Fumiyasu Oba (Professor, Tokyo Institute of Technology)

_images/oba.jpg

Materials and Structures Laboratory, Tokyo Institute of Technology

4259 R3-7 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan

(Also at Department of Materials Science and Engineering and Materials Research Center for Element Strategy)

obaatmsl.titech.ac.jp

Research Interest

Atomistic and electronic structure of point defects, surfaces, and interfaces in compound semiconductors and their impact on the electrical properties: A theoretical approach using first-principles calculations

  • Native defects and dopants:
    ZnO, SrTiO3, BaTiO3, EuTiO3, NaTaO3, KTaO3, Cu2O, SnO, NiO, Ga2O3, Ca2CuO2Cl2, MgAl2O4, MgO, Si3N4, BN, AlN, GaN, Li3N, CuInSe2, CuGaSe2, ZnSnP2, and CdSnP2.
  • Surfaces:
    ZnO, GaN, GaAs, Si, C, BN, CuInSe2, CuGaSe2, ZnSnP2, CdSnP2, etc
  • Heterointerfaces:
    CuInSe2/CdS, ZnS, CdTe/CdS, g-Ga2O3/MgAl2O4, Cu2O/ZnO, etc
  • Grain boundaries:
    ZnO, YSZ, and BaZrO3.

Refereed Journal Publications

  1. Ionization potentials of solids: The importance of vertex corrections

    A. Gruneis, G. Kresse, Y. Hinuma, and F. Oba,

    Phys. Rev. Lett., 112, 096401-1-5 (2014).

  2. Electrostatics-based finite-size corrections for first-principles point defect calculations

    Y. Kumagai and F. Oba,

    Phys. Rev. B, 89, 195205-1-15 (2014). [Editors’ Suggestion]

  3. First-principles study of point defects in chalcopyrite ZnSnP2

    Y. Kumagai, M. Choi, Y. Nose, and F. Oba,

    Phys. Rev. B, 90, 125202-1-12 (2014).

  4. Band alignment of semiconductors from density-functional theory and many-body perturbation theory

    Y. Hinuma, A. Gruneis, G. Kresse, and F. Oba,

    Phys. Rev. B, 90, 155405-1-16 (2014).

  5. Atomic structure of luminescent centers in high-efficiency Ce-doped w-AlN single crystal

    R. Ishikawa, A. R. Lupini, F. Oba, S. D. Findlay, N. Shibata, T. Taniguchi, K. Watanabe, H. Hayashi, T. Sakai, I. Tanaka, Y. Ikuhara, and S. J. Pennycook,

    Sci. Rep., 4, 3778-1-5 (2014).

  6. Anti-ferrodistortive-like oxygen-octahedron rotation induced by the oxygen vacancy in cubic SrTiO3

    M. Choi, F. Oba, Y. Kumagai, and I. Tanaka,

    Adv. Mater., 25, 86-90 (2013).

  7. Strong spin-lattice coupling through oxygen octahedral rotation in divalent europium perovskites

    H. Akamatsu, Y. Kumagai, F. Oba, K. Fujita, K. Tanaka, and I. Tanaka,

    Adv. Funct. Mater., 23, 1864-1872 (2013).

  8. Functional complex point-defect structure in a huge-size-mismatch system

    R. Ishikawa, N. Shibata, F. Oba, T. Taniguchi, S. D. Findlay, I. Tanaka, and Y. Ikuhara,

    Phys. Rev. Lett., 110, 065504-1-5 (2013).

  9. Valence band offsets at zinc-blende heterointerfaces with misfit dislocations: A first-principles study

    Y. Hinuma, F. Oba, and I. Tanaka,

    Phys. Rev. B, 88, 075319-1-8 (2013).

  10. Band offsets of CuInSe2/CdS and CuInSe2/ZnS (110) interfaces: A hybrid density functional theory study

    Y. Hinuma, F. Oba, Y. Kumagai, and I. Tanaka,

    Phys. Rev. B, 88, 035305-1-12 (2013).

  11. Theoretical photovoltaic conversion efficiencies of ZnSnP2 , CdSnP2 , and Zn1-x Cdx SnP2 alloys

    T. Yokoyama, F. Oba, A. Seko, H. Hayashi, Y. Nose, and I. Tanaka,

    Appl. Phys. Express, 6, 061201-1-3 (2013).

  12. First-principles study of valence band offsets at ZnSnP2/CdS, ZnSnP2/ZnS, and related chalcopyrite/zincblende heterointerfaces

    Y. Hinuma, F. Oba, Y. Nose, and I. Tanaka,

    J. Appl. Phys., 114, 043718-1-6 (2013).

  13. Local environment of silicon in cubic boron nitride

    H. Murata, T. Taniguchi, S. Hishita, T. Yamamoto, F. Oba, and I. Tanaka,

    J. Appl. Phys., 114, 233502-1-4 (2013).

  14. Site preference of cation vacancies in Mn-doped Ga2O3 with defective spinel structure

    H. Hayashi, R. Huang, F. Oba, T. Hirayama, and I. Tanaka,

    Appl. Phys. Lett., 101, 241906-1-4 (2012).

  15. Ionization potentials of (112) and (11-2) facet surfaces of CuInSe2 and CuGaSe2

    Y. Hinuma, F. Oba, Y. Kumagai, and I. Tanaka,

    Phys. Rev. B, 86, 245433-1-7 (2012).

