in the Ir–Cd binary system and novel ternary phases in the Ir–Cd–Cu system have been synthesized from the constituent elements using high-temperature solid-state synthesis. The structure of previously reported Ir8Cd41 and newly found ternary phases in the Ir–Cd–Cu system have been characterized by single crystal X-ray diffraction and EDS analysis. The structural analysis reveals that Ir8Cd41 adopts V8Ga41-type structure and ternary Ir–Cd–Cu phases adopt two 2 × 2 × 2-superstructures of the γ-brass-related phase. The structures of ternary Ir–Cd–Cu phases are associated with structural disorder (vacancies as well as mixed site occupancies). The crystal structures of the ternary phases are viewed using layer description and cluster concept. The 2 × 2 × 2-superstructure of γ-brass-related phases in the Cu-poor region are not isostructural with the phases in the Cu-rich region, and they are consistent with the absence of a continuous phase region between two 2 × 2 × 2-superstructures of γ-brass-related phases. In the Cu-poor region, the structures contain ∼404 atoms per unit cell, whereas in the Cu-rich phases the structures contain ∼411 atoms in their respective unit cells. The crystal structures in the Cu-poor region represent a new type in the 2 × 2 × 2-superstructure of γ-brass-related phases in view of the combination of constituent cluster types, whereas the structures in the Cu-rich region adopt the Rh7Mg44 structure type.
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Liu, Chih-Yi, Chao-Cheng Lin, Chun-Hung Lai, Shih-Kun Liu, Chang-Sin Ye, Wei-Chen Tien, and Meng-Ren Hsu. "Characteristics of GZO-based multilayer transparent conducting films." International Journal of Modern Physics B 35, no. 14n16 (June 30, 2021): 2140004. http://dx.doi.org/10.1142/s021797922140004x.
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Ga-doped ZnO (GZO)/metal/GZO structures were fabricated on glass substrates to be the transparent conducting layers in this study. GZO films and metal films were deposited at room-temperature by a radio-frequency sputter and a thermal evaporator, respectively. The GZO/Ag/GZO (GAG) structures had poor electrical and optical properties due to the formation of Ag islands on the GZO layer. A 1-nm Cu seed layer was deposited on the GZO layer to fabricate the GZO/Ag/Cu/GZO (GACG) structure to improve its electrical and optical properties. The GACG structure had sheet resistance of 9 [Formula: see text], average visible transmittance of 86% and figure of merit of [Formula: see text] [Formula: see text]. In addition, the sheet resistance of the GACG structure kept almost the same after annealing at [Formula: see text]C in atmosphere for more than 5 h, which showed good thermal stability.
Dissertations / Theses on the topic "Cu poor layer"
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Patikirige, Yasas R. A. "Optimization of The Absorber/Buffer Interface Region of Cu(In,Ga)Se2 Photovoltaic Devices: A Numerical Simulation Study." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1562432266285967.
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Gião, Madalena Alice Priante. "Caracterização do vapor gerado por ablação de tungstênio por laser de "Cu-HBr"." Instituto Tecnológico de Aeronáutica, 2006. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=287.
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Este trabalho teve como objetivo estudar detalhadamente as propriedades do vapor gerado pela ablação de um alvo sólido de tungstênio por um laser de Cu-HBr, tais como: densidade de átomos, neutros ou ionizados, e a distribuição de velocidades destas mesmas espécies, e obter informações sobre mecanismos de redução das cargas elétricas, de gotículas e de aglomerados no vapor com o objetivo de se obter um jato de vapor monoatômico e neutro, para aplicação de crescimento de filmes finos e espectroscopia de fotoionização. Foram desenvolvidas e testadas três técnicas de monitoramento da pluma de vapor: sensores de PVDF, sondas de Langmuir e ion-gauge. Destas, as duas primeiras se mostraram simples e eficazes para a determinação da distribuição de velocidade de jatos monoatômicos, com a obtenção de parâmetros como temperatura translacional e velocidade de deriva da pluma.
