Scanning Probe Microscopy Analysis Research Articles

Step height measurement of monoatomic silicon crystal lattice steps with a commercial atomic force microscope

Abstract Precise control of advanced materials relies on accurate dimensional metrology at the sub-nanometre scale. At this scale, the accuracy of scanning probe microscopy (SPM) has been limited by the lack of traceable transfer standard artefacts with calibration structures of suitable dimensions. With the adoption in 2019 of the silicon crystal lattice spacing as a secondary realization of the metre in the International System of Units (SI), SPM users have direct access to a realization of the SI metre at the sub-nanometre level by means of the step height of self-assembled monatomic lattice steps that can form on the surface of silicon crystals. A key challenge of successfully adopting this pathway is establishing the need for established protocols to minimize measurement errors and artifacts in routine laboratory use.
In this study, step height measurements of monoatomic lattice steps in an ordinal/staircase structure on a Si(111) crystal surface have been derived from images acquired with a commercially available, research-level atomic force microscope (AFM). Measurement results derived from AFM images using three different SPM image processing and analysis software packages are compared. Significant sources of measurement uncertainty are identified; principally the contribution from the dependence on scan direction. The calibration of the
AFM derived from this measurment was used to traceably measure the sub-nanometre lattice steps on a silicon carbide crystal surface to demonstrate the viability of this calibration pathway.

Farklı Oranlarda Sürfaktan İçeren PbS İnce Filmlerin Fiziksel Özelliklerinin İncelenmesi

Bu çalışmada, polikristal kurşun sülfür ince filmler, kokamid dietanolamin varlığında kimyasal banyo depolama tekniği kullanılarak cam altlıklar üzerinde başarılı bir şekilde biriktirilmiştir. Farklı oranlarda kullanılan kokamid dietanolaminin PbS ince filmlerin yapısal, morfolojik ve optik özellikleri üzerindeki etkileri X-ışını kırınımı (XRD), taramalı elektron mikroskobu (SEM), taramalı prob mikroskopisi (SPM) ve UV-görünür spektroskopi analizleri kullanılarak incelendi. XRD analizlerinden kokamid dietanolamin katkı miktarının artmasıyla PbS ince filmlerin kristal büyüklüklerinin 12.57 nm’ den 5.43 nm’ ye azaldığı elde edilmiştir. Ayrıca mikrogerilme ve dislokasyon yoğunluğu değerleri kokamid dietanolamin katkı miktarına bağlı olarak artmıştır. SEM analizi kokamid dietanolamin katkısının nanoyapılı PbS ince filmlerin yüzey morfolojilerini etkilediğini göstermektedir. SPM analizi kokamid dietanolamin katkısının artmasıyla ince filmlerin yüzey pürüzlülüğü değerlerinin arttığını göstermiştir. UV-görünür spektroskopi analizi ile %1 kokamid dietanolamin katkı miktarında PbS ince filmin optik geçirgenlik değerinin yaklaşık olarak 3 kat arttığı elde edilmiştir. Ayrıca, kokamid dietanolamin miktarına bağlı olarak PbS ince filmlerin optik bant aralığı değerleri 1.87 eV’ tan 2.53 eV’ a artmıştır.

Soft Surface Nanostructure with Semi-Free Polyionic Components for Sustainable Antimicrobial Plastic.

Surface antimicrobial materials are of interest as they can combat the critical threat of microbial contamination without contributing to issues of environmental contamination and the development drug resistance. Most nanostructured surfaces are prepared by post fabrication modifications and actively release antimicrobial agents. These properties limit the potential applications of nanostructured materials on flexible surfaces. Here, we report on an easily synthesized plastic material with inherent antimicrobial activity, demonstrating excellent microbicidal properties against common bacteria and fungus. The plastic material did not release antimicrobial components as they were anchored to the polymer chains via strong covalent bonds. Time-kill kinetics studies have shown that bactericidal effects take place when bacteria come into contact with a material for a prolonged period, resulting in the deformation and rupture of bacteria cells. A scanning probe microscopy analysis revealed soft nanostructures on the submicron scale, for which the formation is thought to occur via surface phase separation. These soft nanostructures allow for polyionic antimicrobial components to be present on the surface, where they freely interact with and kill microbes. Overall, the new green and sustainable plastic is easily synthesized and demonstrates inherent and long-lasting activity without toxic chemical leaching.

