Journal articles: 'Passivation'

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Rong, Hua, Yogesh K. Sharma, and Philip A. Mawby. "Combined N₂O and Phosphorus Passivations for the 4H-SiC/SiO₂ Interface with Oxide Grown at 1400°C." Materials Science Forum 897 (May 2017): 344–47. http://dx.doi.org/10.4028/www.scientific.net/msf.897.344.

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Phosphorus (P) passivation is more effective than N2O passivation in improving the 4H-SiC/ SiO2 interface by reducing the number of traps at the 4H-SiC/SiO2 interface. This paper investigated the effect of combined N2O and phosphorus POA on the 4H-SiC/SiO2 interface with oxides grown at 1400°C and used in the fabrication of MOS capacitors and FETs. These fabricated devices are also compared with the ones which have been N2O and P passivations only. Results demonstrated that the phosphorus passivation technique provides the highest peak field-effect mobility for 4H-SiC MOSFETs (60 cm2/V.s), which is about 5 times higher than the value obtained for devices with N2O annealing. The combined N2O and phosphorus passivation technique, however, has shown a slight decrease in the peak field effect mobility value compared to the phosphorus passivation technique, but it is still much higher than the N2O passivation technique (12 cm2/V.s).

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Daves, Walter, A. Krauss, Martin Le-Huu, S. Kronmüller, Volker Haeublein, Anton J. Bauer, and Lothar Frey. "Comparative Study on Metallization and Passivation Materials for High Temperature Sensor Applications." Materials Science Forum 679-680 (March 2011): 449–52. http://dx.doi.org/10.4028/www.scientific.net/msf.679-680.449.

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We investigated the performance of different metallization/passivation systems for high temperature applications. The metallizations comprised a 150 nm sputtered Pt or a 150 nm e-beam evaporated PtRh layer on Ti/TiN underlayers, respectively. The passivation coatings consisted of amorphous PECVD SiOx, of amorphous stress-reduced PECVD SiNy, and of a SiOx/ SiNy stack. For samples with SiOx and SiOx/ SiNy passivation layers the electrical properties changed after a short high temperature anneal at 600 °C but then remained stable during further annealing. This was attributed to the formation of PtTi alloys, which stabilized the metallization stack. In samples with SiNy passivation a significant Pt out-diffusion into the passivation layer was observed. This led to a degradation of the electrical and mechanical properties. The best performance was achieved with Pt-based metallizations and SiOx or SiOx/SiNy passivations.

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Tyagi, Pawan. "GaAs(100) Surface Passivation with Sulfide and Fluoride Ions." MRS Advances 2, no. 51 (2017): 2915–20. http://dx.doi.org/10.1557/adv.2017.380.

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ABSTRACTInteraction of GaAs with sulfur can be immensely beneficial in reducing the deleterious effect of surface states on recombination attributes. Bonding of sulfur on GaAs is also important for developing novel molecular devices and sensors, where a molecular channel can be connected to GaAs surface via thiol functional group. However, the primary challenge lies in increasing the stability and effectiveness of the sulfur passivated GaAs. We have investigated the effect of single and double step surface passivation of n-GaAs(100) by using the sulfide and fluoride ions. Our single-step passivation involved the use of sulfide and fluoride ions individually. However, the two kinds of double-step passivations were performed by treating the n-GaAs surface. In the first approach GaAs surface was firstly treated with sulfide ions and secondly with fluoride ions, respectively. In the second double step approach GaAs surface was first treated with fluoride ions followed by sulfide ions, respectively. Sulfidation was conducted using the nonaqueous solution of sodium sulfide salt. Whereas the passivation steps with fluoride ion was performed with the aqueous solution of ammonium fluoride. Both sulfidation and fluoridation steps were performed either by dipping the GaAs sample in the desired ionic solution or electrochemically. Photoluminescence was conducted to characterize the relative changes in surface recombination velocity due to the single and double step surface passivation. Photoluminescence study showed that the double-step chemical treatment where GaAs was first treated with fluoride ions followed by the sulfide ions yielded the highest improvement. The time vs. photoluminescence study showed that this double-step passivation exhibited lower degradation rate as compared to widely discussed sulfide ion passivated GaAs surface. We also conducted surface elemental analysis using Rutherford Back Scattering to decipher the near surface chemical changes due to the four passivation methodologies we adopted. The double-step passivations affected the shallower region near GaAs surface as compared to the single step passivations.

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Guo, Xiao Fei, Yue Wang, and Hua Sun. "Comparative Research on Properties of Trivalent and Hexavalent Passive Film on Galvanized Steel." Advanced Materials Research 396-398 (November 2011): 1760–63. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.1760.

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The anticorrosive performances of various kinds of conversion films including hexavalent and trivalent chromium passivation were studied on galvanized steel. The hexavalent and trivalent passivations showed similar protection tendency in the corrosion tests, but the hexavalent passivation had slightly better results than trivalent one. It was found the difference in the corrosion resistance given by the two films was attributed to the difference of their morphology and thickness by SEM test, for the hexavalent film was denser, smoother and thicker. Using EDS and XRD experiments, it was found that the hexavalent and trivalent passive films had the same chemical element but different components. Considering the environmental protection, the trivalent passivation will have better developing prospect in the near future.

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Gaikwad, Pooja Vinod, Nazifa Rahman, Rooshi Parikh, Jalen Crespo, Zachary Cohen, and Ryan M. Williams. "Detection of the Inflammatory Cytokine IL-6 in Complex Human Serum Samples Via Rational Nanotube Surface Passivation Screening." ECS Meeting Abstracts MA2023-01, no. 9 (August 28, 2023): 1124. http://dx.doi.org/10.1149/ma2023-0191124mtgabs.

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In recent years, biosensors have emerged as a tool with strong potential in medical diagnostics. Single-walled carbon nanotube (SWCNT) based optical nanosensors have notably garnered interest due to the unique characteristics of their near-infrared fluorescence emission, including tissue transparency, photostability, and various chiralities with discrete absorption and fluorescence emission bands. The optoelectronic properties of SWCNT are sensitive to the surrounding environment, which makes them suitable for highly selective biosensing. Single-stranded (ss) DNA-wrapped SWCNTs have been reported as optical nanosensors for cancers and metabolic diseases. However, given the complexity of the human protein environment, non-specific interactions occur between SWCNT-based nanosensors and proteins. This inevitably leads to compromised selectivity of SWCNT-based nanosensors unless strategies for prevention are developed and employed. Non-covalent passivation of the ssDNA-SWCNT surface is reported as an excellent strategy to improve nanosensor selectivity in complex biological settings without causing irreversible changes to the optical properties of SWCNTs. Emerging studies have explored and successfully shown passivation using proteins and phospholipids. However, a systematic comparative study of passivating agents has not been done. In this work, we explore and compare the efficacy of select proteins, polymers, and surfactants as passivating agents. We, therefore, sought to evaluate various potential SWCNT surface passivation agents among broad classes of biomolecules and biomaterials. In the category of protein, Bovine serum albumin, dry-fat milk powder, and casein were selected due to their wide application to improve immunoassay selectivity. In the class of polymers, we selected 1 anionic and 2 cationic polymers, namely, polyethylene glycol, poly-ethylene imine, and poly-l-lysine. From surfactants, 2 phospholipids and 1 anionic surfactant: ammonium salt of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (16:0 PE2000PEG); 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE PEG phospholipids), and sodium dodecylbenzene sulfonate (SDBS) were selected. We analyzed the ability of all passivation agents to screen the non-specific interactions of ssDNA- SWCNTs in the presence of fetal bovine serum using fluorescence spectroscopy. The non-specific interactions between ssDNA-SWCNTs and proteins lead to a reorientation of the dipole moments and charge transfer in the corona phase around ssDNA-SWCNTs, leading to modulation in the center wavelength of the fluorescence as well as absorption peaks. We hence hypothesized that smaller changes in the center wavelength of the fluorescence peaks of passivated ssDNA-SWCNTs in presence of serum, lead to higher screening effect of the passivation agent towards non-specific interactions. We found that the most successful candidates were poly-L-lysine, polyethylene imine, dry-fat milk powder, and casein, in that order. Moreover, the ability to screen the interference was retained over a period of at least 3 hours. We further experimented with the four different mass ratios of passivating agents to ssDNA-SWCNTs and found that the mass ratio 50:1 for passivating agents: ss-DNA SWCNTs was most optimal. We confirmed the strength of passivation using absorption spectroscopy. We hypothesized that stronger surface saturation of the SWCNT-TAT6 is by a passivating agent in buffer conditions leads to a larger shift in the absorption peaks. We found that for the above successful passivation agents, the order of passivation strength followed the same trend as the screening abilities of the successful passivating agents, supporting this mechanistic hypothesis. Then, we evaluated an antibody-conjugated ssDNA-SWCNT nanosensor for the pro-inflammatory cytokine IL-6 with our successful passivation agents. We assessed the ability of the passivation agents to confer selective detection of IL-6 detection in clinical serum samples from patients with atherosclerosis and rheumatoid arthritis, both anticipated to have high IL-6 levels. Samples were compared to healthy human serum sample controls. We validated SWCNT fluorescence response with traditional immunoassays (ELISA). We expect this study to provide rational strategies to screen interferences from non-specific interactions and improve the selectivity of the SWCNT-based optical nanosensors for in vivo applications.

