Technological applications of nano-structured materials are steadily increasing and to create materials with optimized properties, it is of utmost importance to have non-destructive techniques to characterize elemental depth distributions at the nm scale. X-ray photoelectron spectroscopy (XPS) is ideal for this because it is sensitive on the nm depth scale and it is today widely used by industry. In the large majority of labs it is used within a formalism that relies on the measured peak intensities. In this paper we first point out the large uncertainties and the misleading results that result from such a formalism. We then review techniques that rely on analysis of a wider range of the energy spectrum around the XPS peak rather than just at the peak energy. This results in a much improved accuracy. It is first shown how a simple visual inspection of a survey XPS spectrum can be used to immediately get a rough picture of the nano-structure of the sample. For more accurate quantitative analysis, algorithms have been developed which are implemented in the QUASES (Quantitative Analysis of Surfaces by Electron Spectroscopy) software. The application of this software in practical analysis is discussed. Then it is discussed how this can be combined with synchrotron radiation at high photon energies (HAXPES) to provide analysis of structures buried more than 50 nm in a stack. Finally we discuss a newer algorithm which is less accurate but which has the advantage that it is suitable for automated XPS analysis for determination of the structure. This can be useful for routine analysis and has also been applied to 3-dimensional imaging of surface nano-structures.

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Quantification of XPS and AES analyses requires a theoretical model that relates measured signal intensity with a given quantity describing a studied surface region. Determination of the following quantities and parameters facilitating quantification is addressed here: surface composition, overlayer thickness, and sampling depth of a particular measurement. It is shown that parameterization of quantitative analysis by XPS and AES can based on the emission depth distribution function for the signal electrons. From this function, the formalism for numerous quantitative applications can be derived. Reliable sources of relevant parameters are briefly discussed.

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The certified reference material BAM-L200 is a nanoscale stripe pattern for length calibration and specification of lateral resolution with stripe widths ranging down to 1 nm. BAM-L200 is prepared from a cross-sectioned epitaxially grown layer stack of Al_xGa_1-xAs and In_xGa_1-xAs on a GaAs substrate. Calibration distances, grating periods and stripe widths have been certified by Transmission Electron Microscopy (TEM) with traceability to the length unit. The combination of gratings, isolated narrow stripes and sharp edges of wide stripes offers a plenty of options for the determination of lateral resolution, sharpness and calibration of length scale at selected settings of imaging surface analytical instruments. BAM-L200 will fully support the implementation of the revised International Standard ISO 18516 which is based on knowledge outlined in the Technical Report ISO⁄TR 19319:2013. Additionally, the determination of the Field of View (FoV) in the small area modes of X-ray Photoelectron Spectroscopy (XPS) is addressed, too. A test sample is introduced for a measurement of the intensity contribution from outside the nominal Field of View (FoV).

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Low-voltage scanning electron microscopy (LV-SEM), imaging and energy dispersive x-ray spectroscopy (EDX) analysis, have been applied to steel surfaces in order to clarify the performance of these techniques as a surface analysis. The information depth of LV-SEM imaging is limited by the penetration range of primary electrons. The range also limits the information depth of LV-SEM-EDX analysis. These situations are quite different from those of surface analysis techniques such as Auger electron microscopy in which the escape depth of signal electrons determines the information depth. The information depths of both LV-SEM imaging and LV-SEM-EDX analysis are an order of 10 nm for the primary electron energy of around 1 keV. We can obtain topographic, material, and elemental information from such shallow region of material surfaces with high spatial resolution. This shows that the techniques are applicable to surface analysis of practical materials although the information depth is still deeper by one order than those of the conventional surface analysis techniques.

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The potential distribution image in the channel plane of an amorphous InGaZnO₄ (a-IGZO) thin film transistor in the device operation was evaluated by bias applied hard X-ray photoelectron spectroscopy (HAXPES). We observed that the potential in the direction of channel length changed as a function of source-drain and⁄or gate voltage condition. In particular, in the case of the turn-on voltage condition (saturation regime), a high potential region in the a-IGZO channel was clearly observed. HAXPES under bias voltage was found to be very useful to evaluate the potential in the channel region during transistor operation.

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Interfaces play a critical role in the properties and lifetime of current generation and advanced batteries. However, detailed characterization of the critical interfaces during battery operation which can enable performance improvements and improved design has been a significant challenge requiring innovative technique development and creative experiments. This paper describes ways that information from a range of microscopy, spectroscopy, and spectrometry tools can be used to address important challenges associated with energy storage science and technology, in particular the development of advanced batteries for consumer use, transportation, and renewable storage. Expanding the types of measurements that can be made on operational model batteries has significantly expanded the type and quality of information that can be obtained. This paper first shows examples of approaches being used to collect in situ transmission electron microscopy (TEM), secondary ion mass spectrometry and x-ray photoelectron spectroscopy (XPS) data. The final section of the paper briefly shows two examples: the use of in situ XPS to examine solid-electrolyte interphase layers and a multimodal chemical imaging approach, including scanning TEM, atom probe tomography, scanning transmission x-ray microscopy, and x-ray adsorption near edge spectroscopy to understand the nanostructure and improve the performance of layered lithium transition metal oxide cathodes.

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We have observed chemical vapor deposition (CVD) processes of single-walled carbon nanotubes (SWCNTs) using scanning electron microscopy (SEM) by repeating ethanol exposure and observation without ethanol at an elevated temperature. The initial stage of SWCNT growth and their extension process were analyzed on the SiO₂⁄Si substrate. On the patterned substrate, suspended SWCNT formation processes were successfully traced. Both the observations of growth on the substrate and that between mesa patterns suggest fluctuation of SWCNT growth direction during CVD cause SWCNTs falling on the substrate, forming nearest neighbor suspension and bundling. For graphene segregation on the nickel surface, the formation process could be observed by SEM, enabling preparation of layer-number defined graphene specimens useful for the researches of secondary electron image formation.

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In our previous studies, some approaches have been taken to get three-dimensional (3D) image for both inorganic and organic materials using FIB-ToF-SIMS technique. Of these, shave-off cross-sectioning and metal-assisted shave-off processes were predominant. In the present study, a further approach has been taken to get a 3D image through developing 3D shave-off cross-sectioning method for the generation of secondary ions. Currently used shave-off cross-sectioning method is able to provide 2D image on X-Z plane and that can be improved into 3D by using resistive anode detector through changing the optical transportation system of the secondary ions. Installation of cylindrical lens along Z-axis shows 1000 times magnification of the real image on the detector. For investigation of angular distribution of secondary ions, shape and/or angle of the shave-off cross-sectioning areas, using W-wires as model samples, was evaluated. Shave-off method exhibited the formation of a certain shape of the sample surface with 87° angle. The peak angle of the generated secondary ions was ~45° for 87° tilted samples (Si-wafer and Al-foil) and the observed secondary ion images were 2D by using a resistive anode detector. No significant change in angular distribution of the secondary ions was observed from highly roughness (Al-foil) and almost flat surfaces (Si-wafer).

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Shave-off method has been proven its efficacy for highly precise depth profiling in secondary ion mass spectrometry (SIMS) analysis. The unique technique, shave-off method has distinctive cross-sectional shape after scanning compared with raster scan method. We investigated the cross sectional shape of three different height tungsten samples using focused ion beam scanning electron microscopes (FIB-SEM) and transmission electron microscope (TEM). Though it is a simple cross-sectional shape, the analysis results enable the investigation of an angle between primary ion beam and sample surface, and sputtering yield.

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