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D-Index & Metrics

Discipline name D-Index World Ranking Current World Ranking National Ranking Current National Ranking Publications Citations
Materials Science 61 6806 6577 358 347 683 13013

Hajime Okumura publications per year

The chart shows the history of publications by Hajime Okumura between 1982 and 2025, highlighting the no. of papers published in each year and offering an overview of the publication velocity of this scholar. Hajime Okumura published across 44 years, from 1982 to 2025, averaging 16.2 papers a year. Output peaked at 41 publications in 2016. 5 of the 712 publications appeared in the last two years.

No. of publications
10 20 30 40
Bar chart. Horizontal axis: year, 1982 to 2025. Vertical axis: number of publications, 0 to 41. Peak 41 publications in 2016. 1982: 3 publications 1983: 1 publication 1984: 3 publications 1985: 5 publications 1986: 2 publications 1987: 8 publications 1988: 7 publications 1989: 15 publications 1990: 5 publications 1991: 9 publications 1992: 13 publications 1993: 7 publications 1994: 7 publications 1995: 4 publications 1996: 12 publications 1997: 17 publications 1998: 30 publications 1999: 15 publications 2000: 32 publications 2001: 31 publications 2002: 34 publications 2003: 23 publications 2004: 14 publications 2005: 14 publications 2006: 26 publications 2007: 28 publications 2008: 26 publications 2009: 14 publications 2010: 20 publications 2011: 9 publications 2012: 15 publications 2013: 22 publications 2014: 37 publications 2015: 24 publications 2016: 41 publications 2017: 37 publications 2018: 37 publications 2019: 30 publications 2020: 22 publications 2021: 2 publications 2022: 3 publications 2023: 3 publications 2024: 4 publications 2025: 1 publication
1982 2025

712 publications in total across all disciplines

View publications per year as a table
Hajime Okumura: publications per year, 1982 to 2025
Year Publications
1982 3
1983 1
1984 3
1985 5
1986 2
1987 8
1988 7
1989 15
1990 5
1991 9
1992 13
1993 7
1994 7
1995 4
1996 12
1997 17
1998 30
1999 15
2000 32
2001 31
2002 34
2003 23
2004 14
2005 14
2006 26
2007 28
2008 26
2009 14
2010 20
2011 9
2012 15
2013 22
2014 37
2015 24
2016 41
2017 37
2018 37
2019 30
2020 22
2021 2
2022 3
2023 3
2024 4
2025 1
Total 712
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Hajime Okumura publication distribution in Materials Science in 2026

The chart shows the distribution of publications by all Research.com ranked scientists in the field of Materials Science in 2026. The highlighted bar marks where Hajime Okumura sits on this spectrum.

No. of scientists
200 400 600 800
Bar chart with 57 bars. Horizontal axis: publications, 50–69 to 1,163+. Vertical axis: number of scientists, 0 to 891. Most scientists, 891, have 190–209 publications. The last bar groups every scientist with 1,163 publications or more. The highlighted bar, 670–689 publications, is where this scientist sits. 50–69 publications: 28 scientists 70–89 publications: 152 scientists 90–109 publications: 356 scientists 110–129 publications: 487 scientists 130–149 publications: 723 scientists 150–169 publications: 835 scientists 170–189 publications: 850 scientists 190–209 publications: 891 scientists 210–229 publications: 862 scientists 230–249 publications: 766 scientists 250–269 publications: 726 scientists 270–289 publications: 665 scientists 290–309 publications: 593 scientists 310–329 publications: 537 scientists 330–349 publications: 477 scientists 350–369 publications: 440 scientists 370–389 publications: 356 scientists 390–409 publications: 321 scientists 410–429 publications: 256 scientists 430–449 publications: 246 scientists 450–469 publications: 216 scientists 470–489 publications: 212 scientists 490–509 publications: 174 scientists 510–529 publications: 194 scientists 530–549 publications: 162 scientists 550–569 publications: 131 scientists 570–589 publications: 111 scientists 590–609 publications: 103 scientists 610–629 publications: 99 scientists 630–649 publications: 77 scientists 650–669 publications: 92 scientists 670–689 publications: 56 scientists 690–709 publications: 53 scientists 710–729 publications: 53 scientists 730–749 publications: 38 scientists 750–769 publications: 52 scientists 770–789 publications: 43 scientists 790–809 publications: 38 scientists 810–829 publications: 34 scientists 830–849 publications: 25 scientists 850–869 publications: 18 scientists 870–889 publications: 20 scientists 890–909 publications: 24 scientists 910–929 publications: 27 scientists 930–949 publications: 20 scientists 950–969 publications: 17 scientists 970–989 publications: 10 scientists 990–1,009 publications: 16 scientists 1,010–1,029 publications: 13 scientists 1,030–1,049 publications: 12 scientists 1,050–1,069 publications: 9 scientists 1,070–1,089 publications: 8 scientists 1,090–1,109 publications: 7 scientists 1,110–1,129 publications: 9 scientists 1,130–1,149 publications: 2 scientists 1,150–1,162 publications: 5 scientists 1,163+ publications: 100 scientists
50–69 publications 1,163+