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Jha, Rajesh Kumar, Prashant Singh, Manish Goswami, and B. R. Singh. "Impact of HfO2 as a Passivation Layer in the Solar Cell Efficiency Enhancement in Passivated Emitter Rear Cell Type." Journal of Nanoscience and Nanotechnology 20, no. 6 (June 1, 2020): 3718–23. http://dx.doi.org/10.1166/jnn.2020.17510.

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We report the simulation of high-efficiency c-silicon Passivated Emitter Rear Contact (PERC) type solar cell structure with rear side passivated with HfO2 as a passivating material. Variation in the half length of pyramid has been carried out to investigate its effect on the solar cell electrical characteristics such as fill factor (FF), open circuit voltage (Voc) and efficiency. Aluminum back Surface Field (Al-BSF) and PERC type solar cell with Al2O3 passivation layer structures were also modeled for comparison. Effect of variation in passivation layer (HfO2) thickness (10 and 15 nm) and permittivity (k = 14 and 25) on the solar cell electrical characteristics has been investigated. Result shows the efficiency improvement in the PERC solar cell with HfO2 passivation layer by 0.5941% and 0.983% as compared to the Al-BSF and PERC with Al2O3 passivation layer at 8 μm pyramid half length. Increased series resistance and reduced FF has been observed with the incorporation of passivation layer at the solar cell structure. Negligible effect of passivation layer thickness has been observed on the solar cell electrical parameters whereas the permittivity value does have significant effect.

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Liu, Xiaoliang, Qian Li, Yan Zhang, Yongbin Yang, Bin Xu, and Tao Jiang. "Formation Process of the Passivating Products from Arsenopyrite Bioleaching by Acidithiobacillus ferrooxidans in 9K Culture Medium." Metals 9, no. 12 (December 6, 2019): 1320. http://dx.doi.org/10.3390/met9121320.

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Arsenopyrite is a common sulphide mineral occurring in deposits of gold ore that makes the extraction of gold difficult and, thus, pre-treatment is necessary prior to gold leaching. Bioleaching pre-treatment of arsenopyrite has drawn significant attention owing to its environmental friendliness, low cost and simple operation. A critical impedance of bioleaching to its large-scale industrial application is the slow leaching kinetics. Various passivating products on the surface of arsenopyrite have been found to limit the bioleaching process. This paper reports results from an in-depth investigation into the formation process of passivating products from arsenopyrite bioleaching by Acidithiobacillus ferrooxidans in 9K culture medium including bioleaching experiments and physicochemical analyses of the materials as well as thermodynamic analyses of the leaching system. The results of phase transformation and morphological change of the solid products suggest that the passivation occurring in the bioleaching of arsenopyrite is largely attributed to an initially formed passivating film consisting mainly of realgar (As2S2), orpiment (As2S3) and elemental sulphur (S0) on the arsenopyrite surface. Based on the results, the paper also proposes possible passivation mechanisms to allow for a better understanding on the passivation behaviour of the bioleaching of arsenopyrite.

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Sioncke, Sonja, Claudia Fleischmann, Dennis Lin, Evi Vrancken, Matty Caymax, Marc Meuris, Kristiaan Temst, et al. "S-Passivation of the Ge Gate Stack Using (NH₄)₂S." Solid State Phenomena 187 (April 2012): 23–26. http://dx.doi.org/10.4028/www.scientific.net/ssp.187.23.

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The last decennia, a lot of effort has been made to introduce new channel materials in a Si process flow. High mobility materials such as Ge need a good gate stack passivation in order to ensure optimal MOSFET operation. Several routes for passivating the Ge gate stack have been explored in the last years. We present here the S-passivation of the Ge gate stack: (NH4)2S is used to create a S-terminated Ge surface. In this paper the S-treatment is discussed. The S-terminated Ge surface is not chemically passive but can still react with air. After gate oxide deposition, the Ge-S bonds are preserved and an adequate passivation is found for pMOS operation.

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9

Jones, K. M., M. M. Al-Jassim, and B. L. Soport. "TEM investigation of hydrogen-implanted polycrystalline Si." Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 868–69. http://dx.doi.org/10.1017/s0424820100088658.

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Hydrogen implantation for passivating grain boundaries and dislocations in polycrystalline silicon solar cells was studied by TEM and HREM. Back-surface passivation is being investigated because studies have shown that front-side passivation causes serious surface damage with resultant surface recombination velocities as high as 7 x 107 cm/sec. Front-side hydrogenation also restricts solar cell fabrication processes. Since the passivation of defects must occur within the entire volume of the cell, particular emphasis was placed on the depth distribution of hydrogen. The hydrogen implantation was carried out In a Kaufman ion beam system using a beam energy of 0.5-1.5 keV and a beam current of 55 mA for 15 minutes.

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Chowdhury, Sanchari, Muhammad Quddammah Khokhar, Duy Phong Pham, and Junsin Yi. "Al₂O₃/MoO_x Hole-Selective Passivating Contact for Silicon Heterojunction Solar Cell." ECS Journal of Solid State Science and Technology 11, no. 1 (January 1, 2022): 015004. http://dx.doi.org/10.1149/2162-8777/ac4d83.

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Carrier selective contact (CSC) layers have been extensively studied to realize high passivation effect in solar cells. Excellent passivation properties of Al2O3 and a-Si:H(i) as passivating interlayers between the hole-selective contact (HSC) MoOx and p-type c-Si wafer surface are reported herein. MoOx single layer exhibits a high work function value (≥5.0 eV), which can cause sufficient band bending in the band structure for HSC. An Al2O3/MoOx contact exhibits a significantly higher transmittance and surface passivation compared with that of an a-Si:H(i)/MoOx contact. The passivation results for Al2O3/MoOx contact are a carrier lifetime (τeff) of 830 μs and implied open circuit voltage (iVOC) of 726 mV, whereas for conventional a-Si:H(i)/MoOx contact, the corresponding values are 770 μs and 716 mV. Delicate thickness optimization was performed using experimental and simulation results for Al2O3/MoOx and a-Si:H(i)/MoOx stacks to achieve high performance in p-type c-Si solar cells.

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Birant, Gizem, Jorge Mafalda, Romain Scaffidi, Jessica de Wild, Dilara Gokcen Buldu, Thierry Kohl, Guy Brammertz, Marc Meuris, Jef Poortmans, and Bart Vermang. "Rear surface passivation of ultra-thin CIGS solar cells using atomic layer deposited HfOx." EPJ Photovoltaics 11 (2020): 10. http://dx.doi.org/10.1051/epjpv/2020007.

