All Stories

  1. Correlation between the internal quantum efficiency and photoluminescence lifetime of the near-band-edge emission in a ZnO single crystal grown by the hydrothermal method

    Article • Applied Physics Express, December 2020, Institute of Physics Publishing

    Dr. Kazunobu Kojima

  2. Detailed analysis of Ga-rich current pathways created in an n-Al0.7Ga0.3N layer grown on an AlN template with dense macrosteps

    Article • Applied Physics Express, December 2020, Institute of Physics Publishing

    Dr. Kazunobu Kojima, Dr. Akira Hirano

  3. Urbach–Martienssen tail as the origin of the two-peak structure in the photoluminescence spectra for the near-band-edge emission of a freestanding GaN crystal observed by omnidirectional photoluminescence spectroscopy

    Article • Applied Physics Letters, October 2020, American Institute of Physics

    Dr. Kazunobu Kojima

  4. Temperature dependence of internal quantum efficiency of radiation for the near-band-edge emission of GaN crystals quantified by omnidirectional photoluminescence spectroscopy

    Article • Applied Physics Express, September 2020, Institute of Physics Publishing

    Dr. Kazunobu Kojima

  5. Self-organized micro-light-emitting diode structure for high-speed solar-blind optical wireless communications

    Article • Applied Physics Letters, July 2020, American Institute of Physics

    Dr. Kazunobu Kojima, Dr. Akira Hirano

  6. Hole capture-coefficient of intrinsic nonradiative recombination centers that commonly exist in bulk, epitaxial, and proton-irradiated ZnO

    Article • Journal of Applied Physics, June 2020, American Institute of Physics

    Dr. Kazunobu Kojima

  7. Impact of high-temperature implantation of Mg ions into GaN

    Article • Japanese Journal of Applied Physics, May 2020, Institute of Physics Publishing

    Dr. Kazunobu Kojima

  8. Ammonothermal growth of 2 inch long GaN single crystals using an acidic NH4F mineralizer in a Ag-lined autoclave

    Article • Applied Physics Express, April 2020, Institute of Physics Publishing

    Dr. Kazunobu Kojima

  9. Analyzing oxygen and silicon incorporation in GaN microstructures composed of c-planes and angled facets by confocal magneto-photoluminescence microscopy

    Article • AIP Advances, March 2020, American Institute of Physics

    Dr. Kazunobu Kojima

  10. Origin and dynamic properties of major intrinsic nonradiative recombination centers in wide bandgap nitride semiconductors

    Article • February 2020, SPIE

    Dr. Kazunobu Kojima

  11. Two-dimensional analysis of the nonuniform IQE of nonflat QWs for AlGaN-based deep-ultraviolet LEDs

    Article • Journal of Applied Physics, December 2019, American Institute of Physics

    Dr. Kazunobu Kojima, Dr. Akira Hirano

  12. Roles of carbon impurities and intrinsic nonradiative recombination centers on the carrier recombination processes of GaN crystals

    Article • Applied Physics Express, December 2019, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  13. Suppression of Green Luminescence of Mg‐Ion‐Implanted GaN by Subsequent Implantation of Fluorine Ions at High Temperature

    Article • physica status solidi (b), December 2019, Wiley

    Dr. Kazunobu Kojima

  14. Theoretical analysis of photo recycling effect on external quantum efficiency considering spatial carrier dynamics

    Article • Japanese Journal of Applied Physics, November 2019, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  15. In-plane optical polarization and dynamic properties of the near-band-edge emission of an m-plane freestanding AlN substrate and a homoepitaxial film

    Article • Applied Physics Letters, October 2019, American Institute of Physics

    Dr. Kazunobu Kojima

  16. Internal quantum efficiency of radiation in a bulk CH3NH3PbBr3 perovskite crystal quantified by using the omnidirectional photoluminescence spectroscopy

    Article • APL Materials, July 2019, American Institute of Physics

    Dr. Kazunobu Kojima

  17. Theoretical Formulation of Experimentally Observed Quantum Efficiency of Radiation in Semiconducting Crystal

    Article • Physical Review Applied, July 2019, American Physical Society (APS)

    Dr. Kazunobu Kojima

  18. Photoluminescence Studies of Sequentially Mg and H Ion-implanted GaN with Various Implantation Depths and Crystallographic Planes

    Article • June 2019, Institute of Electrical & Electronics Engineers (IEEE)

