Solid-state Information Physics Laboratory

Staff & Contact

Educational Staff	Prof. Tomohiro Matsushita Associate Prof. Ken Hattori Assistant Prof. Sakura Takeda Assistant Prof. Yusuke Hashimoto Assistant Prof. Takanobu Jujo Assistant Prof. Yuta Yamamoto
Contact	TEL: +81-743-72-6020
URL	https://mswebs.naist.jp/LABs/surface-material-physics/index.html

Education and Research Activities in the Laboratory

1.　Research purpose and target

Functional materials are created by adding dopant atoms to the material or depositing atoms on the surface. The added atoms in bulk work as active sites and dramatically change the material’s properties. Also slightly deposited atoms on surfaces can change structures and functionalities. Visualizing the three-dimensional atomic arrangement and understanding the function generation mechanism will bring about technological innovation. Our laboratory is the first in the world to develop atomic resolution holography (ARH) such as photoelectron holography (PEH) to visualize active sites, and in developing apparatus in SPring-8. Our laboratory studies surface structures, electronic states, optical properties, and chemical reactions using scanning tunneling microscopy (STM), Raman spectroscopy, reflection high-energy electron diffraction (RHEED), low-energy electron diffraction (LEED), angle-resolved photoelectron spectroscopy (ARPES), etc. For data science, we use a combination of scattering quantum mechanics and sparse-modeled machine learning, and density functional theory (DFT). Our aim is to clarify the physical properties of active sites and modified surfaces, while creating new functions from atomic and electron viewpoints. Our research targets include dopants in materials, atomically-controlled nano-films, nano-wires, nano-dots on surfaces, and artificially-strained sub-surfaces.

2.　Educational policy

We provide education on experiments and physics combined with informatics. Also, we aim to develop important skills for researchers and professional engineers, which include an active attitude toward obtaining knowledge through acquisition of technical expertise (such as shop practices, machine control, and data analysis), cooperation with laboratory members, finding essential points based on logical thinking, presenting ideas, and managing activities. Students are expected to improve or create apparatuses before graduation. It is important for students to not only learn how to think systematically through seminars and lectures, but also to interact with external researchers in addition to the regular laboratory educational staff.

Research Themes

Atomic structural analysis of active sites in/on materials by PEH
Quantum theory of scattering combined with machine learning theory
Reciprocal space mapping (RSM) analysis of 3D-Si surfaces by RHEED
Growth of nano-films with surface modification by STM, LEED, RHEED
Quantization- and strain-modified electronic structure of crystals by ARPES
Raman spectroscopy and cathode luminescence of functional materials

Explanatory Pictures of Research Activities

Fig. 1 Normal mode photoelectron hologram experiment.

Fig. 2 Atomic-scale STM image of ultra-thin film and island of iron-silicides on a Si(111) surface.

Fig. 3 3D-RSM of a 3D elongated island of α-FeSi₂(110) on Si(001).

Fig. 4 Si valence subbands in p-type inversion layer.

Recent Research Papers and Achievements

M. N. Fujii, M. Tanaka, T. Matsushita, et al., Nano Lett. 23, 1189 (2023).
T. Yokoya, T. Matsushita, et al., Nano Lett. 19, 5915 (2019).
H. Tanaka, K. Kuroda, T. Matsushita, J. Elec. Spec. Rel. Phenom. 264, 147927 (2023).
U. Sidik, A. N. Hattori and K. Hattori, Appl. Electron. Mater. 4, 4849 (2022).
K. Hattori, Y. Sakai, L. N. Pamasi, et al., eJSSNT 20, 214 (2022).
N. I. Ayob, T. J. Inagaki, H. Daimon, S. N. Takeda, Jpn. Appl. Phys. 60, 064004-1 (2021).
T. Jujo, J. Phys. Soc. Jpn. 91, 074711 (2022).