Topography and Permeability Analyses of Vasculature-on-a-Chip Using Scanning Probe Microscopies.

Microphysiological systems (MPS) or organs-on-chips (OoC) can emulate the physiological functions of organs in vitro and are effective tools for determining human drug responses in preclinical studies. However, the analysis of MPS has relied heavily on optical tools, resulting in difficulties in real-time and high spatial resolution imaging of the target cell functions. In this study, the role of scanning probe microscopy (SPM) as an analytical tool for MPS is evaluated. An access hole is made in a typical MPS system with stacked microchannels to insert SPM probes into the system. For the first study, a simple vascular model composed of only endothelial cells is prepared for SPM analysis. Changes in permeability and local chemical flux are quantitatively evaluated during the construction of the vascular system. The morphological changes in the endothelial cells after flow stimulation are imaged at the single-cell level for topographical analysis. Finally, the possibility of adapting the permeability and topographical analysis using SPM for the intestinal vascular system is further evaluated. It is believed that this study will pave the way for an in situ permeability assay and structural analysis of MPS using SPM.

Nano-films of carbo-benzene derivatives: Scanning probe microscopy analysis and prospects of use in organic solar cells

Three carbo-mer derivatives based on a C18Ph4 core decorated with two identical electro-active groups X, i.e. two aromatic carbo-benzenes (1 and 2, X = 4-anilinyl) and one pro-aromatic carbo-quinoid (the carbo-TTF 3, X = 1,3-dithiol-2-ylidene) were studied through Scanning Probe Microscopies (SPMs). Self-Assembled Monolayers (SAMs) were fabricated (thickness ~160 pm), for the two centrosymmetric representatives 1 and 3, the organization of which on the HOPG substrate was found to be structure-specific. Electrical/electronic properties of the three carbo-mers were determined by using Atomic Force Microscopy (AFM) and its electrical modes: Kelvin Probe Force Microscopy (KPFM) and conductive Atomic Force Microscopy (c-AFM). Measurements of the work function (∅) through KPFM result in a ∅ = 5.60 eV value for 1, 4.97 eV for 2 and 4.82 eV for 3. Hole mobility (µ) values extracted from local I-V plots by using c-AFM are 15×10−8cm2V−1s−1 for 1, 3×10−6cm2V−1s−1 for 2 and 87×10−8cm2V−1s−1 for 3. A concept test of the possible application of carbo-mers in self-assembled hole transporting monolayer (SA-HTM), with the view to replacing the most common p-type contact used in organic solar cells (OSCs), PEDOT:PSS, is also reported.

Photodegradation pathways of CH3NH3PbI3 organic perovskite polycrystalline film observed by in-situ scanning probe microscopy

In this study, the in-situ observation of degradation-induced local elastic modulus (Young’s modulus) variation in CH3NH3PbI3 (MAPbI3) polycrystalline film was conducted using the continuous scanning by scanning probe microscopy (SPM). We pointed out that the observed degradation in MAPbI3 film under the SPM continuous scanning is a photo-excited process due to the stray laser effect induced by the scattering of the SPM-equipped red laser. The degradation rate was highly accelerated by light illumination when the MAPbI3 polycrystalline films were aged in humid air, O2, dry air, and N2 atmosphere. Significantly, the SPM analysis result shows that several hours is sufficient for MAPbI3 film to undergo red light degradation in N2. Otherwise, under light illumination, the result provides evidence that hydrate, which is the critical intermediate phase to trigger humid degradation, did not occur even in the presence of H2O. It identifies H2O is not the preferential species to react with the photo-excited MAPbI3. Though the laser effect must be carefully taken into account, this study indicates that SPM is an appropriate analysis technique to examine the infinitesimal variation of surface property in organic perovskite material, clarifying the degradation mechanism in the initial period.

Decontamination of Titanium Surface Using Different Methods: An In Vitro Study.

