Passivation Layer Research Articles

Nonflammable All-Fluorinated Electrolyte Enabling High-Voltage and High-Safety Lithium-Ion Cells.

In this study, a nonflammable all-fluorinated electrolyte for lithium-ion cells with a Li(Ni0.8Mn0.1Co0.1)O2 cathode is investigated under high voltages. This electrolyte, named FT46, consists of fluoroethylene carbonate (FEC) and bis(2,2,2-trifluoroethyl) carbonate (TFEC) in a mass ratio of 4:6. Compared to a commercially available electrolyte and several other fluorinated electrolytes, cells containing FT46 demonstrate significantly better cycling performances under high voltage (3.0-4.5 V). This result may be ascribed to the generation of a stable, smooth, and thin passivation layer and the improved solvation structure formed by FT46. The LiF-rich passivation layer strengthens the electrode/electrolyte interface, inhibits the degradation of the electrode, and suppresses side reactions between the electrodes and electrolytes under high voltage. The solvation structure formed by FT46 is derived from anions, enabling an enhanced Li+ migration rate and inhibiting lithium plating generation. Additionally, due to the nonflammability of the electrolyte and the stable passivation layers, FT46 cells also demonstrate promising safety characteristics when exposed to typical abusive conditions, such as thermal abuse, mechanical abuse, and electrical abuse.

Effect of TiC grain size on corrosion behaviors of Ti-Si-C nanocomposite coatings fabricated by heterogeneous targets high-power impulse magnetron sputtering

Ti-Si-C coatings with different carbon contents were prepared on SS316L substrates by heterogeneous targets high-power impulse magnetron sputtering with a repetitive C and TiSi deposition. Various tests were employed to analyze the microstructure, anti-corrosion properties in a simulated proton exchange membrane fuel cells (PEMFC) environment and interfacial conductivity of the coatings. Results indicated that the Ti-Si-C coating possessed a typical nanocomposite structure of TiC nanocrystals embedded in amorphous carbon matrix. With the increase of the carbon content, the grain size of TiC nanocrystals was reduced gradually. Electrochemical measurements revealed that a proper decrease of TiC grain size led to an enhanced corrosion resistance of the as-deposited coating. The smallest interfacial contact resistance and corrosion rate of the Ti-Si-C coating in the simulated PEMFC solution reached 5.07 mΩ cm2 and 5.93E-07 A/cm2, respectively. This improvement could be attributed to the formation of a dense and continuous passivation layer composed of Ti2O3 and SiO2 on the top surface of the coating.

Electrochemical dissolution behavior of Inconel 718 alloy in NaNO3 solution: A comparison between wrought and cast

Cast IN718 and wrought IN718 are highly capable materials for blisks in aeroengines, owing to their high-temperature capabilities. Understanding their anodic electrochemical behavior is crucial for electrochemical machining (ECM) applications. In this study, electrochemical tests and ECM experiments were conducted on both cast IN718 and wrought IN718 alloys in a 10 wt% NaNO3 solution to explore their passivation-related behaviors and interface structures. The investigation included analysis via open circuit potential, polarization curve, and electrochemical impedance spectroscopy (EIS). Results indicate that compared to wrought IN718, the passive layer formed on cast IN718 surfaces contains numerous pores, rendering the corrosion resistance of cast IN718 less challenging in the 10 wt% NaNO3 environment. Additionally, X-ray photoelectron spectroscopy (XPS) was used to characterize the chemical composition of the passive layer. The analysis revealed that the passive layer on both cast and wrought IN718 surfaces primarily consisted of NiO, Ni(OH)2, Cr2O3, CrO3, Fe3O4, α-FeOOH, γ-Fe2O3, Fe2O3, NbO, Nb2O5, MoO2, and MoO3. Notably, the passive layer on cast IN718 was richer in NiO and lacked Cr2O3 and MoO3, which supports its porous and loose structures. Furthermore, ECM experiments were conducted at various current densities (1, 4, 8, and 15 A·cm−2) to identify the dissolution morphology. The results revealed several pitting pits on the machined surface of cast IN718 at low current densities, with lower surface roughness compared to wrought IN718. Conversely, for wrought IN718, the presence of needle-like structures dispersed on the machined surface improved substantially as the current density increased, significantly influencing surface quality.

