Fumio S. Ohuchi, Associate Chair
- Professor of Materials Science & Engineering
- Adjunct Professor of Physics
|Office:||311 Roberts Hall|
Sophia University, Tokyo, Japan, B.S., Physics, 1972
Sophia University, Tokyo, Japan, M.S., Physics, 1974
University of Florida, Gainesville, Florida, Ph.D., Materials Science & Eng., 1981
Overall Research Theme
Understanding physical and chemical processes at dissimilar material interfaces Materials technology in the next generation relies on the manipulation and control of atoms and molecules at surfaces and interfaces. Understanding physical and chemical processes at the material’s surfaces and dissimilar interfaces is an overall theme of Dr. Ohuchi’s research over the past two decades. His primary research is focused on (i) Physical and chemical processes involved in epitaxial growth dissimilar materials, and (ii) Synthesis, characterization and transport properties of the Group VI compounds (oxide, sulfides, selenides, and telluride) thin film materials. Publications listed in the curriculum vitae are divided into three categories: (1) Chalcogenide (sulfide, selenide, and telluride) thin film hetero-epitaxy and their interfaces, (2) Oxide thin films and their surfaces and interfaces, and (3) Electron spectroscopy related work.
Dr. Ohuchi has been involved in a new type of material development strategy called "Combinatorial Materials Exploration (CME)" in collaboration of Dr. Chikyow of National Institute of Materials Science, Tsukuba, Japan. CME as a new research approach to explore an extremely large multi-variant materials space is rapidly becoming a new paradigm for accelerated materials research by enabling both screening and understanding complex material systems in a time- and cost-effective manner. He is now using this technique to explore electrically conductive transition metal oxides for electronic use. His work has recently been published [2.10-1]. Currently he is building his new CME laboratory at the University of Washington. Systematic variance of properties with material’s composition or processing parameters yields information on nanoscale mechanisms underlying structure-property relationships; for example changing average valence or atomic separation [3.1, 3.2, 2.15-11]. He believes that successful application of CME to critical problems in the microelectronics area facilitates further advancement of inorganic materials science programs as a whole.
Brief Summary of Dr. Ohuchi’s Recent Research (2005-2006)
Our research group is investigating how various materials are integrated into "Si". The following two charts explain our strategy of approach, and the type of materials currently working.
Our experimental approach is rather unique. Since "intrinsic properties" of the interface often control entire process of the electronic devices, we fabricate materials and characterize "in-situ". Our experimental facility, shown below, consists of material-growth followed by "in-situ" characterization by various surface science tools, such as XPS, LEED, ISS, STM, AFM and STS.
Introducing our recent research activities, I will use the following two examples. First example is research related to a search for new silicon compatible semiconducting materials, and their interfaces. Silicon has been the backbone of modern microelectronics, and will likely remain so. Successful expansion of silicon technology to the next generation will require combining other crystalline materials with silicon through heteroepitaxy. Integration of conventional semiconductor materials, such as III-V (such as GaAs) and II-VI (such as ZnSe), to silicon has been demonstrated; however, our approach is very different from those: We have chosen unique materials known as Group III-VI compound, as represented by Ga-Se, Al-Se and In-Se. Stoichiometrically, these materials takes a form of III2VI3. For example, Ga2Se3 can be written as Ga3-1Se3, implying that every third of Ga site becomes ‘vacant’. We have shown that these vacancies are perfectly lined up epitaxially, and controlled subsequent crystal structure. We named this growth as "vacancy-induced-growth" and published in PRL 2005.
The group III-VI compounds are also considered as "conventional semiconductor PLUS extra electron system". For example, "Ga-Se" is considered as a material with "(Ga)-(As plus extra electron)", or "(Zn plus extra electron)-(Se)" (see periodic table). Having this extra electron in our system, we are able to control various electronic properties, such as band-offset and dipole formation at the interface. This is shown in the next view graph. Our research focuses on the basic physics and materials science of these new materials and the bridge to new technologies. I believe such long range, exploratory materials development, is essential to expanding America’s technology base.