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Santos, Jonadabe Martins dos. "Atomização e consolidação por fusão seletiva a laser da liga Cu-11,3Al-3,2Ni-3,0Mn-0,5Zr com efeito de memória de forma." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/8078.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
The aim of the present work was the study of the viability of a manufacturing route of parts with the Cu-based Shape Memory Alloy (SMA) Cu- 11,3Al-3,2Ni-3Mn-0,5Zr through gas atomization followed by Selective Laser Melting (SLM) consolidation. The alloy was prepared from high purity elements in an induction furnace with a concentrate argon flow shield above the molten metal. The atomization was carried out using an induction furnace for melting and argon as atomizer gas. The atomized powder was sieved in 32-106 μm range particles sizes and consolidated by SLM 250 HL device settled at the Leibniz Institute for Solid State and Materials Research, Dresden, Germany. In the consolidation step the best combination of power (P in Watts) and velocity (V in mm/s) were selected through the visual aspect criteria. In the following step the hatching track percentage (S) guided by relative density criteria was included. The atomized powder and the consolidated samples were characterized by optical and electron microscopy, X-ray diffraction and differential scanning calorimetry. The composition and the powder morphology were suitable for the SLM processing. The parameters optimization point out that the best combinations were P310v740S40 and P310v740S50, their relative density were around 97 %. The β’ “zig-zag” martensite phase, the SMA effect cause, was prevailing in the consolidated samples microstructure, still, the microstructure although was not-uniform it was relatively grain refined, pointing out the effect of Zr addition. The consolidated samples transformation temperatures were As=172-174C, Af=194-197C, Ms=156-160C, Mf=132- 138C. The results point to a strong indicative of the viability of a manufacturing route of parts with Cu-based SMA through gas atomization followed by SLM consolidation.
O objetivo da dissertação foi o estudo da viabilidade de uma rota de fabricação de peças com liga Cu-11,3Al-3,2Ni-3Mn-0,5Zr a base de cobre com Efeito de Memória de Forma (EMF) por atomização a gás da liga, seguida pela consolidação por Fusão Seletiva por Laser (FSL). A liga foi elaborada a partir de elementos de alta pureza em forno de indução com proteção de fluxo de argônio concentrado acima do banho. As atomizações foram realizadas com fusão por indução e utilizando argônio como gás de atomização. Os pós, separados na faixa granulométrica 32-106 μm foram consolidados por FSL utilizando o equipamento SLM 250 HL do Leibniz Institute for Solid State and Materials Research, Dresden, Alemanha. Para consolidação foram selecionadas as melhores combinações de potência (P em W) e velocidade (V em mm/s) do feixe de laser pelo critério de aspecto visual das trilhas simples. Na etapa seguinte foi considerada a porcentagem de sobreposição de pistas (S) avaliada pelo critério de densidade relativa. O pó atomizado e os corpos consolidados por FSL foram caracterizados por microscopia ótica e eletrônica de varredura, difração de raios-X e por calorimetria diferencial de varredura. A composição e a morfologia do pó atomizado foram adequadas para o processo de FSL. A otimização dos parâmetros de processamento indicaram que as melhores combinações foram de P310v740S40 e P310v740S50, com densidade relativa alcançada em torno de 97%. A fase martensítica β’ “zigzag”, responsável pelo EMF, foi predominante nos corpos consolidados por FSL sendo que a microestrutura, embora não uniforme, foi relativamente refinada, indicando o efeito da adição de Zr na composição da liga. As temperaturas de transformação dos corpos consolidados foram de As=172- 174C, Af=194-197C, Ms=156-160C, Mf=132-138C. Os resultados indicam a viabilidade da rota de fabricação de peças em ligas a base de cobre com EMF por atomização a gás da liga, seguida pela consolidação por FSL.
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Bugot, Cathy. "Elaboration d'oxydes et de sulfures à grande bande interdite pour les cellules photovoltaïques à base de Cu(In,Ga)Se2 par dépôt chimique en phase vapeur par flux alternés (ALD) activé par plasma." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066499/document.