Embedded high-quality ternary GaAs1−x Sb x quantum dots in GaAs nanowires by molecular-beam epitaxy

Semiconductor quantum dots are promising candidates for preparing high-performance single photon sources. A basic requirement for this application is realizing the controlled growth of high-quality semiconductor quantum dots. Here, we report the growth of embedded GaAs1−x Sb x quantum dots in GaAs nanowires by molecular-beam epitaxy. It is found that the size of the GaAs1−x Sb x quantum dot can be well-defined by the GaAs nanowire. Energy dispersive spectroscopy analyses show that the antimony content x can be up to 0.36 by tuning the growth temperature. All GaAs1−x Sb x quantum dots exhibit a pure zinc-blende phase. In addition, we have developed a new technology to grow GaAs passivation layers on the sidewalls of the GaAs1−x Sb x quantum dots. Different from the traditional growth process of the passivation layer, GaAs passivation layers can be grown simultaneously with the growth of the embedded GaAs1−x Sb x quantum dots. The spontaneous GaAs passivation layer shows a pure zinc-blende phase due to the strict epitaxial relationship between the quantum dot and the passivation layer. The successful fabrication of embedded high-quality GaAs1−x Sb x quantum dots lays the foundation for the realization of GaAs1−x Sb x -based single photon sources.

Combined bulk nanostructuring and surface modifications of titanium substrate for improved corrosion behavior

Titanium has proven to be a game-changing biomaterial in biomedical engineering. Titanium and its alloys offer superior properties such as machinability, mechanical strength, biocompatibility, and corrosion resistance, making them indispensable for safer and more efficient biomedical treatments. While commercially pure titanium (Cp-Ti) is an exceptional material for medical applications, it has some limitations. Allergic reactions can manifest as localized inflammation around the implant, and corrosion compromises implant stability. Corrosion starts with cracking from the surface and disrupts the protective passive oxide layer when touching body fluids, and failure occurs. This study utilized a combination of techniques including grain refinement of Cp-Ti via equal channel angular pressing (ECAP), two-step anodization (for creating titanium oxide nanotubes coatings), annealing at 450°C and 570°C, and immersion in simulated body fluid (SBF) to create a Hydroxyapatite (HA) film coating. These methods addressed various challenges and provided a positive approach to improving corrosion behavior. The microstructure of Nano-Ti was evaluated by Transmission Electron Microscopy (TEM). The morphology of the as-anodized samples and corroded areas were investigated using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The crystalline phases of titanium nanotubes (TNTs) were evaluated through X-ray diffraction (XRD). The presence of hydroxyapatite particles was analyzed and characterized by FESEM coupled with Energy Dispersive Spectroscopy (EDS) and Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR). The corrosion behavior was evaluated using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). Results indicated that grain refinement and successive surface modifications significantly impact corrosion performance. The nanostructured (Nano-Ti) sample, after the final modification stage, exhibited an approximately 11-fold decrease in corrosion rate and over a 450-fold rise in polarization resistance (7.4 MΩ) compared to as-anodized Cp-Ti sample and a 7-fold increase in its Cp-Ti counterpart, and showed excellent adhesion strength compared to other samples.

Unraveling the Role and Impact of Alumina on the Nucleation and Reversibility of β‐LiAl in Aluminum Anode Based Lithium‐Ion Batteries

