Publications

◆Paper: 2015 2014 2013 2012 2011 2010 2009 2008 2007 before 2006

◆Conference: 2015 2014 2013 2012 2011 2010 2009 2008 2007 before 2006


Latest publications

-2015-

B. Behaghel R. Tamaki, N. Vandamme, K. Watanabe, C. Dupuis, N. Bardou, H. Sodabanlu, A. Cattoni, Y. Okada, M. Sugiyama, S. Collin, and J.-F. Guillemoles, “Absorption enhancement through Fabry-Pérot resonant modes in a 430 nm thick InGaAs/GaAsP multiple quantum wells solar cell”, Applied Physics Letters 106, 081107 (2015); http://dx.doi.org/10.1063/1.4913469

Shunya Naitoh and Yoshitaka Okada, “Efficiency Estimations for Multijunction and Intermediate Band Solar Cells Using Actual Measured Solar Spectra in Japan”, Journal of Solar Energy Engineering 137, 034504 (2015); doi: 10.1115/1.4029382


-2014-

M. M. Islam, N. Miyashita, N. Ahsan, T. Sakurai, K. Akimoto, and Y. Okada, “Effect of antimony on the deep-level traps in GaInNAsSb thin films”, Applied Physics Letters 105, 112103 (2014); http://dx.doi.org/10.1063/1.4895940.

Efrain E. Tamayo R., K. Watanabe, R. Tamaki, T. Hoshii, M. Sugiyama, Y. Okada, K. Miyano, A. Cvetkovic, R. Mohedano, and M. Hernandez, “Plasma etching antireflection nanostructures on optical elements in concentrator photovoltaic systems”, Journal of Photonics for Energy, 5, 057006 (2014); doi:10.1117/1.JPE.5.057006.

Yoshitaka Okada, Tomah Sogabe, and Yasushi Shoji, “Intermediate Band Solar Cells”, in Advanced Concepts in Photovoltaics, edited by A. J Nozik, G. Conibeer, and M. C. Beard (2014, Royal Society of Chemistry, UK)

Shuhei Yagi, Shunsuke Noguchi, Yasuto Hijikata, Shigeyuki Kuboya, Kentaro Onabe, Yoshitaka Okada, and Hiroyuki Yaguchi, “Enhanced optical absorption due to E+-related band transition in GaAs:N δ-doped superlattices”, Applied Physics Express 7, 102301 (2014); http://dx.doi.org/10.7567/APEX.7.102301

Ryo Tamaki, Yasushi Shoji, Yoshitaka Okada, and Kenjiro Miyano, “Spectrally resolved intraband transitions on two-step photon absorption in InGaAs/GaAs quantum dot solar cell”, Applied Physics Letters 105, 073118 (2014); http://dx.doi.org/10.1063/1.4893879

Tomah Sogabe, Yasushi Shoji, Peter Mulder, John Schermer, Efrain Tamayo, and Yoshitaka Okada, “Enhancement of current collection in epitaxial lift-off InAs/GaAs quantum dot thin film solar cell and concentrated photovoltaic study”, Applied Physics Letters 105, 113904 (2014); http://dx.doi.org/10.1063/1.4896114

P. G. Linares, E. López, I. Ramiro, A. Datas, E. Antolín, Y. Shoji, T. Sogabe, Y. Okada, A. Martí, and A. Luque, “Voltage limitation analysis in strain-balanced InAs/GaAsN quantum dot solar cells applied to the intermediate band concept”, Solar Energy Materials & Solar Cells 132, 178 (2015); http://dx.doi.org/10.1016/j.solmat.2014.08.041

Tomah Sogabe, Yasushi Shoji, Mitsuyoshi Ohba, Katsuhisa Yoshida, Ryo Tamaki, Hwen-Fen Hong, Chih-Hung Wu, Cherng-Tsong Kuo, Stanko Tomić, and Yoshitaka Okada, "Intermediate-band dynamics of quantum dots solar cell in concentrator photovoltaic modules", Scientific Reports (Nature Publishing Group), 4, 2014/4/25.
doi:10.1038/srep04792
(OPEN ACCESS)  

Akio Ogura, Tomah Sogabe, Mitsuyoshi Ohba, and Yoshitaka Okada, "Extraction of electrical parameters in multi-junction solar cells from voltage dependent spectral response without light bias", Japanese Journal of Applied Physics 53, 066601 (2014); doi:10.7567/JJAP.53.066601

Tomah Sogabe, Akio Ogura, Yoshitaka Okada, "Analysis of bias voltage dependent spectral response in Ga0.51In0.49P/Ga0.99In0.01As/Ge triple junction solar cell",  Journal of Applied Physics 115, 7, 074503 (2014)

Stanko Tomić, Tomah Sogabe, and Yoshitaka Okada, "In-plane coupling effect on absorption coefficients of InAs/GaAs quantum dots arrays for intermediate band solar cell", Progress in Photovoltaics: Research and Applications; doi 10.1002/pip.2455

Tomah Sogabe, Toshiyuki Kaizu, Yoshitaka Okada, and Stanko Tomić, "Theoretical analysis of GaAs/AlGaAs quantum dots in quantum wire array for intermediate band solar cell", Journal of Renewable Sustainable Energy, 6, 011206 (2014); doi: 10.1063/1.4828359


-2013-

Tomah Sogabe, Akio Ogura, Chao-Yu Hung, Valery Evstropov, Mikhali Mintairov, Maxim Shvarts, and Yoshitaka Okada, "Experimental characterization and self-consistent modeling of luminescence coupling effect in III-V multijunction solar cells", Applied Physics Letters 103, 263907 (2013) http://dx.doi.org/10.1063/1.4858970

Tomah Sogabe, Akio Ogura, Mitsuyoshi Ohba, and Yoshitaka Okada, "Self-consistent electrical parameter extraction from bias dependent spectral response measurements of III-V multi-junction solar cells", Progress in Photovoltaics: Research and Applications; doi: 10.1002/pip.2392

Naoya Miyashita, Nazmul Ahsan, Muhammad Monirul Islam, and Yoshitaka Okada, "Composition control of quinary GaInNAsSb alloy grown by molecular beam epitaxy", Physica Status Solidi C, 10, 1369 (2013); DOI 10.1002/pssc.201300283

F. K. Tutu, J. Wu, P. Lam, M. Tang, N. Miyashita, Y. Okada, J. Wilson, R. Allison, and H. Liu, "Antimony mediated growth of high-density InAs quantum dots for photovoltaic cells", Applied Physics Letters, 103, 043901 (2013); http://dx.doi.org/10.1063/1.4816503

Yoshitaka Okada, Katsuhisa Yoshida, Yasushi Shoji, Tomah Sogabe, "Recent progress on quantum dot intermediate band solar cells", IEICE Electronics Express, 10, 1 (2013); DOI: 10.1587/elex.10.20132007

