Dynamic Secondary Ion Mass Spectrometry Research Articles

Nanopore structure relevant to the D2O permeation into silica thin films as studied by secondary ion mass spectrometry, ellipsometric porosimetory and positron annihilation

Subnanoscopic pore structure relevant to the water permeation for two types of silica thin films, fabricated by plasma-enhanced chemical vapor deposition (PECVD) and thermal oxidization (TO), were examined by means of dynamic secondary ion mass spectrometry (D-SIMS), vapor-adsorption ellipsometric porosimetry (EP), and low-energy positron annihilation spectroscopy (PALS). The D− secondary ion intensity for the PECVD film, observed using D-SIMS, was much higher than for the TO film, indicative of the higher permeance of D2O molecules in the matrix of the PECVD film. The results from PALS and EP suggest that this is ascribed to the larger pores and the higher open porosity of the PECVD film as compared to the TO film.

Crevice Corrosion of Grade-2 Titanium in Saline Solutions at Different Temperatures and Oxygen Concentrations

Titanium alloys are candidate materials for the fabrication of high level nuclear waste containers but may be susceptible to crevice corrosion in the initial warm oxidizing conditions anticipated in a deep geological repository. The crevice corrosion of Grade-2 titanium has been studied in 1.0 mol/L NaCl at various temperatures (120°C and 150°C) and oxygen concentrations using a galvanic coupling technique. The current due to propagation supported by oxygen reduction on the surface external to the crevice was monitored electrochemically and the total propagation determined from weight change measurements. The redistribution of impurities (Fe, V, Mo) during corrosion was determined by dynamic secondary ion mass spectrometry. Propagation was dominantly driven by the reduction of protons created inside the crevice by cation hydrolysis. Damage accumulated at the locations of TixFe intermetallic particles, which are both anodically reactive and function as catalytic cathodes for proton reduction. The compact TiO2·xH2O deposits at active sites led to stifling of corrosion when only between 9 and 56% of the available oxygen had been consumed. While propagation was more rapid at 150°C than at 120°C, it was more readily stifled at the higher temperature, leading to the accumulation of less damage.

Synthesis of the solution-processed wide band-gap chalcopyrite CuGa(S,Se)2 thin film and its application to photovoltaics

A wide band-gap chalcopyrite CuGa(S,Se)2 (CGSSe) thin film was synthesized via the simple solution based method of precursor solution coating and subsequent heat treatment processes. Various characterizations such as X-ray diffraction, UV–vis–NIR spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Hall measurement, and dynamic secondary ion mass spectroscopy revealed a successful formation of the wide band-gap polycrystalline chalcopyrite film with nearly the same amounts of S and Se elements. The synthesized CGSSe film was applied as an absorber layer to the conventional thin film solar cell construction, which yielded an open circuit voltage (Voc) of 0.52V, a short circuit current density (Jsc) of 3.5mA·cm−2, and an overall power conversion efficiency (PCE) of 1.0%. The photovoltage was lower than the expected value implying that there is a large voltage loss relative to the wide band-gap (~2.11eV). It would be attributable to improper combination of the CGSSe absorber film and the CdS buffer layer in the conventional cell architecture, which may promote interface recombination due to an absence of a “spike” band alignment (i.e. conduction band offsets are slight positive values, 0.1eV<ΔEc<0.4eV) with the CGSSe absorber layer. Moreover, improvements in morphologies, such as enlarged grains and reduced pore sizes, need to be achieved for higher solar cell efficiency.

Simultaneous depth-profiling of electrical and elemental properties of ion-implanted arsenic in silicon by combining secondary-ion mass spectrometry with resistivity measurements.

A method is proposed to extract the electrical data for surface doping profiles of semiconductors in unison with the chemical profile acquired by secondary-ion mass spectrometry (SIMS)-a method we call SIMSAR (secondary-ion mass spectrometry and resistivity). The SIMSAR approach utilizes the inherent sputtering process of SIMS, combined with sequential four-point van der Pauw resistivity measurements, to surmise the active doping profile as a function of depth. The technique is demonstrated for the case of ion-implanted arsenic doping profiles in silicon. Complications of the method are identified, explained, and corrections for these are given. While several techniques already exist for chemical dopant profiling and numerous for electrical profiling, since there is no technique which can measure both electrical and chemical profiles in parallel, SIMSAR has significant promise as an extension of the conventional dynamic SIMS technique, particularly for applications in the semiconductor industry.