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In this work, hafnium oxide layer is investigated as rear surface passivation layer for ultra-thin (550 nm) CIGS solar cells. Point contact openings in the passivation layer are realized by spin-coating potassium fluoride prior to absorber layer growth. Contacts are formed during absorber layer growth and visualized with scanning electron microscopy (SEM). To assess the passivating qualities, HfOx was applied in a metal-insulator-semiconductor (MIS) structure, and it demonstrates a low interface trap density in combination with a negative density of charges. Since we used ultra-thin devices that are ideal to probe improvements at the rear, solar cell results indicated improvements in all cell parameters by the addition of 2 nm thick HfOx passivation layer with contact openings.

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Özeren, Mehmet Derya, Áron Pekker, Katalin Kamarás, and Bea Botka. "Evaluation of surface passivating solvents for single and mixed halide perovskites." RSC Advances 12, no. 44 (2022): 28853–61. http://dx.doi.org/10.1039/d2ra04278a.

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Various surface passivating solvents with different functional groups were used to investigate solvent–perovskite interactions. The identification of the underlying mechanisms provides insight for new surface passivation strategies.

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Kabalan, Amal. "A Comparative Study on the Effects of Passivation Methods on the Carrier Lifetime of RIE and MACE Silicon Micropillars." Applied Sciences 9, no. 9 (April 30, 2019): 1804. http://dx.doi.org/10.3390/app9091804.

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Silicon micropillars have been suggested as one of the techniques for improving the efficiency of devices. Fabrication of micropillars has been done in several ways—Metal Assisted Chemical Etching (MACE) and Reactive Ion Etching (RIE) being the most popular techniques. These techniques include etching through the surface which results in surface damage that affects the carrier lifetime. This paper presents a study that compares the carrier lifetime of micropillars fabricated using RIE and MACE methods. It also looks at increasing carrier lifetime by surface treatment using three main approaches: surface passivation by depositing Al2O3, surface passivation by depositing SiO2/SiN, and surface passivation by etching using KOH and Hydrofluoric Nitric Acetic (HNA) solution. It was concluded that passivating with SiO2 and SiN results in the highest carrier lifetime on the MACE and RIE pillars.

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Park, HyunJung, Soohyun Bae, Se Jin Park, Ji Yeon Hyun, Chang Hyun Lee, Dongjin Choi, Dongkyun Kang, et al. "Role of polysilicon in poly-Si/SiOx passivating contacts for high-efficiency silicon solar cells." RSC Advances 9, no. 40 (2019): 23261–66. http://dx.doi.org/10.1039/c9ra03560e.

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The efficiency of silicon solar cell with poly-Si/SiOx passivating contact was improved by etching of poly-Si which improves short circuit current density without affecting passivation quality and fill factor.

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Maslov, V. P., A. V. Fedorenko, V. P. Kladko, O. Yo Gudymenko, K. M. Bozhko, and N. M. Zashchepkina. "Structure and electrical resistance of the passivating ZnSe layer on Ge." Semiconductor Physics, Quantum Electronics and Optoelectronics 24, no. 04 (November 23, 2021): 425–30. http://dx.doi.org/10.15407/spqeo24.04.425.

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In this article, we have considered the p-i-n Ge photodetector with ZnSe passivating layer. Passivation layer needs to be protected photodetector from dust, rain drops and other external influences. However, this passivation layer can cause errors in photodetector image. When creating a passivating ZnSe layer on Ge, which is used in p-i-n Ge photodetectors, we found two additional phases GeSe and GeSe2 that do not contradict with their state diagram. The above phases can have an essential effect on performances of the passivating layer. Therefore, to study the electrical resistance of this layer, we prepared model samples of layers containing the GeSe and GeSe2 with the thickness 0.5…1.8 µm and area 1 cm2. To measure the electrical resistance of these layers, we used elastic contacts. The performed measurements have shown that Se layers on Ge have an intermediate resistance between that of ZnSe on Ge and pure Ge, and, therefore, the effect of additional phases practically does not worsen the passivating properties of the ZnSe layer on Ge.

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Tung, Ha Thanh, Nguyen Thu Thao, and Lam Quang Vinh. "The Reduced Recombination and the Enhanced Lifetime of Excited Electron in QDSSCs Based on Different ZnS and SiO2 Passivation." International Journal of Photoenergy 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/8545207.

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In this study, we focus on the enhanced absorption and reduced recombination of quantum dot solar cells based on photoanodes which were coated by different ZnS or SiO2 passivations using the successive ionic layer absorption and reaction methods. The quantum dot solar cells based on photoanode multilayers, which were coated with a ZnS or SiO2 passivation, increased dramatic absorption in the visible light region as compared with other photoanodes and reduced rapid recombination proccesses in photovoltaic. As a result, the performance efficiency of TiO2/CdS/CdSe photoanode with SiO2 passivation increased by 150% and 375% compared with TiO2/CdS/CdSe with ZnS passivation and TiO2/CdSe photoanode, respectively. For this reason, we note that the tandem multilayers can absorb more wavelengths in the visible light region to increase a large amount of excited electrons, which are transferred into the TiO2 conduction band, and decrease number of electrons returned to the polysulfide electrolyte from QDs when a ZnS or SiO2 passivation is consumed. Moreover, it is obvious that there was a far shift towards long waves in UV-Vis spectra and a sharp drop of intensity in photoluminescence spectra. In addition, the dynamic process in solar cells was carried out by electrochemical impedance spectra.

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Fan, Bin, Guo Wei He, Ling Hui Liu, and Jing Xin Wang. "Study on Clean Production Technologies of Electrolysis Manganese Passivation." Advanced Materials Research 308-310 (August 2011): 790–95. http://dx.doi.org/10.4028/www.scientific.net/amr.308-310.790.

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The passivator of potassium dichromate is one of the main electrolysis manganese passivation technologies in China. The biggest problem of hexavalent chromium passivation is chromium emission. The end-pipe treatment of Cr-containing effluents can be understood as detoxification and precipitation. Here the highly toxicity Cr(Ⅵ) is reduced to low toxicity Cr(Ⅲ) . In alkaline conditions, Cr (Ⅲ)is precipitated in the type of chromium hydroxide and produce chromium residue. The landfill of Chromium residue is a big problem to environment safety. The measures of clean process were reviewed around with emission reduction of Cr.

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Abbas, Mahmoud, M. A. Shahin, Mohamed M. I. Ahmed, and Magdy Kasem. "Passivation of Recirculating Open Water Cooling Systems Using New Organic Passivator." Journal of University of Shanghai for Science and Technology 23, no. 12 (December 22, 2021): 375–86. http://dx.doi.org/10.51201/jusst/21/121028.

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It is well know that recirculating open cooling water system at metal/ water surface contact appear frequent corrosion products, like scales, foaling and material losses which are have great effect on cooling process. Passivation helps to maintain clean heat transfer surface by inhibiting oxides scales through creating outer passive layer. Passivators are substances which usually have a sufficiently high equilibrium potential and sufficiently low over potential decrease corrosion rate on attainment of passivity. One of the most popular passivator is organic phosphate Phosphinosuccinic oligomer C15H14O4P component (PSO) The study of passivation of carbon steel pipe line in recirculating open cooling water system was the aim of this present work. Maximum efficiency of passivator was determined and surface morphology were investigated using optical, scanning microscopy, phase analysis of the formed protective layer was exam by XRD and EDX. Corrosion in running water with and without PSO at 2 m3/hr flow rate was investigated using corrosion coupon rack. It was found that 200 ppm (PSO) decreases corrosion rate of carbon steel pipe in 3.5% NaCL solution from 23 to 7 mpy in stagnate water corrosion testing, while in running water in 3.5% NaCL solution it decreases from 45 to 18 mpy. XDR showed that the protective layer due to passivation is mainly Magnetite (Fe3O4) compound.

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Desthieux, Anatole, Jorge Posada, Pierre-Philippe Grand, Cédric Broussillou, Barbara Bazer-Bachi, Gilles Goaer, Davina Messou, Muriel Bouttemy, Etienne Drahi, and Pere Roca i Cabarrocas. "Impact of PECVD μc-Si:H deposition on tunnel oxide for passivating contacts." EPJ Photovoltaics 11 (2020): 3. http://dx.doi.org/10.1051/epjpv/2020001.

