Name HOSHI Yusuke
Official Title Associate Professor
Affiliation Electrical, Electronic and Communication Engineering
Profile My specialty is fundamental physics, crystal growth and device applications of semiconductors such as transition metal dichalcogenides and group IV materials. In particular, I have an interest in researches on investigation of optical properties and development of functional optoelectronic devices on two-dimensional (2D) materials. Recently, van der Waals heterostrutures, which are obtained by artificially and arbitrarily stacking the 2D materials like graphene, hexagonal boron nitride and transition metal dichalcogenides have attracting considerable attentions for emergence of intrinsic characterizations and novel functionalities in 2D materials. Therefore, I am studying about valley polarization, which is one of specific properties in two dimensional materials. I have skills to stack the 2D materials and some optical measurement systems of photo- and electroluminsecence at 20 - 300 K, time-resolved photoluminescence and Raman spectroscopy.
In device applications, I have some knowledges of transistors, photovoltaics and light emitting diodes.
Research Field(Keyword & Summary)
  1. (1)Atomically thin-layered materials

    The aim of this research is to realize functional optoelectronic devices by utilizing 2D materials, which are a new stage of research in materials science. 2D materials where graphene is a representative material, are crystals composed of one atomic layer sheet. Among various 2D materials, semiconducting transition metal dichalcogenides are the most central materials for realization of functional optoelectronic devices owing to unique properties of extraordinarily large excitonic binding energy and valley polarization. In this study, we investigate the fundamental optical properties of TMDs in detail, and aim to use their properties to develop circularly polarized light emitting diode.

Representative Papers
  1. (1) S. Hayashida, R. Saitoh, K. Watanabe, T. Taniguchi, K. Sawano, and Y. Hoshi: “Reduced inhomogeneous broadening in hBN-encapsulated MoTe2 monolayers by thermal treatment” ACS Applied Electronic Materials Vol. 2, pp.2739 (2020)
  2. (2) T. Kuroda, Y. Hoshi, S. Masubuchi, M. Okada, R. Kitaura, K. Watanabe, T. Taniguchi, and T. Machida: “Dark-state impact on the exciton recombination of WS2 monolayers as revealed by multi-time-scale pump-probe spectroscopy” Physical Review B Vol. 102, pp.195407 (2020)
  3. (3) Y. Hoshi, M. Okada, R. Moriya, S. Masubuchi, K. Watanabe, T. Taniguchi, R. Kitaura, and T. Machida: “Effect of a pick-and-drop process on optical properties of a CVD-grown monolayer tungsten disulfide” Physical Review Materials, Vol.2, pp.064003 (2018)
  4. (4) K. Takeda, J. Yoneda, T. Otsuka, T. Nakajima, M.R. Delbecq, G. Allison, Y. Hoshi, N. Usami, K.M. Itoh, S. Oda, T. Kodera, and S.Tarucha: “Optimized electrical control of a Si/SiGe spin qubit in the presence of an induced frequency shift” npj Quantum information Vol. 4, pp.54-1-6 (2018)
  5. (5) J. Yoneda, K. Takeda, T. Otsuka, T. Nakajima, M.R. Delbecq, G. Allison, T. Honda, T. Kodera, S. Oda, Y. Hoshi, N. Usami, K.M. Itoh, and S. Tarucha: “A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise” Nature Nanotechnology, Vol. 13, pp. 102 (2018)
  6. (6) Y. Hoshi, T. Kuroda, M. Okada, R. Moriya, S. Masubuchi, K. Watanabe, T. Taniguchi, R. Kitaura, and T. Machida: “Suppression of exciton-exciton annihilation in tungsten disulfide monolayers encapsulated by hexagonal boron nitrides” Physical Review B: Rapid Communications, Vol. 95, pp. 241403-1 – 241403-6 (2017)
  7. (7) Y. Hoshi, T. Tayagaki, T. Kiguchi, N. Usami: “Control of geometry in Si-based photonic nanostructures formed by maskless wet etching process and its impact on optical properties” Thin Solid Films, Vol.557, pp.338-341 (2014)
  8. (8) Y. Hoshi, W. Pan, T. Kiguchi, K. Ooi, T. Tayagaki, N. Usami: “Control of Dip Shape in Photonic Nanostructures by Maskless Wet-Etching Process and Its Impact on Optical Properties” Japanese Journal of Applied Physics, Vol.52, pp.080202-1 - 080202-4 (2013)
  9. (9) T. Tanaka, Y. Hoshi, K. Sawano, N. Usami, Y. Shiraki, K.M. Itoh: “Upper limit of two-dimensional hole gas mobility in strained Ge/SiGe heterostructures”. Applied Physics Letters, Vol.100, pp.222102-1 - 222102-3 (2012)
  10. (10) Y. Hoshi, K. Sawano, K. Hamaya, M. Miyao Y. Shiraki: “Formation of Tensilely Strained Germanium-on-Insulator” Applied Physics Express, Vol.5, pp.015701-1 - 015701-3 (2012)
Award Young Poster Award (Summit of Materials Science 2012)
Grant-in-Aid for Scientific Research Support: Japan Society for Promotion of Science (JSPS)
Recruitment of research assistant(s) No
Affiliated academic society (Membership type) The Japan Society of Applied Physics (Regular)
Education Field (Undergraduate level) Electromagnetism
Education Field (Graduate level) Advanced Theory of Semiconductor Devices