Combining combing and secondary ion mass spectrometry to study DNA on chips using 13C and 15N labeling

Dynamic secondary ion mass spectrometry ( D-SIMS) imaging of combed DNA – the combing, imaging by SIMS or CIS method – has been developed previously using a standard NanoSIMS 50 to reveal, on the 50 nm scale, individual DNA fibers labeled with different, non-radioactive isotopes in vivo and to quantify these isotopes. This makes CIS especially suitable for determining the times, places and rates of DNA synthesis as well as the detection of the fine-scale re-arrangements of DNA and of molecules associated with combed DNA fibers. Here, we show how CIS may be extended to 13C-labeling via the detection and quantification of the 13C 14N - recombinant ion and the use of the 13C: 12C ratio, we discuss how CIS might permit three successive labels, and we suggest ideas that might be explored using CIS.

Combining combing and secondary ion mass spectrometry to study DNA on chips using 13C and 15N labeling

Dynamic secondary ion mass spectrometry ( D-SIMS) imaging of combed DNA - the combing, imaging by SIMS or CIS method - has been developed previously using a standard NanoSIMS 50 to reveal, on the 50 nm scale, individual DNA fibers labeled with different, non-radioactive isotopes in vivo and to quantify these isotopes. This makes CIS especially suitable for determining the times, places and rates of DNA synthesis as well as the detection of the fine-scale re-arrangements of DNA and of molecules associated with combed DNA fibers. Here, we show how CIS may be extended to (13)C-labeling via the detection and quantification of the (13)C (14)N (-) recombinant ion and the use of the (13)C: (12)C ratio, we discuss how CIS might permit three successive labels, and we suggest ideas that might be explored using CIS.

Chemical imaging of molecular changes in a hydrated single cell by dynamic secondary ion mass spectrometry and super-resolution microscopy.

Chemical imaging of single cells at the molecular level is important in capturing biological dynamics. Single cell correlative imaging is realized between super-resolution microscopy, namely, structured illumination microscopy (SIM), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) using a multimodal microreactor (i.e., System for Analysis at the Liquid Vacuum Interface, SALVI). SIM characterized cells and guided subsequent ToF-SIMS analysis. Lipid fragments were identified in the cell membrane via dynamic ToF-SIMS depth profiling. Positive SIMS spectra show intracellular potassium and sodium ion transport due to exposure to nanoparticles. Spectral principal component analysis elucidates differences in chemical composition among healthy alveolar epithelial mouse lung C10 cells, cells that uptake zinc oxide nanoparticles, and various wet and dry control samples. The observation of Zn(+) gives the first direct evidence of ZnO NP uptake and dissolution by the cell membrane. Our results provide submicron chemical mapping for investigating cell dynamics at the molecular level.

The Role of Copper on the Crevice Corrosion Behavior of Nickel-Chromium-Molybdenum Alloys in Aggressive Solutions

The effect of Cu on the localized corrosion of Ni-Cr-Mo alloys has been investigated in hot saline solutions by comparing the behavior of N06059 and N06200 alloys, using electrochemical and surface analytical techniques. No measurable effect of copper on anodic film growth kinetics and passive film properties was detected and the breakdown and repassivation potentials of the alloys were very similar. Angle-resolved x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy demonstrated that the copper segregated to the oxide/solution interface during anodic film growth and that this process was enhanced as the pH decreased, as would occur in a crevice prior to initiation. Galvanostatically controlled crevice corrosion experiments demonstrated that this surface accumulation suppressed the metastable breakdown events that preceded initiation on the Cu-free alloy. Dynamic secondary ion mass spectrometry showed that copper accumulated with molybdates in crevice corroded locations but ...