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Passivating contacts are becoming a mainstream option in current photovoltaic industry due to their ability to provide an outstanding surface passivation along with a good conductivity for carrier collection. However, their integration usually requires long annealing steps which are not desirable in industry. In this work we study PECVD as a way to carry out all deposition steps: silicon oxide (SiOx), doped polycrystalline silicon (poly-Si) and silicon nitride (SiNx:H), followed by a single firing step. Blistering of the poly-Si layer has been avoided by depositing (p+) microcrystalline silicon (μc-Si:H). We report on the impact of this deposition step on the SiOx layer deposited by PECVD, and on the passivation properties by comparing PECVD and wet-chemical oxide in this hole-selective passivating contact stack. We have reached iVoc > 690 mV on p-type FZ wafers for wet-chemical SiOx\(p+) μc-Si\SiNx:H with no annealing step.

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Barek, Jiri. "How to Improve the Performance of Electrochemical Sensors via Minimization of Electrode Passivation." Chemosensors 9, no. 1 (January 6, 2021): 12. http://dx.doi.org/10.3390/chemosensors9010012.

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It follows from critical evaluation of possibilities and limitations of modern voltammetric/amperometric methods that one of the biggest obstacles in their practical applications in real sample analysis is connected with electrode passivation/fouling by electrode reaction products and/or matrix components. This review summarizes possibilities how to minimise these problems in the field of detection of small organic molecules and critically compares their potential and acceptability in practical laboratories. Attention is focused on simple and fast electrode surface renewal, the use of disposable electrodes just for one and/or few measurements, surface modification minimising electrode fouling, measuring in flowing systems, application of rotating disc electrode, the use of novel separation methods preventing access of passivating particles to electrode surface and the novel electrode materials more resistant toward passivation. An attempt is made to predict further development in this field and to stress the need for more systematic and less random research resulting in new measuring protocols less amenable to complications connected with electrode passivation.

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Solcansky, M., J. Vanek, and A. Poruba. "Quinhydrone Chemical Passivation of a Silicon Surface for Minority Carrier Bulk-Lifetime Measurements." International Journal of Photoenergy 2012 (2012): 1–4. http://dx.doi.org/10.1155/2012/732647.

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For the measurement of the minority carrier bulk-lifetime the characterization method MW-PCD is used, where the result of measurement is the effective carrier lifetime, which is very dependent on the surface recombination velocity and therefore on the quality of a silicon surface passivation. This work deals with an examination of a different solution types for the chemical passivation of a silicon surface. Various solutions are tested on silicon wafers for their consequent comparison. The main purpose is to find optimal solution, which suits the requirements of a time stability and start-up velocity of passivation, reproducibility of the measurements and a possibility of a perfect cleaning of a passivating solution remains from a silicon surface, so that the parameters of a measured silicon wafer will not worsen and there will not be any contamination of the other wafers series in the production after a repetitive return of the measured wafer into the production process. The cleaning process itself is also a subject of a development.

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Zhao, Yang, Yuchen Liu, Xin Gai, Yun Bai, Tao Zhang, Dake Xu, and Fuhui Wang. "Investigating the Stress Corrosion Cracking (SCC) Susceptibility of Ti-6Al-4V Alloys Fabricated by Electron Beam Melting in Deep-Sea Environment." Corrosion 77, no. 8 (May 11, 2021): 853–65. http://dx.doi.org/10.5006/3822.

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The stress corrosion cracking (SCC) susceptibility of electron beam melted Ti-6Al-4V alloy (ET) was compared with the conventional wrought alloy (WT). The electrochemical and slow strain rate tensile (SSRT) tests, as well as surface analysis, were conducted under simulated shallow and deep-sea environment. Under shallow conditions, the SCC susceptibility of both alloys was almost the same because of consistent passivation and repassivation performance of the passivating film. However, under deep-sea conditions, SCC susceptibility of ET was higher than that of WT due to stronger textured-like surface that appeared on ET alloy, where early developed passive film broke down, demonstrating lower passivation and repassivation rate.

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Sharma, Yogesh K., Ayayi C. Ahyi, Tamara Isaacs-Smith, Aaron Modic, Yi Xu, Eric Granfukel, Mike R. Jennings, et al. "Thin PSG Process for 4H-SiC MOSFET." Materials Science Forum 778-780 (February 2014): 513–16. http://dx.doi.org/10.4028/www.scientific.net/msf.778-780.513.

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The use of phosphorous as a passivating agent for the SiO2/4H-SiC interface increases the field effect channel mobility of 4H-SiC MOSFET to twice the value, 30-40cm2/V-s, that is obtained with a high temperature anneal in nitric oxide (NO). A solid SiP2O7planar diffusion source is used to produce P2O5for the passivation of the interface. Incorporation of phosphorous into SiO2leads to formation of phosphosilicate glass (PSG) which is known to be a polar material causes device instability. With a new modified thin phosphorous (P) passivation process, as described in this abstract, we can improve the stability of MOSFETs significantly with mobility around 75cm2/V.s.

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Clerix, Jan-Willem J., Golnaz Dianat, Annelies Delabie, and Gregory N. Parsons. "In situ analysis of nucleation reactions during TiCl₄/H₂O atomic layer deposition on SiO₂ and H-terminated Si surfaces treated with a silane small molecule inhibitor." Journal of Vacuum Science & Technology A 41, no. 3 (May 2023): 032406. http://dx.doi.org/10.1116/6.0002493.

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Small-molecule inhibitors have recently been introduced for passivation during area-selective deposition (ASD). Small silanes like ( N, N-dimethylamino)trimethylsilane (DMATMS) selectively react with −OH sites on SiO2 to form a less reactive –OSi(CH3)3 terminated surface. The –OSi(CH3)3 surface termination can inhibit many atomic layer deposition (ALD) processes, including TiCl4/H2O ALD. However, the mechanisms by which ALD is inhibited and by which selectivity is eventually lost are not well understood. This study uses in situ Fourier-transform infrared spectroscopy to probe the adsorption of DMATMS on SiO2 and the subsequent reactions when the passivated surface is exposed to TiCl4/H2O ALD. The chemisorption of DMATMS on isolated –OH groups on SiO2 is shown to inhibit the reaction with TiCl4. Further, we find that starting with an inherently inhibiting H-terminated Si surface, DMATMS can also react with residual –OH groups and reduce the extent of nucleation. Finally, using Rutherford backscattering spectrometry, the effectiveness of DMATMS passivation on SiO2 and H-terminated Si is quantified during extended ALD cycle numbers. The insight into the mechanisms of passivation by DMATMS and passivation loss can enable the rational design of highly selective ASD processes by carefully matching compatible surfaces, passivating agents, and ALD precursors.

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Ghandi, Reza, Martin Domeij, Romain Esteve, Benedetto Buono, Adolf Schöner, Ji Sheng Han, Sima Dimitrijev, Sergey A. Reshanov, Carl Mikael Zetterling, and Mikael Östling. "Experimental Evaluation of Different Passivation Layers on the Performance of 3kV 4H-SiC BJTs." Materials Science Forum 645-648 (April 2010): 661–64. http://dx.doi.org/10.4028/www.scientific.net/msf.645-648.661.

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In this work, the electrical performance in terms of maximum current gain, ON-resistance and blocking capability has been compared for 4H-SiC BJTs passivated with different surface passivation layers. Variation in BJT performance has been correlated to densities of interface traps and fixed oxide charge, as evaluated through MOS capacitors. Six different methods were used to fabricate SiO2 surface passivation on BJT samples from the same wafer. The highest current gain was obtained for PECVD deposited SiO2 which was annealed in N2O ambient at 1100 °C during 3 hours. Variations in breakdown voltage for different surface passivations were also found, and this is attributed to differences in fixed oxide charge that can affect the optimum dose of the high voltage JTE termination.

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Li, Yujie. "Effects of Different Passivating Agents on Cd Pollution in Alkaline Farmland Soil." Academic Journal of Science and Technology 10, no. 2 (April 15, 2024): 129–32. http://dx.doi.org/10.54097/ftb33025.