Yukiko Kamikawa-Shimizu, Robert Patterson, Alexander Milekhin, Kouichi Akahane, Yasushi Shoji, Dietrich R.T. Zahn, Yoshitaka Okada, and Gavin Conibeer, “Study of phonons in self-assembled InAs quantum dots embedded in an InGaAlAs matrix”, Physica E 57, 1 (2014. doi: 10.1016/j.physe.2013.10.023

N. Ahsan, N. Miyashita, M. M. Islam, K. M. Yu, W. Walukiewicz, and Y. Okada, "Effect of Sb on GaNAs Intermediate Band Solar Cells", IEEE Journal of Photovoltaics, 3, 730 (2013): DOI 10.1109/JPHOTOV.2012.2228296

F. K. Tutu, P. Lam, J. Wu, N. Miyashita, Y. Okada, K-H. Lee, N. J. Ekins-Daukes, J. Wilson, and H. Liu, "InAs/GaAs quantum dot solar cell with an AlAs cap layer",
Applied Physics Letters, 102, 163907 (2013): DOI: 10.1063/1.4803459

Muhammad Monirul Islam, Naoya Miyashita, Nazmul Ahsan, and Yoshitaka Okada, "Defect study of molecular beam epitaxy grown undoped GaInNAsSb thin film using junction-capacitance spectroscopy", Applied Physics Letters 102, 074104 (2013); http://dx.doi.org/10.1063/1.4793430

Yoshitaka Okada, Katsuhisa Yoshida and Yasushi Shoji, "Quantum Dot Solar Cells", Advanced Solar Cell Materials, Technology, Modeling and Simulation, edited by Laurentiu Fara and Masafumi Yamaguchi (2013 IGI Global, USA)

Muhammad Monirul Islam, Naoya Miyashita, Nazmul Ahsan, Takeaki Sakurai, Katsuhiro Akimoto, and Yoshitaka Okada, "Photocapacitance study of MBE grown GaInNAsSb thin film solar cells", Journal of Crystal Growth, in press.
http://dx.doi.org/10.1016/j.jcrysgro.2012.12.150

Yasushi Shoji, Katsuhiro Akimoto, and Yoshitaka Okada, "(INVITED PAPER) Self-organized InGaAs/GaAs quantum dot arrays for use in high-efficiency intermediate-band solar cells", Journal of Physics D: Applied Physics 46, 024002 (2013); doi:10.1088/0022-3727/46/2/024002

Naoya Miyashita, Nazmul Ahsan, and Yoshitaka Okada, "Effect of antimony on uniform incorporation of nitrogen atoms in GaInNAs films for solar cell application", Solar Energy Materials and Solar Cells, 111, 127–132 (2013); http://dx.doi.org/10.1016/j.solmat.2012.12.036

-2012-

Yoshitaka Okada, Katsuhisa Yoshida, Yasushi Shoji, Akio Ogura, Pablo Garcia-Linares, Antonio Marti, and Antonio Luque, "The effect of concentration on the performance of quantum dot intermediate-band solar cells", AIP Conference Proceedings 1477, pp. 10-13 (2012); doi:http://dx.doi.org/10.1063/1.4753822

岡田 至崇,「量子ドット太陽電池の現状と将来展望」,Journal of Vacuum Society of Japan, 55, 556 (2012)

Daisuke Sato, Junya Ota, Kazutaka Nishikawa, Yasuhiko Takeda, Naoya Miyashita, and Yoshitaka Okada, "Extremely long carrier lifetime at intermediate states in wall-inserted type II quantum dot absorbers", Journal of Applied Physics, 112, 094305 (2012); http://dx.doi.org/10.1063/1.4764030

Muhammad Monirul Islam, Naoya Miyashita, Nazmul Ahsan, Takeaki Sakurai, Katsuhiro Akimoto, and Yoshitaka Okada, "Identification of defect types in moderately Si-doped GaInNAsSb layer in p- GaAs/n- GaInNAsSb/n-GaAs solar cell structure using admittance spectroscopy", Journal of Applied Physics 112, 114910 (2012); http://dx.doi.org/10.1063/1.4768716

Naoya Miyashita, Nazmul Ahsan, Makoto Inagaki, Muhammad Monirul Islam, Masafumi Yamaguchi, and Yoshitaka Okada, "High electron mobility in Ga(In)NAs films grown by molecular beam epitaxy", Applied Physics Letters 101, 222112 (2012); http://dx.doi.org/10.1063/1.4768949

Katsuhisa Yoshida, Yoshitaka Okada and Nobuyuki Sano, "Device simulation of intermediate band solar cells: Effects of doping and concentration", Journal of Applied Physics 112, 0814510 (2012); http://link.aip.org/link/japiau/v112/i8/p084510/s1

Yasushi Shoji, Katsuhiro Akimoto, and Yoshitaka Okada, “Optical properties of multi-stacked InGaAs/GaNAs quantum dot solar cell fabricated on GaAs (311)B substrate”, Journal of Applied Physics 112, 064314 (2012); http://dx.doi.org/10.1063/1.4752733

Toshiyuki Kaizu, Yosuke Tamura, Makoto Igarashi, Weiguo Hu, Rikako Tsukamoto, Ichiro Yamashita, Seiji Samukawa, and Yoshitaka Okada, “Photoluminescence from GaAs nanodisks fabricated by using combination of neutral beam etching and atomic hydrogen-assisted molecular beam epitaxy regrowth”, Applied Physics Letters 101, 113108 (2012); http://dx.doi.org/10.1063/1.4752233

Nazmul Ahsan, Naoya Miyashita, Muhammad Monirul Islam, Kin Man Yu, Wladek Walukiewicz, and Yoshitaka Okada, “Two-photon excitation in an intermediate band solar cell structure”, Applied Physics Letters 100 (2012) 172111; http://dx.doi.org/10.1063/1.4709405

Yoshitaka Okada, “High-efficiency Quantum Nanostructure Solar Cells: Present and Future Opportunities (Special article)”, Journal of the Japan Institute of Energy 91 (2012) 382

Yasushi Shoji, Kohei Narahara, Hideharu Tanaka, Takashi Kita, Katsuhiro Akimoto, and Yoshitaka Okada, “Effect of spacer layer thickness on multi-stacked InGaAs quantum dots grown on GaAs (311)B substrate for application to intermediate band solar cells” Journal of Applied Physics, 111, 074305 (2012)

Kazutaka Nishikawa, Yasuhiko Takeda, Tomoyoshi Motohiro, Daisuke Sato, Junya Ota, Naoya Miyashita, and Yoshitaka Okada, “Extremely long carrier lifetime over 200 ns in GaAs wall-inserted type II InAs quantum dots” Applied Physics Letters, 100, 113105 (2012)

Kazutaka Nishikawa, Yasuhiko Takeda, Ken-ichi Yamanaka, Tomoyoshi Motohiro, Daisuke Sato, Junya Ota, Naoya Miyashita, and Yoshitaka Okada, “Over 100 ns intrinsic radiative recombination lifetime in type-II InAs/GaAs1−xSbx quantum dots” Journal of Applied Physics, 111, 044325 (2012)