Atomic Recombination in Nanosims as a Method to Measure Nanometer-Scale Intermolecular Distances in Lipid Bilayers

The nanometer scale organization of the eukaryotic plasma membrane, often described in terms of the lipid raft hypothesis, is presumed to be critical for signaling, viral budding, and other membrane phenomena. Here, we use secondary ion mass spectrometry (SIMS) to probe the nanometer scale structure of supported lipid bilayers (SLBs) by taking advantage of the intermolecular recombination of atomic ions into diatomic species that occurs in dynamic SIMS. In this experiment, one can measure mean distances between molecules on a length scale far below the lateral resolution of the NanoSIMS 50L instrument, which combines high spatial resolution and high mass resolution for chemical imaging. As an example, we show that in lipid bilayers, the efficiency of atomic recombination to form secondary 13C15N- ions depends on the distance between 13C and 15N atoms installed on headgroups of different lipid molecules. Specifically, with site-specific isotopic labeling of lipid headgroups, we determine the dependence of recombination efficiency on the average distance between 13C- and 15N-labeled phospholipids in supported monolayers and SLBs. We refer to this method of measuring nanometer-scale distances between isotopically-labeled molecules as a chemical ruler, similar in concept to FRET but different in physical phenomenon. High precision isotope ratio analysis with the NanoSIMS 50L makes this a potentially unique way to study proximity between membrane-associated components on the sub-5 nm length scale without the use of fluorescent dyes that perturb bilayer structure. We then apply this chemical ruler to study the structure of SLBs of lipid compositions commonly believed to contain nanometer-scale liquid-ordered domains that often serve as models for lipid rafts.

Boosting the Boron Dopant Level in Monolayer Doping by Carboranes.

Monolayer doping (MLD) presents an alternative method to achieve silicon doping without causing crystal damage, and it has the capability of ultrashallow doping and the doping of nonplanar surfaces. MLD utilizes dopant-containing alkene molecules that form a monolayer on the silicon surface using the well-established hydrosilylation process. Here, we demonstrate that MLD can be extended to high doping levels by designing alkenes with a high content of dopant atoms. Concretely, carborane derivatives, which have 10 B atoms per molecule, were functionalized with an alkene group. MLD using a monolayer of such a derivative yielded up to ten times higher doping levels, as measured by X-ray photoelectron spectroscopy and dynamic secondary mass spectroscopy, compared to an alkene with a single B atom. Sheet resistance measurements showed comparably increased conductivities of the Si substrates. Thermal budget analyses indicate that the doping level can be further optimized by changing the annealing conditions.

Silver Diffusion in Organic Optoelectronic Devices: Deposition-Related Processes versus Secondary Ion Mass Spectrometry Analysis Artifacts

The development of organic optoelectronic devices relies on controlling interfaces during thin-film deposition and requires an accurate characterization of the film composition at these interfaces. Dynamic secondary ion mass spectrometry (SIMS) is widely used to investigate multilayer thin-film structures. Routine analysis protocols are well established for classical semiconductor samples, but for organic or mixed metallic–organic samples the limitations of the technique are less well established. In the current work, low-energy dynamic SIMS is used on metal–organic multilayered model structures similar to those in organic optoelectronic devices to study the origin of diffusion of metal into the organic layer (e.g., irradiation-induced diffusion during SIMS analysis or during the deposition process). Samples contain silver and organic compounds sequentially deposited by thermal evaporation in vacuum onto a Si substrate. They are analyzed using a 250 eV to 1 keV Cs+ primary ion beam. It is found that the m...

Significance of miscibility in multidonor bulk heterojunction solar cells

ABSTRACTTernary organic blends have potential in realizing efficient bulk heterojunction (BHJ) organic solar cells by harvesting a larger portion of the solar spectrum than binary blends. Several challenging requirements, based on the electronic structure of the components of the ternary blend and their nanoscale morphology, need to be met in order to achieve high power conversion efficiency in ternary BHJs. The properties of a model ternary system comprising two donor polymers, poly(3‐hexylthiophene) (P3HT) and a furan‐containing, diketopyrrolopyrrole‐thiophene low‐bandgap polymer (PDPP2FT), with a fullerene acceptor, PC61BM, were examined. The relative miscibility of PC61BM with P3HT and PDPP2FT was examined using diffusion with dynamic secondary ion mass spectrometry (dynamic SIMS) measurements. Grazing incidence small and wide angle X‐ray scattering analysis (GISAXS and GIWAXS) were used to study the morphology of the ternary blends. These measurements, along with optoelectronic characterization of ternary blend solar cells, indicate that the miscibility of the fullerene acceptor and donor polymers is a critical factor in the performance in a ternary cell. A guideline that the miscibility of the fullerene in the two polymers should be matched is proposed and further substantiated by examination of known well‐performing ternary blends. The ternary blending of semiconducting components can improve the power conversion efficiency of bulk heterojunction organic photovoltaics. The blending of P3HT and PDPP2FT with PC61BM leads to good absorptive coverage of the incident solar spectrum and cascading transport energy levels. The performance of this ternary blend reveals the impact of the miscibility of PC61BM in each polymer as a function of composition, highlighting an important factor for optimization of ternary BHJs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 237–246