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La thèse présentée ici a pour objectif de développer des matériaux innovants et performants pour la fabrication de la couche tampon des cellules photovoltaïques en couches minces à base de Cu(In,Ga)Se2 (CIGS). Pour la première fois, des couches minces d'In2(S,O)3 et de Zn(O,S) ont été réalisées par dépôt chimique en phase vapeur par flux alternés assisté par plasma afin de remplacer la couche tampon traditionnelle en sulfure de cadmium. En apportant des espèces plus réactives, cette méthode permet d'effectuer des réactions qui ne pourraient pas avoir lieu par procédé thermique. La comparaison des deux procédés a permis l'évaluation de leurs atouts et de leurs contraintes. Par exemple, l'In2(S,O)3 n'a pu être synthétisé que par cette méthode, via des mécanismes surfaciques d'échange entre des radicaux d'oxygène et le soufre de l'In2S3. Pour augmenter les performances des cellules CIGS/In2(S,O)3 jusqu'à 11,9%, le procédé de synthèse initial a été amélioré en corrélant les études de Spectroscopie Photoélectronique X et celles de spectrométrie de masse. En parallèle, il a été montré que la température de croissance avait un effet notable sur les propriétés opto-électroniques des cellules CIGS/Zn(O,S) et qu'il existait des optimums de performance à basse (Tdep < 160°C) et haute (Tdep > 200°C) températures. L'optimum situé à basse température s'explique par les propriétés favorables des couches minces de Zn(O,S) synthétisées par procédé thermique, tandis que celui situé à haute température est dû à l'existence de mécanismes d'interdiffusion à l'interface Zn(O,S)/CIGS. Un rendement de 15,6% a pu ainsi être obtenuThis thesis focuses on the development of innovative and efficient materials for the fabrication of the buffer layer of Cu(In,Ga)Se2 (CIGS) thin film solar cells. For the first time, In2(S,O)3 and Zn(O,S) thin films were synthesized by Plasma Enhanced Atomic Layer Deposition (PEALD) in order to substitute the conventional cadmium sulfide buffer layer. By creating reactive species, this deposition technique allows reactions which could not be possible using thermal ALD. The comparison of both methods allows the evaluation of their respective assets and constraints. For instance, In2(S,O)3 thin films could only be achieved using PEALD through exchange reaction mechanisms between oxygen radicals from the plasma and sulfur atoms of In2S3 growing film. In order to obtain CIGS/In2(S,O)3 solar cells with efficiencies of 11.9%, the initial deposition process was improved by correlating X-Ray Photoelectron Spectroscopy and Quadrupole Mass Spectrometry analyses. At the same time, the deposition temperature proved to have a crucial effect on CIGS/Zn(O,S)-ALD device opto-electronic properties and we evidenced the existence of two deposition temperature ranges, at Tdep < 160°C and Tdep > 200°C, where the performances are enhanced. In the low temperature range, the high performances were explained by specific Zn(O,S) properties, while at high temperature they are enhanced by favorable interdiffusion mechanisms at the CIGS/Zn(O,S) interface. Increasing the deposition temperature allowed the fabrication of CIGS/Zn(O,S) solar cells with efficiencies up to 15.6%
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Lamirault, Sylvie. "Comportement du cuivre dans les melanges hf-mf (m = k ou nh : :(4)) fondus utilises pour l'obtention electrolytique du fluor." Paris 6, 1987. http://www.theses.fr/1987PA066467.
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Etude thermodynamique et cinetique de la corrosion electrochimique dans les melanges hf-mf(m=k ou nh::(4)) du cuivre metal entrant, soit pur, soit sous forme d'alliage (monel) dans la construction des cellules industrielles d'electrolyse. Mise en evidence de la formation d'une couche de fluorure de cuivre passivante. Evaluation de l'epaisseur limite de la couche. Etablissement de l'influence de la densite de courant sur le caractere passivant de la couche formee. Proposition d'un mecanisme de corrosion du cuivre
Book chapters on the topic "Cu poor layer"
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Barcones, B., A. Romano-Rodríguez, J. Álvarez-Garcia, L. Calvo-Barrio, A. Pérez-Rodríguez, J. R. Morante, R. Scheer, et al. "Rapid thermal sulphurisation of Cu-rich and Cu-poor Cu-In precursors for the production of CuInS2 layers for photovoltaic applications: a microstructural study." In Microscopy of Semiconducting Materials 2001, 507–10. CRC Press, 2018. http://dx.doi.org/10.1201/9781351074629-109.