  16. First-principles calculations of the phase diagrams and band gaps in CuInSe2-CuGaSe2 and CuInSe2-CuAlSe2 pseudobinary systems

    Y. Kumagai, Y. Soda, F. Oba, A. Seko, and I. Tanaka,

    Phys. Rev. B, 85, 033203-1-4 (2012).

  17. Ground-state search in multicomponent magnetic systems

    Y. Kumagai, A. Seko, F. Oba, and I. Tanaka,

    Phys. Rev. B, 85, 012401-1-4 (2012).

  18. Crystal and electronic structure and magnetic properties of divalent europium perovskite oxides EuMO3 (M = Ti, Zr, and Hf): Experimental and first-principles approaches

    H. Akamatsu, K. Fujita, H. Hayashi, T. Kawamoto, Y. Kumagai, Y. Zong, K. Iwata, F. Oba, I. Tanaka, and K. Tanaka,

    Inorg. Chem., 51, 4560-4567 (2012).

  19. Defect chemistry of a BaZrO3 S3 (111) grain boundary by first principles calculations and space-charge theory

    J. M. Polfus, K. Toyoura, F. Oba, I. Tanaka, and R. Haugsrud,

    Phys. Chem. Chem. Phys., 14, 12339-12346 (2012).

  20. Point defects in ZnO: An approach from first principles

    F. Oba, M. Choi, A. Togo, and I. Tanaka,

    Sci. Tech. Adv. Mater., 12, 034302-1-14 (2011). [Topical Review]

  21. Electronic and structural properties of the oxygen vacancy in BaTiO3

    M. Choi, F. Oba, and I. Tanaka,

    Appl. Phys. Lett., 98, 172901-1-3 (2011).

  22. Hybrid density functional study of oxygen vacancies in KTaO3 and NaTaO3

    M. Choi, F. Oba, and I. Tanaka,

    Phys. Rev. B, 83, 214107-1-6 (2011).

  23. Antiferromagnetic superexchange via 3d states of titanium in EuTiO3 as seen from hybrid Hartree-Fock density functional calculations

    H. Akamatsu, Y. Kumagai, F. Oba, K. Fujita, H. Murakami, K. Tanaka, and I. Tanaka,

    Phys. Rev. B, 83, 214421-1-6 (2011).

  24. Epitaxial growth of Mn-doped g-Ga2O3 on spinel substrate

    H. Hayashi, R. Huang, F. Oba, T. Hirayama, and I. Tanaka,

    J. Mater. Res., 26, 578-583 (2011).

  25. Atomistic structure and energetics of interface between Mn-doped g-Ga2O3 and MgAl2O4

    H. Hayashi, R. Huang, F. Oba, T. Hirayama, and I. Tanaka,

    J. Mater. Sci., 46, 4169-4175 (2011).

  26. Epitaxial growth and characterization of rocksalt ZnO thin films with low-level NiO alloying

    S. Katayama, H. Hayashi, F. Oba, and I. Tanaka,

    Jpn. J. Appl. Phys., 50, 075503-1-5 (2011).

  27. Doping of hexagonal boron nitride via intercalation: A theoretical prediction

    F. Oba, A. Togo, I. Tanaka, K. Watanabe, and T. Taniguchi,

    Phys. Rev. B, 81, 075125-1-6 (2010).

  28. Classification of spinel structures based on first-principles cluster expansion analysis

    A. Seko, F. Oba, and I. Tanaka,

    Phys. Rev. B, 81, 054114-1-7 (2010).

  29. Native defects in oxide semiconductors: A density functional approach

    F. Oba, M. Choi, A. Togo, A. Seko, and I. Tanaka,

    J. Phys.: Condens. Matter, 22, 384211-1-9 (2010). [in JPCM Highlights of 2010]

  30. Phase relationships and structures of inorganic crystals by combination of cluster expansion method and first principles calculations

    I. Tanaka, A. Seko, A. Togo, Y. Koyama, and F. Oba,

    J. Phys.: Condens. Matter, 22, 384207-1-8 (2010).

  31. Non-Fermi-liquid behavior on an iron-based itinerant electron magnet Fe3Mo3N

    T. Waki, S. Terazawa, Y. Tabata, F. Oba, C. Michioka, K. Yoshimura, S. Ikeda, H. Kobayashi, K. Ohoyama, and H. Nakamura,

    J. Phys. Soc. Jpn., 79, 043701-1-4 (2010).

  32. Thermodynamics and structures of oxide crystals by a systematic set of first principles calculations

    I. Tanaka, A. Togo, A. Seko, F. Oba, Y. Koyama, and A. Kuwabara,

    J. Mater. Chem., 20, 10335-10344 (2010).

  33. Role of Ti antisite-like defects in SrTiO3

    M. Choi, F. Oba, and I. Tanaka,

    Phys. Rev. Lett., 103, 185502-1-4 (2009).

  34. First-principles study of defect-induced potentials in Ca2CuO2Cl2

    Y. Kumagai, F. Oba, I. Yamada, M. Azuma, and I. Tanaka,

    Phys. Rev. B, 80, 085120-1-9 (2009).

  35. Variable anisotropy of ionic conduction in lithium nitride: Effect of duplex-charge transfer

    I. Kishida, F. Oba, Y. Koyama, A. Kuwabara, and I. Tanaka,

    Phys. Rev. B, 80, 024116-1-6 (2009).