Potential-induced degradation of Cu(In,Ga)Se2 photovoltaic modules

Potential-induced degradation (PID) of Cu(In,Ga)Se2 (CIGS) photovoltaic (PV) modules fabricated from integrated submodules is investigated. PID tests were performed by applying a voltage of −1000 V to connected submodule interconnector ribbons at 85 °C. The normalized energy conversion efficiency of a standard module decreases to 0.2 after the PID test for 14 days. This reveals that CIGS modules suffer PID under this experimental condition. In contrast, a module with non-alkali glass shows no degradation, which implies that the degradation occurs owing to alkali metal ions, e.g., Na+, migrating from the cover glass. The results of dynamic secondary ion mass spectrometry show Na accumulation in the n-ZnO transparent conductive oxide layer of the degraded module. A CIGS PV module with an ionomer (IO) encapsulant instead of a copolymer of ethylene and vinyl acetate shows no degradation. This reveals that the IO encapsulant can prevent PID of CIGS modules. A degraded module can recover from its performance losses by applying +1000 V to connected submodule interconnector ribbons from an Al plate placed on the test module.

Evidence for enhanced oxygen surface exchange reaction in nanostructured Gd2O3-doped CeO2 films

The effect of microstructure of Gd2O3-doped CeO2 (GDC) films on oxygen surface exchange and diffusion is reported. Epitaxial GDC (10 mol% Gd) films up to 1 μm in thickness are prepared using pulsed laser deposition on (100) yttria-stabilized zirconia single-crystal substrates and subjected to high-temperature annealing at 1300 °C in air to induce microstructural modifications. Characterization using atomic force microscopy and transmission electron microscopy reveals granular morphologies comprised of densely packed columnar nanostructures for the as-grown GDC films; however, significant microstructural reconstruction of the entire GDC layer occurs after high-temperature annealing. 18O isotope exchange depth profiling with dynamic secondary ion mass spectroscopy is employed to evaluate the oxygen surface exchange coefficient k* and the diffusion coefficient D* at T = 600 °C. The as-grown GDC exhibits up to 10 times higher k* than the annealed film. The strong differences in oxygen surface reaction are correlated to the observed film properties including surface microstructure and cerium oxidation state as evaluated using electron energy loss spectroscopy in scanning transmission electron microscopy.

Origin analysis of thermal neutron soft error rate at nanometer scale

Recently, thermal neutrons have been identified as a cause of soft errors in advanced electronic devices. To analyze the origin of such errors, dynamic secondary ion mass spectrometry (SIMS), time-of-flight (TOF)-SIMS, and three-dimensional atom probe (3DAP) methods have been used systematically. TOF-SIMS results showed that the existence region of 10B, the source of soft errors, has a high correlation to the existence region of W. Furthermore, 3DAP results for the sample extracted from the area near the W-plug revealed high 10B concentration at the W-plug.

Controlling the dopant dose in silicon by mixed-monolayer doping.

Molecular monolayer doping (MLD) presents an alternative to achieve doping of silicon in a nondestructive way and holds potential for realizing ultrashallow junctions and doping of nonplanar surfaces. Here, we report the mixing of dopant-containing alkenes with alkenes that lack this functionality at various ratios to control the dopant concentration in the resulting monolayer and concomitantly the dopant dose in the silicon substrate. The mixed monolayers were grafted onto hydrogen-terminated silicon using well-established hydrosilylation chemistry. Contact angle measurements, X-ray photon spectroscopy (XPS) on the boron-containing monolayers, and Auger electron spectroscopy on the phosphorus-containing monolayers show clear trends as a function of the dopant-containing alkene concentration. Dynamic secondary-ion mass spectroscopy (D-SIMS) and Van der Pauw resistance measurements on the in-diffused samples show an effective tuning of the doping concentration in silicon.