Mohd Fairuz Budiman, Weiguo Hu, Makoto Igarashi, Rikako Tsukamoto, Taiga Isoda, Kohei M Itoh, Ichiro Yamashita, Akihiro Murayama, Yoshitaka Okada and Seiji Samukawa, “Control of optical bandgap energy and optical absorption coefficient by geometric parameters in sub-10 nm silicon-nanodisc array structure” Nanotechnology, 23, 065302 (2012)

Kouichi Akahane, Naokatsu Yamamoto, Tetsuya Kawanishi, Sergio Bietti, Ayami Takata, and Yoshitaka Okada, “Stacking-layer-number dependence of highly stacked InAs quantum dot laser diodes fabricated using strain-compensation technique” Proceedings of SPIE, 8277, 827703 (2012)

-2011-

C-H. Huang, X-Y. Wang, M. Igarashi, A. Murayama, Y. Okada, I. Yamashita, and S. Samukawa "Optical absorption characteristic of highly ordered and dense two-dimensional array of silicon nanodisks" Nanotechnology, 22 (2011) 105301

Ayami Takata, Ryuji Oshima, Yasushi Shoji, Kouichi Akahane, and Yoshitaka Okada “Evaluation of multi-stacked InAs/GaNAs self-assembled quantum dots on GaAs (001) grown using different As species” Journal of Crystal Growth 324 (2011) 158

Ayami Takata, Kouichi Akahane, Naoki Yamamoto, and Yoshitaka Okada
“Optical gain of multi-stacked InAs quantum dots grown on InP (311)B substrate by strain-compensation technique” physica status solidi (c) 8 (2011) 254

Ryuji Oshima, Yoshitaka Okada, Ayami Takata, Shuhei Yagi, Kouichi Akahane, Ryo Tamaki, and Kenjiro Miyano “High-density quantum dot superlattice for application to high-efficiency solar cells” physica status solidi (c) 8 (2011) 619

Takayuki Morioka and Yoshitaka Okada “Dark current characteristics of InAs/GaNAs strain-compensated quantum dot solar cells” Physica E 44 (2011) 390

R. Oshima, J. Y. Huang, N. Miyashita, K. Matsubara, Y. Okada, and F. A. Ponce “Transmission electron microscopy study of GaInNAs(Sb) thin films grown by atomic hydrogen-assisted molecular beam epitaxy” Applied Physics Letters 99 (2011) 191907

Yoshitaka Okada, Takayuki Morioka,  Katsuhisa Yoshida, Ryuji Oshima, Yasushi Shoji, Tomoya Inoue, and Takashi Kita
“Increase in photocurrent by optical transitions via intermediate quantum states in direct-doped InAs/GaNAs strain-compensated quantum dot solar cell” Journal of Applied Physics 109 (2011) 024301
 

-2010-

Katsuhisa Yoshida, Yoshitaka Okada, and Nobuyuki Sano
“Self-consistent simulation of intermediate band solar cells: Effect of occupation rates on device characteristics” Applied Physics Letters. 97 (2010) 133503

Ayami Takata, Ryuji Oshima, Yasushi Shoji, Kouichi Akahane, and Yoshitaka Okada
“Growth of multi-stacked InAs/GaNAs quantum dots grown with As2 source in atomic hydrogen-assisted molecular beam epitaxy” Physica E, 42 (2010) 2745 

Ryuji Oshima, Ayami Takata, Yasushi Shoji, Kouichi Akahane, and Yoshitaka Okada
“InAs/GaNAs starain-compensated quantum dots stacked up to 50 layers for use in high-efficiency solar cell” Physica E, 42 (2010) 2757 

Yasushi Shoji, Ryuji Oshima, and Ayami Takata, and Yoshitaka Okada
“The effect of spacer layer thickness on vertical alignment of InGaAs/GaNAs quantum dots grown on GaAs(311)B substrate” Physica E, 42 (2010) 2768  

Yasushi Shoji, Ryuji Oshima, Ayami Takata, and Yoshitaka Okada
“Structural properties of multi-stacked self-organized InGaAs quantum dots grown on GaAs (3 1 1)B substrate” Journal of Crystal Growth, 312 (2010) 226

-2009-

Yoshitaka Okada, Ryuji Oshima,  and Ayami Takata
“Characteristics of InAs/GaNAs strain-compensated quantum dot solar cell” Journal of Applied Physics 106 (2009) 024306

Naoya Miyashita, Shuhei Ichikawa, Yoshitaka Okada
“Improvement of GaInNAsSb films fabricated by atomic hydrogen-assisted molecular beam epitaxy” Journal of Crystal Growth, 311 (2009) 3249

Ayami Takata, Ryuji Oshima, Yasushi Shoji, and Yoshitaka Okada 
“Optical studies on InAs/InGaAs/GaNAs strain-compensated quantum dots grown on GaAs (001) by molecular beam epitaxy” Journal of Crystal Growth, 311 (2009) 1774

Ryuji Oshima, Yasushi Shoji, Ayami Takata, and Yoshitaka Okada 
“Growth of InGaAs/GaNAs strain-compensated quantum dot superlattice on GaAs (311)B by molecular beam epitaxy” Journal of Crystal Growth, 311 (2009) 1770

Ryuji Oshima, Ayami Takata, Yasushi Shoji and Yoshitaka Okada 
“The effect of pacer layer thickness on the properties of quantum dot solar cells” Proceedings of 18th International Photovoltaic Science and Engineering Conference, 6-3o-016, Kolkata, India (2009)

Yasushi Shoji, Ryuji Oshima, Ayami Takatai, and Yoshitaka Okada 
“Fabrication of InGaAs/GaNAs strain-compensated quantum dot solar cell on GaAs (311)B substrate” Proceedings of 18th International Photovoltaic Science and Engineering Conference, 6-3p-023, Kolkata, India (2009)

Naoya Miyashita, Shuhei Ichikawa, and Yoshitaka Okada
“Characteristics of GaInNAsSb Solar Cells Grown by Atomic Hydrogen-Assisted Molecular Beam Epitaxy” Proceedings of 18th International Photovoltaic Science and Engineering Conference, 5-1o-014, Kolkata, India (2009)


TOPへ

-2008-

Ryuji Oshima, Ayami Takata, and Yoshitaka Okada 
“Strain-compensated InAs/GaNAs quantum dots for use in high-efficiency solar cells”Applied Physics Letters 93 (2008) 083111 

Ayami Takata, Ryuji Oshima, Hidemi Shigekawa, and Yoshitaka Okada 
“Growth of GaNAs films with As2 source in atomic hydrogen-assisted molcular beam epitaxy” Journal of Crystal Growth, 310 (2008) 2234

Ryuji Oshima, Yuta Nakamura, Ayami Takata, and Yoshitaka Okada
“Optical properties of multi-stacked InAs/GaNAs strain-compensated quantum dots” Journal of Crystal Growth, 310 (2008) 3710