  36. 27Al NMR chemical shifts in oxide crystals: A first-principles study

    M. Choi, K. Matsunaga, F. Oba, and I. Tanaka,

    J. Phys. Chem. C, 113, 3869-3873 (2009).

  37. Defect energetics in ZnO: A hybrid Hartree-Fock density functional study

    F. Oba, A. Togo, I. Tanaka, J. Paier, and G. Kresse,

    Phys. Rev. B, 77, 245202-1-6 (2008).

  38. Transition pathway of CO2 crystals under high pressures

    A. Togo, F. Oba, and I. Tanaka,

    Phys. Rev. B, 77, 184101-1-5 (2008).

  39. Structure and stability of homologous series of tin oxides

    A. Seko, A. Togo, F. Oba, and I. Tanaka,

    Phys. Rev. Lett., 100, 045702-1-4 (2008).

  40. First-principles study of native defects and lanthanum impurities in NaTaO3

    M. Choi, F. Oba, and I. Tanaka,

    Phys. Rev. B, 78, 014115-1-8 (2008).

  41. Effects of crystal structure on Co-L2,3 x-ray absorption near-edge structure and electron-energy-loss near-edge structure of trivalent cobalt oxides

    Y. Kumagai, H. Ikeno, F. Oba, K. Matsunaga, and I. Tanaka,

    Phys. Rev. B, 77, 155124-1-9 (2008).

  42. First-principles-based phase diagram of the cubic BNC ternary system

    K. Yuge, A. Seko, Y. Koyama, F. Oba, and I. Tanaka,

    Phys. Rev. B, 77, 094121-1-8 (2008).

  43. First-principles calculations of the ferroelastic transition between rutile-type and CaCl2-type SiO2 at high pressures

    A. Togo, F. Oba, and I. Tanaka,

    Phys. Rev. B, 78, 134106-1-9 (2008).

  44. First-principles approach to chemical diffusion of lithium atoms in a graphite intercalation compound

    K. Toyoura, Y. Koyama, A. Kuwabara, F. Oba, and I. Tanaka,

    Phys. Rev. B, 78, 214303-1-12 (2008).

  45. First principles calculations for modern ceramic science and engineering

    I. Tanaka and F. Oba,

    J. Phys.: Condens. Matter, 20, 064215-1-6 (2008).

  46. Atomic structures of supersaturated ZnO-Al2O3 solid solutions

    S. Yoshioka, F. Oba, R. Huang, I. Tanaka, T. Mizoguchi, and T. Yamamoto,

    J. Appl. Phys., 103, 014309-1-9 (2008).

  47. First-principles investigation of R2O3(ZnO)3 (R=Al, Ga, and In) in homologous series of compounds

    S. Yoshioka, K. Toyoura, F. Oba, A. Kuwabara, K. Matsunaga, and I. Tanaka,

    J. Solid State Chem., 181, 137-142 (2008).

  48. First principles calculation of CO and H2 adsorption on strained Pt surface

    A. Kuwabara, Y. Saito, Y. Koyama, F. Oba, K. Matsunaga, and I. Tanaka,

    Mater. Trans., 49, 2484-2490 (2008).

  49. Ordering and segregation of Cu75Pt25 (111) surface: A first-principles cluster expansion study

    K. Yuge, A. Seko, A. Kuwabara, F. Oba, and I. Tanaka,

    Phys. Rev. B, 76, 045407-1-8 (2007).

  50. Awaking of ferromagnetism in GaMnN through control of Mn valence

    S. Sonoda, I. Tanaka, F. Oba, H. Ikeno, H. Hayashi, T. Yamamoto, Y. Yuba, K. Yoshida, M. Aoki, M. Asari, Y. Akasaka, K. Kindo, and H. Hori,

    Appl. Phys. Lett., 90, 012504-1-3 (2007).

  51. Microstructure of Mn-doped g-Ga2O3 epitaxial film on sapphire (0001) with room temperature ferromagnetism

    R. Huang, H. Hayashi, F. Oba, and I. Tanaka,

    J. Appl. Phys., 101, 063526-1-6 (2007).

  52. Structures and energetics of Ga2O3 polymorphs

    S. Yoshioka, H. Hayashi, A. Kuwabara, F. Oba, K. Matsunaga, and I. Tanaka,

    J. Phys.: Condens. Matter, 19, 346211-1-11 (2007).

  53. First-principles study of defect equilibria in lithium zinc nitride

    K. Toyoura, F. Oba, T. Ninomiya, A. Kuwabara, and I. Tanaka,

    J. Phys.: Condens. Matter, 19, 046201-1-11 (2007).

  54. First-principles calculations of native defects in tin monoxide

    A. Togo, F. Oba, I. Tanaka, and K. Tatsumi,

    Phys. Rev. B, 74, 195128-1-8 (2006).

  55. First-principles study of cation disordering in MgAl2O4 spinel with cluster expansion and Monte Carlo simulation

    A. Seko, K. Yuge, F. Oba, A. Kuwabara, I. Tanaka, and T. Yamamoto,

    Phys. Rev. B, 73, 094116-1-6 (2006).

  56. Debye temperature and stiffness of carbon and boron nitride polymorphs from first principles calculations

    T. Tohei, A. Kuwabara, F. Oba, and I. Tanaka,

    Phys. Rev. B, 73, 064304-1-7 (2006).

