Papers - Koji Asaka

Ultrahigh porosity photoluminescent silicon aerocrystals with greater than 50% nanocrystal ensemble quantum yields Reviewed

Bernard Gelloz, Leigh Canham, Koji Asaka, Yuto Nakamura, and Hideo Kishida

Journal of Applied Physics   134   033103   2023

Self-organized Ge_1−xSn_x quantum dots formed on insulators and their room temperature photoluminescence Reviewed

Kaoru Hashimoto, Shigehisa Shibayama, Koji Asaka, Mitsuo Sakashita, Masashi Kurosawa, and Osamu Nakatsuka

Japanese Journal of Applied Physics   62   075506   2023

Solid-phase crystallization of ultra-thin amorphous Ge layers on insulators Reviewed

Ryo Oishi, Koji Asaka, Leonid Bolotov, Noriyuki Uchida, Masashi Kurosawa, and Osamu Nakatsuka

Japanese Journal of Applied Physics   61   SC1086   2022

Critical current density for layer-by-layer breakdown of a multiwall carbon nanotube Reviewed

Koji Asaka, Kentaro Yamauchi, and Yahachi Saito

Diamond and Related Materials   124   108907   2022

　More details

Electric-current-induced structural changes in a suspended multiwall carbon nanotube (MWCNT) were observed through in-situ transmission electron microscopy. The bias voltage and electric current were measured simultaneously as the MWCNT was imaged. The passage of excessive current led to breakdown of the surface of the MWCNT and to subsequent layer-by-layer removal of the broken outermost shell via sublimation of carbon atoms. The surface breakdown of the MWCNT was accompanied by a discrete decrease in the current. Under the assumption that the current passes solely through the outermost shell of the MWCNT, we found that the critical current densities at which the breakdown in the renewed outermost shell occurred after the removal of the broken outermost shell were limited to a remarkably narrow range of (2.4 ± 0.2)×10⁹ A/cm², irrespective of the outermost diameter of the MWCNT. The present results provide invaluable information about electron transport phenomena in MWCNTs and about the durability of CNT nanocircuits.

Impact of wet annealing on ferroelectric phase formation and phase transition of HfO2-ZrO2 system Reviewed

Shigehisa Shibayama, Jotaro Nagano, Koji Asaka, Mitsuo Sakashita, and Osamu Nakatsuka

ACS Applied Electronic Materials   3   2203 - 2211   2021

Hole doping in polythiophenes encapsulated in semiconducting and metallic single-walled carbon nanotubes: Impact of the electronic structure Reviewed

Hiroto Kageyama, Koji Asaka, Hideo Kishida, and Takeshi Koyama

Macromolecules   54   11147 - 11153   2021

Light emission and structural changes in a suspended multiwall carbon nanotube on application of electric current Reviewed

Koji Asaka, Koshi Nishikawa, and Yahachi Saito

Diamond and Related Materials   111   108175   2021

Raman spectroscopy and TEM of long linear carbon chain formed in CNT field emission cathode Reviewed

Koji Asaka, Satoshi Toma, and Yahachi Saito

e-Journal of Surface Science and Nanotechnology   18   159 - 163   2020

Excitation energy transfer by electron exchange via two-step electron transfer between single-walled carbon nanotube and encapsulated magnesium porphyrin Reviewed

Takeshi Koyama, Junpei Sugiura, Tomonari Koishi, Ryosuke Ohashi, Koji Asaka, Takeshi Saito, Yanlin Gao, Susumu Okada, and Hideo Kishida

The Journal of Physical Chemistry C   124   19406 - 19412   2020

Application of multiwall carbon nanotubes to conductive manipulation-probe tips for in-situ transmission electron microscopy of nanometer-sized material: Electrical measurement of a silicon nanoparticle Reviewed

Koji Asaka, Tomohiro Terada, and Yahachi Saito

Materials Research Express   6   015038-1-5   2019

Raman spectroscopy and transmission electron microscopy study on long linear atomic carbon chains generated by field electron emission accompanied with electrical discharge of carbon nanotube films Reviewed

Koji Asaka, Satoshi Toma, and Yahachi Saito

SN Applied Sciences   1   493   2019

Si/SiO2 core/shell luminescent silicon nanocrystals and porous silicon powders with high quantum yield, long lifetime and good stability Reviewed

Bernard Gelloz, Firman Bagja Juangs, Tomohiro Nozaki, Koji Asaka, Nobuyoshi Koshida, and Lianhua Jin

Frontiers in Physics   7   47-1-7   2019

Bulk synthesis of linear carbon-chains confined inside single-wall carbon nanotubes by vacuum discharge Reviewed

Satoshi Toma, Koji Asaka, Masaru Irita, and Yahachi Saito

Surface and Interface Analysis   51   131 - 135   2019

Different molecular arrangement of perylene in metallic and semiconducting carbon nanotubes: Impact of van der Waals interaction Reviewed