AbstractAluminum, due to its high abundance, very attractive theoretical capacity, low cost, low (de−) lithiation potential, light weight, and effective suppression of dendrite growth, is considered as a promising anode candidate for lithium‐ion batteries (LIBs). However, its practical application is hindered due to multiple detrimental challenges, including the formation of an amorphous surface oxide layer, pulverization, and insufficient lithium diffusion kinetics in the α‐phase. These outstanding intrinsic challenges need to be addressed to facilitate the commercial production of Al‐based batteries. The native passivation layer, Al2O3, plays a critical role in the nucleation and reversibility of lithiating aluminum and is thoroughly investigated in this study using high precision electrochemical micro calorimetry. The enthalpy of crystallization of β‐LiAl is found to be 40.5 kJ mol−1, which is in a strong agreement with the value obtained by calculation using Nernst equation (40.04 kJ mol−1). Surface treatment of the active material by the addition of 25 nm of alumina increases the nucleation energy barrier by 83 % over the native oxide layer. After the initial nucleation, the added alumina does not negatively impact the reversibility at 0.1 C rate, suggesting the removal of alumina is not necessary for improving the cyclability of aluminum anode based lithium‐ion batteries. Moreover, the coulombic efficiencies are also found to be slightly higher in the alumina treated samples compared to the untreated ones.

Tailoring Interfacial Structures to Regulate Carrier Transport in Solid-State Batteries.

Solid-state lithium-ion batteries (SSLIBs) have been considered as the priority candidate for next-generation energy storage system, due to their advantages in safety and energy density compare with conventional liquid electrolyte systems. However, the introduction of numerous solid-solid interfaces results in a series of issues, hindering the further development of SSLIBs. Therefore, a thorough understanding on the interfacial issues is essential to promote the practical applications for SSLIBs. In this review, the interface issues are discussed from the perspective of transportation mechanism of electrons and lithium ions, including internal interfaces within cathode/anode composites and solid electrolytes (SEs), as well as the apparent electrode/SEs interfaces. The corresponding interface modification strategies, such as passivation layer design, conductive binders, and thermal sintering methods, are comprehensively summarized. Through establishing the correlation between carrier transport network and corresponding battery electrochemical performance, the design principles for achieving a selective carrier transport network are systematically elucidated. Additionally, the future challenges are speculated and research directions in tailoring interfacial structure for SSLIBs. By providing the insightful review and outlook on interfacial charge transfer, the industrialization of SSLIBs are aimed to promoted.

Impact of oxygen plasma power on the performance of Ga2O3 passivated GaN ultraviolet photodetectors

The role of oxygen plasma power on the extent of surface passivation of Gallium Nitride (GaN) epitaxial layers and the photo-response of Au/Ni/GaN Schottky detectors is investigated. The surface morphology is found to be preserved in oxide passivated GaN at intermediate plasma power which significantly deteriorates at higher power. The photoluminescence spectrum shows a fall in the intensity of band edge and defects related yellow luminescence at higher power indicating the generation of non-radiative recombination centres. The chemical and electronic structures of the passivated layer investigated by x-ray photoelectron spectroscopy revealed the formation of stoichiometric Ga2O3 up to intermediate plasma power and partial decomposition of Ga2O3 along with formation of gallium sub-oxides at higher power. This leads to an enhancement in the responsivity of the photodetector after passivation at an intermediate plasma power followed by a considerable reduction at higher power. From the electrical transport measurement across the Au/Ni/GaN Schottky diode, it is observed that the diode manifests more Schottky (Ohmic) character after oxygen plasma treatment at intermediate (higher) power. The present investigations provide a clear guideline on the selection of oxygen plasma power for surface passivation on GaN, which is highly beneficial in optimizing the performance of GaN-based optoelectronic and power devices.

The carbon activation of electric furnace ferronickel slag and its utilization in cement-based materials

The high annual emissions and low utilization rate of electric furnace ferronickel slag (EFS) have brought enormous impacts on environment. This work intends to propose a methodology for the carbon activation of EFS to improve its resource utilization. To this end, the exfoliation-carbonation (i.e., hybrid aqueous carbonation) was developed and compared with CO2 bubbling carbonation (i.e., direct aqueous carbonation). The carbonation process of EFS and the hydration and mechanical strength of activated EFS blended cement-based materials was evaluated. Experimental results indicated that mechanical pre-treatment could disorder forsterite crystal and promote the dissolution of Mg to form Si enriched mineral surface. The direct aqueous carbonation led to the formation of passivation layer which could be striped by hybrid aqueous carbonation to facilitate further carbon mineralization. Increase in temperature significantly improved the decomposition of forsterite and accelerated the carbon mineralization kinetics. The activated EFS could accelerate the hydration and promote the mechanical strength of cement-based materials. Carbon mineralization is an effective method to strengthening the activity of EFS.