Full textConference papers on the topic "Cu poor layer"
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Younan, Hua, Zhou Yongkai, Chen Yixin, Fu Chao, and Li Xiaomin. "Failure Mechanism Studies and Root Cause Identification of Nonstick on Pad on Microchip Al Bondpads." In ISTFA 2014. ASM International, 2014. http://dx.doi.org/10.31399/asm.cp.istfa2014p0215.
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Abstract It is well-known that underetch material, contamination, particle, pinholes and corrosion-induced defects on microchip Al bondpads will cause non-stick on pads (NSOP) issues. In this paper, the authors will further study NSOP problem and introduce one more NSOP failure mechanism due to Cu diffusion caused by poor Ta barrier metal. Based on our failure analysis results, the NSOP issue was not due to the assembly process, but due to the wafer fabrication. The failure mechanism might be that the barrier metal Ta was with pinholes, which caused Cu diffused out to the top Al layer, and then formed the “Bump-like” Cu defects and resulted in NSOP on Al bondpads during assembly process.
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Hung, L. Y., Y. P. Wang, and C. S. Hsiao. "Evaluation of Surface Finish on Build Up Substrate." In ASME 2003 International Electronic Packaging Technical Conference and Exhibition. ASMEDC, 2003. http://dx.doi.org/10.1115/ipack2003-35153.
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In recent years, the most explosive technologies in electronic systems have demanded ever-higher functionality, ever-faster circuit speeds, and always increasing interconnection density. Electrolytic and electroless nickel/gold (Ni/Au) deposition process are used commonly to provide flat, solderable pad surface finish on area array (BGA or CSP) packages and printed wiring boards (PWB). The electroless nickel/immersion gold (ENIG) process is widely used which do not requires plating lines for electrolytic plating, better meets the fine pitch wiring requirements. However, ENIG deposition process may cause or contribute to catastrophic, brittle, interfacial solder joint fractures. ENIG plating has previously shown lower reliability at solder joints. This is because Phosphorous segregation at the interface Sn-Ni intermetallic and Ni layer caused poor adhesion at that interface, especially high phosphorous content (10∼15%) of the electroless Ni. There have been many studies verified that Ni3P formation is a major factor, which causes weaker joint strength and flat fracture surface. Owing to sodium hypophosphite (NaH2PO2) was used to provide electron and return Ni ion to deposit on Cu pad for ENIG plating, it is not dodge that phosphorous element exist at the Ni layer. Hence, ph value, temperature and loading factor (plating area/ plating tank volume) in the plating path are controlled to reduce phosphorous content (less than 10%) to avoid Ni3P formation. Furthermore, ENIG has a potential risk of black pad, because Porous Au plating layer caused the oxidation of Ni layer underneath the Au plating to occur solder joint failure and low shear forces after assembly. In order to overcome foregoing problem, a flip chip ball grid array (FCBGA) test vehicle is used to compare three kinds surface finish electroless Ni/Au, direct gold and solder on Cu pad in this study 63Sn/37Pb solder bump is reflowed onto these substrates. High temperature storage test (HTS) is used to evaluate thickness and structure of IMC to affect solder joint attachment reliability. Ball shear test is used to measurement joint strength at various HTS time. Optical microscopy (OM) and scanning electron mcroscopy (SEM) are used to observe failure modes after ball shear.
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Talukdar, Tushar K., Liang Wang, and Sergio D. Felicelli. "Simulation of Residual Stress in Lens Deposited H13 Tool Steel on Copper Substrate." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62321.