    Dr. Kazunobu Kojima

  19. Annealing Behavior of Vacancy‐Type Defects in Mg‐ and H‐Implanted GaN Studied Using Monoenergetic Positron Beams

    Article • physica status solidi (b), May 2019, Wiley

    Dr. Kazunobu Kojima

  20. Quantification of the quantum efficiency of radiation of a freestanding GaN crystal placed outside an integrating sphere

    Article • Applied Physics Express, May 2019, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  21. Impact of growth temperature on the structural properties of BGaN films grown by metal-organic vapor phase epitaxy using trimethylboron

    Article • Japanese Journal of Applied Physics, May 2019, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  22. Room temperature photoluminescence lifetime for the near-band-edge emission of epitaxial and ion-implanted GaN on GaN structures

    Article • Japanese Journal of Applied Physics, May 2019, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  23. Around 285 nm, difference of LED will appear

    Article • Applied Physics Express, May 2019, Japan Society of Applied Physics

    Dr. Akira Hirano, Dr. Kazunobu Kojima

  24. Carrier localization structure combined with current micropaths.

    Article • Applied Physics Letters, January 2019, American Institute of Physics

    Dr. Akira Hirano, Dr. Kazunobu Kojima

  25. DUV-LED has high response speed.

    Article • January 2019, Optical Society of America (OSA)

    Dr. Akira Hirano, Dr. Kazunobu Kojima

  26. Room-temperature photoluminescence lifetime for the near-band-edge emission of (000 1 ¯ ) p-type GaN fabricated by sequential ion-implantation of Mg and H

    Article • Applied Physics Letters, November 2018, American Institute of Physics

    Dr. Kazunobu Kojima

  27. 1.6-Gbps LED-Based Ultraviolet Communication at 280 nm in Direct Sunlight

    Article • September 2018, Institute of Electrical & Electronics Engineers (IEEE)

    Dr. Kazunobu Kojima

  28. Determination of Deformation Potentials in InGaN Alloy Material for Theoretical Prediction of Optical Gain Characteristics in Semipolar and Nonpolar InGaN Quantum Wells Laser Diodes

    Article • September 2018, Institute of Electrical & Electronics Engineers (IEEE)

    Dr. Kazunobu Kojima

  29. Large electron capture-cross-section of the major nonradiative recombination centers in Mg-doped GaN epilayers grown on a GaN substrate

    Article • Applied Physics Letters, May 2018, American Institute of Physics

    Dr. Kazunobu Kojima

  30. The origins and properties of intrinsic nonradiative recombination centers in wide bandgap GaN and AlGaN

    Article • Journal of Applied Physics, March 2018, American Institute of Physics

    Dr. Kazunobu Kojima

  31. Polarity-dependence of the defect formation in c-axis oriented ZnO by the irradiation of an 8 MeV proton beam

    Article • Journal of Applied Physics, January 2018, American Institute of Physics

    Dr. Kazunobu Kojima

  32. Photocatalytic NO removal over calcium-bridged siloxenes under ultraviolet and visible light irradiation

    Article • Dalton Transactions, January 2018, Royal Society of Chemistry

    Dr. Kazunobu Kojima

  33. Carrier Trapping by Vacancy-Type Defects in Mg-Implanted GaN Studied Using Monoenergetic Positron Beams

    Article • physica status solidi (b), December 2017, Wiley

    Dr. Kazunobu Kojima

  34. High temperature degradation mechanism of a red phosphor, CaAlSiN3:Eu for solid-state lighting

    Article • Journal of Applied Physics, September 2017, American Institute of Physics

    Dr. Kazunobu Kojima

  35. Demonstration of omnidirectional photoluminescence (ODPL) spectroscopy for precise determination of internal quantum efficiency of radiation in GaN single crystals

    Article • Applied Physics Letters, July 2017, American Institute of Physics

    Dr. Kazunobu Kojima

  36. A Low-Symmetry Cubic Mesophase of Dendronized CdS Nanoparticles and Their Structure-Dependent Photoluminescence

    Article • Chem, June 2017, Elsevier

    Dr. Kazunobu Kojima

  37. Nitrogen vacancies as a common element of the green luminescence and nonradiative recombination centers in Mg-implanted GaN layers formed on a GaN substrate

    Article • Applied Physics Express, May 2017, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  38. Photocatalytic activity of silicon-based nanoflakes for the decomposition of nitrogen monoxide