Our second area of research is to investigate transport properties of the transition metal oxides. Recent technology demands a use of materials at extreme conditions, such as high temperature, high pressure, high radiation environments. Oxides are inherently sustainable to those conditions. Electrical and thermal transport properties are most fundamental ones among various properties, yet difficult to study. Shown below an example from NiO-CuO-Mn2O3 ternary oxide system, where we are searching compositions that give good electrical conductivity. For this, we are using an intelligent way of searching new materials, called "Combinatorial Materials Exploration". Thin films are fabricated using a pulsed laser deposition technique, where the materials are alternatively deposited in a tapered shape from three directions, ultimately forming a ternary diagram shown above. This sample (combinatorial library) contains all possible ternary and binary compositions on “one wafer”, so that the property related to specific compositions can be probed using appropriate techniques. This is illustrated below.
Materials technology in the next generation relies on the manipulation and control of atoms and molecules at surfaces and interfaces. Understanding physical and chemical processes at the material’s surfaces and dissimilar interfaces is a key to the development of new technology. Our primarily research is focused on (i). Integration of dissimilar materials to silicon, (ii) Synthesis and characterization of chalcogenide and oxide thin film materials, and (iii). Transport processes. Specific materials of current interest include new family of semiconducting materials consisting of groups III and VI elements, and transition metal oxides. Publications were divided into three categories: (1) Chalcogenide thin film heteroepitaxy and Interface, (2). Oxide thin films and their surfaces and interfaces, and (3) Electron spectroscopy related work.
(1). Chalcogenide Thin Film Hetero-Epitaxy and Interface related work
1.1 Chemical passivity of III-VI bilayer terminated Si(111), J. A. Adams, A. A. Bostwick, F. S. Ohuchi and M.A. Olmstead, Applied Physics Letter 87 171906 (2005).
1.2 Intrinsic vacancy induced nanoscale wire structure in heteroepitaxial Ga2Se3/Si(001), T. Ohta, D. A. Schmidt, S. Meng, A. Klust, A. Bostwick, Q. Yu, M. A. Olmstead, and F. S. Ohuchi, Physical Review Letters 94(11) 116102/1-4 (2005).
1.3 Heterointerface formation of aluminum selenide with silicon: Electronic and atomic structure of Si(111):AlSe, J. A. Adams, A. Bostwick, T. Ohta, F. S. Ohuchi, and M. A. Olmstead, Physical Review B71(19) 195308-1-8 (2005).
1.4 Electronic structure of the Si(111):GaSe surface termination, R. Rudolph, C. Pettenkofer, J. A. Adams, M. A. Olmstead, F. S. Ohuchi, B. Jaeckel, A. Klein and W. Jaegermann, Accepted from New Journal of Physics, Focus Issue on Photoemission and Electronic Structure (F. Himpsel and P. –O. Nilsson, eds.) Vol 7, 108 (2005).
1.5 Atomically resolved imaging of a CaF bilayer on Si(111): subsurface atoms and the image contrast in scanning force microscopy, A. Klust, T. Ohta, A.A. Bostwick, Yu Qiuming, F.S. Ohuchi, and M.A. Olmstead, Physical Review B 69(3), 35405-1-5 (2004).
1.6 Atomic structures of defects at GaSe/Si(111) heterointerfaces studied by scanning tunneling microscopy, T. Ohta, A. Klust, J. A. Adams, Q. Yu, M. A. Olmstead, and F. S. Ohuchi, Physical Review B 69(12), 125322-1-8 (2004).
(2). Oxide Thin Films, Surface and Interface related work related work
2.1 Combinatorial Fabrication and Characterization of Ternary La2O3-Mn2O3-Co3O4 Composition Spreads”, Dmitry A. Kukuruznyak, Parhat Ahmet, Atsushi Yamamoto, Fumio Ohuchi, and Toyohiro Chikyow, Accepted from The Japanese Journal of Applied Physics 44(8) 6164-6166 (2005).