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Solidification cracking represents a significant scientific and technical challenge in the rapid fabrication of bimetallic parts involving Cu and H13 tool steel. The main cause of the cracking formation is attributed to the residual stress accumulation, which depends on the thermal history and phase transformation during the deposition. In this research, a thermomechanical three-dimensional finite element model is developed to determine the temperature history and residual stress in Cu-H13 samples deposited by the Laser Engineered Net Shaping (LENS) process. The development of the model was carried out using the SYSWELD software package. The metallurgical transformations are taken into account using the temperature dependent material properties and the continuous cooling transformation diagram. Two different scanning strategies — alternative and unidirectional — are studied. The same model is also applied to a H13-H13 sample to compare the results. The input laser power is optimized for each layer and three different scanning speeds to maintain a steady molten pool size. It is observed that for a constant scanning speed the required laser power decreases with addition of more layers, and with the increase of scanning speed the laser power needs to be increased. The residual stress is found to be compressive near the center of the deposited wall and tensile at the free edges, which is consistent with the published experimental results in the literature. Similar stress distributions are obtained for both scanning strategies with higher stress concentration at the free edges of the interface between the substrate and the first layer. In these regions, the use of H13 substrate results in a higher stress accumulation than the Cu substrate.
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Udupa, Anirudh, Tatsuya Sugihara, and James B. Mann. "Glues Make Gummy Metals Easy to Cut." In ASME 2019 14th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/msec2019-2922.
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Abstract Metals such as Cu, Al, Ni, Ta and stainless steels, despite their softness and ductility, are considered difficult to machine. This is due to large cutting forces and corresponding formation of a very thick chip during cutting and hence these metals are referred to as “gummy”. Their poor machinability of these materials arises because of an unsteady and highly redundant mode of plastic deformation referred to as sinuous flow. The prevailing plastic deformation mode during machining can be overcome by the application of certain coatings and chemical media on the un-deformed free surface of the workpiece ahead of the cutting process. Using in-situ imaging and concurrent force measurements we present two different mechanochemical routes through which these media can improve machinability. The first route, which requires chemicals that adhere to the metal surface, such as glues and inks, improves cutting by inducing a change in the local plastic deformation mode — from sinuous flow to one characterized by periodic fracture or segmented flow. The second route, which requires chemicals that can react with the workpiece to form a low-friction layer, changes the sinuous flow mode to a smooth, laminar one. Both routes decrease cutting forces by more than 50% with order of magnitude improvement in surface texture as characterized by measured roughness and defect density. The results suggest a broad range of opportunities for improving performance of machining processes for many difficult-to-cut gummy metals.
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Babbe, Finn, Leo Choubrac, and Susanne Siebentritt. "Study on the quasi Fermi level splitting of Cu(In, Ga)Se2 absorber layers with Cu-rich and Cu-poor composition." In 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC). IEEE, 2016. http://dx.doi.org/10.1109/pvsc.2016.7749793.
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Rahman, M. Shafiqur, Paul J. Schilling, Paul D. Herrington, and Uttam K. Chakravarty. "Thermal Behavior and Melt-Pool Dynamics of Cu-Cr-Zr Alloy in Powder-Bed Selective Laser Melting Process." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11087.
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Abstract Selective laser melting (SLM) is a growing additive manufacturing (AM) technology which is capable of rapidly fabricating functional components in the medical and aviation industries. The thermophysical properties and melt-pool dynamics involved in the powder-bed SLM process play a crucial role to determine the part quality and process optimization. In this study, a 3-D computational fluid dynamics (CFD) model with Cu-Cr-Zr (C-18150) powder-bed is developed incorporating a moving conical volumetric heat source and temperature-dependent thermal properties to conduct the Multiphysics simulations of the SLM process. The melt-pool dynamics and its thermal behavior are investigated numerically and results for temperature profile, cooling rate, variation in density, thermal conductivity, specific heat capacity, and velocity in the melt pool are obtained for different laser beam specifications. The validation of the CFD model is conducted by comparing the simulation results for temperature and the melt-front motion with the analytical results found from the classical Stefan problem of the phase-change material. Studying the process parameters, melt-pool geometry, and thermal behavior of Cu-Cr-Zr alloy can generate valuable information to establish Cu-Cr-Zr as a low-cost engineering material in the AM industry.
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Rishi, Aniket M., and Anju Gupta. "Fundamental Insight on Morphological Changes of Graphene Nanoplatelets-Copper (GNP-Cu) Coatings: Effects of Repetitive Pool Boiling Tests." In ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2020 Heat Transfer Summer Conference and the ASME 2020 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/icnmm2020-1027.