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In this study, cadmium-polluted farmland in the southern suburbs of Jiaozuo, Henan Province was selected as the research object. Under the field conditions, two passivating agents such as aluminosilicate and calcium-aluminum hydrotalcite were added respectively, and the cadmium form content was analyzed by BCR extraction method. The passivating effect of different passivating agents on soil cadmium in alkaline farmland in northern China was studied under the application rate of 200 and 400kg/mu. The results showed that silicoaluminate and calcium-aluminum hydrotalcite reduced soil pH value in different degrees, but had little effect on soil pH value. The two passivating agents can convert the soluble Cd of weak acid to the residual Cd, and the transformation effect is more significant with the increase of the applied amount. The passivation effect is ranked as calcium aluminum hydrotalcite > silicaluminate, among which 400 kg/mu of calcium aluminum hydrotalcite has the most obvious passivation effect, and the effective content of Cd is reduced by 70.5% compared with group CK. In general, after the application of two passivators and different amounts, the soluble Cd content of weak acid in soil decreased significantly, the reducible Cd content decreased slightly, the oxidizable Cd content increased slightly, and the residual Cd content increased significantly.

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Shu, Xiaohua, Wei Tian, Shiqing Xiong, Wenlong Zhang, and Qian Zhang. "Straw Biochar at Different Pyrolysis Temperatures Passivates Pyrite by Promoting Electron Transfer from Biochar to Pyrite." Processes 10, no. 10 (October 21, 2022): 2148. http://dx.doi.org/10.3390/pr10102148.

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To control acid mine drainage (AMD) at source, biochar, a new green and environmentally friendly passivator has been introduced to passivate pyrite. However, the raw material and pyrolysis temperature largely determine the physical and chemical properties of biochar, the causal relationship between biochar and pyrite and the underlying mechanism are still unknown. Here, biochar materials (rice-straw biochar (RSB) and sugarcane bagasse biochar (SBB)) at different pyrolysis temperatures (300–600 °C) were utilized for the passivation of pyrite. The results of our investigations revealed that the passivation ability of RSB was superior to that of SBB. The addition of RSB with higher pyrolysis temperatures could greatly enhance the passivation efficiency of pyrite. RSB-500 (produced at a pyrolysis temperature of 500 °C) achieved the best passivation effect on pyrite. RSB can form Fe-O bonds through C=O bonding with pyrite. Moreover, the addition of RSB created a reducing environment in the mixture system because of its strong electron-donation capacity (EDC) and altered the energy-band structure of pyrite, which promoted the transfer of electrons from biochar to pyrite. On the contrary, the addition of SBB did not result in the formation of Fe-O bonds with pyrite. In addition, the EDC of SBB was also lower than that of RSB and it had almost no effect on the band structure of pyrite. Hence it did not alter the direction of the electron migration. These findings shed light on the mechanism of biochar passivation of pyrite and provide a theoretical foundation for selecting suitable biochar materials for AMD prevention at source.

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Martinez, Brisa, Citlalli Gaona Tiburcio, David Bastidas, Maria Lara-Banda, Oliver Samaniego, and Facundo Almeraya Calderon. "Electrochemical Evaluation of 15-5PH Stainless Steel Passivated in Citric Acid." ECS Transactions 106, no. 1 (January 31, 2022): 223–28. http://dx.doi.org/10.1149/10601.0223ecst.

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Most of the current aircraft are made of metal, which are exposed throughout their useful life to extreme meteorological conditions, defying the design factors in the aircraft, where the fight against corrosion has always been a determining factor. One of the protection methods used in aircraft components made of stainless steel is passivation. The study carried out consisted of the evaluation of 15-5PH stainless steel, passivated. Citric acid was used as passivating agent for passivation for 30 and 90 min with a temperature of 25 ° C. The electrochemical evaluation was carried out through the techniques of Cyclic Potentiodynamic Polarization Curves in the electrolytes of NaCl at 3.5% wt and H2SO4 at 1% wt.

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Zhang, Jun, Wei Ming Lu, Chun Lan Zhou, Zhen Li Wen, Lei Zhao, Hai Ling Li, Hong Wei Diao, Yao Zhang, and Wen Jing Wang. "Excellent Surface Passivation by Silicon Dioxide Grown with a Electrochemical Method." Materials Science Forum 685 (June 2011): 48–54. http://dx.doi.org/10.4028/www.scientific.net/msf.685.48.

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A novel method to grow silicon dioxide layers for passivating the silicon surface is given more attention. SiO2was grown by applying a positive voltage across silicon wafers in a nitric acid solution at low temperature. After annealing in N2media at 900°C for 20min, excellent surface passivation was achieved. The maximum effective lifetime of the silicon arrived at 29.8μs and 29.75μs, which was three times the value of silicon without passivation. The effective lifetime of other types of silicon could be ten times the initial value without the silicon dioxide. A comparison study of the effect of the FGA, annealing at low temperature and annealing in N2or O2containing medium at high temperature were investigated.

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Matsui, Takuya, and Hitoshi Sai. "(Invited, Digital Presentation) Advanced Passivating Contacts for Silicon Photovoltaics." ECS Meeting Abstracts MA2022-02, no. 16 (October 9, 2022): 827. http://dx.doi.org/10.1149/ma2022-0216827mtgabs.

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Carrier selective passivating contacts, which provide dual functions of surface defect passivation and extracting one type of charge carriers, is a key enabler for high efficiency Si solar cells. Here we introduce two passivating contact materials developed in our lab: one is the hydrogenated nanocrystalline silicon (nc-Si:H) and the other is the metal-oxide (non-silicon) material. For the nc-Si:H, it is demonstrated that the use of the (p)nc-Si:H/(i)a-Si:H stack instead of the conventional (p)a-Si:H/(i)a-Si:H in silicon heterojunction solar cells provides not only a mitigation of the parasitic absorption loss but also improvements in passivation and electrical contact properties. This results in an efficiency increase by 0.3-0.6% absolute compared to our reference cell, and a best cell efficiency of 23.5%. For metal-oxide material, we have developed an atomic-layer-deposited titanium oxide (TiOx) that functions as an efficient and transparent hole-selective passivating contact without using buffer layer, leading to the proof-of-concept solar cells with efficiencies above 20%. An example of applying the developed contact material as a recombination junction layer of the perovskite/Si tandem solar cell will be presented.

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Köhler, Malte, Manuel Pomaska, Paul Procel, Rudi Santbergen, Alexandr Zamchiy, Bart Macco, Andreas Lambertz, et al. "A silicon carbide-based highly transparent passivating contact for crystalline silicon solar cells approaching efficiencies of 24%." Nature Energy 6, no. 5 (April 15, 2021): 529–37. http://dx.doi.org/10.1038/s41560-021-00806-9.

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AbstractA highly transparent passivating contact (TPC) as front contact for crystalline silicon (c-Si) solar cells could in principle combine high conductivity, excellent surface passivation and high optical transparency. However, the simultaneous optimization of these features remains challenging. Here, we present a TPC consisting of a silicon-oxide tunnel layer followed by two layers of hydrogenated nanocrystalline silicon carbide (nc-SiC:H(n)) deposited at different temperatures and a sputtered indium tin oxide (ITO) layer (c-Si(n)/SiO2/nc-SiC:H(n)/ITO). While the wide band gap of nc-SiC:H(n) ensures high optical transparency, the double layer design enables good passivation and high conductivity translating into an improved short-circuit current density (40.87 mA cm−2), fill factor (80.9%) and efficiency of 23.99 ± 0.29% (certified). Additionally, this contact avoids the need for additional hydrogenation or high-temperature postdeposition annealing steps. We investigate the passivation mechanism and working principle of the TPC and provide a loss analysis based on numerical simulations outlining pathways towards conversion efficiencies of 26%.