  57. Prediction of ground-state structures and order-disorder phase transitions in II-III spinel oxides: A combined cluster-expansion method and first-principles study

    A. Seko, K. Yuge, F. Oba, A. Kuwabara, and I. Tanaka,

    Phys. Rev. B, 73, 184117-1-5 (2006).

  58. First-principles study of bulk ordering and surface segregation in PtRh binary alloys

    K. Yuge, A. Seko, A. Kuwabara, F. Oba, and I. Tanaka,

    Phys. Rev. B, 74, 174202-1-13 (2006).

  59. Room temperature ferromagnetism in Mn-doped g-Ga2O3 with spinel structure

    H. Hayashi, R. Huang, H. Ikeno, F. Oba, S. Yoshioka, I. Tanaka, and S. Sonoda,

    Appl. Phys. Lett., 89, 181903-1-3 (2006).

  60. Carbon supersaturation due to paraequilibrium carburization: Stainless steels with greatly improved mechanical properties

    G. M. Michal, F. Ernst, H. Kahn, Y. Cao, F. Oba, N. Agarwal, and A. H. Heuer,

    Acta Mater., 54, 1597-1606 (2006).

  61. First principles calculations of migration energy of lithium ions in halides and chalcogenides

    I. Kishida, Y. Koyama, A. Kuwabara, T. Yamamoto, F. Oba, and I. Tanaka,

    J. Phys. Chem. B, 110, 8258-8262 (2006).

  62. Coexistence of Mn2+ and Mn3+ in ferromagnetic GaMnN

    S. Sonoda, I. Tanaka, H. Ikeno, T. Yamamoto, F. Oba, T. Araki, Y. Yamamoto, K. Suga, Y. Nanishi, Y. Akasaka, K. Kindo, and H. Hori,

    J. Phys.: Condens. Matter, 18, 4615-4621 (2006).

  63. Gas-phase surface alloying under “kinetic control”: A novel approach to improving the surface properties of titanium alloys

    F. Ernst, G. M. Michal, F. Oba, L. Liu, J. Blush, and A. H. Heuer,

    Int. J. Mater. Res., 97, 597-606 (2006).

  64. Epitaxial growth of cuprous oxide electrodeposited onto semiconductor and metal substrates

    F. Oba, F. Ernst, Y. Yu, R. Liu, H. M. Kothari, and J. A. Switzer,

    J. Am. Ceram. Soc., 88, 253-270 (2005). [Feature Article]

  65. Local environment of Mn dopant in ZnO by near-edge x-ray absorption fine structure analysis

    M. Kunisu, F. Oba, H. Ikeno, I. Tanaka, and T. Yamamoto,

    Appl. Phys. Lett., 86, 121902-1-3 (2005).

  66. Epitaxial electrodeposition of high-aspect-ratio Cu2O (110) nanostructures on InP(111)

    R. Liu, E. A. Kulp, F. Oba, E. W. Bohannan, F. Ernst, and J. A. Switzer,

    Chem. Mater., 17, 725-729 (2005).

  67. General rule for displacive phase transitions in perovskite compounds revisited by first principles calculations

    T. Tohei, A. Kuwabara, T. Yamamoto, F. Oba, and I. Tanaka,

    Phys. Rev. Lett., 94, 035502-1-4 (2005).

  68. Pressure-induced phase transition in ZnO and ZnO-MgO pseudobinary system: A first-principles lattice dynamics study

    A. Seko, F. Oba, A. Kuwabara, and I. Tanaka,

    Phys. Rev. B, 72, 024107-1-10 (2005).

  69. Arrangement of multiple structural units in a [0001] S49 tilt grain boundary in ZnO

    Y. Sato, T. Mizoguchi, F. Oba, Y. Ikuhara, and T. Yamamoto,

    Phys. Rev. B, 72, 064109-1-7 (2005).

  70. Effect of boundary plane on the atomic structure of [0001] S7 tilt grain boundaries in ZnO

    F. Oba, Y. Sato, T. Yamamoto, H. Ohta, H. Hosono, and Y. Ikuhara,

    J. Mater. Sci., 40, 3067-3074 (2005).

  71. Atomic and electronic structure of [0001]/(-1-230) S7 symmetric tilt grain boundary in undoped ZnO bicrystal with linear current-voltage characteristic

    Y. Sato, T. Mizoguchi, F. Oba, M. Yodogawa, T. Yamamoto, and Y. Ikuhara,

    J. Mater. Sci., 40, 3059-3066 (2005).

  72. Systematic study of grain boundary atomistic structures and related properties in cubic zirconia bicrystals

    N. Shibata, F. Oba, T. Yamamoto, and Y. Ikuhara,

    Z. Metallkd., 96, 177-185 (2005).

  73. Atomic structure of [0001]-tilt grain boundaries in ZnO: A high-resolution TEM study of fiber-textured thin films

    F. Oba, H. Ohta, Y. Sato, H. Hosono, T. Yamamoto, and Y. Ikuhara,

    Phys. Rev. B, 70, 125415-1-12 (2004).