Corrosion resistance of magnesium alloy surfaces substantially upgraded by gradient energy irradiation of femtosecond lasers

The poor corrosion resistance of magnesium (Mg) alloys is known to constitute a major obstacle to their practical applications. In this work, we proposed an approach of femtosecond laser multi-grid-scanning with the gradual decreasing energy fluence, to modulate the surface oxide properties for the anti-corrosion performance enhancement. This kind of laser processing can significantly increase the oxide passivation layer thickness by more than 100 times compared with the bare sample, and improve the oxygen content on the material surface to as high as 55.87 %. Simultaneously, the available size of MgO nanograins is further refined and has more spatially uniform distribution. Moreover, the massive production of micro/nano-structures by the femtosecond laser irradiation tends to promote the surface into the superhydrophobic with a contact angle of CA=162 ± 2 ° and a slide angle of SA=1.5 ± 0.5 °. As a result, the obtained optimal values for the corrosion current density and the annual corrosion rate are reduced to Icorr = 0.5 μA/cm2 and CR = 7×10−3 mm/y, respectively, more than 2 orders of magnitude lower than the bare sample. Such a method provides an efficient strategy to enhance the corrosion resistance of metal surfaces for future applications.

Valorisation of leather buffing dust as corrosion inhibitor for mild steel in H2SO4 acid

This work discusses the valorisation and efficacy of the acid-extracted collagenous proteins from leather buffing dust (LBD) on the corrosion inhibition of mild steel (MS) in 0.5 M H2SO4 solution using electrochemical analysis. The extract shows ~95 % inhibition efficiency at 1 wt% of raw LBD loading. The inhibitor interaction follows Langmuir adsorption isotherm, indicating monolayer adsorption through physisorption, leading to complex formation on the MS surface. Post-corrosion characterizations reveal film-forming nature of the inhibitor and the involvement of organic compounds in the complex protective layer formation on the MS in the corrosive media. In addition, surface study through an optical profilometer helps to understand the nature of the corroded MS. In summary, the LBD-H2SO4 extract is extremely capable in mitigating the corrosion of MS in H2SO4 solution, and the inhibition phenomenon is governed by a complex passive layer formation on the MS subjected to the corrosive media.

Ultrafine Grain 316L Stainless Steel Manufactured by Ball Milling and Spark Plasma Sintering: Consequences on the Corrosion Resistance in Chloride Media

This paper reports experimental results concerning the corrosion of 316L austenitic stainless steels produced by ball milling and spark plasma sintering in NaCl electrolyte. Specimens with grain sizes ranging from 0.3 µm to 3 µm, without crystallographic texture, were obtained and compared with a cast that is 110 µm in grain size and an annealed reference. The potentiodynamic experiments showed that the reduction in grain size leads to a degradation of the electrochemical passivation behavior. This detrimental effect can be overcome by appropriate passivation in a HNO3 concentrated solution before consolidation. The Mott–Schottky measurements showed that the semiconducting properties of the passive layer do not vary significantly on the grain size, especially the donor density, which is responsible for the chemical passivation breakdown by chloride anions. The total electrical resistance of the layer, measured by impedance spectroscopy is always lower than the one of a cast and annealed 316L, but it slightly increases with a reduction in grain size in the ultrafine grain range. This is followed by a slight increase in the thickness of the oxide layer. The effect of chloride ions is very pronounced in terms of passivation breakdown if the powder is not passivated prior to sintering. This leads to the nucleation and growth of subsurface main pits and the formation of secondary satellite pits, especially for the smallest grain sizes. Passivation of the 316L powder before sintering has been found to be an effective way to prevent this phenomenon.