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Perera, Yasiru Randika, Joanna Xiuzhu Xu, Dhanush L. Amarasekara, Alex C. Hughes, Ibraheem Abbood, and Nicholas C. Fitzkee. "Understanding the Adsorption of Peptides and Proteins onto PEGylated Gold Nanoparticles." Molecules 26, no. 19 (September 24, 2021): 5788. http://dx.doi.org/10.3390/molecules26195788.

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Polyethylene glycol (PEG) surface conjugations are widely employed to render passivating properties to nanoparticles in biological applications. The benefits of surface passivation by PEG are reduced protein adsorption, diminished non-specific interactions, and improvement in pharmacokinetics. However, the limitations of PEG passivation remain an active area of research, and recent examples from the literature demonstrate how PEG passivation can fail. Here, we study the adsorption amount of biomolecules to PEGylated gold nanoparticles (AuNPs), focusing on how different protein properties influence binding. The AuNPs are PEGylated with three different sizes of conjugated PEG chains, and we examine interactions with proteins of different sizes, charges, and surface cysteine content. The experiments are carried out in vitro at physiologically relevant timescales to obtain the adsorption amounts and rates of each biomolecule on AuNP-PEGs of varying compositions. Our findings are relevant in understanding how protein size and the surface cysteine content affect binding, and our work reveals that cysteine residues can dramatically increase adsorption rates on PEGylated AuNPs. Moreover, shorter chain PEG molecules passivate the AuNP surface more effectively against all protein types.

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33

Theeuwes, Roel J., Jimmy Melskens, Wolfhard Beyer, Uwe Breuer, Astrid Gutjahr, Agnes A. Mewe, Bart Macco, and Wilhelmus M. M. Kessels. "Hydrogenation of p⁺ poly-Si by Al₂O₃ nanolayers prepared by atomic layer deposition." Journal of Applied Physics 133, no. 14 (April 14, 2023): 145301. http://dx.doi.org/10.1063/5.0141029.

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Polysilicon (poly-Si) passivating contacts have enabled some of the highest lab-scale crystalline silicon (c-Si) solar cell conversion efficiencies, largely due to their excellent surface passivation quality, which can be aided by means of hydrogenation treatments. One frequently applied method is to use hydrogen-rich capping layers, such as Al2O3 or SiNx, which can provide hydrogen to the poly-Si/SiOx/Si interface upon annealing. In this work, the effect of the deposition conditions of the Al2O3 layers, fabricated by various types of atomic layer deposition (ALD), on the hydrogenation of p+ poly-Si is investigated, and it is compared to the direct passivation of c-Si by the same Al2O3 layers. It is found that excellent hydrogenation of the p+ poly-Si by Al2O3 could be reached by a wide range of ALD conditions, but higher annealing temperatures were required as compared to passivation of c-Si. The different ALD conditions result in Al2O3 layers with varying refractive indices, O/Al ratios, and hydrogen content, although these material properties become highly similar upon annealing. Furthermore, the p+ poly-Si layer appears to act as a reservoir for hydrogen, which alters the hydrogen effusion profiles of the Al2O3 layers. The results show that a wide range of Al2O3 layers are highly suitable for hydrogenation of p+ poly-Si and provide more insight into the hydrogenation process of poly-Si passivating contacts.

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Matkivskyi, Vladyslav, Oskari Leiviskä, Sigurd Wenner, Hanchen Liu, Ville Vähänissi, Hele Savin, Marisa Di Sabatino, and Gabriella Tranell. "Atomic Layer Deposition of Titanium Oxide-Based Films for Semiconductor Applications—Effects of Precursor and Operating Conditions." Materials 16, no. 16 (August 8, 2023): 5522. http://dx.doi.org/10.3390/ma16165522.

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Two widely used atomic layer deposition precursors, Tetrakis (dimethylamido) titanium (TDMA-Ti) and titanium tetrachloride (TiCl4), were investigated for use in the deposition of TiOx-based thin films as a passivating contact material for solar cells. This study revealed that both precursors are suited to similar deposition temperatures (150 °C). Post-deposition annealing plays a major role in optimising the titanium oxide (TiOx) film passivation properties, improving minority carrier lifetime (τeff) by more than 200 µs. Aluminium oxide deposited together with titanium oxide (AlOy/TiOx) reduced the sheet resistance by 40% compared with pure TiOx. It was also revealed that the passivation quality of the (AlOy/TiOx) stack depends on the precursor and ratio of AlOy to TiOx deposition cycles.

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Tian, Xin Li, Zhi Yuan Wu, An Ying She, and Zhong Xiang Hu. "Passivation Model of Diamond Grinding Wheel in Constant-Force Grinding of Si₃N₄ Ceramic." Key Engineering Materials 359-360 (November 2007): 94–97. http://dx.doi.org/10.4028/www.scientific.net/kem.359-360.94.

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Grinding wheel passivation is an inevitable phenomenon during grinding process. It has important guiding significance for the formulation of grinding technique to unveil the passivation rule and generation mechanism. Taking grinding efficiency as evaluation indicator, the passivation curve of grinding wheel during full passivation period under the constant-force grinding condition is established through experiments in this dissertation, which is divided into three stages according to passivation speeds and passivation patters, i.e. early passivation stage, stable passivation stage and sharp passivation stage. Of which, the passivation speed is the slowest but with the highest grinding efficiency in early passivation stage. The change of passivation curve with the time is a process from concave to convex, which is totally different from the wearing process of grinding wheel in this stage. With combination of experiment conditions and wearing characteristics of grinding wheel, the passivation rule and its generation reasons are discussed deeply. Furthermore the exponential function y = abx is adopted to make fitting for passivation curve based on the scatter plot of stable passivation stage and regression equation is derived through the fitting result of origin thus to testify the correctness of the inference.

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Sugimoto, Katsuhisa. "Artificial Passivation Films and Real Passivation Films." Materia Japan 34, no. 9 (1995): 1042–46. http://dx.doi.org/10.2320/materia.34.1042.

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Kaur, Gurleen, Antonio J. Olivares, and Pere Roca i Cabarrocas. "Development of n-Type, Passivating Nanocrystalline Silicon Oxide Films via Plasma-Enhanced Chemical Vapor Deposition." Solar 4, no. 1 (March 11, 2024): 162–78. http://dx.doi.org/10.3390/solar4010007.

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Nanocrystalline silicon oxide (nc-SiOx:H) is a multipurpose material with varied applications in solar cells as a transparent front contact, intermediate reflector, back reflector layer, and even tunnel layer for passivating contacts, owing to the easy tailoring of its optical properties. In this work, we systematically investigate the influence of the gas mixture (SiH4, CO2, PH3, and H2), RF power, and process pressure on the optical, structural, and passivation properties of thin n-type nc-SiOx:H films prepared in an industrial, high-throughput, plasma-enhanced chemical vapor deposition (PECVD) reactor. We provide a detailed description of the n-type nc-SiOx:H material development using various structural and optical characterization techniques (scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Raman spectroscopy, and spectroscopic ellipsometry) with a focus on the relationship between the material properties and the passivation they provide to n-type c-Si wafers characterized by their effective carrier lifetime (τeff). Furthermore, we also outline the parameters to be kept in mind while developing different n-type nc-SiOx:H layers for different solar cell applications. We report a tunable optical gap (1.8–2.3 eV) for our n-type nc-SiOx:H films as well as excellent passivation properties with a τeff of up to 4.1 ms (implied open-circuit voltage (iVoc)~715 mV) before annealing. Oxygen content plays an important role in determining the crystallinity and hence passivation quality of the deposited nanocrystalline silicon oxide films.

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Cuevas, Jose Luis, Miguel Ojeda Martinez, and Saravana Prakash Thirumuruganandham. "Band-Gap Engineering: Lithium Effect on the Electronic Properties of Hydrogenated 3C-SiC (1 1 0) Surfaces." Batteries 8, no. 11 (November 18, 2022): 247. http://dx.doi.org/10.3390/batteries8110247.