Contamination of implants is inevitable during different steps of production as well as during the clinical use. We devised a new implant cleaning strategy to restore the bioactivities on dental implant surfaces. We evaluated the efficiency of the Finevo cleaning system, and Ultraviolet and Plasma treatments to decontaminate hydrocarbon-contaminated titanium disks. The surfaces of the contaminated titanium disks cleaned using the Finevo cleaning system were similar to those of the uncontaminated titanium disks in scanning electron microscopy and X-ray photoelectron spectroscopy analysis, but no obvious change in the roughness was observed in the scanning probe microscopy analysis. The rat bone marrow mesenchymal stem cells (rBMMSCs) cultured on the treated titanium disks attached to and covered the surfaces of disks cleaned with the Finevo cleaning system. The alkaline phosphatase activity, calcium deposition, and osteogenesis-related gene expression in rBMMSCs on disks cleaned using the Finevo cleaning system were higher compared to those in the ultraviolet and plasma treatments, displaying better cell functionality. Thus, the Finevo cleaning system can enhance the attachment, differentiation, and mineralization of rBMMSCs on treated titanium disk surfaces. This research provides a new strategy for cleaning the surface of contaminated titanium dental implants and for restoration of their biological functions.

Wettability Recovery Behavior Governed by Desorption of Hydroxyl Species in Steel.

The radiation induced surface activation (RISA) effect which occurs at the bilayer of metal and oxide due to irradiation contributes to improving the materials surface wettability and enhancing electrothermal characteristics and corrosion resistance. The purpose of the present study is to reveal the correlation between the wettability recovery behavior and the microstructural features of the adsorbed water and/or hydroxyl species on the surfaces. The wettability change due to the RISA effect was investigated in the oxidized austenitic stainless steel with various holding times under darkness after UV irradiation. The microstructure features of the adsorbed water and/or hydroxyl species on the surfaces were characterized by Raman spectroscopy and scanning probe microscopy (SPM). Results show that the contact angle of the specimen after UV irradiation parabolically increased with increasing holding time, regardless of the chemical composition within these two steels. The absorbed water layer was observed in both specimens by Raman analysis, and its intensity decreased with increasing holding time. From the force-distance curves of SPM analysis, the hydrophilic component was rapidly decreased at a holding time below 200 h, then gradually saturated when the holding time increased above 200 h from the SPM analysis. These results reveal that the wettability recovery behavior in oxidized austenitic stainless steels after UV irradiation can be ascribed to two kinds of mechanisms. One is the desorption of the hydrophilic components which are predominant when the contact angle is less than 30°, and the other is the absorption of the hydrophobic components which works mainly when the contact angle is above 30°.

Conductive Polymer-Ag Honeycomb Thin Film: The Factors Affecting the Complexity of the Microstructure

We present control of morphology of conductive polymer-Ag honeycomb thin films prepared by a facile directed self-assembly process based on metal-complexation-induced phase separation at the air/water interface. Continuous Ag honeycombs with pore sizes controlled from 1 μm to 500 nm were grown on the polymer matrix. The current-sensing scanning probe microscopy analysis proved that the Ag-hybrid pattern is conductive. The honeycomb film can be transformed to a semi-transparent film by hybridization with poly(methyl methacrylate). These materials are potentially applicable in fabrication of electronic devices.

Nanoscale Measurements of Lithium‐Ion‐Battery Materials using Scanning Probe Techniques

AbstractState‐of‐the‐art scanning probe microscopy (SPM) methods as applied to energy conversion and storage devices, specifically lithium‐ion batteries, are reviewed with an emphasis on the electroactive elements. The unique ability of SPM‐based methods to provide localized information has proven highly valuable for the in‐depth understanding of the fundamental mechanisms, processes, and degradation of lithium‐ion batteries (LIBs). As such, SPM analysis is poised to play a strong role in the competition for new higher performing LIBs, especially given the unprecedented choice and availability of SPM techniques tailored to provide physical and chemical information at the nanoscale.

Scanning Probe Microscopy Analysis of the Adsorption of Volatile Organic Compounds on Carbonaceous Films with Microcolumnar Structure

Scanning Probe Microscopy Analysis of the Adsorption of Volatile Organic Compounds on Carbonaceous Films with Microcolumnar Structure

Physicochemical characterization of amino functionalized synthetic clay/Nafion nanocomposite film with embedded platinum nanoparticles for PEM fuel cells