    Article • Dalton Transactions, January 2017, Royal Society of Chemistry

    Dr. Kazunobu Kojima

  39. A design strategy for achieving more than 90% of the overlap integral of electron and hole wavefunctions in high-AlN-mole-fraction AlxGa1−xN multiple quantum wells

    Article • Applied Physics Express, December 2016, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  40. Defect-Resistant Radiative Performance ofm-Plane Immiscible Al1−xInxN Epitaxial Nanostructures for Deep-Ultraviolet and Visible Polarized Light Emitters

    Article • Advanced Materials, November 2016, Wiley

    Dr. Kazunobu Kojima

  41. Determination of absolute value of quantum efficiency of radiation in high quality GaN single crystals using an integrating sphere

    Article • Journal of Applied Physics, July 2016, American Institute of Physics

    Dr. Kazunobu Kojima

  42. Spectroscopic ellipsometry studies on them-plane Al1−xInxN epilayers grown by metalorganic vapor phase epitaxy on a freestanding GaN substrate

    Article • Japanese Journal of Applied Physics, April 2016, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  43. Electronic and optical characteristics of anm-plane GaN single crystal grown by hydride vapor phase epitaxy on a GaN seed synthesized by the ammonothermal method using an acidic mineralizer

    Article • Japanese Journal of Applied Physics, March 2016, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  44. Controlling the carrier lifetime of nearly threading-dislocation-free ZnO homoepitaxial films by 3d transition-metal doping

    Article • Applied Physics Letters, January 2016, American Institute of Physics

    Dr. Kazunobu Kojima

  45. Low-resistivity m -plane freestanding GaN substrate with very low point-defect concentrations grown by hydride vapor phase epitaxy on a GaN seed crystal synthesized by the ammonothermal method

    Article • Applied Physics Express, August 2015, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  46. Polarity dependent radiation hardness of GaN

    Article • June 2015, Institute of Electrical & Electronics Engineers (IEEE)

    Dr. Kazunobu Kojima

  47. Pulse capture without carrier absorption in dynamic Q photonic crystal nanocavities

    Article • Optics Express, June 2014, Optical Society of America (OSA)

    Dr. Kazunobu Kojima

  48. Far off-resonant coupling between photonic crystal microcavity and single quantum dot with resonant excitation

    Article • Applied Physics Letters, December 2013, American Institute of Physics

    Dr. Kazunobu Kojima

  49. Modal volume control of a photonic crystal nanocavity

    Article • June 2013, Institute of Electrical & Electronics Engineers (IEEE)

    Dr. Kazunobu Kojima

  50. Accurate alignment of a photonic crystal nanocavity with an embedded quantum dot based on optical microscopic photoluminescence imaging

    Article • Applied Physics Letters, January 2013, American Institute of Physics

    Dr. Kazunobu Kojima

  51. Alignment between a single quantum dot and a photonic crystal nanocavity by a microscopic photoluminescence imaging

    Article • September 2012, Institute of Electrical & Electronics Engineers (IEEE)

    Dr. Kazunobu Kojima

  52. Control of the Purcell effect of quantum dots embedded in photonic crystal nanocavity by manipulating Q-factor

    Article • February 2012, SPIE

    Dr. Kazunobu Kojima

  53. Optical polarization and anisotropic gain characteristics in semipolar and nonpolar InGaN quantum well lasers

    Article • physica status solidi c, February 2012, Wiley

    Dr. Kazunobu Kojima

  54. Controlling the emission of quantum dots embedded in photonic crystal nanocavity by manipulating Q-factor and detuning

    Article • Physical Review B, December 2011, American Physical Society (APS)

    Dr. Kazunobu Kojima

  55. Improving the laser performances for sterilization and water purification

    Article • Journal of Applied Physics, August 2011, American Institute of Physics

    Dr. Kazunobu Kojima

  56. A simple theoretical approach to analyze polarization properties in semipolar and nonpolar InGaN quantum wells

    Article • Applied Physics Letters, March 2011, American Institute of Physics

    Dr. Kazunobu Kojima

  57. Impact of onpolar plane for deep ultraviolet laser diodes based on AlGa/AlN quantum wells

    Article • September 2010, Institute of Electrical & Electronics Engineers (IEEE)