TOP へ

-2007-

Naoya Miyashita, Yukiko Shimizu, and Yoshitaka Okada
“Carrier mobility characteristics in GaInNAs dilute nitride films grown by atomic hydrogen-assisted molecular beam epitaxy”, Journal of Applied Physics, 102, 044904 (2007)

Yukiko Shimizu, Naoya Miyashita, Yusuke Mura, Akira Uedono, and Yoshitaka Okada
“Effect of growth temperature on the properties of Ga(In)NAs thin films by atomic hydrogen-assisted RF-MBE”, Journal of Crystal Growth, 301-302, 579 (2007)

Ryuji Oshima, Ayami Takata, and Yoshitaka Okada 
“Increased photoabsorption in strain-compensated quantum dot solar cells” Proceedings of 17th International Photovoltaic Science and Engineering Conference, 925 (2007)

Ryuji Oshima, Yuta Nakamura, Ayami Takata, and Yoshitaka Okada
“Multi-stacked InAs/GaNAs strain-compensated quantum dot solar cells” 
Proceedings of 22nd European Photovoltaic Solar Energy Conference, 60 (2007)

Ryuji Oshima, Kouichi Akahane, Masahiro Tsuchiya, Hidemi Shigekawa, and Yoshitaka Okada 
“Optical properties of stacked InAs self-organized quantum dots on InP(311)B” The 37th International Symposium on Compound Semiconductors, Kagawa (2010)

Ryuji Oshima, Takayuki Hashimoto, Hidemi Shigekawa, and Yoshitaka Okada 
“InAs self-assembled quantum dots superlattice structure fabricated by strain compensation technique” AIP conference proceedings, 893 (2007) 811

TOP へ

Conference

-2015-

Ryo Tamaki, Yasushi Shoji, Shunya Naitoh, Yoshitaka Okada, and Kenjiro Miyano, “Extreme broadband photocurrent spectroscopy on InAs quantum dot solar cells”, SPIE Photonics West, San Francisco (February 2015).

-2014-

Yoshitaka Okada (INVITED), “Intermediate Band Materials for High Efficiency Solar Cells”, The 41st International Conference on Metallurgical Coatings and Thin Films (ICMCTF), San Diego (April, 2014).

Yoshitaka Okada (INVITED), “Self-organized QDs for intermediate-band solar cells”, 2014 Workshop on High-efficiency material for photovoltaics (HEMP), Imperial College London (July, 2014).

Yoshitaka Okada (INVITED), “Recent Progress on Quantum Dot Intermediate Band Solar Cells”, The 27th International Microprocesses and Nanotechnology Conference (MNC), Fukuoka (Nov. 2014).

Yoshitaka Okada (INVITED), “Quantum Dot Superlattice for High-efficiency Intermediate Band Solar Cells”, OSA Congress on Optical Nanostructures and Advanced Materials for Photovoltaics (PV), Canberra (Dec. 2014).

Jean-François Guillemoles, Laurent Lombez, Amaury Delamarre, Gilbert El-Hajje,Pierre Rale, Kentaroh Watanabe, Masakazu Sugiyama, Yoshitaka Okada, Ryo Tamaki, and Yasushi Shoji, “Imaging quasi fermi level splitting in intermediate-band solar cells”, SPIE Photonics West, San Francisco (February 2014).

N. Miyashita, N. Ahsan, and Y. Okada, “Improved Carrier Collection in Thick GaInNAsSb Solar Cells”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

N. Miyashita, N. Ahsan, and Y. Okada, “Evaluation of Concentrator Photovoltaic Properties of GaInNAsSb Solar Cells”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

Y. Shoji, R. Tamaki, A. Datas, A. Marti, A. Luque, and Y. Okada, “Effect of Field Damping Layer on Two Step Absorption of Quantum Dots Solar Cells”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).  Best Poster Award受賞!

R. Tamaki, Y. Shoji, Y. Okada, and K. Miyano, “Photofilling Effect on Optical Transitions in InGaAs/GaAs Quantum Dot Solar Cells”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

T. Sogabe, Y. Shoji, C-Y. Hung, D. J. Farrell, and Y. Okada, “InAs/GaAs Quantum Dot Solar Cell with 26.8% Efficiency Achieved Through Current Constraint Engineering”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

A. Ogura, T. Sogabe, and Y. Okada, “Evaluation of Conversion Efficiency for Multijunction Solar Cell with Luminescent Coupling Considering Series and Shunt Resistance Effects”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

C-Y. Hung, T. Sogabe, N. Miyashita, S. Naitoh, and Y. Okada, “Fabrication of Hybrid ErAs:InAs Quantum Dots for Solar Cell Application”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

S. Tomic´, T. Sogabe, and Y. Okada, “Theory of Quantum Coupling and Efficiency in QD Array Based Intermediate Band Solar Cells”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

K. Yoshida, Y. Okada, and N. Sano, “Effect of Sequential Tunneling in Quantum Dot Intermediate Band Solar Cells”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

B. Behaghel, P. Rale, Y. Shoji, R. Tamaki, N.Vandamme, L. Lombez, C. Dupuis, A. Cattoni, K. Watanabe, H. Sodabanlu, M. Sugiyama, Y. Okada, S. Collin, and J-F. Guillemoles, “Strong Absorption Exaltation in Ultrathin QDs and MQWs for Tandem and Intermediate Band Solar Cells”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

T. Thomas, M. Führer, D. Alonso Alvarez, N. J. Ekins-Daukes, D. Lackner, P. Kailuweit, S. P. Philipps, A. W. Bett, M. Sugiyama, and Y. Okada, “Potential for Reaching 50% Power Conversion Efficiency Using Quantum Heterostructures”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).  Best Paper Award受賞!

D. Lackner, S. P. Philipps, F. Dimroth, H. Sodabanlu, K. Watanabe, N. Miyashita, M. Sugiyama, Y. Okada, and A. W. Bett, “Monolithically Integrated Multi-Junction Cells built
by Multiple Separate Growths in Different Epitaxy Reactors”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

E. E. Tamayo R., K. Watanabe, T. Hoshii, R. Tamaki, M. Sugiyama, Y. Shoji, Y. Okada, and K. Miyano, “Maskless Broadband Antireflection Technology on Glass for Flat and Concentrator PV”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

T. Kada, S. Asahi, T. Kaizu, T. Kita, R. Tamaki, Y. Okada, and K. Miyano, “Efficient Two-step Photon Absorption in InAs/GaAs Quantum Dot Solar Cells”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

T. Suzuki, K. Osada, S. Yagi, S. Naito, Y. Hijikata, Y. Okada, and H. Yaguchi, “Molecular Beam Epitaxy Growth of Intermediate Band Materials Based on GaAs:N δ-Doped
Superlattices”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).  Young Researcher Award受賞!

K. Osada, T, Suzuki, S. Yagi, S. Naito, Y. Shoji, Y. Okada, Y. Hijikata, and H. Yaguchi, “Control of Intermediate Band Configuration in GaAs:N δ-doped Superlattice”, The 6th World Conference on Photovoltaic Energy Conversion (WCPEC-6), Kyoto (Nov. 2014).

