Fig. 1 IXS spectra of (a) Ta and (b) Ti-doped Fe2VAl at Q=(6.88, 0, 0). 50Fe2VAl has attracted much attention as a high-performance thermoelectric material. To improve its Figures 1(a)(b) show the IXS spectra of Ta- and Ti-doped Fe2VAl. The spectra are not significantly changed by adding Ta, except for the appearance of a broad peak at ~17 meV. On the other hand, the overall shape of the spectra is largely changed with increasing Ti concentration (Fig. 1(b)). Based on these results, the underlying mechanisms for the reduction of κph will be discussed. Defects in wide-bandgap semiconductors can act as single-photon emitters (SPEs), with potential applications in quantum sensors. Generating SPEs near the surface enables the detection of small magnetic fields. SPEs formed at the oxide/SiC interface during thermal oxidation are promising candidates for surface-proximal single-photon sources [1]. However, previous research has struggled with atomic-level control of the interface structure, resulting in SPEs with varying emission wavelengths [2]. This variability may be caused by the formation of native oxide layers during transport before thermal oxidation, leading to non-uniform interfaces. To address this issue, we developed a method to form ultrathin oxide films and generate uniform SPEs near the surface. Silicon atomic layers were epitaxially grown on 4H-SiC(0001), followed by in-situ oxidization in a molecular beam epitaxy facility, to achieve an atomically flat interface. Scanning probe microscopy confirmed atomically flat step-terrace structures, while X-ray photoelectron spectroscopy revealed increased oxidation components, with oxide film thicknesses measured at 1.3 nm. Photoluminescence measurements showed a sharp emission peak at 740 nm, indicating superior monochromaticity and selective generation of carbon-related defects at the atomically flat interface. Poster Award NomineePoster Award NomineeP1-09Phonon Dispersions of Element-doped Fe2VAl Thermoelectric Compounds Studied by Inelastic X-ray ScatteringKoji Kimura1,2,3, Satoshi Tsutsui2,4, Hidetoshi Miyazaki1, Yoichi Nishino1, and Koichi Hayashi1,21 Department of Physical Science and Engineering, Nagoya Institute of Technology2 Japan Synchrotron Radiation Research Institute (JASRI), SPring-83 Center for Basic Research on Materials, National Institute for Materials Science (NIMS)4 Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki Universityperformance, it is necessary to reduce the lattice thermal conductivity, κph. It is well-known that κph is suppressed by adding forth element. Here, we performed inelastic X-ray scattering (IXS) measurements on Ta- and Ti-doped Fe2VAl to reveal the mechanism of κph reduction through their phonon dispersions [1].[1] K. Kimura et al. Acta Mater. (in press).P1-10Formation of Ultrathin Oxide Films and Controlled Single-Photon Emitters at SiC Interfaces Yasuaki Miyakawa, Satoru Ichinokura, and Toru HiraharaDepartment of Physics, Institute of Science Tokyo [1] A. Lohrmann, Appl. Phys. Lett., 108, 021107 (2016). [2] S. Castelletto, J. Phys.: Photonics, 2, 022001 (2020).
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