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Silicon carbide has structural strength, high electronic conductivity, low diffusion barrier and high storage capacity, which are suitable for engineering applications such as lithium-ion batteries, electric vehicles, uninterruptible power supplies and SiC diodes. In particular, 3C-SiC monolayers oriented along the (1 1 0) crystallographic direction that could have symmetric surfaces have been poorly studied, as have the effects of surface passivation on their physical and electronic properties. In this work, we investigate the influence of lithium on the electronic properties of hydrogenated surfaces in 3C-SiC monolayers using density functional theory. We examine the electronic properties of surfaces fully passivated with hydrogen with those of surfaces fully passivated with lithium and those with mixed passivation. Our results show that only fully hydrogenated surfaces exhibit a direct band-gap, while the full Li, CH+SiLi, and H+Lic passivations exhibit metallic behavior. The CLi+SiH, H+1LiC, and H+1LiSi passivation systems decrease the band-gap compared to the hydrogenated case and show an indirect band-gap. The formation energy of the system shows that the most stable arrangement is full-H, followed by H+1LiC, and the most unstable system is full-Li, which has a positive formation energy.

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Villegas-Tovar, José, Citlalli Gaona-Tiburcio, María Lara-Banda, Erick Maldonado-Bandala, Miguel Angel Baltazar-Zamora, Jose Cabral-Miramontes, Demetrio Nieves-Mendoza, Javier Olguin-Coca, Francisco Estupiñan-Lopez, and Facundo Almeraya-Calderón. "Electrochemical Corrosion Behavior of Passivated Precipitation Hardening Stainless Steels for Aerospace Applications." Metals 13, no. 5 (April 24, 2023): 835. http://dx.doi.org/10.3390/met13050835.

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Precipitation-hardening (PH) stainless steels (SS) are widely used in various aerospace applications. These steels exhibit good mechanical and corrosion resistance. The electrochemical behavior of 15-5PH, 17-4PH, Custom450 and AM 350 stainless steels passivated with citric and nitric acid baths for 60 and 90 min at 25 and 49 °C were evaluated in 5 wt.% sodium chloride (NaCl) and 1 wt.% sulfuric acid (H2SO4) solutions. The electrochemical behavior was studied with potentiodynamic polarization curves (PPC) according to the ASTM G5-13 standard. The results indicated that there are two characteristic mechanisms that are present in the potentiodynamic polarization curves. When the PHSS is immersed in an H2SO4 solution, there is a secondary passivation, and in the NaCl solution, there is a pseudo-passivation (not stable passivation film). The current densities in the NaCl solution were between 10−4 and 10−5 mA/cm2, while those of H2SO4 were recorded around 10−2 and 10−3 mA/cm2. Citric acid does work as a passivating solution, and in some cases, the corrosion resistance of the stainless steel was comparable to that of nitric acid.

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Peng, Biao, and Yulu Wei. "Mechanism of Different Passivating Agents on the Solidification of Heavy Metals in Soil." Scientific Journal of Technology 4, no. 6 (June 20, 2022): 62–66. http://dx.doi.org/10.54691/sjt.v4i6.882.

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Through the mechanism study, it can be seen that the three kinds of passivating agents can increase the soil pH value and cation exchange capacity, which is beneficial to the transformation of heavy metals from ion exchange state to residue state. The addition of organic fertilizer can increase the activities of urease and acid phosphatase, and montmorillonite is beneficial to activate the activity of catalase in the soil. MO treatment can simultaneously increase the activities of the three enzymes and increase the absorption of soil carbon, nitrogen and organic phosphorus. Electron microscope scanning results showed that MO effectively increased the connectivity between soil particles and increased the specific surface area of soil. Therefore, the synergistic effect of MO treatment on the passivation of heavy metals is obvious, and the passivation effect is the best.

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Choi, Jun-Hyeok, Woo-Seok Kang, Dohyung Kim, Ji-Hun Kim, Jun-Ho Lee, Kyeong-Yong Kim, Byoung-Gue Min, Dong Min Kang, and Hyun-Seok Kim. "Enhanced Operational Characteristics Attained by Applying HfO2 as Passivation in AlGaN/GaN High-Electron-Mobility Transistors: A Simulation Study." Micromachines 14, no. 6 (May 23, 2023): 1101. http://dx.doi.org/10.3390/mi14061101.

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This study investigates the operating characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) by applying HfO2 as the passivation layer. Before analyzing HEMTs with various passivation structures, modeling parameters were derived from the measured data of fabricated HEMT with Si3N4 passivation to ensure the reliability of the simulation. Subsequently, we proposed new structures by dividing the single Si3N4 passivation into a bilayer (first and second) and applying HfO2 to the bilayer and first passivation layer only. Ultimately, we analyzed and compared the operational characteristics of the HEMTs considering the basic Si3N4, only HfO2, and HfO2/Si3N4 (hybrid) as passivation layers. The breakdown voltage of the AlGaN/GaN HEMT having only HfO2 passivation was improved by up to 19%, compared to the basic Si3N4 passivation structure, but the frequency characteristics deteriorated. In order to compensate for the degraded RF characteristics, we modified the second Si3N4 passivation thickness of the hybrid passivation structure from 150 nm to 450 nm. We confirmed that the hybrid passivation structure with 350-nm-thick second Si3N4 passivation not only improves the breakdown voltage by 15% but also secures RF performance. Consequently, Johnson’s figure-of-merit, which is commonly used to judge RF performance, was improved by up to 5% compared to the basic Si3N4 passivation structure.

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Madeira, Alexandra, Marie Plissonneau, Laurent Servant, Irene A. Goldthorpe, and Mona Tréguer-Delapierre. "Increasing Silver Nanowire Network Stability through Small Molecule Passivation." Nanomaterials 9, no. 6 (June 20, 2019): 899. http://dx.doi.org/10.3390/nano9060899.

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Silver nanowire (AgNW) transparent electrodes show promise as an alternative to indium tin oxide (ITO). However, these nanowire electrodes degrade in air, leading to significant resistance increases. We show that passivating the nanowire surfaces with small organic molecules of 11-mercaptoundecanoic acid (MUA) does not affect electrode transparency contrary to typical passivation films, and is inexpensive and simple to deposit. The sheet resistance of a 32 nm diameter silver nanowire network coated with MUA increases by only 12% over 120 days when exposed to atmospheric conditions but kept in the dark. The increase is larger when exposed to daylight (588%), but is still nearly two orders of magnitude lower than the resistance increase of unpassivated networks. The difference between the experiments performed under daylight versus the dark exemplifies the importance of testing passivation materials under light exposure.

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Cai, Wei, Li Li, Ren Hui Liu, and Zhen Zhen Wan. "Passivator Composition of Rich of Phytic Acid Used for Brass-Strip." Advanced Materials Research 399-401 (November 2011): 36–39. http://dx.doi.org/10.4028/www.scientific.net/amr.399-401.36.

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Passivator components of phytic acid, hydrogen peroxide, boric acid and polyethylene glycol was optimized by orthogonal experiment. Corrosion resistance of passivation film of brass-strip was invertigated by salt spraying, weight loss and electrochemical test. The results show that the optimization passivator consists of phytic acid (50% mass fraction) 8ml/L, hydrogen peroxide (mass fraction 30%) 30ml/L, boric acid 5g/L, polyethylene glycol 15ml/L and additive 4g/L. Corrosion current density and corrosion rate of the brass-strip specimens coated by rich-phytic acid passivator are similar to that treated by traditional sodium dichromate passivator, the characteristic of anti-tarnish slightly better than that coated by sodium dichromate passivator. The feature of rich-phytic acid passivator is environmental protection.

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Chen, Naifeng, Tian Xia, and Xiaoyong Zhang. "Research on the Passivation Process of Iron Nanopowder as Catalyst for Ammonia Synthesis." Journal of Physics: Conference Series 2510, no. 1 (June 1, 2023): 012018. http://dx.doi.org/10.1088/1742-6596/2510/1/012018.