N. Ahsan, N. Miyashita, K. M. Yu, W. Walukiewicz, and Y. Okada, “Improving the Multiband Character of GaAs-based Dilute Nitrides”, 18th International Conference on Molecular Beam Epitaxy, Flagstaff, Arizona (September, 2014)

Daniel J Farrell, Hassanet Sodabanlu, Yunpeng Wang, Masakazu Sugiyama, and Yoshitaka Okada, “Can a hot-carrier solar cell also be an efficient up-converter?”, The 40th IEEE Photovoltaic Specialists Conference, Denver (June 2014).

Yasushi Shoji and Yoshitaka Okada, “Effect of External Bias on Multi-stacked InAs/AlGaAs Quantum Dots Solar Cell”, The 40th IEEE Photovoltaic Specialists Conference, Denver (June 2014).

Tomah Sogabe, Yasushi Shoji, Peter Mulder, John Schermer, Efrain Tamayo, and Yoshitaka Okada, “Enhancement of current collection in epitaxial lift-off InAs/GaAs quantum dot thin film solar cell and concentrated photovoltaic study”, The 40th IEEE Photovoltaic Specialists Conference, Denver (June 2014).

Akio Ogura, Tomah Sogabe, Daniel J Farrell, and Yoshitaka Okada, “Analysis of GaAs/AlGaAs quantum nanodisk solar cell with intermediate band carrier transportation”, The 40th IEEE Photovoltaic Specialists Conference, Denver (June 2014).

Ryo Tamaki, Yasushi Shoji, Yoshitaka Okada, and Kenjiro Miyano, “Spectrally resolved interband and intraband transitions by two-step photon absorption in InGaAs/GaAs quantum dot solar cells”, The 40th IEEE Photovoltaic Specialists Conference, Denver (June 2014).

Benoît Behaghel, Ryo Tamaki, Nicolas Vandamme, Kentaroh Watanabe, Christophe Dupuis, Nathalie Bardou, Hassanet Sodabanlu, Andrea Cattoni, Yoshitaka Okada, Masakazu Sugiyama, Stéphane Collin, and Jean-François Guillemoles, “Four-fold MQWs Absorption Enhancement in a 430 nm Thick InGaAs/GaAsP MQWs Solar Cell”, The 40th IEEE Photovoltaic Specialists Conference, Denver (June 2014).

Chao-Yu Hung, Tomah Sogabe, Naoya Miyashita, Yasushi Shoji, Shunya Naito, and Yoshitaka Okada, “Local conductivity characteristics of individual ErAs nanoparticle for solar cell tunnel junction application”, The 40th IEEE Photovoltaic Specialists Conference, Denver (June 2014).

Naoya Miyashita, Nazmul Ahsan, and Yoshitaka Okada, “Concentrating Photovoltaic Properties of GaInNAsSb/Ge Dual Junction Tandem Solar Cell”, The 40th IEEE Photovoltaic Specialists Conference, Denver (June 2014).

Nazmul Ahsan, Naoya Miyashita, Kin Man Yu, Wladek Walukiewicz, and Yoshitaka Okada, “Electron barrier engineering in a thin-film intermediate band solar cell”, The 40th IEEE Photovoltaic Specialists Conference, Denver (June 2014).

T. Sogabe, V. Evstropov, C. Hung, M. Mintairov, A. Ogura, Y. Okada, and M. Shvarts, "Self-consistent Modeling and Bias Dependent Spectral Response Measurement of Luminescence Coupling Effect in Concentrator III-V Multijunction Solar Cells", 10th International Conference on Concentrator Photovoltaic Systems (CPV-10),, Albuquerque (April 2014), Tue-D-13.

A. Ogura, C. Hung, M. Ohba, T. Sogabe, and Y. Okada, "Characterization of Triple-Junction Tandem Solar Cells with Voltage Dependent Spectral Response (SR-V) without Light Bias", 10th International Conference on Concentrator Photovoltaic Systems (CPV-10),, Albuquerque (April 2014), Wed-D-18.

-2013-

Yoshitaka Okada (INVITED), "Quantum dot superlattice for high-efficiency intermediate band solar cells", The 2013 International Symposium on Advanced Nanodevices and Nanotechnology (ISANN 2013), Poipu Beach (Dec. 2013).

Yoshitaka Okada, Yasushi Shoji, Ryo Tamaki, and Tomah Sogabe, "Operation Characteristics of InAs Quantum Dot Intermediate-Band Solar Cells", MRS Fall Meeting, Boston (Nov. 2013).

Yoshitaka Okada (INVITED), "Recent Progress and Future Prospect of Quantum Dot Intermediate-Band Solar Cells", The 23rd Photovoltaic Science and Engineering Conference (PVSEC-23), Taipei (October 2013).

Tomah Sogabe, "Self-consistent Approach for Modeling the Luminescent Coupling in Concentrator III-V Multijunction Solar Cells", The 23rd Photovoltaic Science and Engineering Conference (PVSEC-23), Taipei (October 2013).

Akio Ogura, Tomah Sogabe, Y. Saito, A. Kotagiri, and Y. Okada, "Electrical Parameters Extraction from Voltage Dependent Spectral Response in Multi-junction Solar Cells without Bias Light", The 23rd Photovoltaic Science and Engineering Conference (PVSEC-23), Taipei (Oct. 2013).

Shuhei Yagi, Shunsuke Noguchi, Yasuto Hijikata, Hiroyuki Yaguchi, Shigeyuki Kuboya, Kentaro Onabe, and Yoshitaka Okada, "Fabrication and Characterization of Intermediate Band Solar Cells Using GaAs:N Delta-Doped Superlattice", The 23rd Photovoltaic Science and Engineering Conference (PVSEC-23), Taipei (October 2013).

Yoshitaka Okada, Katsuhisa Yoshida, Yasushi Shoji and Tomah Sogabe (INVITED), "Operation Characteristics of Quantum Dot Intermediate-Band Solar Cells", 2013 JSAP-MRS Joint Symposia, Kyoto (Sept. 2013).

E. E. Tamayo Ruiz, R. Tamaki, K. Watanabe, M. Sugiyama, Y. Shoji, D. J.
Farrell, Y. Okada, and K. Miyano, "Antireflection Structures on Fresnel Lenses Fabricated by Induced Coupled Plasma Etching for Improving CPV Systems",  The 28th European Photovoltaic Solar Energy Conference and Exhibition (EU-PVSEC), Paris (Sept. 2013).

Yoshitaka Okada, Katsuhisa Yoshida, YasushiShoji and Tomah Sogabe, "Operation Characteristics of Quantum Dot Intermediate-Band Solar Cells under Sunlight Concentration", The 55th Electronic Materials Conference (EMC), Univ. Notre Dame (June 2013).