This scientist: 683 publications — 95th percentile

95% of scientists in this discipline score the same or lower.

The last bar groups every scientist with 1,163 publications or more.

View publications distribution as a table
Number of Materials Science scientists by publication count, Research.com 2026 ranking edition. Based on 12,847 ranked scientists.
Publications Scientists This scientist
50–69 28
70–89 152
90–109 356
110–129 487
130–149 723
150–169 835
170–189 850
190–209 891
210–229 862
230–249 766
250–269 726
270–289 665
290–309 593
310–329 537
330–349 477
350–369 440
370–389 356
390–409 321
410–429 256
430–449 246
450–469 216
470–489 212
490–509 174
510–529 194
530–549 162
550–569 131
570–589 111
590–609 103
610–629 99
630–649 77
650–669 92
670–689 56 683
690–709 53
710–729 53
730–749 38
750–769 52
770–789 43
790–809 38
810–829 34
830–849 25
850–869 18
870–889 20
890–909 24
910–929 27
930–949 20
950–969 17
970–989 10
990–1,009 16
1,010–1,029 13
1,030–1,049 12
1,050–1,069 9
1,070–1,089 8
1,090–1,109 7
1,110–1,129 9
1,130–1,149 2
1,150–1,162 5
1,163+ 100
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Hajime Okumura D-index placement in Materials Science in 2026

The chart shows the D-index (discipline H-index) distribution of Materials Science scientists ranked by Research.com in 2026. The highlighted bar marks where Hajime Okumura sits on this spectrum.

No. of scientists
200 400 600
Bar chart with 64 bars. Horizontal axis: D-Index, 40–41 to 165+. Vertical axis: number of scientists, 0 to 667. Most scientists, 667, have 52–53 D-Index. The last bar groups every scientist with 165 D-Index or more. The highlighted bar, 60–61 D-Index, is where this scientist sits. 40–41 D-Index: 211 scientists 42–43 D-Index: 450 scientists 44–45 D-Index: 612 scientists 46–47 D-Index: 612 scientists 48–49 D-Index: 598 scientists 50–51 D-Index: 657 scientists 52–53 D-Index: 667 scientists 54–55 D-Index: 621 scientists 56–57 D-Index: 597 scientists 58–59 D-Index: 610 scientists 60–61 D-Index: 587 scientists 62–63 D-Index: 606 scientists 64–65 D-Index: 533 scientists 66–67 D-Index: 490 scientists 68–69 D-Index: 469 scientists 70–71 D-Index: 378 scientists 72–73 D-Index: 421 scientists 74–75 D-Index: 359 scientists 76–77 D-Index: 323 scientists 78–79 D-Index: 299 scientists 80–81 D-Index: 230 scientists 82–83 D-Index: 210 scientists 84–85 D-Index: 195 scientists 86–87 D-Index: 203 scientists 88–89 D-Index: 175 scientists 90–91 D-Index: 175 scientists 92–93 D-Index: 142 scientists 94–95 D-Index: 121 scientists 96–97 D-Index: 117 scientists 98–99 D-Index: 107 scientists 100–101 D-Index: 88 scientists 102–103 D-Index: 85 scientists 104–105 D-Index: 68 scientists 106–107 D-Index: 62 scientists 108–109 D-Index: 57 scientists 110–111 D-Index: 45 scientists 112–113 D-Index: 49 scientists 114–115 D-Index: 50 scientists 116–117 D-Index: 34 scientists 118–119 D-Index: 38 scientists 120–121 D-Index: 37 scientists 122–123 D-Index: 29 scientists 124–125 D-Index: 28 scientists 126–127 D-Index: 24 scientists 128–129 D-Index: 33 scientists 130–131 D-Index: 28 scientists 132–133 D-Index: 21 scientists 134–135 D-Index: 20 scientists 136–137 D-Index: 23 scientists 138–139 D-Index: 17 scientists 140–141 D-Index: 12 scientists 142–143 D-Index: 17 scientists 144–145 D-Index: 21 scientists 146–147 D-Index: 13 scientists 148–149 D-Index: 11 scientists 150–151 D-Index: 14 scientists 152–153 D-Index: 13 scientists 154–155 D-Index: 9 scientists 156–157 D-Index: 10 scientists 158–159 D-Index: 7 scientists 160–161 D-Index: 4 scientists 162–163 D-Index: 4 scientists 164 D-Index: 3 scientists 165+ D-Index: 98 scientists
40–41 D-Index 165+