Takeshi Koyama, Kazuma Fujiki, Yuya Nagasawa, Susumu Okada, Koji Asaka, Yahachi Saito, and Hideo Kishida

The Journal of Physical Chemistry C   122   5805 - 5812   2018

High-temperature reaction of amorphous silicon with carbon on a multiwall carbon nanotube heater and temperature measurement by thermal radiation spectra Reviewed

Koji Asaka, Tomohiro Terada, and Yahachi Saito

Journal of Materials Science   52   7232 - 7238   2017

In-situ TEM study on structural change and light emission of a multiwall carbon nanotube during Joule heating Reviewed

Koshi Nishikawa, Koji Asaka, Hitoshi Nakahara, and Yahachi Saito

IOP Conference Series: Materials Science and Engineering   304   012011   2017

Facile synthetic route to atomically thin conductive wires from single-species molecules in one-dimensionally confined space: Doped conjugated polymers inside single-walled carbon nanotubes Reviewed

Makoto Sasaki, Takeshi Koyama, Hideo Kishida, Koji Asaka, Yahachi Saito, Yukihiro Yoshida, and Gunzi Saito

The Journal of Physical Chemistry Letters   8   1702 - 1706   2017

Ultrafast excitation energy transfer from encapsulated quaterrylene to single-walled carbon nanotube Reviewed

Takeshi Koyama, Takuya Tsunekawa, Takeshi Saito, Koji Asaka, Yahachi Saito, Hideo Kishida, and Arao Nakamura

Journal of Luminescence   169   645 - 648   2016

Spontaneous graphenization of amorphous carbon on clean surfaces of nanometer-sized nickel particles at room temperature Reviewed

Koji Asaka and Yahachi Saito

Carbon   103   352 - 355   2016

Field emission patterns showing symmetry of electronic states in graphene edges Reviewed

Noboru Yokoyama, Kazuya Nakakubo, Kohji Iwata, Koji Asaka, Hitoshi Nakahara, and Yahachi Saito

Surface and Interface Analysis   48   1217 - 1220   2016

In situ TEM study on structural and electric conduction properties of a multiwall carbon nanotube connected to a Mo electrode Reviewed

Yuji Shinomiya, Koji Asaka, Hitoshi Nakahara, and Yahachi Saito

Surface and Interface Analysis   48   1206 - 1209   2016

Structure of amorphous carbon films deposited on Ni nanoparticles under ultrahigh vacuum at room temperature Reviewed

Koji Asaka and Yahachi Saito

Surface and Interface Analysis   48   1203 - 1205   2016

Transformation of silicon nanoparticles on carbon nanotube heater to hollow graphitic nanocapsules via silicon carbide Reviewed

Koji Asaka, Tomohiro Terada, and Yahachi Saito

Diamond and Related Materials   50   49 - 54   2014

Synthesis and photophysics of quaterrylene molecules in single-walled carbon nanotubes: excitation energy transfer between a nanoscale cylinder and encapsulated molecules Reviewed

Takeshi Koyama, Takuya Tsunekawa, Takeshi Saito, Koji Asaka, Yahachi Saito, Hideo Kishida, and Arao Nakamura

The Journal of Physical Chemistry C   118   21671 - 21681   2014

In situ TEM study on changes in structure and electrical conductance of carbon nanotube-gold contact induced by local joule heating Reviewed

Motoyuki Karita, Koji Asaka, Hitoshi Nakahara, and Yahachi Saito

Journal of Materials Science   48   936 - 940   2013

Few-layer epitaxial graphene with large domains on C-terminated 6H-SiC Reviewed

Hailong Hu, Akkawat Ruammaitree, Hitoshi Nakahara, Koji Asaka, and Yahachi Saito

Surface and Interface Analysis   44   793 - 796   2012

Study on structure of heat-treated fullerene nanowhiskers and their field electron emission characteristics Reviewed

Koji Asaka, Tadachika Nakayama, Kun’ichi Miyazawa, and Yahachi Saito

Surface and Interface Analysis   44   780 - 783   2012

In situ TEM study on the improvement of contact resistance between a carbon nanotube and metal electrodes by local melting Reviewed

Motoyuki Karita, Koji Asaka, Hitoshi Nakahara, and Yahachi Saito

Surface and Interface Analysis   44   674 - 677   2012

Evolution of field electron emission pattern from multilayered graphene induced by structural change of edge Reviewed

Kazuya Nakakubo, Koji Asaka, Hitoshi Nakahara, and Yahachi Saito

Applied Physics Express   5   055101-1-3   2012

Structures and field emission properties of heat-treated C60 fullerene nanowhiskers Reviewed