A novel aminopropyl functional group bearing magnesium phyllosilicate clay (AC)/Nafion nanocomposite films with embedded platinum nanoparticles (Pt/AC/N) was prepared by sol–gel method followed by solution casting for various compositions of AC in Nafion. The as prepared nanocomposite films were subjected to surface characterization by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The thermal and mechanical stabilities were analyzed by thermogravimetric analysis (TGA) and nanoindentation coupled scanning probe microscopy analysis (SPM). The protonic conductivity of AC/Nafion nanocomposite films with and without Pt nanoparticles was measured by electrochemical impedance spectroscopy (EIS) using a two-probe conductivity cell. It was found that 6wt.% AC/Nafion possesses a high proton conductivity of 1.38×10−4Scm−1, a thermal stability of up to 360°C (60°C higher than pristine Nafion) and a high mechanical stability (78.76MPa) among the different compositions studied. The catalytic activity of the optimized nanocomposite film containing Pt nanoparticles (Pt/6wt.% AC/N) towards oxygen reduction reaction (ORR) was investigated by cyclic voltammetry (CV) and linear scan voltammetry (LSV) techniques under hydrodynamic conditions. It was observed that 35.4μgcm−2 Pt/6wt.% AC/N composite film has higher ORR limiting current density of 4.2mAcm−2, and also it is interesting to note that this composition exhibited a high conductivity of 1.75×10−3Scm−1 indicating that the nanocomposite catalyst film could be used as a proton conductor as well as a catalyst layer for the fabrication of membrane electrode assemblies in PEM fuel cells.

Agglomeration behavior of nickel particles on YSZ electrolyte

Agglomeration behavior of nickel particles on yttria stabilized zirconia (YSZ), NiO doped YSZ and TiO2 doped YSZ substrates was examined by scanning electron microscopy (SEM) as two dimensional (2D) analysis and scanning probe microscopy (SPM) as three‐dimensional (3D) analysis. For 2D analysis, binarized SEM image was analyzed to examine the agglomeration factor. In 3D analysis, wettability analyzing method was adopted for solid particle on solid substrate, and “apparent” contact angle was evaluated by the following equation;θ=2tan−12h/dwhere d and h are the observed particle diameter and the observed particle height of each agglomerated particle obtained by SPM analysis. Results from both analysis techniques revealed that NiO doped YSZ tend to enhance the nickel agglomeration, whereas TiO2 doped YSZ shows better wettability especially for larger nickel particles.

Synthesis and Properties of BaZr0.1Ce0.7Y02-xMxO3-δ (x = 0, 0.1; M = Dy, Yb) Compounds

The following barium cerate zirconate compounds were prepared by the solid state route: BaZr0.1Ce0.7Y0.2O3-δ, BaZr0.1Ce0.7Dy0.2O3-δ, BaZr0.1Ce0.7Y0.1Dy0.1O3-δ, The powders were attrition milled, pressed and sintered at 1550 °/4 h. X-ray diffraction data of all compositions show the perovskite orthorhombic phase (powders) and the perovskite cubic phase (pellets). Impedance spectroscopy measurements in the 5 Hz-13 MHz frequency range show that Dy may substitute total or partially for Y without noticeable change in the electrical conductivity, whereas the Yb substitution leads to a decrease in the electrical conductivity. The bulk electrical resistivity follows the trend: Yb- < Dy- < Dy-Y- < Yb-Y- < Y-doped barium cerate zirconate sintered ceramics. A detailed scanning probe microscopy analysis of the polished and thermally etched surfaces of the sintered pellets show images of sub-intergranular regions, which are further evidences of the large grain boundary electrical resistivity of barium cerate compounds.

X-ray Photoelectron Spectroscopy and Scanning Probe Microscopy Analysis of Polymethylmetacrylate Surface Etched by Charged Water Droplets

X-ray Photoelectron Spectroscopy and Scanning Probe Microscopy Analysis of Polymethylmetacrylate Surface Etched by Charged Water Droplets

Surface modification of porous scaffolds with nanothick collagen layer by centrifugation and freeze‐drying

Three-dimensional (3D) porous scaffolds constructed from biodegradable synthetic polymers are frequently used in tissue engineering. Their surfaces are hydrophobic and require treatment to be changed to hydrophilic before use in cell culture. We developed a novel surface modification for 3D porous scaffolds made of synthetic polymers by coating the surfaces of the pores with a nanothick collagen layer. First, a collagen aqueous solution was introduced under reduced pressure to fully fill the pores of the PLGA sponges. The collagen-containing sponges were then centrifuged to remove any excess collagen solution. Finally, the sponges were freeze-dried to form a thin collagen layer. Scanning electron microscopy observation and water absorption tests demonstrated that the excess collagen was removed; the effect of modification was evident when the collagen-containing sponges were centrifuged at high centrifugal acceleration. Scanning probe microscopy analysis demonstrated the formation of a nanometer-thick collagen layer on the PLGA surface. The collagen-coated PLGA sponges facilitated cell seeding and spatial distribution. The method will be useful for the surface modification of 3D porous scaffolds.