Passivation Behavior of Chromium Alloyed High-Strength Rebar in Simulated Concrete Pore Solution

In this study, SEM, AFM, TEM, XPS, and electrochemical tests are used to study the passivation behavior of chromium alloyed high-strength rebar in simulated concrete pore (SCP) solutions with different pH values. The results show that after passivation in SCP solution with different pH values, the passivating film on the surface of the chromium alloyed rebar primarily consists of a layer of nanoscale oxide particles, which makes the passive film exhibit a p-n type semi-conductor, and the passive film presents a rhombohedral crystal structure. As the pH value of the SCP solution decreases, the nanoscale oxide particles on the surface of the rebar become denser, which leads to a reduction in the carrier density (Nq and Na) of the passive film and an increase in film resistance (R2) and charge transfer resistance (R3), thus increasing the corrosion resistance of the passive film. The passive film on the surface of the chromium alloyed high-strength rebar predominantly exhibits a three-layer structure, the outer passive film layer is composed of Fe oxides, the stable layer of the passive film is composed of Fe oxides and Cr oxides, and the growth layer of inner passive film is composed of Cr oxides. Compared with passivation 10 d in SCP solutions with pH 13.5 and pH 12.5, the passive film on the surface of the rebar has good stability at pH 10.5, which indicates that the addition of Cr is beneficial to promote the corrosion resistance of the rebar.

How to achieve nanometer flat surfaces: Pulsed electrochemical machining of bulk metallic glass

The Bulk Metallic Glass (BMG) Vitreloy 105 (Zr52.5Ti5Ni14.6Cu17.9Al10) as well as two crystalline reference materials of the same composition were machined with Pulsed Electrochemical Machining (PECM). One reference material was nano crystalline with an average grain size of 11 nm and the second one was a fine grain crystalline sample with an average grainsize of 110 nm. The goal was to achieve maximum surface quality in terms of roughness by utilizing a readily available industrial process. Samples were characterized by tactile profilometer, atomic force microscopy and electron microscopy methods. The results show superior surface quality of the amorphous samples over the reference materials with an average roughness depth as low as 1 nm. The observed dissolution mechanism of the BMG differs from the reference materials -as in contrast to the crystalline alloys that show a passive layer formation - no such surface layer other than the native oxide could be observed. The PECM procedure is found to be a promising post-processing step for BMGs with a resulting surface that can face even the most challenging surface quality requirements.

Corrosion behaviour of aluminum and copper in dimethyl- and diethyl phosphate ionic liquids

The effect of phosphonium—based ionic liquids (ILs): 1,3-dimethyl-imidazolium dimethyl phosphate, [C1C1IM][DMP], 1-ethyl-1-methylpyrrolidinium dimethyl phosphate, [C1C2PYR][DMP], 1-hydroxyethyl-1-methylpyrrolidinium dimethyl phosphate, [C1C2OHPYR][DMP], 1-methylpyridinium dimethyl phosphate, [C1Py][DMP], 1-ethyl-1-methylmorpholinium dimethyl phosphate, [C1C2MOR][DMP], 1-ethyl-1-methylpiperidinium dimethyl phosphate, [C1C2PIP][DMP], N,N,N-trimethyl-N-methylammonium dimethyl phosphate, [N1,2,2,2][DMP], 1-ethyl-3-methylimidazolium diethyl phosphate, [C1C2IM][DEP], 1-ethyl-1-methylpyrrolidinium diethyl phosphate, [C1C2PYR][DEP], 1-ethyl-1-methyl-morpholinium diethyl phosphate, [C1C2MOR][DEP] and tri(butyl)ethylphosphonium diethyl phosphate, [P2,4,4,4][DEP] on the corrosion of aluminium and copper were investigated using potentiodynamic polarization. All tested ionic liquids formed a passivation layer on the surface of the tested metals and due to their low affinity to promote corrosion of Cu and Al, can be used in refrigeration technology.