  74. Effectiveness of BaZrO3buffer layer in SmBa2Cu3Oy epitaxial growth on MgO substrate: A first-principles study

    F. Oba, Y. Sugawara, K. Hasegawa, T. Izumi, Y. Shiohara, T. Hirayama, T. Yamamoto, and Y. Ikuhara,

    J. Appl. Phys., 95, 2309-2318 (2004).

  75. Grain boundary dependency of nonlinear current-voltage characteristics in Pr and Co doped ZnO bicrystals

    Y. Sato, F. Oba, M. Yodogawa, T. Yamamoto, and Y. Ikuhara,

    J. Appl. Phys., 95, 1258-1264 (2004).

  76. Identification of native defects around grain boundary in Pr-doped ZnO bicrystal using electron energy loss spectroscopy and first-principles calculations

    Y. Sato, T. Mizoguchi, F. Oba, M. Yodogawa, T. Yamamoto, and Y. Ikuhara,

    Appl. Phys. Lett., 84, 5311-5313 (2004).

  77. Structure, energy and solute segregation behaviour of [110] symmetric tilt grain boundaries in yttria-stabilized cubic zirconia

    N. Shibata, F. Oba, T. Yamamoto, and Y. Ikuhara,

    Philos. Mag., 84, 2381-2415 (2004).

  78. Interfacial structures of Y123 and Nd123 films formed on MgO(001) substrates by liquid phase epitaxy

    J. S. Matsuda, F. Oba, T. Murata, T. Yamamoto, Y. Ikuhara, M. Mizuno, K. Nomura, T. Izumi, and Y. Shiohara,

    J. Mater. Res., 19, 2674-2682 (2004).

  79. Current-voltage characteristics of cobalt-doped inversion boundaries in zinc oxide bicrystals

    F. Oba, Y. Sato, T. Yamamoto, Y. Ikuhara, and T. Sakuma,

    J. Am. Ceram. Soc., 86, 1616-1618 (2003).

  80. Grain boundary faceting at S=3, [110]/{112} grain boundary in cubic zirconia bicrystal

    N. Shibata, F. Oba, T. Yamamoto, T. Sakuma, and Y. Ikuhara,

    Philos. Mag., 83, 2221-2246 (2003).

  81. Shape control in epitaxial electrodeposition: Cu2O nanocubes on InP (001)

    R. Liu, F. Oba, E. W. Bohannan, F. Ernst, and J. A. Switzer,

    Chem. Mater., 15, 4882-4885 (2003).

  82. Epitaxial electrodeposition of Cu2O films onto InP (001)

    R. Liu, E. W. Bohannan, J. A. Switzer, F. Oba, and F. Ernst,

    Appl. Phys. Lett., 83, 1944-1946 (2003).

  83. Improvement of superconducting properties of SmBa2Cu3Oy films on MgO substrate by using BaZrO3 buffer layer

    K. Hasegawa, J. Shibata, T. Izumi, Y. Shiohara, Y. Sugawara, T. Hirayama, F. Oba, and Y. Ikuhara,

    Physica C, 392-396, 835-845 (2003).

  84. Al-doped ZnO ceramics fabricated by mechanical alloying and high-pressure sintering technique

    Y. Sato, F. Oba, M. Yodogawa, T. Yamamoto, and Y. Ikuhara,

    J. Mater. Sci. Lett., 22, 1201-1204 (2003).

  85. First principles calculations of the formation energy of Cr/Al vacancies in spinel-type MgCr2O4and MgAl2O4

    H. Moriwake, I. Tanaka, F. Oba, Y. Koyama, and H. Adachi,

    Int. J. Quantum Chem., 91, 208-210 (2003).

  86. Non-linear current-voltage characteristics related to native defects in SrTiO3 and ZnO bicrystals

    Y. Sato, T. Tanaka, F. Oba, T. Yamamoto, Y. Ikuhara, and T. Sakuma,

    Sci. Tech. Adv. Mater., 4, 605-611 (2003).

  87. Effective doping in cubic Si3N4 and Ge3N4: A first-principles study

    F. Oba, K. Tatsumi, I. Tanaka, and H. Adachi,

    J. Am. Ceram. Soc., 85, 97-100 (2002).

  88. Atomic structure and solute segregation of a S=3, [110]/{111} grain boundary in an yttria stabilized cubic zirconia bicrystal

    N. Shibata, F. Oba, T. Yamamoto, Y. Ikuhara, and T. Sakuma,

    Philos. Mag. Lett., 82, 393-400 (2002).

  89. Current-voltage characteristics across [0001] twist boundaries in zinc oxide bicrystals

    Y. Sato, F. Oba, T. Yamamoto, Y. Ikuhara, and T. Sakuma,

    J. Am. Ceram. Soc., 85, 2142-2144 (2002).

  90. First-principles calculations of anion-vacancies in oxides and nitrides

    I. Tanaka, K. Tatsumi, M. Nakano, H. Adachi, and F. Oba,

    J. Am. Ceram. Soc., 85, 68-74 (2002).

  91. Theoretical prediction of post-spinel phases of Si3N4

    K. Tatsumi, I. Tanaka, H. Adachi, F. Oba, and T. Sekine,

    J. Am. Ceram. Soc., 85, 7-10 (2002).

  92. Formation energy of Cr/Al-vacancies in spinel MgCr2O4 and MgAl2O4 by first principles calculations

    H. Moriwake, I. Tanaka, F. Oba, Y. Koyama, and H. Adachi,

    Phys. Rev. B, 65, 153103 1-4 (2002).