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Abstract Being an extremely vigorous process involving a continuous intense bubble activity, repetitive pool boiling study is essential for many industrial applications. In this work, we have utilized highly thermally conductive and highly wettable graphene nanoplatelets (GNP) to form GNP-Copper based composite coatings for enhancing the pool boiling heat transfer performance. A multi-step electrodeposition technique was implemented to develop robust coatings on the copper substrates. Repetitive pool boiling studies were conducted on the 2% GNP-Cu coating which achieved the highest CHF of 286 W/cm2 and HTC of 204 kW/m2-°C. After investigating the effect of repetitive boiling on deposited GNP layers and morphology, it was found that GNP were reduced to form r-GNP (reduced GNP) and small increment in pore sizes was observed. Additionally, with repetitive boiling, it was observed that the heat transfer coefficient was continuously increased and compared to pristine copper surface 2% GNP-Cu coating yielded ∼456% increment in HTC at the end of third repetitive test.
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Suszko, Arthur, and Mohamed S. El-Genk. "A Composite Cu/HOPG Heat Spreader for Immersion Cooling of High Power Chips." In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48678.
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Presented are the results of a 3-D numerical analysis of a composite heat spreader for immersion cooling of a 20 × 20 mm microprocessor. The spreader is comprised of two 0.5 mm thick Copper (Cu) laments separated by a layer of highly ordered pyrolytic graphite (HOPG), 0.25–1.0 mm thick. The exposed surface of the top Cu lament has an average roughness, Ra = 1.79 μm and is cooled by saturation nucleate pool boiling of PF-5060 dielectric liquid. Investigate is the impact of δHOPG on the total power removed, the maximum temperature of the underlying chip, Tmax, and mitigating the chip hot spots. Increasing δHOPG increases the total power removed, but also increases Tmax. The spreader with a 1.0 mm-thick δHOPG is capable of removing 318 W, without exceeding 90% of the critical heat flux (CHF), at Tmax = 120°C. This power removal is significantly higher than that with an all Cu spreader of the same thickness of 90 W, but at much lower Tmax of 67°C. Composite spreaders with δHOPG = 0.25, 0.5, and 0.75 mm are capable of removing up to 160 W at Tmax = 85°C, 228 W at 100°C, and 292W at 115°C, respectively. The HOPG suppresses the transmission of hot spots to the spreader surface and increasing δHOPG does not mitigate the hot spots.
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Shuting, Chen, Zhu Lei, Teo Han Wei, Liu Binghai, Huang Yanhua, Ong Kenny, Mo Zhiqiang, et al. "A Comprehensive Failure Analysis Method and Mechanism Study on Ultra-Low-K Film Adhesion Failure." In ISTFA 2012. ASM International, 2012. http://dx.doi.org/10.31399/asm.cp.istfa2012p0203.
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Abstract The back-end-of-line (BEOL) structure of current IC devices fabricated for advanced technologies is composed of film stacks with multiple interfaces. The requirement of high interfacial strength is therefore necessary between the different layers in the BEOL stacks to ensure device reliability. To enhance the IC performance for new technologies, inter-level dielectric (ILD) made of SiO2 is replaced by low-k and ultra low-k (ULK) dielectrics, which possess a low dielectric constant but have poor mechanical strength. Therefore, the challenge in maintaining BEOL film stack integrity and reliability becomes even greater for advanced technologies. In this paper, we show failure analysis results on a case study of ULK adhesion failure during the IC manufacturing process. The symptoms of the BEOL failure are due to debris dropping on the wafer during chemical mechanical polishing (CMP) after Cu thin film deposition and failure of focusing at wafer extreme edge during the subsequent photolithography process. Extensive mechanical and chemical analyses were conducted on the ULK and adjacent thin films. It was revealed that the interface of ULK and Silicon Nitride from a suspected problematic machine showed abnormally low adhesion energy and high carbon composition. Troubleshooting on that suspected machine found a clog in the foreline. Based on the failure analysis and machine troubleshooting results, the failure mechanism of the case was discussed.
