Surface and Materials Science Laboratory
|Staff & Contact|
|Educational Staff||Prof. Jun Ohta
Associate Prof. Ken Hattori
Assistant Prof. Sakura Takeda
Education and Research Activities in the Laboratory
All materials, when smaller than one nanometer in size, begin to exhibit different properties from those under normal conditions as exemplified by iron and gold: iron becomes nonmagnetic, while gold becomes highly reactive. These materials are the new microscopic materials essential for resource saving, energy saving, element strategy, and nanotechnology. They can be manufactured and analyzed on the surface of a solid at the atomic and electron levels. Our laboratory studies atomic and electronic structures of surfaces and nanomaterials, and their functionalities such as electric conductivity and gas-molecule reaction using scanning tunneling microscopy (STM), Raman spectroscopy, reflection high-energy electron diffraction (RHEED), low-energy electron diffraction (LEED), angle-resolved photoelectron spectroscopy (ARPES), four-point probe method, desorption detection, and so on, working in ultra-high vacuum. The aim is to clarify the physical properties of nanomaterials and to create new functions from atomic and electron viewpoints. Our research targets include superstructures on semiconductor surfaces and magnetic thin-films, as well as organic and biological molecule adsorbing surfaces vital to catalysis and molecular electronics.
We provide education not only on experiments but also on what is important as a researcher and a professional engineer, including having an active attitude toward obtaining knowledge through research, originality training, acquisition of technical skills to enhance laboratory techniques (such as shop practices, machine control, and data analysis), and cooperation with laboratory members. 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 have contact with external researchers as well as the regular educational staff in the laboratory.
1.Atomic structural analysis of surface nano-materials by STM, LEED, and RHEED. Azimuth-scanning RHEED: three-dimensional reciprocal space mapping (3D-RSM)
2.Energy bands on surfaces studied with ARPES and their modification by electric field and strain
3.Adsorption and desorption of molecules from surfaces: atomic analysis of surface-molecular reactions
4.Surface nanomaterial physical property analysis
5.Density functional theoretical (DFT) calculations
- Fig. 1 Atomic-scale STM image of ultra-thin film and island of iron-silicides on a Si(111) surface.
- Fig. 2 RHEED pattern of Si(111)7x7 surface, and 3D-RSM of a 3D elongated island of α-FeSi2(110) on Si(001).
- Fig. 3 Si valence subbands in p-type inversion layer.
- Fig. 4 Ge and Pb/Ge valence band dispersions.
Recent Research Papers and Achievements
1.N. Hirota, K. Hattori, et al., Appl. Phys. Express 9, 047002 (2016).
2.O. Romanyuk, K. Hattori, et al., Phys. Rev. B 90, 155305 (2014).
3.S. N. Takeda, et al., Phys. Rev. B 93, 125418 (2016).
4.T. Sakata, S. N. Takeda et al., Semicon. Sci. and Technol. 31, 085012 (2016)