  93. Hardness of cubic silicon nitride

    I. Tanaka, F. Oba, T. Sekine, E. Ito, A. Kubo, K. Tatsumi, H. Adachi, and T. Yamamoto,

    J. Mater. Res., 17, 731-733 (2002).

  94. First-principles calculations of Co impurities and native defects in ZnO

    F. Oba, T. Yamamoto, Y. Ikuhara, I. Tanaka, and H. Adachi,

    Mater. Trans., 43, 1439-1443 (2002).

  95. Current-voltage characteristics across small-angle symmetric tilt boundaries in Nb-doped SrTiO3 bicrystals

    T. Yamamoto, F. Oba, Y. Ikuhara, and T. Sakuma,

    Mater. Trans., 43, 1537-1541 (2002).

  96. Theoretical formation energy of oxygen-vacancies in oxides

    I. Tanaka, F. Oba, K. Tatsumi, M. Kunisu, M. Nakano, and H. Adachi,

    Mater. Trans., 43, 1426-1429 (2002).

  97. n- and p-type dopants for cubic silicon nitride

    F. Oba, K. Tatsumi, H. Adachi, and I. Tanaka,

    Appl. Phys. Lett., 78, 1577-1579 (2001).

  98. Ab initio study of symmetric tilt boundaries in ZnO

    F. Oba, S. R. Nishitani, H. Adachi, I. Tanaka, M. Kohyama, and S. Tanaka,

    Phys. Rev. B, 63, 045410-1-10 (2001).

  99. Energetics of native defects in ZnO

    F. Oba, S. R. Nishitani, S. Isotani, H. Adachi, and I. Tanaka,

    J. Appl. Phys., 90, 824-828; 3665 (2001).

  100. Electron-energy-loss near edge structures of six-fold-coordinated Zn in MgO

    T. Mizoguchi, M. Yoshiya, J. Li, F. Oba, I. Tanaka, and H. Adachi,

    Ultramicroscopy, 86, 363-370 (2001).

  101. Energetics and electronic structure of point defects associated with oxygen excess at a tilt boundary of ZnO

    F. Oba, H. Adachi, and I. Tanaka,

    J. Mater. Res., 15, 2167-2175 (2000).

  102. Geometry and electronic structure of [0001] / (-1-230) S=7 symmetric tilt boundary in ZnO

    F. Oba, I. Tanaka, S. R. Nishitani, H. Adachi, B. Slater, and D. H. Gay,

    Philos. Mag. A, 80, 1567-1581 (2000).

  103. Core-hole effects on theoretical electron-energy-loss near-edge structure and near-edge x-ray adsorption fine structure of MgO

    T. Mizoguchi, I. Tanaka, M. Yoshiya, F. Oba, K. Ogasawara, and H. Adachi,

    Phys. Rev. B, 61, 2180-2187 (2000).

  104. Electronic structure and chemical bonding of MgCr2-xO4

    H. Moriwake, I. Tanaka, F. Oba, and H. Adachi,

    Jpn. J. Appl. Phys., Part 1, 39, 513-516 (2000).

  105. Effect of oxidation on chemical bonding around 3d transition-metal impurities in ZnO

    F. Oba, I. Tanaka, and H. Adachi,

    Jpn. J. Appl. Phys., Part 1, 38, 3569-3575 (1999).

  106. Valence band structure of ZnO (10-10) surface by cluster calculation

    K. Matsunaga, F. Oba, I. Tanaka, and H. Adachi,

    J. Electroceram., 4:S1, 69-80 (1999).

  107. Theoretical calculation of oxygen K electron-energy-loss near-edge structure of Si-doped MgO

    T. Mizoguchi, I. Tanaka, M. Yoshiya, F. Oba, and H. Adachi,

    J. Phys.: Condens. Matter, 11, 5661-5670 (1999).

  108. Cluster calculation of oxygen K-edge electron-energy-loss near-edge structure of NiO

    H. Kanda, M. Yoshiya, F. Oba, K. Ogasawara, I. Tanaka, and H. Adachi,

    Phys. Rev. B, 58, 9693-9696 (1998).

International Conference Proceedings

  1. Finite-size correction for first-principles point defect calculations using a supercell approach

    Y. Kumagai and F. Oba,

    AMTC Lett., 4, 88-89 (2014).

  2. Effects of misfit dislocations on the band alignment of zincblende semiconductors

    Y. Hinuma, F. Oba, and I. Tanaka,

    AMTC Lett., 4, 90-91 (2014).

  3. Fabrication and characterization of Sn2M2O7(M=Nb, Ta) thin films

    S. Katayama, Y. Ogawa, H. Hayashi, F. Oba, and I. Tanaka,

    AMTC Lett., 4, 174-175 (2014).

  4. First-principles study of electronic structure in Mn-doped g-Ga2O3

    H. Hayashi, R. Huang, F. Oba, T. Hirayama, and I. Tanaka,

    AMTC Lett., 3, 118-119 (2012).

  5. Fabrication and characterization of rocksalt Zn1-xNixO thin films

    S. Katayama, H. Hayashi, F. Oba, and I. Tanaka,

    AMTC Lett., 3, 244-245 (2012).

  6. Role of d states of B-site cations for spin-lattice coupling in Eu2+perovskite oxides

    H. Akamatsu, F. Oba, Y. Kumagai, K. Fujita, K. Tanaka, and I. Tanaka,

    AMTC Lett., 3, 250-251 (2012).