    Dr. Kazunobu Kojima

  58. Gain Anisotropy Analysis in Green Semipolar InGaN Quantum Wells with Inhomogeneous Broadening

    Article • Japanese Journal of Applied Physics, August 2010, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  59. Valence band effective mass of non-c-plane nitride heterostructures

    Article • Journal of Applied Physics, June 2010, American Institute of Physics

    Dr. Kazunobu Kojima

  60. Quantum electrodynamics of a nanocavity coupled with exciton complexes in a quantum dot

    Article • Physical Review B, October 2009, American Physical Society (APS)

    Dr. Kazunobu Kojima

  61. Optical Anisotropy Control of Non-c-plane InGaN Quantum Wells

    Article • Japanese Journal of Applied Physics, August 2009, Japan Society of Applied Physics

    Dr. Kazunobu Kojima

  62. Polarization switching phenomena in semipolarInxGa1−xN/GaNquantum well active layers

    Article • Physical Review B, December 2008, American Physical Society (APS)

    Dr. Kazunobu Kojima

  63. Theoretical investigations on anisotropic optical properties in semipolar and nonpolar InGaN quantum wells

    Article • physica status solidi c, July 2008, Wiley

    Dr. Kazunobu Kojima

  64. Inhomogeneously broadened optical gain spectra of InGaN quantum well laser diodes

    Article • physica status solidi c, May 2008, Wiley

    Dr. Kazunobu Kojima

  65. Analysis of Gain and Luminescence in Violet and Blue GaInN–GaN Quantum Wells

    Article • IEEE Journal of Quantum Electronics, February 2008, Institute of Electrical & Electronics Engineers (IEEE)

    Dr. Kazunobu Kojima

  66. Stimulated emission at 474nm from an InGaN laser diode structure grown on a (112¯2) GaN substrate

    Article • Applied Physics Letters, December 2007, American Institute of Physics

    Dr. Kazunobu Kojima

  67. Interplay of built-in potential and piezoelectric field on carrier recombination in green light emitting InGaN quantum wells

    Article • Applied Physics Letters, September 2007, American Institute of Physics

    Dr. Kazunobu Kojima

  68. Comparison between optical gain spectra of InxGa1-xN/In0.02Ga0.98N laser diodes emitting at 404 nm and 470 nm

    Article • phys stat sol (a), June 2007, Wiley

    Dr. Kazunobu Kojima

  69. Photoluminescence and optical reflectance investigation of semipolar and nonpolar GaN

    Article • physica status solidi (b), June 2007, Wiley

    Dr. Kazunobu Kojima

  70. Investigation and comparison of optical gain spectra of (Al,In)GaN laser diodes emitting in the 375nm to 470 nm spectral range

    Article • February 2007, SPIE

    Dr. Kazunobu Kojima

  71. Optical gain spectra for near UV to aquamarine (Al,In)GaN laser diodes

    Article • Optics Express, January 2007, Optical Society of America (OSA)

    Dr. Kazunobu Kojima

  72. Gain suppression phenomena observed in InxGa1−xN quantum well laser diodes emitting at 470nm

    Article • Applied Physics Letters, December 2006, American Institute of Physics

    Dr. Kazunobu Kojima

  73. Epitaxial growth and optical properties of semipolar (112¯2) GaN and InGaN∕GaN quantum wells on GaN bulk substrates

    Article • Applied Physics Letters, November 2006, American Institute of Physics

    Dr. Kazunobu Kojima

  74. Suppression mechanism of optical gain formation in InxGa1−xN quantum well structures due to localized carriers

    Article • Solid State Communications, October 2006, Elsevier

    Dr. Kazunobu Kojima

  75. Dynamic polarization rotation in pump-and-probe transients of anisotropically strainedM -plane GaN films on LiAlO2

    Article • physica status solidi c, June 2006, Wiley

    Dr. Kazunobu Kojima

  76. Dynamic polarization filtering in anisotropically strained M-plane GaN films

    Article • Applied Physics Letters, May 2005, American Institute of Physics

    Dr. Kazunobu Kojima

  77. Optically pumped lasing and gain formation properties in blue Inx Ga1–x N MQWs

    Article • physica status solidi (b), October 2004, Wiley

    Dr. Kazunobu Kojima

  78. The hot carrier dynamics in InGaN multi-quantum well structure

    Article • physica status solidi (b), November 2003, Wiley

    Dr. Kazunobu Kojima