Yasushi Shoji and Yoshitaka Okada, "InGaAs Quantum Dot Solar Cells With High Energy Gap Matrix Layers", The 39th IEEE Photovoltaic Specialists Conference, Tampa (June 2013).

Stanko Tomic, Tomah Sogabe, and Yoshitaka Okada, "In-Plane Coupling Effect In Inas/Gaas Quantum Dots Arrays For Intermediate Band Solar Cell", The 39th IEEE Photovoltaic Specialists Conference (PVSC), Tampa (June 2013).

Efrain E. Tamayo R., Kentaroh Watanabe, Masakazu Sugiyama, Yasushi Shoji, Yoshitaka Okada, and Kenjiro Miyano, "Fabrication of broadband antireflection structures on glass substrates by Reactive Ion Etching for application on homogenizers in CPV systems", The 39th IEEE Photovoltaic Specialists Conference (PVSC) , Tampa (June 2013). ポスター賞受賞!

Naoya Miyashita, Muhammad Monirul Islam, Nazmul Ahsan, and Yoshitaka Okada, "Device Structure Engineering of GaInNAsSb/GaAs Hetero-junction Solar Cells", The 39th IEEE Photovoltaic Specialists Conference (PVSC), Tampa (June 2013).

Shuhei Yagi, Shunsuke Noguchi, Yasuto Hijikata, Shigeyuki Kuboya, Kentaro Onabe, Yoshitaka Okada, and Hiroyuki Yaguchi, "Optical Absorption by E + Miniband of GaAs:N Delta-Doped Superlattices",  The 39th IEEE Photovoltaic Specialists Conference (PVSC), Tampa (June 2013).


N. Miyashita, Y. Okada, and K. Watanabe, "Photovoltaic Characteristics of GaInNAsSb Solar Cells under Concentrated Light Source", 9th Conference on Concentrator Photovoltaics (CPV-9), Miyazaki (April, 2013)

S. Naito and  Y. Okada, "Power Generation of Series and Series/Parallel Triple Tandem Solar Cells Derived from Measured Spectra in Japan", 9th Conference on Concentrator Photovoltaics (CPV-9), Miyazaki (April, 2013)

A. Ogura, T. Sogabe,  M. Ohba, and Y. Okada, "Self-consistent Fitting of Electrical Parameters for InGaAs/Ge Dual Junction Solar Cells from Bias-dependent Spectral Response", 9th Conference on Concentrator Photovoltaics (CPV-9), Miyazaki (April, 2013)

T. Sogabe, Y. Shoji1, M. Ohba , H-F. Hong, C-H. Wu, C-T. Kuo, and Y. Okada, "First Demonstration of InAs/GaAs Quantum Dot CPV Module", 9th Conference on Concentrator Photovoltaics (CPV-9), Miyazaki (April, 2013)

F. K. Tutu, P. Lam, J. Wu, N. Miyashita, Y. Okada, K-H. Lee, N. J. Ekins-Daukes,J. Wilson, and H. Liu, "Influence of a thin AlAs cap layer on the performance of InAs/GaAs quantum dot solar cells", Semiconductor and Integrated OptoElectronics Conference, Cardiff (April, 2013)

-2012-

N. Ahsan, "Photoluminescence in GaNAs(Sb) thin films and carrier localization",
2012 Collaborative Conference on Crystal Growth (3CG), Orlando (December, 2012)

Naoya Miyashita (Invited), "Fabrication of nip and pin structure GaInNAsSb solar cells", 2012 Collaborative Conference on Crystal Growth (3CG), Orlando (December, 2012)

Stanko Tomic, Tomah Sogabe, and Yoshitaka Okada, "Modelling of Vertical and In-plane Quantum Dots Arrays for High Efficiency Solar Cells", 2012 MRS Fall Meeting, Boston (Nov. 2012), E8.04.

Kazutaka Nishikawa, Yasuhiko Takeda, Ken-ichi Yamanaka, Tomoyoshi Motohiro, Daisuke Sato, Junya Ota, Naoya Miyashita, and Yoshitaka Okada, "Long Carrier Lifetime at Intermediate States over 200ns Using InAs/GaAsSb Type II Quantum Dots", 2012 MRS Fall Meeting, Boston (Nov. 2012), E10.03.

(Invited) Katsuhisa Yoshida and Yoshitaka Okada, "Device simulation of intermediate band solar cells", 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD'12), Shanghai (Aug. 2012).

Nazmul Ahsan, Naoya Miyashita, Muhammad Monirul Islam and Yoshitaka Okada, “Effect of Sb on the optical properties of MBE-grown GaNAs films”, The 17th International Conference on Molecular Beam Epitaxy, Nara (Sept. 2012).

Toshiyuki Kaizu, Yosuke Tamura, Makoto Igarashi, Weiguo Hu, Seiji Samukawa and Yoshitaka Okada, “Observation of photoluminescence from 2-dimentional GaAs nanodisk array regrown by atomic hydrogen-assisted molecular beam epitaxy”, The 17th International Conference on Molecular Beam Epitaxy, Nara (Sept. 2012).

Naoya Miyashita, Nazmul Ahsan, Makoto Inagaki, Muhammad Monirul Islam, Masafumi Yamaguchi and Yoshitaka Okada, “High electron mobility in Ga(In)NAs films grown by MBE”, The 17th International Conference on Molecular Beam Epitaxy, Nara (Sept. 2012).

Muhammad Monirul Islam, Naoya Miyashita, Nazmul Ahsan, Takeaki Sakurai, Katsuhiro Akimoto and Yoshitaka Okada, “Photocapacitance study of MBE grown GaInNAsSb thin film solar cell”, The 17th International Conference on Molecular Beam Epitaxy, Nara (Sept. 2012).

Yasushi Shoji, Katsuhiro Akimoto and Yoshitaka Okada, “InAs quantum dots grown on GaAsSb layer on different substrate orientation”, The 17th International Conference on Molecular Beam Epitaxy, Nara (Sept. 2012).

Yoshitaka Okada (Invited), "InAs Quantum Dots-Based Intermediate Band Solar Cells", 2nd Workshop on High-efficiency material for photovoltaics, Imperial College London (2012).

Y. Okada (Invited), "High-Efficiency Quantum Dot Intermediate-Band Solar Cells", IUMRS International Conference on Electronic Materials (IUMRS-ICEM2012) , Yokohama (Sept. 2012).

Y. Okada (Invited), "Intermediate-band photovoltaics based on quantum dot superlattice", 2012 International Conference on Superlattices, Nanostructures, and Nanodevices, Dresden (July 2012).

Efrain Eduardo Tamayo Ruiz, Kentaroh Watanabe, Ryosuke Watanabe, Masakazu Sugiyama, Yoshitaka Okada, Kenjiro Miyano, "Efficiency Simulations of Top Surface Light Management Structures for Concentrator Solar Cells Using RCWA and Detailed Balance Theory", The 38th IEEE Photovoltaic Specialists Conference, Austin (June 2012).