Koji Asaka, Tadachika Nakayama, Kun’ichi Miyazawa, and Yahachi Saito

Carbon   50   1209 - 1215   2012

Ultrafast energy transfer of one-dimensional excitons between carbon nanotubes: a femtosecond time-resolved luminescence study Reviewed

Takeshi Koyama, Yasumitsu Miyata, Koji Asaka, Hisanori Shinohara, Yahachi Saito, and Arao Nakamura

Physical Chemistry Chemical Physics   14   1070 - 1084   2012

Fabrication of gas field ion emitter by field induced oxygen etching method Reviewed

Yasushi Sugiura, Huarong Liu, Tatsuo Iwata, Shigekazu Nagai, Kazuo Kajiwara, Koji Asaka, Yahachi Saito, and Koichi Hata

e-Journal of Surface Science and Nanotechnology   9   344 - 347   2011

Graphitization of amorphous carbon on a multiwall carbon nanotube surface by catalyst-free heating Reviewed

Koji Asaka, Motoyuki Karita, and Yahachi Saito

Applied Physics Letters   99   091907-1-3   2011

Chirality assignment to carbon nanotubes integrated in MEMS by tilted-view transmission electron microscopy Reviewed

Matthias Muoth, Fabian Gramm, Koji Asaka, Lukas Durrer, Thomas Helbling, Cosmin Roman, Shih-Wei Lee, and Chiristofer Hierold

Sensors and Actuators B   154   155 - 159   2011

Joining of multiwall carbon nanotubes for the end-contact configuration by applying electric current Reviewed

Koji Asaka, Motoyuki Karita, and Yahachi Saito

Materials Letters   65   1832 - 1834   2011

Femtosecond luminescence decay due to exciton energy transfer in single-walled carbon nanotube bundles Reviewed

Takeshi Koyama, Koji Asaka, Naoki Hikosaka, Hideo Kishida, Yahachi Saito, and Arao Nakamura

Journal of Luminescence   131   494 - 497   2011

Ultrafast exciton energy transfer in bundles of single-walled carbon nanotubes Reviewed

Takeshi Koyama, Koji Asaka, Naoki Hikosaka, Hideo Kishida, Yahachi Saito, and Arao Nakamura

The Journal of Physical Chemistry Letters   2   127 - 132   2011

Modification of interface structure and contact resistance between a carbon nanotube and a gold electrode by local melting Reviewed

Koji Asaka, Motoyuki Karita, and Yahachi Saito

Applied Surface Science   257   2850 - 2853   2011

Enhancement of third-order optical nonlinearities in carbon nanotubes by encapsulated fullerenes Reviewed

Daksuke Hosooka, Takeshi Koyama, Hideo Kishida, Koji Asaka, Yahachi Saito, Takeshi Saito, and Arao Nakamura

AIP Conference Proceedings   1399   831 - 832   2011

Exciton energy transfer between single-walled carbon nanotubes in femtosecond regime Reviewed

Takeshi Koyama, Koji Asaka, Naoki Hikosaka, Hideo Kishida, Yahachi Saito, and Arao Nakamura

AIP Conference Proceedings   1399   759 - 760   2011

Field emission microscopy of Al-deposited carbon nanotubes: emission stability improvement and image of an Al atom cluster Reviewed

Yahachi Saito, Tomohiro Matsukawa, Koji Asaka, and Hitoshi Nakahara

Journal of Vacuum Science and Technology B   28   C2A5 - C2A8   2010

Electric and mass transport of a suspended multiwall carbon nanotube studied by in situ transmission electron microscopy Reviewed

Yasunobu Suzuki, Koji Asaka, Hitoshi Nakahara, and Yahachi Saito

Japanese Journal of Applied Physics   49   02BD07-1-3   2010

Electric and mass transport of a carbon nanotube encapsulating a copper nano-rod studied by in-situ transmission electron microscopy Reviewed

Fumitaka Kimura, Koji Asaka, Hitoshi Nakahara, Fumio Kokai, and Yahachi Saito

Journal of Nanoscience and Nanotechnology   10   3907 - 3909   2010

Tilted-view transmission electron microscopy-access for chirality assignment to carbon nanotubes integrated in MEMS Reviewed

Matthias Muoth, Fabian Gramm, Koji Asaka, Lukas Durrer, Thomas Helbling, Cosmin Romana, Shih-Wei Lee, and Chiristofer Hierold

Procedia Chemistry   1   601 - 604   2009

The toughness of multi-wall carbon nanocapsules Reviewed

Koji Asaka, Kun’ichi Miyazawa, and Tokushi Kizuka

Nanotechnology   20   385705-1-4   2009

Nanowelding of a multiwalled carbon nanotube to metal surface and its electron field emission properties Reviewed

Koji Asaka, Hitoshi Nakahara, and Yahachi Saito

Applied Physics Letters   92   023114-1-3   2008

Fracture surface and correlation of buckling force with aspect ratio of C60 crystalline whiskers Reviewed