  7. Atomic-resolution STEM imaging in nitrides

    R. Ishikawa, N. Shibata, F. Oba, T. Taniguchi, S. D. Findlay, I. Tanaka, and Y. Ikuhara,

    AMTC Lett., 3, 174-175 (2012).

  8. First principles calculations of point defects in acceptor-doped BaZrO3

    A. Kuwabara, K. Toyoura, Y. Koyama, C. A. J. Fisher, F. Oba, K. Matsunaga, H. Moriwake, and I. Tanaka,

    AMTC Lett., 3, 120-121 (2012).

  9. Density functional study of Ti antisites in SrTiO3, BaTiO3, and PbTiO3

    M. Choi, F. Oba, and I. Tanaka,

    AMTC Lett., 2, 160-161 (2010).

  10. Synthesis of Mn-doped Ga2O3 epitaxial thin film with spinel structure

    H. Hayashi, R. Huang, X. Wang, F. Oba, T. Hirayama, and I. Tanaka,

    AMTC Lett., 2, 234-235 (2010).

  11. Ground-state structures in MgO-NiO crystalline solutions

    Y. Kumagai, A. Seko, F. Oba, and I. Tanaka,

    AMTC Lett., 2, 180-181 (2010).

  12. Statistical thermodynamics of oxides by combination of cluster expansion method and first principles calculations

    I. Tanaka, A. Seko, A. Togo, and F. Oba,

    AMTC Lett., 2, 154-155 (2010).

  13. First-principles study of magnetism and electronic structure in Eu2+ perovskite oxides

    H. Akamatsu, Y. Kumagai, F. Oba, K. Fujita, K. Tanaka, and I. Tanaka,

    AMTC Lett., 2, 162-163 (2010).

  14. First principles calculations of advanced nitrides, oxides and alloys

    I. Tanaka, A. Kuwabara, K. Yuge, A. Seko, F. Oba, and K. Matsunaga,

    Key. Eng. Mater., 403, 73-76 (2009).

  15. Energetics and electronic structure of point defects in NaTaO3

    M. Choi, F. Oba, and I. Tanaka,

    AMTC Lett., 1, 204-205 (2008).

  16. Structure and phase stability of nonstoichiometric compounds of tin oxides

    A. Seko, A. Togo, F. Oba, and I. Tanaka,

    AMTC Lett., 1, 198-199 (2008).

  17. Characterization of Ga2O3:Mn thin films with room temperature ferromagnetism

    H. Hayashi, R. Huang, H. Ikeno, S. Sonoda, F. Oba, and I. Tanaka,

    AMTC Lett., 1, 276-277 (2008).

  18. First-principles study of Co L2,3 XANES and ELNES of trivalent cobalt compounds

    Y. Kumagai, H. Ikeno, F. Oba, K. Matsunaga, and I. Tanaka,

    AMTC Lett., 1, 138-139 (2008).

  19. First-principles study on segregation and surface structures of Pt-Rh alloys

    K. Yuge, A. Seko, Y. Koyama, A. Kuwabara, F. Oba, and I. Tanaka,

    ECS Trans., 11, 749-758 (2007).

  20. Atomic-scale processes of grain-boundary faceting in a zirconia bicrystal

    N. Shibata, F. Oba, T. Yamamoto, and Y. Ikuhara,

    Mater. Sci. Forum, 558-559, 955-958 (2007).

  21. Microstructure of interfaces made by epitaxial electrodeposition

    F. Oba, R. Liu, E. W. Bohannan, F. Ernst, and J. A. Switzer,

    Interfaces in Electronic Materials, ed. by L. P. Cook, The Electrochemical Society Proceedings Series PV2003-31, 101-110 (2006).

  22. Grain-boundary atomic structures in zirconia ceramics

    N. Shibata, F. Oba, T. Yamamoto, and Y. Ikuhara,

    Ceram. Eng. Sci. Proc., 27, 171-181 (2006).

  23. Identification of Mg vacancy in MgO by positron lifetime measurements and first-principles calculations

    M. Mizuno, H. Araki, Y. Shirai, F. Oba, and I. Tanaka,

    Diffus. Defect Data. Pt. A Defect Diffus. Forum, 242-244, 1-7 (2005).

  24. Paraequilibrium surface alloying with interstitial solutes: A new concept for improving the performance of medical devices

    F. Ernst, G. M. Michal, Y. Cao, N. Agarwal, H. Kahn, F. Oba, and A. H. Heuer,

    Proceedings of Materials & Processes for Medical Devices Conference, Boston, Nov 14-16, 2005.

  25. Current-voltage characteristic and grain boundary structure in undoped and Pr and Co doped ZnO bicrystals

    Y. Sato, F. Oba, M. Yodogawa, T. Yamamoto, and Y. Ikuhara,

    Proceedings of the 5th Pacific Rim International Conference on Advanced Materials and Processing (PRICM-5), Beijing, Nov 2-5, 2004 [Materials Science Forum, 475-479, 3867-3870 (2005).]

  26. Improvement of in-plane alignment and superconducting characteristics of SmBa2Cu3Oy film on textured NiO/Ni substrate by using BaZrO3 buffer layer

    T. Izumi, K. Hasegawa, Y. Shiohara, Y. Sugawara, T. Hirayama, F. Oba, and Y. Ikuhara,

    Epitaxial Growth of Functional Oxides, ed. by A. Goyal, Y. Kuo, O. Leonte, and W. Wong-Ng, The Electrochemical Society Proceedings Series PV 2003-29, 270-282 (2005).

