The Surface Analysis Research Group planned the topical issues on “Development and application in surface analysis.” Nowadays, when material research results are required in a short period of time, science and technology must provide reliable information. Even in surface analysis, analysts, manufacturers, academic societies, and journals must take actions to ensure restorability, replicability, and reproducibility based on repeatability from their respective standpoints.
Four physical parameters describing the inelastic scattering of electrons, which is a measure of surface sensitivity, were described. The definitions of four parameters, namely, inelastic mean free path (IMFP), mean escape depth (MED), effective attenuation length (EAL), and information depth (ID), are given, and their determination methods and predictive equations were explained. Most of these equations are also applicable to hard X-ray photoelectron spectroscopy. At this time, the author concludes that IMFP and MED are the most appropriate parameters to describe surface sensitivity and detection depth from the standpoint of clarity of definition and practicality.
In this paper, we describe the basic performance of laboratory-based hard X-ray photoelectron spectroscopy (HAXPES Lab.) as well as various measurement examples and future prospects. We investigated the energy resolution and measurement time using Au plate and 30 nm thickness thermal oxide on the Si substrate. The energy resolution of HAXPES Lab. is comparable to that of conventional XPS with AlKα X-ray source, and the measurement time is only 10 times longer than that of synchrotron radiation facilities to ensure the same photoelectron counts. As real device samples, we evaluated the location dependence of the chemical bonding states of the high aspect ratio trench structure, one of the structures of LSI devices, and protein adsorption by controlling the orientation of biomaterials.
Originally developed high-spatial focused ion beam secondary ion mass spectrometer (FIB-TOF-SIMS) is described. The FIB-TOF-SIMS has a unique function such as micro-cross-sectioning of small particles and analysis of interior of the particle. Three types of applications are explained. The first one is individual particle analysis of aerosol. Chemical reaction of yellow sands in air was revealed with the FIB-TOF-SIMS analysis. The second one is biological application. A 3D-culture (spheroid) sample was analyzed after cross-sectioning. The last one is application to decommissioning of the Fukushima-Daiichi power plant. The most important feature, isotope imaging without isobaric interference by means of resonance ionization using tunable Ti:Sapphire lasers integrated on the FIB-TOF-SIMS.
This is a research report about fully automated analysis of X-ray photoelectron spectroscopy (XPS). We developed a fully automated method to perform XPS spectral analysis based on the information criteria. Our method searches a large number of initial fitting models by changing the degree of smoothing, and obtains a series of fitting results. The goodness of those optimized models is ranked using information criteria. We found that, using the Akaike information criterion, a complicated model tended to be selected, with a larger number of peaks than expected from the spectral shape. On the other hand, using the Bayesian information criterion (BIC), a simple model with reasonably good agreement and a moderate number of peaks was selected. The model selected by the BIC was close to the result of peak fitting performed by XPS analysis experts. We also present the difference in modeling between Gaussian noise and Poisson noise.
In order to utilize data science such as artificial intelligence (AI) and materials informatics (MI) for measurement analysis data, it is necessary to use correct data. To do this, the sample must be handled correctly and cross-checked in a combined analysis. We will describe the combined measurement and analysis by the Cyber Physical System (CPS) for that purpose, and give an overview of the future of analysis technology aiming to create high-value-added data.
Ever since the invention of photoelectron spectroscopy, researchers have attempted to analyze materials under conditions closely resembling their application environment. Near-Ambient Pressure X-ray Photoelectron Spectroscopy is a logical development in this quest, since it allows for analyzing non-vacuum compatible samples in general, and phase boundaries, such as solid|liquid or solid|gas interfaces, in particular. With the development of spectrometer systems compatible with analysis pressures of up to 100 mbar, many novel experimental geometries have been realized since the early 2000s. Since then, experimental capability and variety have further progressed through the proliferation of off-synchrotron laboratory systems, and advanced sample environments to simulate material usage conditions. This progress has, e.g., enabled the performance of operando spectroscopy during catalytic or electrochemical experiments. The present work gives, from an instrumental point of view, a short overview over basic system design considerations and recent developments in the field.
We report the fabrication and characterization of indium oxide (In2O3) thin-film transistors (TFTs) with excimer light irradiation and heat treatment by solution process. We evaluated the impact of varying the irradiation time of excimer light and the temperature of heat treatment on the In2O3 thin films. The combined process of excimer light irradiation and thermal treatment reacted with the formation and decomposition of OH groups. As a result, we were able to efficiently produce In2O3 in this fabrication process. Transfer characteristics of In2O3-TFTs with excimer light irradiation and heat treatment showed better than these of In2O3-TFTs with heat treatment, and On/Off ratio of the In2O3-TFT with excimer light irradiation and heat treatment was 3.26×104. Furthermore, the transfer characteristics of In2O3-TFT irradiated by excimer lamp in O2 atmosphere were improved, and O2 in the atmosphere during excimer light irradiation was important for the low-temperature formation of the thin films.
Optimized mechanical grinding (OMG) was developed as a low outgassing surface finishing for aluminum alloys (A5052). Surface morphology and depth profile for aluminum alloys with four types of surface finishes, i.e. conventional mechanical grinding (MG), mechanical grinding with optimized process (OMG), combination of mechanical grinding and chemical polishing (MG＋CP) and combination of optimized mechanical grinding and chemical polishing (OMG＋CP), were investigated using Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The surfaces of MG and MG＋CP were rough, whereas OMG and OMG＋CP were smooth. The composition of the surface layer of MG was composed of Al2O3 and γ–AlOOH, whereas OMG, MG＋CP, and OMG＋CP was composed of Al2O3. Therefore, OMG was considered to have low outgassing property due to the smooth surface and thin surface oxide layer compose of Al2O3, which were originated from the small surface alteration by the processing.