Designing and simulating of new highly efficient ultra-thin CIGS solar cell device structure: Plan to minimize cost per watt price

This research paper examines the execution of ultra-thin solar cells made from chalcopyrite copper indium gallium diselenide (CIGS). The study presents a new CIGS heterojunction solar cell structure, which includes a Cd-free tungsten disulfide (WS2) buffer layer and poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT: PSS) passivation layer. The performance of the solar cell is raised by a back surface field (BSF). A highly recombining rear surface is kept away from minority carriers by a field created by further strong doping at the back. The structure is Ni/PEDOT:PSS/CIGS/WS2/ZnO/Al and has been estimated numerically using the Opto-electrical stimulation of semiconductor layers simulator SCAPS-1D. A high efficiency with a Back surface passivated layer of 25.70 % with Voc of 0.81 V, Jsc of 39.33 mA/cm2, and FF of 79.89 % and without passivated layer efficiency of 17.58 % with Voc of 0.73 V, Jsc of 32.18 mA/cm2, and FF of 74.78 % is found for the intended CIGS-based solar cell with WS2 buffer. The interface between CIGS and WS2 forms a band structure that resembles spikes. This structure is crucial in enhancing the outputs by reducing carrier recombination. The optimal thicknesses for the buffer and CIGS absorber layers are 0.02 μm and 0.2 μm, respectively. These findings help reduce the cost per watt of the solar cell. Fabrication at a mass production scale, minimizing the thickness will have a significant impact on reducing cost.

Material Characterization and Electrochemical Properties of Titanium Alloy 5553 Prepared by Selective Laser Melting as Processed and after Abrading and Polishing.

The microstructure, Vickers microhardness, and electrochemical properties of an additive manufactured titanium alloy, Ti-5553 (Ti-5Al-5Mo-5V-3Cr wt %), are reported on. The alloy specimens were fabricated by selective laser melt processing. The surface morphology and electrochemical properties of the as-processed and surface-pretreated (abraded and polished) Ti-5553 specimens were investigated. The as-processed specimens had a nominal density of 4.62 ± 0.04 g/cm3. Based on comparison with the reported density for the die-cast alloy, the specimens were 99-100% dense with ca. 1% porosity. Optical microscopy and scanning electron microscopy revealed some micropores, balling features, and fusion pore defects across the surface of the alloy (XZ plane-orthogonal to the build direction). The nominal Vickers microhardness was 292 ± 2 HV. Detailed electrochemical characterization of the as-processed and surface-pretreated alloys revealed reproducible open-circuit potentials (OCPs), linear polarization resistances (R p), and potentiodynamic polarization curves for both specimen types in naturally aerated 3.5 wt % NaCl at room temperature. For the surface-pretreated alloys, the OCP was 225 mV more noble, the anodic current in the potentiodynamic polarization curves was 72× lower, the cathodic current was 8× lower, and R p was larger by 426× than the values for the as-processed specimens. The collective electrochemical data revealed that the surface-pretreated alloys exhibit greater corrosion resistance than the as-processed alloys due to a reduction of the real area and the formation of a more passivating oxide layer.

Single step grown porous polycrystalline nickel microstructures with ultra-thin defect rich surface oxide for alkaline water oxidation

Investigation on the intrinsic catalytic activity of structurally diverse polycrystalline nickel microstructures such as porous nickel sheets (PNS), porous folded/curled nickel structures (PFNS) and porous nickel balls (PNB) revealed the surface bounded electrocatalytic activities within an alkaline reaction environment for water oxidation. Nickel microstructures were grown via template/surfactant-free, single step solution combustion technique in air atmosphere. The distinct morphologies (porous nickel sheets, porous folded/curled nickel structures and porous nickel balls) were achieved through changing the quantity of HNO3 in the reaction mixture. The physicochemical characterisations were done with XRD, FESEM, EDS and XPS. Microscopic studies revealed the growth of nickel grains with numerous macro pores forming microstructures in distinct morphologies. The O ls spectra of XPS studies revealed the presence of O−/O2− sites and Ni 2p spectra were distinguished between the formation of Ni0/Ni2+/Ni3+ states, implied the existence of surface oxide with plenty of defects. The synergistic effect results from the formation of microscopic porous architectures with defect rich surface oxide on the electrochemical behaviour and OER activity of PNS, PFNS and PNB were discussed with electrochemical techniques such as CV, LSV, EIS and CP. The OER kinetics in terms of relatively low value of overpotential at 10 mA cm−2 and Tafel slope along with high specific activity of PNS/GCE with respect to PFNS/GCE and PNB/GCE were attributed to the combined effect of increase in electrochemical surface area, high roughness factor and fast charge transfer kinetics. The better electrochemical performance and OER activities of porous nickel sheets in comparison with folded/curled nickel structures and nickel balls is contributed to the unique 2D porous architecture with plenty of oxygen vacancies. This structure not only expose more surface for the formation of passive oxide layer in an alkaline reaction environment but also exhibit facile charge transport properties, causes the generation of numerous surface-active sites for electrocatalytic water oxidation. The outcome of our work gives new insights on the surface electrochemistry of polycrystalline nickel, enables micro-structuring as a prospective strategy towards the optimization of electrocatalysts as anode material for alkaline water oxidation.