  27. TEM Studies of Cu2O-Si and Cu2O-InP interfaces made by epitaxial electrodeposition

    F. Oba, R. Liu, Y. Yu, E. W. Bohannan, F. Ernst, J. A. Switzer,

    Proceedings of Microscopy & Microanalysis, Savannah, Georgia, USA, August 1-5, 2004.

  28. Electronic states associated with bond disorder at ZnO grain boundaries

    F. Oba, I. Tanaka, and H. Adachi,

    Adv. Quantum Chem., 42, 175-186 (2003).

  29. First-principles calculations of silicon nitrides and SiAlONs

    I. Tanaka, K. Tatsumi, F. Oba, and H. Adachi,

    Key. Eng. Mater., 247, 149-153 (2003).

  30. Atomic and electronic structure of symmetric tilt boundaries in ZnO

    F. Oba, S. R. Nishitani, H. Adachi, I. Tanaka, M. Kohyama, and S. Tanaka,

    Mater. Res. Soc. Symp. Proc., 654, AA1.2.1-6 (2001).

  31. Interaction of Co impurities and native defects in ZnO

    F. Oba, T. Yamamoto, Y. Ikuhara, I. Tanaka, and H. Adachi,

    Proceedings of the 4th Pacific Rim International Conference on Advanced Materials and Processing (PRICM4), 1, 555-558 (2001).

  32. First principles calculations of oxygen-vacancies in oxides

    I. Tanaka, F. Oba, K. Tatsumi, M. Nakano, and H. Adachi,

    Proceedings of the 4th Pacific Rim International Conference on Advanced Materials and Processing (PRICM4), 1, 545-548 (2001).

  33. Electronic structure calculation of symmetric tilt boundaries in ZnO

    F. Oba, S. R. Nishitani, H. Adachi, and I. Tanaka,

    Ceram. Trans., 118, 223-230 (2000).

  34. First-principles calculation of optical spectra for transition-metal impurities doped in ZnO and ZnS

    K. Ogasawara, T. Ishii, F. Oba, I. Tanaka, and H. Adachi,

    Mater. Res. Soc. Symp. Proc., 560, 341-346 (1999).

  35. The role of Co ions on the appearance of non-linear I-V characteristics of ZnO-based ceramics

    M. Yodogawa, Y. Ikuhara, F. Oba, and I. Tanaka,

    Key Eng. Mater., 157-158, 249-255 (1999).

  36. Interaction between oxygen and 3d transition-metal impurities on ZnO (10-10) surface

    F. Oba, I. Tanaka, K. Ogasawara, and H. Adachi,

    Proceedings of US-Japan Workshop on Electrically Active Ceramic Interfaces, 141-144 (1998).

Books

  1. First-principles approaches to defect energetics in ZnO: A review

    F. Oba,

    Chapter publication in Zinc oxide, the future material for electronics: A Comprehensive review on ZnO physics and defects (Research Signpost, Trivandrum), 1-23 (2012).

Invited Talks at International Conferences

  1. Complex behavior of point defects in functional oxides and nitrides: Insights from first principles

    F. Oba,

    Energy Materials Nanotechnology Summer Meeting, Cancun, Jun. 10, 2014

  2. Band alignment of zinc-blende and chalcopyrite semiconductors: Effects of misfit dislocations

    F. Oba,

    APS March Meeting 2014, Denver, Mar. 3, 2014

  3. Point defects in oxide and nitride semiconductors: Understanding and prediction toward material screening

    F. Oba,

    2013 MRS Fall Meeting, Boston, Dec. 3, 2013

  4. Complex behavior of defects in oxide semiconductors: Insights from first-principles calculations

    F. Oba,

    International Symposium on Compound Semiconductors 2013 (ISCS2013), Kobe, May. 21, 2013

  5. Complex behavior of point defects in oxide and nitride semiconductors: Insights from density functional calculations

    F. Oba,

    The 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials (ISAEM-2012), Toyohashi, Nov. 8, 2012

  6. Native point defects in functional oxides: An approach from first principles

    F. Oba,

    Materials Science & Technology 2011, Columbus, Oct. 19, 2011

  7. Density functional approach to point defects in oxide semiconductors

    F. Oba,

    3rd International Congress on Ceramics(ICC3), Osaka, Nov. 15, 2010

  8. Point defects in oxide semiconductors: A density functional approach

    F. Oba,

    4th International Conference on the Science and Technology for Advanced Ceramics(STAC-4), Yokohama, Jun. 23, 2010

  9. Energetics and electronic structure of native defects and dopants in ZnO

    F. Oba,

    12th International Ceramics Congress, Montecatini Terme, Jun. 10, 2010

  10. Point defects in oxide semiconductors: An approach from first principles

    F. Oba,

    The 3rd Theory Meets Industry International Workshop, Nagoya, Nov. 13, 2009

  11. Room temperature ferromagnetism in manganese-doped gallium oxide

    F. Oba, H. Hayashi, R. Huang, H. Ikeno, S. Sonoda, and I. Tanaka,

    Materials Science & Technology 2007, Detroit, Sep. 19, 2007

  12. Microstructure of interfaces made by epitaxial electrodeposition

    F. Oba, R. Liu, E. W. Bohannan, F. Ernst, and J. A. Switzer,

    204th Meeting of the Electrochemical Society, Orlando, Oct. 14, 2003