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Abstract This paper aims to study a passivation technology and process of iron nanopowder, and provides basic theory and experimental data for promoting the practical application of iron nanopowder as a high-efficiency catalyst in the production of ammonia. There are two specific objectives. The first one is to provide a nanometal powder passivation device to prevent the nano metal powder from being oxidized and deactivated. The second one is to provide a method for using the nano metal powder passivation device to passivate the nano metal powder. Meanwhile, the research on iron nano-powder passivation technology and process is also beneficial to the application of iron nano-materials in other fields. The metal nanopowder passivation equipment provided in this paper can control the passivation reaction speed by adjusting the ratio and flow rate of the passivation gas during the passivation process, and identify the occurrence and stop of the passivation reaction by detecting the composition of the passivation reactant. Overall, the technology has the advantages of easy operation, uniform powder passivation, adjustable reaction speed, high product purity, etc. Therefore, it is suitable for industrial production.

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Hu, Xiaochen, Pei Zhang, Yong Zhou, and Fuan Yan. "The electrochemical behavior of corrosion and passivation for Q235 carbon steel in acidic phosphate buffer solutions without and with NO2−." Anti-Corrosion Methods and Materials 67, no. 5 (August 5, 2020): 473–81. http://dx.doi.org/10.1108/acmm-03-2020-2285.

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Purpose The purpose of this paper is to reveal the mechanism of nitrite (NO2−) for the surface passivation of carbon steels in acidic environments through investigating the influences of 0.01 mol/L NaNO2 addition on the corrosion and passivation behaviors of Q235 carbon steel in acidic phosphate buffer (APB) solutions (pH 2 to 6). Design/methodology/approach The electrochemical techniques including open circle potential evolution, potentiodynamic polarization, electrochemical impedance spectroscopy and cyclic voltammetry were applied. Findings In APB solutions without NO2−, the Q235 steel presented the electrochemical behaviors of activation (A), activation-passivation-transpassivation and self-passivation-transpassivation at pH 2 to 4, pH 5 and pH 6, respectively; the corrosion rate decreased with the up of pH value, and the surface passivation occurred in the pH 5 and pH 6 solutions only: the anodic passivation at pH 5 and the spontaneous passivation at pH 6. Originality/value In APB solutions without NO2−, the corrosion rate decreased with the up of pH value, and the surface passivation occurred in the pH 5 and pH 6 solutions only: the anodic passivation at pH 5 and the spontaneous passivation at pH 6. With the addition of 0.01 mol/L NaNO2, into APB solutions, the variation of corrosion rate showed the same rule, but the surface passivation occurred over the whole acidic pH range, including the anodic passivation at pH 2 to 4 and the spontaneous passivation at pH 5 to 6.

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Yang, Xiao Ke, Yun Ying Fan, Ye Hua Jiang, and Zu Lai Li. "Study on Chromium-Free Color Passivation for Zinc Coating Treated with Silicate." Advanced Materials Research 154-155 (October 2010): 1301–4. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.1301.

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This paper mainly focuses on how the silicate liquid composition of chromium-free color passivation affects on passivation result, and confirmes the optimum passivation conditions, and uses two zinc plating system of alkaline and acid deposition. Silicate passivation system is compared with hexavalent chromium passivation technology and the results showed that: the appearance and corrosion resistance of passive films formed on zinc coatings plated with alkaline system are better than samples plated with acid system, and have the same corrosion resistanc with hexavalent chromium passivation. The silicate passivation films can keep 200 hours with no white rust in neutral salt spray test.

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Wan, Yi, Qiaoping Liu, and Yunying Fan. "Research on Corrosion Resistance and Formation Mechanism of Molybdate Composite Film." Crystals 12, no. 11 (November 1, 2022): 1559. http://dx.doi.org/10.3390/cryst12111559.

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In order to reduce phosphorus pollution, the low phosphorus passivation process on Q235 steel was studied. The electrochemical method was used to test the corrosion resistance of sodium molybdate low phosphorus passivation. The polarization curve shows that the corrosion current of the sample passivated by low phosphorus is only 1/4 of that of the blank sample. Under scanning electron microscopy, the passivation film obtained by low phosphorus passivation treatment had the lowest phosphorus content and was more uniform and compact. The XPS (X-ray photoelectron spectroscopy) and OCP (open circuit potential) were used to study the film formation regularity and mechanism of low molybdenum sodium passivation. The results show that sodium molybdate low phosphorus passivation film has good corrosion resistance. The formation process of a passivation film can be divided into four stages alternating phosphating and passivation. The surface of the passivation film is mainly composed of phosphate, molybdate, molybdenum oxide, and their crystalline hydrates. The low phosphorus passivation process of sodium molybdate can reduce the concentration of phosphorus ions and reduce its pollution to the environment, which has broad application prospects.

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Cao, Fan, Peng Cao, Yangyang Li, Yi Wang, Lei Shi, and Di Wu. "Inhibition of Surface Corrosion Behavior of Zinc-Iron Alloy by Silicate Passivation." Coatings 13, no. 6 (June 7, 2023): 1057. http://dx.doi.org/10.3390/coatings13061057.

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The passivation of zinc alloy coating was achieved through the utilization of both silicate and trivalent chromium passivation systems, employing a specific process formula consisting of Co(NO3)2 at a concentration of 2.5 g/L, C76H52O46 at 3 mL/L, Na2SiO3 at 25 g/L, C6H5Na3O7 at 15 g/L, and an appropriate amount of organic accelerator. The composite passivation of silicate and tannic acid was found to be more effective than the trivalent chromium passivation film, as it successfully eliminated the dendrite structure on the coating surface and reduced surface defects. The coordination between negatively charged SiO2− or SiO2 micelles and Zn2+ results in the formation of a passivation film that exhibits lower corrosion current and higher corrosion potential compared to the trivalent chromium passivation film. Additionally, the impedance test fitting results indicate that the silicate passivation film possesses a higher resistance value. Overall, the proposed silicate passivation system presents a viable alternative to the toxic chromate passivation system, offering non-toxicity and superior protective performance relative to the trivalent chromium passivation system.

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Li, Zai Jin, Yi Qu, Te Li, Peng Lu, Bao Xue Bo, Guo Jun Liu, and Xiao Hui Ma. "The Characteristics of Facet Coatings on Diode Lasers." Advanced Materials Research 1089 (January 2015): 202–5. http://dx.doi.org/10.4028/www.scientific.net/amr.1089.202.

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The effect of the output power with different facet passivation methods on 980 nm graded index waveguide structure InGaAs/AlGaAs laser diodes was studied. The output power of the 980 nm laser diodes with Si passivation, and ZnSe passivation at the front and the back facet were compared. The test results show that output power of the ZnSe passivation method is 11% higher than Si passivation method. The laser diode with the Si passivation film is failure when current is 5.1 A, the laser diode with the ZnSe passivation film is not failure until current is 5.6 A And we analyzed the failure reasons for each method. In conclusion, the method of coated ZnSe passivation on the laser diode facet can effectively increase the output power of semiconductor lasers.

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Wang, Nan, Runze Wang, Qingzhao Zhang, Yuanjie Luo, and Hui Xu. "Study on the Water-Sensitivity Passivation Effect and Mechanism of PA-ES Composite Materials." Materials 16, no. 17 (August 28, 2023): 5872. http://dx.doi.org/10.3390/ma16175872.

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The water-sensitive effect of expansive soil (ES) poses a serious challenge to the safety and durability of infrastructure. To reduce the effect of water sensitivity on expansive soil, a new powder soil passivator with polyacrylic (PA) as the main component was proposed. In this paper, a series of macroscopic and microscopic tests were conducted to evaluate the water-sensitive passivation effect and mechanism of PA-ES composites. The results showed that PA significantly attenuated the water sensitivity of ES. With the increase in PA content in the PA-ES composites, the water sensitivity of the composites decreased, swelling and shrinkage deformation decreased, and the strength of the composites increased significantly. In addition, when the content of PA in the PA-ES composite is 6%, it can significantly alleviate the deformation of the composite and improve the saturated shear strength of the composite, meeting the requirements of ES engineering disposal. Finally, the results show that the mechanism of PA passivation of ES water-sensitive effect mainly includes adsorption, binding, and filling. The study shows that PA has a broad engineering application prospect as an ES passivator.

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Journal articles on the topic 'Passivation'

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