This scientist: 61 D-Index — 48th percentile

48% of scientists in this discipline score the same or lower.

The last bar groups every scientist with 165 D-Index or more.

View D-Index distribution as a table
Number of Materials Science scientists by D-index, Research.com 2026 ranking edition. Based on 12,847 ranked scientists.
D-Index Scientists This scientist
40–41 211
42–43 450
44–45 612
46–47 612
48–49 598
50–51 657
52–53 667
54–55 621
56–57 597
58–59 610
60–61 587 61
62–63 606
64–65 533
66–67 490
68–69 469
70–71 378
72–73 421
74–75 359
76–77 323
78–79 299
80–81 230
82–83 210
84–85 195
86–87 203
88–89 175
90–91 175
92–93 142
94–95 121
96–97 117
98–99 107
100–101 88
102–103 85
104–105 68
106–107 62
108–109 57
110–111 45
112–113 49
114–115 50
116–117 34
118–119 38
120–121 37
122–123 29
124–125 28
126–127 24
128–129 33
130–131 28
132–133 21
134–135 20
136–137 23
138–139 17
140–141 12
142–143 17
144–145 21
146–147 13
148–149 11
150–151 14
152–153 13
154–155 9
156–157 10
158–159 7
160–161 4
162–163 4
164 3
165+ 98
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Overview

Hajime Okumura is affiliated with the National Institute of Advanced Industrial Science and Technology in Japan, focusing primarily on engineering disciplines. Their research is concentrated in the field of Electrical and Electronic Engineering, with significant contributions spanning 50 publications. Additional subfields include Atomic and Molecular Physics, and Optics; Materials Chemistry; Electronic, Optical and Magnetic Materials; and Epidemiology.

The scientist's research topics predominantly encompass Silicon Carbide Semiconductor Technologies, a field covered in 42 of their publications. Further areas of study include Semiconductor materials and devices, Semiconductor materials and interfaces, Thin-Film Transistor Technologies, Silicon and Solar Cell Technologies, Advanced ceramic materials synthesis, and Bacterial Identification and Susceptibility Testing.

Notable frequent co-authors working closely with Hajime Okumura include:

  • Tomohisa Kato
  • Kazutoshi Kojima
  • Kazuma Eto
  • Shiyang Ji
  • Sadafumi Yoshida

Publications with multiple contributions have appeared in key venues such as:

  • Japanese Journal of Applied Physics
  • Journal of Crystal Growth
  • Extended Abstracts of the 2020 International Conference on Solid State Devices and Materials
  • Applied Physics Letters
  • Materials science forum

Representative recent papers by Hajime Okumura illustrate a focus on semiconductor interfaces, epitaxial layers, and device performance:

  • Difference in electron mobility at 4H-SiC/SiO2 interfaces with various crystal faces originating from effective-field-dependent scattering (2020), Applied Physics Letters
  • Nondestructive measurements of depth distribution of carrier lifetimes in 4H-SiC thick epitaxial layers using time-resolved free carrier absorption with intersectional lights (2020), Review of Scientific Instruments
  • Influence of CMP damage induced during flattening SiC epitaxial layer on device performances (2020), Materials Science in Semiconductor Processing
  • Single-phase high-quality semipolar (10-13) AlN epilayers on m-plane (10-10) sapphire substrates (2020), Applied Physics Express
  • Photoluminescence wavelength from stacking fault with complicated structure in 4H-SiC epitaxial layer (2022), Japanese Journal of Applied Physics

Best Publications

  • Present Status and Future Prospect of Widegap Semiconductor High-Power Devices

    Hajime Okumura

  • Epitaxial growth of cubic and hexagonal GaN on GaAs by gas‐source molecular‐beam epitaxy