2.2 Combinatorial screening of ternary NiO-Mn2O3-CuO composition spreads, Dmitry A. Kukuruznyak, Parhat Ahmet, Atsushi Yamamoto, Fumio Ohuchi, and Toyohiro Chikyow, Accepted from Journal of Applied Physics 98 043710 (2005).
2.3 Electrical screening of ternary NiO-Mn2O3-Co3O4 composition spreads, Dmitry A. Kukuruznyak, Parhat Ahmet, Atsushi Yamamoto, Fumio Ohuchi, and Toyohiro Chikyow, Accepted from Applied surface Science (to be appeared in 2005).
2.4 Improved Aging Characteristics of NTC Thermistor Thin Films Fabricated by a Hybrid Sol Gel - MOD Process, D. A. Kukuruznyak, J. G. Moyer, F. S. Ohuchi, Accepted from Journal of the American Ceramic Society (to be appeared in 2005).
2.5 High-throughput screening of thermoelectric materials: application of thermal probe method to composition-spread samples, Yamamoto, A. (Energy Electron. Inst., Nat. Inst. of Adv. Ind. Sci. & Technol., Tsukuba, Japan;) ;Kukuruznyak, D. ;Ahmet, P. ;Chikyow, T. ;Ohuchi, F.S. Source: Combinatorial and Artificial Intelligence Methods in Materials Science II Symposium (Mater. Res. Soc. Symposium Proceedings Vol.804) , 2004, p 3-14.
2.6 Compositional Design and Property Adjustment of Multi-component Oxides for Thermoelectric Applications, F. S. Ohuchi, D. A. Kukuruznyak, and T. Chikyow, Materials Science Forum 502 3-6 (2005).
2.7 Fast response thin-film thermistor for measurements in ocean waters, D.A. Kukuruznyak, J.B. Miller, M.C. Gregg, and F.S. Ohuchi, Review of Scientific Instruments 76(2), 24905-1-3 (2005).
(3). Electron Spectroscopy related work
3.1 Relationship between Electronic and Crystal structure in Cu-Ni-Co-Mn-O Spinels, Part-A: Temperature-induced Structural Transformation, D. A. Kukuruznyak, J. G. Moyer, M. S. Prowse, N. Nguyen. and F. S. Ohuchi, Journal of Electron Spectroscopy and Related Phenomena 150(2-3)271-281 (2005).
3.2 Relationship between Electronic and Crystal structure in Cu-Ni-Co-Mn-O Spinels, Part B: Binding Energy Anomaly in Cu+1 Photoemission Spectrum, D. A. Kukuruznyak, J. G. Moyer, M. S. Prowse, N. Nguyen. J. J. Rehr, and F. S. Ohuchi, Journal of Electron Spectroscopy and Related Phenomena 150(2-3)282-287 (2005).
- University of Washington, Center for Nanotechnology: Co-Principal Investigator Nanotechnology :IGERT (2004 – pr.); co-PI for Co-PI for IGERT proposal (2005 - 2010).
- Developed new short course activities at Pacific Northwest National Laboratories
- ADVANCE Project Leadership Team (2002 - pr.)
Professional Recognition and Honors
- Visiting scholar at Hahn Meitner Institute, Berlin, Germany (1987)
- Visiting faculty at Chemistry Department, Univ. of Tokyo (1989)
- Research committee for International Frontier Research Program (Phase II) of the Institute of Chemical and Physical Research, Japan, 1991.
- NORCUS Professorship at the Battle Pacific Northwest Lab., Richland,WA.
- Panel mem ber for The Clean Washington Center of the Department of Trade and Economic Development, State of Washington, 1992 - present.
- International Research Advisor for the "Solid Fusion Project",ERATO-JRDC (Japan)
- Research Initiation Award from NSF (1992 )
- Institute for Industrial Science Award, University of Tokyo, (1989).
- NEDO International Research Award (MITI-Japan) (1994)
- American Vacuum Society (2001-pr); Pacific Northwest Chapter (1994-pr); Chapter Chair (2001-02)
- Science Advisory Board for the Frontier Research System at the RIKEN Institute (1998-2003)
- Science Advisor for Glass Museum, Tacoma, WA
UW Department of Materials Science & Engineering
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