Inward Migration of Glass‐Modifier Cations During Heat Treatment Under an N2 Atmosphere

An Na+/Ca2+‐deficient layer is observed to form on the glass surface region up to a depth of hundreds of nanometers when a soda‐lime‐silicate glass is heat treated under an N2 atmosphere near its glass‐transition temperature. The measurements were performed using X‐ray photoelectron spectroscopy with C60‐ion sputtering (C60‐XPS) and dynamic secondary‐ion mass spectrometry (D‐SIMS) with consideration of the mass and charge balances. The increase in the amount of hydrogen is substantially less than the decrease in the total charge due to the loss of modifier cations in the Na+/Ca2+‐deficient layer; furthermore, the oxygen concentration in this layer is lower than the bulk value, suggesting that the silanol groups in the surface layer of the glass are dehydrated. A high‐concentration layer of Ca2+ is also confirmed in the dehydration layer of the glass heat treated under an N2 atmosphere, suggesting that Na+ and Ca2+ ions migrate inward into the glass via an ion‐exchange reaction with protons, which migrate toward the surface from the bulk. We also confirmed that a thicker Na+/Ca2+‐deficient layer is formed on glass surfaces with higher water content. Our results suggest that the dehydration of the silanol groups is the driving force of the inward migration of Na+ and Ca2+ ions.

環状及び線状高分子の界面物質拡散現象に関する研究

Diffusion of cyclic and linear polymers at interfaces was studied. Interdiffusion of cyclic polystyrene/cyclic deuterated polystyrene was measured by dynamic secondary ion mass spectroscopy as functions of temperature and molecular weight. Diffusion coefficient of cyclic polystyrene with weight-average molecular weight of 113k is twice as large as that of the corresponding linear one at all the temperatures employed. This result clearly shows that both the linear and cyclic polystyrenes have the same temperature dependence of segmental frictional coefficient. At an iso-free volume condition, diffusion coefficient of cyclic polystyrene is larger than that of the linear one at a given molecular weight. The short-time interdiffusion at an interface of linear polystyrene / linear deuterated polystyrene having different molecular weights was examined by time-resolved neutron reflectivity measurements. The model scattering length density profiles obtained by solving a partial differential equation for the diffusion process were used to analyze the data. The results indicate that even though the molecular weights of both components are larger than the critical molecular weight for entanglement, the initial interfacial broadening of bilayer films with different molecular weight proceeds with asymmetric mobility being inversely proportional to the molecular weight.

Retracted: Mass analysis by Ar-GCIB-dynamic SIMS for organic materials

Generally, dynamic secondary ion mass spectrometry (SIMS) has been mainly used as one of the most powerful tools for inorganic mass analysis. On the other hand, an Ar gas cluster ion beam (GCIB) has been developed and spread as a processing tool for surface flattening and also a projectile for time-of-flight (ToF) SIMS. In this study, we newly introduced an Ar-GCIB as a primary ion source to a commercially available dynamic SIMS apparatus, and investigated mass spectra of amino acid films (such as Arginine and Glycine) and polymer films (Polyethylene: PE and Polypropylene: PP) as organic model samples. As a result, each characteristic fragment peak indicating the original molecular organic structure was observed in the acquired mass spectra. In addition, their own molecular ions of the amino acids were also clearly observed. Mass spectra of PE/PP blended-polymer films acquired using Ar-GCIB-dynamic SIMS could be identified between pure PE and PE:PP = 1:3 mixture by applying principal component analysis (PCA). Copyright © 2014 John Wiley & Sons, Ltd.

Retracted: Mass analysis by Ar-GCIB-dynamic SIMS for organic materials

Generally, dynamic secondary ion mass spectrometry (SIMS) has been mainly used as one of the most powerful tools for inorganic mass analysis. On the other hand, an Ar gas cluster ion beam (GCIB) has been developed and spread as a processing tool for surface flattening and also a projectile for time-of-flight (ToF) SIMS. In this study, we newly introduced an Ar-GCIB as a primary ion source to a commercially available dynamic SIMS apparatus, and investigated mass spectra of amino acid films (such as Arginine and Glycine) and polymer films (Polyethylene: PE and Polypropylene: PP) as organic model samples. As a result, each characteristic fragment peak indicating the original molecular organic structure was observed in the acquired mass spectra. In addition, their own molecular ions of the amino acids were also clearly observed. Mass spectra of PE/PP blended-polymer films acquired using Ar-GCIB-dynamic SIMS could be identified between pure PE and PE:PP = 1:3 mixture by applying principal component analysis (PCA). Copyright © 2014 John Wiley & Sons, Ltd.