M. M. Islam, N. Miyashita, N. Ahsan, and Y. Okada, "Bias-Dependent Admittance Measurement of GaInNAsSb-Based Solar Cell Structure", The 38th IEEE Photovoltaic Specialists Conference, Austin (June 2012).

N. Miyashita, N. Ahsan, M. M. Islam, and Y. Okada, "Study on the Device Structure of GaInNAs(Sb)-Based Solar Cells for Use in 4-Junction Tandem Solar Cells", The 38th IEEE Photovoltaic Specialists Conference, Austin (June 2012).

N. Ahsan, N. Miyashita, M.M. Islam, K.M. Yu, and W. Walukiewicz, and Y. Okada, "Two-Photon Excitation in a Dilute Nitride Intermediate-Band Solar Cell", The 38th IEEE Photovoltaic Specialists Conference, Austin (June 2012).

K. Yoshida, N. Sano, and Y. Okada, "Device Simulation of Intermediate-Band Solar Cells: Dependence on Number of Intermediate-Band Layers", The 38th IEEE Photovoltaic Specialists Conference, Austin (June 2012).

Y. Shoji, K. Akimoto, and Y. Okada, "InGaAs/GaAsSb Type-II Quantum Dots for Intermediate-Band Solar Cell", The 38th IEEE Photovoltaic Specialists Conference, Austin (June 2012)

Y. Okada, P. García-Linares, A. Luque, A. Martí, A. Ogura, Y. Shoji, and K. Yoshida, “Effect of Concentration on the Performance of Quantum Dot Intermediate-Band Solar Cells”, 8th International Conference on Concentrating Photovoltaic Systems, Toledo (April 2012) 


-2011-
Yoshitaka Okada (Invited), “Growth and application of three-dimensional quantum dot superlattice for high-efficiency intermediate band solar cells”, International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures (SemiconNano 2011), Traunkirchen (Sept. 2011)

Yoshitaka Okada (Invited), “High efficiency quantum dot intermediate band solar cells”, 6th International Symposium on Surface Science, Tokyo (Dec. 2011)

Mohammad Monirul Islam, Naoya Miyashita, Nazmul Ahsan, and Yoshitaka Okada “ELECTRICAL CHARACTERIZATION OF GaInNAsSb THIN FILM” The 21th International Photovoltaic Science and Engineering Conference, Fukuoka (2011)

Yasushi Shoji, Kohei Narahara, H. Tanaka, Takashi Kita, Katsuhiro Akimoto, and Yoshitaka Okada “EFFECT OF SPACER LAYER THICKNESS ON MULTI-STACK InGaAs QUANTUM DOTS GROWN ON GaAs (311)B SUBSTRATE FOR USE IN INTERMEDIATE BAND SOLAR CELLS” The 21th International Photovoltaic Science and Engineering Conference, Fukuoka (2011)

Nazmul Ahsan, Naoya Miyashita, Tooru Tanaka, Kin Man Yu, Wladek Walukiewicz, and Yoshitaka Okada "INHOMOGENEITY IN THE PHOTOREFLECTANCE OF GANAS GROWN BY ATOMIC H-ASSISTED MBE" The 21th International Photovoltaic Science and Engineering Conference, Fukuoka (2011)

Yoshitaka Okada “Self-organized heteroepitaxy of InAs quantum dots and application to intermediate band solar cells” Workshop on High-efficiency material for photovoltaics, Imperial College London (2011)

Markus F Führer, Jessica GJ Adams, Keith WJ Barnham, Ben C Browne, Ngai LA Chan, Daniel J Farrell, Louise Hirst, Kan-Hua Lee, Ned J Ekins-Daukes, Akio Ogura, Katsuhisa Yoshida, Yoshitaka Okada "EXTENSIBLE MODELLING FRAMEWORK FOR NANOSTRUCTURED III-V SOLAR CELLS" The 37th IEEE Photovoltaic Specialists Conference, Seattle (2011)

X-Y. Wang, C-H. Huang, R. Tsukamoto, T. Kaizu, M. Igarashi, P-A. Mortemousque, H. Shinohara, Y. Okada, A. Murayama, K. Itoh, Y. Ohno, Y. Ichiro, and S. Samukawa "Damage-free Top-down Processes of Fabricating Two-dimensional Array of Sub-10nm Nanometer GaAs Nanodisks using Bio-template and Neutral Beam Etching for Intermediate Band Solar Cell Applications" The 37th IEEE Photovoltaic Specialists Conference, 759 (Seattle, 2011)

M. Igarashi, C-H. Huang, X-Y. Wang, M. F. Budiman, Y. Tamura, T. Kiba, A. Murayama, T. Kaizu, Y. Okada, and S. Samukawa "Optical Absorption, Photo-Luminescence and Miniband Formation of a Highly Ordered and Dense 2-Dimensional Array of Si Nanodisks for quantum Dot Solar Cells" The 37th IEEE Photovoltaic Specialists Conference, 992 (Seattle, 2011)

Takayuki Morioka, Yasushi Shoji, and Yoshitaka Okada “Current Enhancement in Direct Si-Doped InAs/GaNAs Strain-Compensated Quantum Dot Solar Cells” The 37th IEEE Photovoltaic Specialists Conference, Seattle (2011)

A. Ogura, T. Morioka, P. Garcia-Linares, E. Hernandez, I. Ramiro, I. Artacho, E. Antolin, A. Marti, A. Luque, M. Yamaguchi, and Y. Okada “Modeling of Quantum Dot Solar Cells for Concentrator PV Applications” The 37th IEEE Photovoltaic Specialists Conference, Seattle (2011)

Katsuhisa Yoshida, Yoshitaka Okada, and Nobuyuki Sano “Effects of Absorption Spectra Overlapping on Structure Design of Intermediate Band Solar Cells” The 37th IEEE Photovoltaic Specialists Conference, Seattle (2011)

Naoya Miyashita, Nazmul Ahsan, M. Monirul Islam, Yoshitaka Okada “Evaluation of GalnNAs(Sb) Solar Cells for Use in Next Generation lll-V Tandem Solar Cells” The 37th IEEE Photovoltaic Specialists Conference, Seattle (2011)

Akio Ogura, Takayuki Morioka, and Yoshitaka Okada “Modeling of GaAs p-i-n solar cells on dark and concentration characteristics by using a modified equivalent circuit” 7th International Conference on Concentrating Photovoltaic Systems (CPV-7), Las Vegas (2011)

Naoya Miyashita, Nazmul Ahsan, Kin M. Yu, Wladek Walukiewicz and Yoshitaka Okada
“Antimony Surfactant Mediated Improvement of the Properties of GaInNAsSb Films for Multi-junction Tandem Solar Cells”
Materials research society 2011 spring meeting, Sanfrancisco (2011), B7.3

Nazmul Ahsan, Naoya Miyashita, Tooru Tanaka, Kin M. Yu, Wladek Walukiewicz and Yoshitaka Okada
“Photo-modulated Reflectance of GaNAs Grown by Atomic Hydrogen-assisted MBE”
Materials research society 2011 spring meeting, Sanfrancisco (2011), B7.8