    H. Okumura;S. Misawa;S. Yoshida

  • Growth and characterization of cubic GaN

    H. Okumura;K. Ohta;G. Feuillet;K. Balakrishnan

  • GAN HETEROEPITAXIAL GROWTH ON SILICON NITRIDE BUFFER LAYERS FORMED ON SI (111) SURFACES BY PLASMA-ASSISTED MOLECULAR BEAM EPITAXY

    Yoshinobu Nakada;Igor Aksenov;Hajime Okumura

  • Intrinsic defects in cubic silicon carbide

    H. Itoh;A. Kawasuso;T. Ohshima;M. Yoshikawa

  • The origin of persistent photoconductivity and its relationship with yellow luminescence in molecular beam epitaxy grown undoped GaN

    C. V. Reddy;K. Balakrishnan;H. Okumura;S. Yoshida

  • Raman scattering of SiC: Application to the identification of heteroepitaxy of SiC polytypes

    H. Okumura;E. Sakuma;J. H. Lee;H. Mukaida

  • Monitoring surface stoichiometry with the (2×2) reconstruction during growth of hexagonal‐phase GaN by molecular beam epitaxy

    P. Hacke;G. Feuillet;H. Okumura;S. Yoshida

  • Reduction of the threading dislocation density in GaN films grown on vicinal sapphire (0001) substrates

    X. Q. Shen;H. Matsuhata;H. Okumura

  • Short minority carrier lifetimes in highly nitrogen-doped 4H-SiC epilayers for suppression of the stacking fault formation in PiN diodes

    T. Tawara;T. Miyazawa;M. Ryo;M. Miyazato

  • Determination of the conduction‐band discontinuities of GaAs/AlxGa1−xAs interfaces by capacitance‐voltage measurements

    H. Okumura;S. Misawa;S. Yoshida;S. Gonda

  • Characterization of traps at nitrided SiO2/SiC interfaces near the conduction band edge by using Hall effect measurements

    Tetsuo Hatakeyama;Yuji Kiuchi;Mitsuru Sometani;Shinsuke Harada

  • High breakdown voltage AlGaN/GaN MIS–HEMT with SiN and TiO2 gate insulator

    S. Yagi;M. Shimizu;M. Inada;Y. Yamamoto

  • Localized exciton dynamics in strained cubic In0.1Ga0.9N/GaN multiple quantum wells

    S. F. Chichibu;M. Sugiyama;T. Onuma;T. Kitamura

  • OPTICAL PROPERTIES NEAR THE BAND GAP ON HEXAGONAL AND CUBIC GAN

    H. Okumura;S. Yoshida;T. Okahisa

  • Growth of cubic III-nitrides by gas source MBE using atomic nitrogen plasma: GaN, AlGaN and AlN

    H Okumura;H Hamaguchi;T Koizumi;K Balakrishnan

  • Cloning of the Membrane-Bound Aldehyde Dehydrogenase Gene of Acetobacter polyoxogenes and Improvement of Acetic Acid Production by Use of the Cloned Gene.

    Masahiro Fukaya;Kenji Tayama;Toshimi Tamaki;Haruko Tagami

  • Homoepitaxial growth of 4H-SiC on on-axis (0001) C-face substrates by chemical vapor depositon

    K. Kojima;H. Okumura;S. Kuroda;K. Arai

  • Raman scattering of SiC: Estimation of the internal stress in 3C-SiC on Si

    H. Mukaida;H. Okumura;J. H. Lee;H. Daimon

  • Radiation induced defects in CVD-grown 3C-SiC

    H. Itoh;M. Yoshikawa;I. Nashiyama;S. Misawa

  • Raman studies on phonon modes in cubic AlGaN alloy

    H. Harima;T. Inoue;S. Nakashima;H. Okumura

Frequent Co-Authors

Sadafumi Yoshida
Sadafumi Yoshida National Institute of Advanced Industrial Science and Technology
Shigefusa F. Chichibu
Shigefusa F. Chichibu Tohoku University
Tsunenobu Kimoto
Tsunenobu Kimoto Kyoto University
Takeshi Ohshima
Takeshi Ohshima Japan Atomic Energy Agency
Takashi Sekiguchi
Takashi Sekiguchi University of Tsukuba
Hiromichi Ohashi
Hiromichi Ohashi Tokyo Institute of Technology
Yasuo Cho
Yasuo Cho Tohoku University
Yuji Matsumoto
Yuji Matsumoto Nara Institute of Science and Technology
Teruhiko Beppu
Teruhiko Beppu University of Tokyo
Shuji Nakamura
Shuji Nakamura University of California, Santa Barbara

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