Three-dimensional topological insulators (3D TIs) with a gapless topological surface state in a bulk energy gap induced by a strong spin-orbit coupling have attracted much attention as key materials to revolutionize current electronic devices. A spin helical texture of a topological surface state, where the electron spin is locked to its momentum, is a manifestation of a 3D TI.
  A number of well-known thermoelectric and phase-change materials have so far been predicted to be 3D TIs. In order to experimentally confirm their topological characteristics, spin- and angle- resolved photoemission spectroscopy is one of the most powerful tools and it has actually been playing major roles in finding some real 3D TIs.
  In this article, after extensive introduction of topological insulators and spin- and angle- resolved photoemission spectroscopy, some of the ternary 3D TIs are shown to possess topological surface states with marked spin polarizations. It has been revealed for GeBi₂Te₄ that an intermixing effect in the crystal has a minor effect on the surface-state spin polarization, which is ∼70% near the Dirac point in the bulk energy gap region (∼180 meV), which promises to future technological application.

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  Narrow-gap III-V compound semiconductors such as InSb and InAs are indispensable materials for highly sensitive magnetic sensors. We have systematically studied transport properties of Al_0.1In_0.9Sb/InSb and Al_0.1In_0.9Sb/InAs_0.1Sb_0.9 quantum wells: the well-width dependence of sheet resistivity, carrier density and mobility. The carrier density and mobility of InAsSb QWs are higher than those of InSb QWs. The InAs_0.1Sb_0.9 QWs, which lattice mismatch between the well and barrier layers is 0%, shows high mobility regardless of the well width. The calculated band-alignment of these QWs revealed that the bottom of the conduction band of InSb QWs is above the Fermi level, while that of InAs_0.1Sb_0.9 QWs is under the Fermi level, which leads the differece of the carrier density. We also discussed the doping effect into InSb QWs. The doping improves temperature dependence of the mobility and resistivity.

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  Graphene has attracted much attention since the discovery of its superior carrier-transport-properties. In this paper, we report the intercalation of Cu atoms under a zero layer graphene (ZLG) formed on a SiC(0001) substrate, which makes a “free-standing” single layer graphene. Cu atoms are deposited on the ZLG at room temperature. After annealing of the substrate above 600℃, it is confirmed by various experimental methods that a single layer graphene is formed as a consequence of the intercalation of Cu atoms between the ZLG and the SiC substrate. A honeycomb lattice corresponding to the graphene with a moiré pattern is observed by scanning tunneling microscopy. A specific linear dispersion at the K point and a characteristic peak in the C1s core level spectrum, which is originated from a free-standing graphene, are demonstrated by angle-resolved photoemission spectroscopy and X-ray photoemission spectroscopy, respectively.

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  An electrostatic chuck (ESC) wafer stage with a built-in thin type acoustic emission (AE) sensor has been developed for in situ detection of micro-arc discharges occurring around a wafer during plasma processing. The thin AE sensor, which is made of aluminum nitride piezoelectric films, has a detector that is less than 1 mm thick, and it can be installed in a modified ESC wafer stage. The results of this study demonstrate that the sensor can detect acoustic waves propagating through the wafer stage that are generated by micro-arc discharges around the wafer. This in situ detection method is expected to help improve production yield in semiconductor manufacturing.

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  Atomic oxygen adsorption on core-shell Ni@Pt and pure Pt nanoparticles composed of 55 atoms each is investigated using first-principles calculations. Results show that 5d-5d hybridization between Pt(core) and Pt(shell) in pure Pt cluster demonstrates both attractive and repulsive bonding characters depending on oxygen adsorption site. However, for Ni@Pt cluster, 3d-5d hybridization between Ni(core) and Pt(shell) in the presence of oxygen always impose repulsive bonding character, which in turns, weakens the bonding at Ni/Pt interface.

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