We have developed a scanning photoelectron microscope system with the capability of depth profiling in electron spectroscopy for chemical analysis (ESCA). We call this system “3D nano-ESCA.” The system has been installed at the University-of-Tokyo Materials Science Outstation beamline, BL07LSU, at SPring-8. A total spatial resolution is achieved to be better than 70 nm. A photoelectron analyzer with an acceptance angle of 60 degrees enables us to obtain the angular dependence of the photoelectron spectra for the depth-profile analysis without rotating the sample. In this article, we introduce the capability of the 3D nano-ESCA system and recent research activities on high-k gate insulator, graphene, and metal-nanowire devices using the 3D nano-ESCA system.
X-ray ptychography, which is one of the coherent X-ray diffractive imaging techniques, allows us to observe extended objects with a high-spatial resolution and a wide field of view. We have developed high-resolution and high-sensitivity X-ray ptychography using the high-intensity X-ray beam focused by total reflection mirrors at SPring-8. In addition, we have applied it to the elemental mapping of metallic nanoparticles and the imaging of the dislocation strain fields of a silicon film. This method will be available to observe various materials and biological specimen.
The synergy of scanning probe microscope and optical microscope realizes a promising sensing technique in surface characterization in the nanoscale with a high chemical sensitivity, which is not attainable by a simple topographic contrast. This paper introduces one of the synergy tools, that is, near-field scanning optical microscope particularly the use of a sharp metallic probe tip. While optical microscope exhibits a high chemical sensitivity, the spatial resolution of conventional optical microscopes using lens is diffraction limited due to wave nature of light. The key technique to break through this limitation is surface plasmon polariton excitation at the tip, which is promising for both high spatial resolution and high sensitivity. This technique has been recently recognized as tip-enhanced near-field spectroscopy.
The observation method of photoemission electron microscopy (PEEM) on insulating samples has been established by introducing simple Au pattern evaporation equipment. Surface conductivity is induced locally on an insulating surface by continuous radiation of soft x-rays, and Au films close to the area of interest allow the accumulated charges to be released to a ground. Using this technique, all usersʼ experiments on poorly conducting samples have been performed successfully at the PEEM experimental station in SPring-8.
In this article, we introduce our recent works of x-ray fluorescence holography (XFH) to investigate atomic configurations in some functional materials, such as Zn1−xMnxTe diluted magnetic semiconductor and Ge1−xMnxTe high-temperature ferromagnetic thin films. From these experiments, we found that diffraction methods reflecting long-range periodicity have a crucial disadvantage in studying local-and intermediate-range atomic configurations, which are very important to determine physical properties of these materials. We present new aspects on the local structures of these materials by our XFH experiments and their analyses.
Pump-probe technique enables to capture short-lived photo-excited molecule. Herein, pump-probe single crystal X-ray structure analysis about a photo-excited organic photocatalyst is described. Owing to atomic-resolved observation by single crystal X-ray structure analysis, three-dimensional geometrical feature of a target photocatalyst at a photo-excited state revealed in detail. Effects of steric hindrances and intermolecular interactions in a crystal on photoinduced geometrical change were also clarified. Those ensure the electronic feature of the target photocatalyst in action and elucidate a long-lived character of its photo-excited state.