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Rutile-related (tetragonal rutile and monoclinic distorted rutile) ReO2 epitaxial thin films were grown on rutile TiO2 single crystalline substrates by reactive pulsed laser deposition of the Re metal target under a N2O atmosphere. The ReO2 film underwent structural phase transition from the monoclinic to tetragonal phase with the decreasing film thickness, driven by compressive lattice strain from the substrate. X-ray photoelectron spectroscopy and electrical transport measurements revealed that both phases had metallic properties above 25 K. The distinct difference in valence band spectra between the two phases might be due to reconstruction of the band structure dominated by Re 5d t2g. [ABSTRACT FROM AUTHOR]

The electronic band structure of thin films and superlattices made of Heusler compounds with NiTiSn and NiZr0.5Hf0.5Sn composition was studied by means of polarization dependent hard x-ray photoelectron spectroscopy. The linear dichroism allowed to distinguish the symmetry of the valence states of the different types of layered structures. The films exhibit a larger amount of "in-gap" states compared to bulk samples. It is shown that the films and superlattices grown with NiTiSn as starting layer exhibit an electronic structure close to bulk materials. [ABSTRACT FROM AUTHOR]

Epitaxial semiconducting NiYBi thin films were directly prepared on MgO(100) substrates by magnetron sputtering. The intensity ratio of the (200) and (400) diffraction peaks, I(200)/I(400) = 2.93, was close to the theoretical value (3.03). The electronic structure of NiYBi was calculated using wien2k, and a narrow indirect band gap of width of 210 meV was found. The valence band spectra of the films obtained by linear dichroism in hard x-ray photoelectron spectroscopy exhibit clear structures that are in good agreement with the calculated band structure of NiYBi. [ABSTRACT FROM AUTHOR]

Abstract: High-density and similarly-sized Si nanodots were formed by annealing ultra-thin amorphous Si (a-Si) films deposited on SiO2/Si substrates in vacuum. Dependences of density and diameter of the Si nanodots on the a-Si film thickness and, annealing temperature and time were investigated by scanning electron microscopy. It is found that drastic increase (decrease) in the density (diameter) occurred at an a-Si thickness of 1 nm. By agglomeration of sub-nanometer thick a-Si films, a density larger than 1012 cm−2, an average diameter smaller than 5 nm, and a dispersion of diameter less than 15% were achieved. [Copyright &y& Elsevier]

The change in electronic structure of V1-xWxO2 thin films across a metal-insulator transition (MIT) is investigated in terms of hard x-ray photoemission spectroscopy and x-ray absorption spectroscopy. In the lower doping range (0 ≤ x ≤ 0.08), the spectra exhibit the characteristic features for the dimerization of V ions in the monoclinic phase, indicating that Peierls-like instability predominately causes the MIT in this range. Conversely, in the higher doping range (0.1 ≤ x), spectral weight transfer is observed from the coherent part at the Fermi level to the incoherent part, indicating that the ground state of V1-xWxO2 films in this range is a typical Mott insulator. The results suggest that the unusual phase diagram of the V1-xWxO2 thin films originates from the competition between the Peierls and Mott instabilities. [ABSTRACT FROM AUTHOR]

This work reports the measurement of magnetic dichroism in angular-resolved photoemission from in-plane magnetized buried thin films. The high bulk sensitivity of hard x-ray photoelectron spectroscopy (HAXPES) in combination with circularly polarized radiation enables the investigation of the magnetic properties of buried layers. HAXPES experiments with an excitation energy of 8 keV were performed on exchange-biased magnetic layers covered by thin oxide films. Two types of structures were investigated with the IrMn exchange-biasing layer either above or below the ferromagnetic layer: one with a CoFe layer on top and another with a Co2FeAl layer buried beneath the IrMn layer. A pronounced magnetic dichroism is found in the Co and Fe 2p states of both materials. The localization of the magnetic moments at the Fe site conditioning the peculiar characteristics of the Co2FeAl Heusler compound, predicted to be a half-metallic ferromagnet, is revealed from the magnetic dichroism detected in the Fe 2p states. [ABSTRACT FROM AUTHOR]

Abstract: Surface modification of polymethylmethacrylate (PMMA) films has been investigated with argon–oxygen mixture plasmas sustained with multiple low-inductance antenna units. PMMA films were exposed to argon–oxygen mixture (20%) plasmas on a water-cooled substrate holder. Average ion energies bombarding onto the PMMA films was estimated to be as low as 6eV, which was evaluated from the gap between plasma potential and floating potential. The etching depth of PMMA surface increased linearly with increasing plasma-exposure time and the etching rate was 170nm/min. Surface roughness of PMMA slightly increased from 0.3nm to 1.4nm with increasing exposure time. Hard X-ray photoelectron spectroscopy (HXPES) was carried out to examine chemical bonding states of the PMMA surface in deeper regions (about 54nm) as compared with those observed in shallower regions (27nm). [Copyright &y& Elsevier]

Abstract: Plasma–polymer interactions have been investigated on the basis of hard X-ray photoelectron spectroscopy (HXPES) together with conventional X-ray photoelectron spectroscopy (XPS) for analysis of chemical bonding states in the surface nano-layers of polymethylmethacrylate (PMMA) films, which were exposed to argon plasmas sustained via RF inductive coupling with multiple low-inductance antenna units. The PMMA films were exposed to argon plasmas on a water-cooled substrate holder. Average ion energies bombarding onto PMMA films were varied in the range of 6–16eV, which were evaluated as ion kinetic energies at the sheath edge to the ground potential using a mass-separated ion-energy analyzer. The etching of PMMA surface after Ar plasma exposure with an ion dose of 3.4×1018 ions/cm2 was measured to be insignificant (less than 20nm). Surface roughness of PMMA slightly increased from 0.3nm to 0.4nm with increasing ion bombardment energy from 6eV to 16eV. HXPES was carried out together with conventional XPS to examine chemical bonding states of the PMMA surface in deeper regions (about 54nm) with HXPES as compared to those observed in shallower regions (8nm) with the conventional XPS. [Copyright &y& Elsevier]