Koji Asaka, Ryoei Kato, Ryozo Yoshizaki, Kun’ichi Miyazawa, and Tokushi Kizuka

Diamond and Related Materials   16   1936 - 1939   2007

Conductance of carbon nanocapsule junctions Reviewed

Koji Asaka, Ryoei Kato, Ryozo Yoshizaki, Kun’ichi Miyazawa, and Tokushi Kizuka

Physical Review B   76   113404-1-3   2007

Deformation of multiwalled nanometer-sized carbon capsules Reviewed

Koji Asaka, Ryoei Kato, Kun’ichi Miyazawa, and Tokushi Kizuka

Applied Physics Letters   89   191914-1-3   2006

In situ high-resolution transmission electron microscopy of elastic deformation and fracture of nanometer-sized fullerene C60 whiskers Reviewed

Ryoei Kato, Koji Asaka, Kun’ichi Miyazawa, and Tokushi Kizuka

Japanese Journal of Applied Physics   45   8024 - 8026   2006

Buckling of C60 whiskers Reviewed

Koji Asaka, Ryoei Kato, Kun’ichi Miyazawa, and Tokushi Kizuka

Applied Physics Letters   89   071912-1-3   2006

Light-emitting filaments composed of nanometer-sized carbon hollow capsules Reviewed

Koji Asaka, Ryoei Kato, Yoshinari Maezono, Ryozo Yoshizaki, Kun’ichi Miyazawa, and Tokushi Kizuka

Applied Physics Letters   88   051914-1-3   2006

Measurements of the atomistic mechanics of single crystalline silicon wires of nanometer width Reviewed

Tokushi Kizuka, Yasuhiro Takatani, Koji Asaka, and Ryozo Yoshizaki

Physical Review B   72   035333-1-6   2005

Atomistic dynamics of deformation, fracture, and joining of individual single-walled carbon nanotubes Reviewed

Koji Asaka and Tokushi Kizuka

Physical Review B   72   115431-1-5   2005

Direct observation of excitonic lasing from single ZnO nanobelts at room temperature Reviewed

Kazuki Bando, Taiki Sawabe, Koji Asaka, and Yasuaki Masumoto

AIP Conference Proceedings   772   894 - 895   2004

Room-temperature excitonic lasing from ZnO single nanobelts Reviewed

Kazuki Bando, Taiki Sawabe, Koji Asaka, and Yasuaki Masumoto

Journal of Luminescence   108   385 - 388   2004

Transmission electron microscopy and electron diffraction studies on martensitic transformations in nanometer-sized particles of Au-Cd alloys of near-equiatomic compositions Reviewed

Koji Asaka, Tsugio Tadaki, and Yoshihiko Hirotsu

Philosophical Magazine A   82   463 - 478   2002

Structure of nanometer-sized Au-Cd alloy particles near equiatomic compositions at room temperature Reviewed

Koji Asaka, Yoshihiko Hirotsu, and Tsugio Tadaki

Materials Science and Engineering A   312   232 - 236   2001

Structure and displacive phase transformations of small particles of In-Pb alloys Reviewed

Koji Asaka, Eri Kitahata, Yoshihiko Hirotsu, Kouichi Kifune, Yoshiki Kubota, and Tsugio Tadaki

Scripta Materialia   44   2043 - 2046   2001

Facets of nanometer-sized Fe-Ni alloy particles and their change upon the martensitic transformation Reviewed

Koji Asaka, Yoshihiko Hirotsu, and Tsugio Tadaki

Materials Science Forum   327-328   409 - 412   2000

Lattice softening and Its relation to the martensitic transformation in nanometer-sized particles of Fe-Ni alloys Reviewed

Koji Asaka, Yoshihiko Hirotsu, and Tugio Tadaki

Solid-Solid Phase Transformations, Japan Institute of Metals   Pts1 and 2   1068 - 1071   1999

Martensitic transformation in nanometer-sized particles of Fe-Ni alloys Reviewed

Koji Asaka, Yoshihiko Hirotsu, and Tsugio Tadaki

Materials Science and Engineering A   273-275   262 - 265   1999

Transmission electron microscopy and electron diffraction study on structure and phase transformation of nanometer-sized Fe-15-30 at.% Ni alloy particles Reviewed

Koji Asaka, Yoshihiko Hirotsu, and Tsugio Tadaki

Journal of Electron Microscopy   48   387 - 391   1999

TEM and electron diffraction on structure and phase transformation of nanometer-sized Fe-Ni alloy particles Reviewed

Koji Asaka, Tsugio Tadaki, Yoshihisa Sechi, Bian Bo, Tadakatsu Ohkubo, and Yoshihiko Hirotsu

The Third Pacific Rim International Conference on Advanced Materials and Processing, Minerals, Metals & Materials Society   1   1467 - 1473   1998