Examining amino acids as environmentally friendly corrosion inhibitors for Cu and Co chemical mechanical planarization

Aliphatic amino acids (AAs) were investigated as environmentally friendly alternatives to benzotriazole (BTA) in the chemical mechanical planarization (CMP) process for Cu interconnects. The study evaluated the corrosion resistance, galvanic corrosion, and polishing removal rates (RR) for Cu and Co in a silica-based slurry containing methionine, glutamic acid, and leucine. Corrosion characteristics were determined using linear sweep voltammetry, and the removal rate was assessed by polishing wafers under controlled CMP conditions. Metal surfaces were analyzed by X-ray photoelectron spectroscopy, and scanning electron microscopy. Results indicated that the distinctive functional groups in the amino acids influenced corrosion and polishing behaviors driven by different Cu species in the passivating film layer. Methionine with its sulfur-containing side chain, exhibited exceptional inhibition capabilities by stabilizing Cu(Ⅰ) species compared to Cu(Ⅱ), involving a combination of physisorption and chemisorption. It also effectively controlled Cu-Co galvanic corrosion with a low igc = 0.9 μA/cm². Leucine, with its branched hydrocarbon chain, mitigated Cu corrosion through physisorption (20.5 kJ/mol), but increased galvanic corrosion for Co (igc = 45 μA/cm²). Leucine formed a thin passive layer that easily broke down during the Cu(I) to Cu(II) transition. Glutamic acid, with its additional carboxylic acid group, was not effective as a corrosion inhibitor but showed a relatively low |∆Ecorr| = 5 mV. Metal removal rates of Cu and Co followed the same trend with corrosion results. The selectivity of Cu:Co:TEOS removal with methionine was more comparable than that achieved with other additives, beneficial for Cu barrier CMP.

Columnar self-assembled heteroatom bay-annulated perylene bisimide as passivating layer for high performance perovskite solar cells

The interfaces within Perovskite solar cells (PSCs) are imperative for regulating defects, managing carrier dynamics, preventing ion migration, optimizing energy band alignment, and controlling morphology. The interfaces amidst the absorber layer and the hole transport layer (HTL) pose challenges related to ineffective charge extraction and charge recombination, necessitating enhancement. Spiro-OMeTAD is commonly utilized as p-type material in the HTL of planar architecture, entailing the inclusion of diverse additives to enhance solar cell efficiency, which can restrict device performance and stability. Herein, we explore the influence of a discotic liquid crystalline (DLCs) based semiconductor, a heteroatom bay-annulated perylene bisimide (PBI-SeO10), which is derived from tri-n-alkoxy anilines. Our study examines the function of PBI-SeO10 as an interfacial passivation layer within the perovskite/Spiro-OMeTAD interface, assessing its effects on both device performance and stability. Our results indicate that integrating PBI-SeO10 as a surface passivation layer not only aids in effective hole extraction from the perovskite layer but also substantially diminishes defects, leading to an improvement in overall device performance by approximately 7 %. Furthermore, PBI-SeO10 passivation also reduces ionic/molecular species diffusion into the device and provides good moisture resistivity leading to improved device stability.