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Zhong, Zhaoping, Basheng Jin, Jixiang Lan, Changqing Dong, and Hongchang Zhou. "Experimental Study of Municipal Solid Waste (MSW) Incineration and Its Flue Gas Purification." In 17th International Conference on Fluidized Bed Combustion. ASMEDC, 2003. http://dx.doi.org/10.1115/fbc2003-011.
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This paper presents experimental study of fluidized absorption process for flue gas purification of co-combustion of municipal solid waste (MSW) and coal in a circulating fluidized bed Combustor (CFBC) test rig. The test rig is composed of a CFBC, coal/MSW feeding subsystem, ash cycle subsystem and flue gas purification subsystem. In the circulating fluidized bed, section area of fluidized bed is 230mm × 230mm and the freeboard is 460mm × 395mm. The total height of the test facility is 8m; height of bed and freeboard are 1.5m and 6m respectively. The preheated air enters the bed as primary air passing through distributor and provides oxygen for combustion. Six movable tubes immerged within the bed are used in adjusting the bed temperature. The cyclone separator is fixed up at the exit of chamber. The separated ashes return to chamber through the recycling feeder for decreasing the carbon content in fly ash and promoting the combustion efficiency. The flue gas from the exit of cyclone separator enters the air preheater to preheat the cold air at first, then enters the flue gas purification facility, finally be discharged into air by induced drafted fan passing through the stack. Coal is carried to a positive pressure feeding entrance by screw feeder and enters the bed. Secondary air is injected into a sealed end feeding pipe under MSW feeder, for enhancing the mixture in furnace, providing the oxygen for combustion and preventing from MSW remaining in the feeding pipe. The material of bed is silicon sand. Fluidized absorption facility for flue gas purification in MSW incineration is mainly composed of humidification system, absorption tower, flue gas reheater, fabric filter, slurry making pool, sediment pool and measurement subsystem. The temperature of flue gas from boiler by induced draft fan reduces to 120°C when flue gas enters the humidification region, which can increase the ability of acid gas absorption and prevent the slurry evaporation. When flue gas and limestone slurry enter the absorption tower, the three-phase material of gas, liquid and solid generates intense mixing and forms bubbling layer. The acid gases in flue gas are absorbed by limestone slurry, and a large amount of dusts are collected in reaction tank. Feeding oxidation air into slurry and agitating slurry simultaneously so as to promote the inner circulation of slurry and oxygenization of calcium sulphite. Flue gas passes through undulate demister which has high efficiency and low resistance, then enters fabric filter after reheating, finally be discharged into the stack by induced draft fan. The mixture of slurry and gypsum is emitted into the sediment pool through bottom and clear liquid in sediment pool returns to slurry making pool or absorption tower. The test results are as follows: the combustion efficiency is greater than 95%, the carbon content of fly ash is lower than 8%, and the loss of slag combustion is lower than 5%. When sorbent is limestone slurry, the concentration of slurry is 1%, the circulating ratio is 3, the jet rate is 5∼15m/s. The immerged depth of bubbling pipe under the slurry is 140mm. In the fluidized absorption facility for flue gas purification of MSW incineration, the desulfurization efficiency is >90%, the de-nitrification efficiency is 20∼30%, the de-chlorination efficiency is >80%, the removal efficiency of dust, heavy metal and dioxins are >99%, >98.6% and 99.35% respectively. After passing through fluidized absorption facility for flue gas purification of MSW incineration, when the concentration of O2 is 11%, the emission concentration of every components in flue gas are: SO2 is 20∼50mg/Nm3, NOx is 130∼270 mg/Nm3, HCl is 7∼12 mg/Nm3, HF is ∼8 mg/Nm3, CO2 is7∼8%, dust is 23∼67 mg/Nm3, Cr is 0.2172 mg/Nm3, Cu is 0.0454 mg/Nm3, Pb is 0.2963 mg/Nm3, Zn is 0.2074 mg/Nm3, Fe is 2.834 mg/Nm3, As is 1.112 × 10−3 mg/Nm3, Hg is 2.38 × 10−4 mg/Nm3 and dioxins is 0.1573 ng/Nm3. These emission concentrations are all lower than the Chinese emission standards. Some of them come close to the emission standards of developed country.