Tsuyoshi Yoshitake

Semiconducting β-FeSi2 thin films were epitaxially as-grown on Si(111) substrates at a substrate temperature of 600°C, which is at least 200°C lower than ordinary annealing temperatures, by using the facing targets direct-current sputtering (FTDCS) method using an FeSi2 target without annealing. The deposited film exhibits a smooth surface with a surface roughness root mean square of 1.47nm. The direct and indirect optical band gaps estimated from the experiment were in agreement with those of t

Ferromagnetic Fe3Si thin films with an extremely smooth surface morphology can be epitaxially grown on Si(111) at room temperature by facing target direct-current sputtering. The epitaxial relationship is Fe3Si(111)‖Si(111) with Fe3Si[11¯0]‖Si[1¯10]. By the application of the extinction rule of x-ray diffraction, the generated Fe3Si was confirmed to possess a B2 structure and not a DO3 one. The film showed a saturation magnetization value of 960emu∕cm3, which was slightly lower than that of bulk

The chemical bonding structure of ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite films prepared by pulsed laser deposition was examined by near-edge X-ray absorption fine-structure (NEXAFS), X-ray photoemission, and Fourier transform infrared (FTIR) spectroscopies. An intense sp3-CH peak was observed in the FTIR spectrum. This implies that the sp3-CH peak originates from the grain boundaries between UNCD crystallites, wherein dangling bonds are terminated wit

The spectral absorption properties of ultrananocrystalline diamond (UNCD)/amorphous carbon composite films grown by pulsed laser deposition with graphite were experimentally investigated. The indirect optical band gaps estimated from the absorption spectrum were 1.0 eV and approximately 5.65 eV, which correspond to those for the amorphous carbon surrounding the UNCDs and for UNCDs themselves, respectively. In addition, the spectrum revealed a direct gap having a value of approximately 2.2 eV. On

Amorphous iron silicide was reported to be semiconducting as well as β-FeSi2, and it has received considerable attention from both the physical and engineering points of view. However, there have been few studies and its basic properties are still unknown. We could grow the semiconducting nanocrystalline iron disilicide thin films by pulsed-laser deposition using an FeSi2 target. They consist of crystallites with diameters ranging from 3 to 5 nm. The carrier density and the mobility at 300 K wer

Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) films were formed without initial nucleation using a coaxial arc plasma gun. The UNCD crystallite diameters estimated from the X-ray diffraction peaks were approximately 2 nm. The Fourier transform infrared absorption spectrum exhibited an intense sp3-CH peak that might originate from the grain boundaries between UNCD crystallites whose dangling bonds are terminated with hydrogen atoms. A narrow sp3 peak in the photoemissi

Raman spectroscopic studies on nanodiamond composite (NDC) films, comprising nano-sized diamond grains and an amorphous carbon (a-C) matrix, deposited by coaxial arc plasma deposition are challenging because the scattering of the nano-sized diamond grains competes with the strong signal of the a-C matrix. To unravel the nanocomposite structure of NDC films, both far- and near-field Raman spectroscopy were employed. Based on the comparison of visible and ultraviolet far-field Raman data, componen