Scanning probe microscopy analysis of delaminated thin films

In this article the results of atomic force microscopy (AFM) and scaning thermal microscopy (SThM) of delaminated thin films are presented. It is shown that SThM data can be used for a very precise localisation of the delaminated areas that is necessary for the analysis of film material properties. Moreover, by using AFM it is also possible to characterize morphology of the blister upper boundary with a high resolution too. The quantitative results obtained by the above mentioned methods are compared with nanoindentation measurements.

Physical and chemical properties of hybrid barrier coatings obtained in an atmospheric pressure dielectric barrier discharge

The aim of this work is to develop barrier coatings by using an atmospheric pressure dielectric barrier discharge (DBD). For this purpose the plasma polymers obtained from a hybrid organic–inorganic precursor compound as well as from a purely organic compound were compared. The physical properties of the coatings were determined by scanning electron microscopy and scanning probe microscopy analysis as well as by profilometry and by determining their oxygen transmission rates. The chemical structure was revealed by ATR-FTIR analysis and 13C- and 29Si-CP/MAS solid-state nuclear magnetic resonance measurements. It is shown that atmospheric pressure plasma polymerization of hybrid polymer precursors leads to coatings with excellent barrier properties due to the unique synergistic effect of the organic and the inorganic network structures that are formed in the plasma.

Fracture morphology and mechanical properties of ethylene/vinyl acetate rubber vulcanizates reinforced by in situ prepared sodium methacrylate

AbstractEthylene/vinyl acetate rubber (EVM) was reinforced by sodium methacrylate (NaMAA) that was in situ prepared through the neutralization of sodium hydroxide and methacrylic acid in EVM during mixing. The mechanical properties of EVM vulcanizates with different NaMAA loadings and at different crosslink densities were studied and compared with those of high abrasion furnace carbon black (HAF) filled EVM vulcanizates. The fracture surfaces of gum and filled EVM vulcanizates were observed with scanning electron microscopy. The results showed that NaMAA‐reinforced EVM vulcanizates had better mechanical properties than HAF/EVM vulcanizates. When the NaMAA loading was 50 phr, the tensile strength of the NaMAA/EVM vulcanizate was 30 MPa, the tear strength was 102 kN/m, and the elongation at break was over 400%. Fourier transform infrared analysis confirmed that NaMAA formed in the compounding process and underwent polymerization during vulcanization. Scanning probe microscopy analysis revealed that nanoscale particles dispersed in the NaMAA/EVM vulcanizates. The mechanical properties were correlated with the fracture morphology of all the vulcanizates. The tensile rupture of NaMAA‐filled EVM vulcanizates occurred through tearing from a crack in the bulk of the samples. Tear deviation occurred with the addition of NaMAA and resulted in a rough surface, leading to an improvement in the tear strength of NaMAA‐filled EVM vulcanizates. The micrographs of the tear surfaces of the vulcanizates indicated that the different fracture modes depended on the NaMAA loading and the crosslink density. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1715–1724, 2004

Ion sputtering, surface topography, SPM and surface analysis of electronic materials

Two side effects introduced on surfaces of electronic materials by ion bombardment, namely compositional changes (for compound semiconductors) and topography changes are discussed. Based on the relative elemental sensitivity factor method with matrix corrections for quantitative AES or XPS analysis, a sputter correction factor is defined to compensate for bombardment induced surface compositional changes. Using several popular preferential sputter models and comparing their predictions to a synopsis of published experimental AES and XPS measurements on argon bombarded binary compound semiconductors, a sputter correction factor for these materials are proposed. The extent of bombardment-induced topography depends primarily on the substrate material while the ion beam characteristics play only a secondary role. Due to the complexity of and the many processes involved in ion/solid interactions, bombardment-induced topography is not well understood. Several quantitative and qualitative theories have been proposed to explain the experimental data. Most of these theories are based on SEM or TEM data. The major disadvantage of these data is the lack of quantitative information. The advent of SPM (scanning probe microscopy) and the subsequent development of software have reversed this. A brief summary of SPM (AFM and STM) investigations of bombardment induced topography on semiconductor surfaces is given. Most studies have concentrated on the topography on Si, Ge, GaAs and InP surfaces with special emphasis on ripple development.