Muhammad M. Islam, Naoya Miyashita, Nazmul Ahsan, Takeaki Sakurai, Katsuhiro Akimoto and Yoshitaka Okada
“Admittance Spectroscopy Study of MBE Grown Undoped-GaInNAsSb Thin Film for Multi-junction Tandem Solar Cell”
Materials research society 2011 spring meeting, Sanfrancisco (2011), B7.20

Yasushi Shoji, Takayuki Morioka, Katsuhiro Akimoto and Yoshitaka Okada
“Multi-stacked InGaAs/GaNAs Self-organized Quantum Dot Arrays for Use in Intermediate Band Solar Cells”
Materials research society 2011 spring meeting, Sanfrancisco (2011), B5.56


-2010-
C-H. Huang, M. Igarashi, M. F. Budiman, R. Oshima, I. Yamashita, Y. Okada, and S. Samukawa "Optical Characteristics of Two-dimensional Array of Si Nano-disks Fabricated by Defect-free Neutral Beam Etching with Bio-template" 2010 International Conference on Solid State Devices and Materials, L-3-5 (Tokyo, 2010)

Yoshitaka Okada (Invited) “Quantum Dot Superlattice for High Efficiency Intermediate Band Solar Cells” 2010 International Conference on Solid State Devices & Materials, Tokyo (2010)

Yoshitaka Okada (Invited) “Quantum Dot Superlattice Intermediate Band Solar Cell; Proving the Concept and Beyond” Workshop on Information, Nano and Photonics Technology 2010 (Kobe)

Katsuhisa Yoshida, Yoshitaka Okada, and Nobuyuki Sano “Numerical analysis of intermediate band (IB) solar cells: effect of absorption coefficients and doping of IB state” Workshop on Information, Nano and Photonics Technology 2010 (Kobe)

Takayuki Morioka, Ryuji Oshima, Yasushi Shoji, Tomoya Inoue, Takashi Kita, and Yoshitaka Okada “Multi-stacked InAs/GaNAs quantum dots with direct Si doping for use in intermediate band solar cell” Workshop on Information, Nano and Photonics Technology 2010 (Kobe)

Ayami Takata, Kouichi Akahane, Naokatsu Yamamoto and Yoshitaka Okada
“Optical gain of multi-stacked InAs quantum dots grown on InP(311)B substrate by strain-compensation technique” The 16th International Conference on Molecular Beam Epitaxy, Berlin (2010)

Ayami Takata, Ryuji Oshima, Yasushi Shoji, Kouichi Akahane, and Yoshitaka Okada
“Evaluation of multi-stacked InAs/GaNAs self-assembled quantum dots on GaAs (001) grown using different As species” The 37th International Symposium on Compound Semiconductors, Kagawa (2010)

Katsuhisa Yoshida, Yoshitaka Okada, Nobuyuki Sano
“Self-Consistent Drift-Diffusion Approach for Analysis Intermediate Band Solar Cells with Multi-Stacked Quantum Dots ” 25th European Photovoltaic Solar Energy Conference and Exhibition  / 5th World Conference on Photovoltaic Energy Conversion, Valencia (2010)

Naoya Miyashita, Haruhiro Oigawa, Yoshitaka Okada
“Effect of Antimony on Electron Trap Density in GaInNAsSb Solar Cell Grown by Atomic Hydrogen-Assisted Molecular Beam Epitaxy ” 25th European Photovoltaic Solar Energy Conference and Exhibition  / 5th World Conference on Photovoltaic Energy Conversion, Valencia (2010)

Katsuhisa Yoshida, Yoshitaka Okada, Nobuyuki Sano
“Self-consistent drift-diffusion analysis of intermediate band solar cell (IBSC) : Effect of energetic position of IB on conversion efficiency” 35th IEEE Photovoltaic Specialists Conference, Hawaii (2010)

Naoya Miyashita, Nazmul Ahsan, Yoshitaka Okada
“Antimony enhanced homogeneous nitrogen incorporation into GaInNAs films grown by atomic hydrogen-assisted molecular beam epitaxy” 35th IEEE Photovoltaic Specialists Conference, Hawaii (2010)

Ayami Takata, Ryuji Oshima, Yasushi Shoji, Koichi Akahane, Yoshitaka Okada
“Fabrication of 100 layer-stacked InAs/GaNAs strain-compensated quantum dots on GaAs(001) for application to intermediate band solar cell” 35th IEEE Photovoltaic Specialists Conference, Hawaii (2010)

Yasushi Shoji, Ryuji Oshima, Ayami Takata, Takayuki Morioka, Yoshitaka Okada
“Multi-staqcked InGaAs/GaNAs quantum dot solar cell fabricated on GaAs (311)B substrate” 35th IEEE Photovoltaic Specialists Conference, Hawaii (2010)
(Poster Award 受賞)

Takayuki Morioka,  Ryuji Oshima, Ayami Takata, Yasushi Shoji, Tomoya Inoue, Takashi Kita, Yoshitaka Okada
“Multi-staqcked InAs/GaNAs quantum dots with direct Si doping for use in intermediate-band solar cells” 35th IEEE Photovoltaic Specialists Conference, Hawaii (2010)

Shuhei Yagi, Yoshitaka Okada
“Fabrication of resonant tunneling structures for selective energy contact of hot carrier solar cell based on III-V semiconductors” 35th IEEE Photovoltaic Specialists Conference, Hawaii (2010)

-2009-
Shuhei Yagi, Ryuji Oshima, Yoshitaka Okada
“Evaluation of selective energy contact for hot carrier solar cells based on III-V semiconductors” 34th IEEE Photovoltaic Specialists Conference, Philadelphia (2009)

Naoya Miyashita, Shuhei Ichikawa, and Yoshitaka Okada
“Effect of Indium Composition on GaInNAsSb Solar Cells Grown by Atomic Hydrogen-Assisted Molecular Beam Epitaxy” 34th IEEE Photovoltaic Specialists Conference, Philadelphia (2009)

Yasushi Shoji, Ryuji Oshima, Ayami Takatai, Akira Uedono, and Yoshitaka Okada
“The effect of spacer layer thickness on vertical alignment of InGaAs/GaNAs quantum dots grown on GaAs(311)B substrate” The 14 th International Conference on Modulated Semiconductor Structures, Mo-mP41, Kobe (2009)

Ayami Takatai, Ryuji Oshima, Yasushi Shoji, and Yoshitaka Okada
“Growth of multi-stacked InAs/GaNAs quantum dots grown with As2 source in atomic hydrogen-assisted molecular beam epitaxy” The 14 th International Conference on Modulated Semiconductor Structures, Mo-mP42, Kobe  (2009)

Ryuji Oshima, Ayami Takatai, Yasushi Shoji, and Yoshitaka Okada
“InAs/GaNAs strain-compensated quantum dots stacked over 50 layers for use in high-efficiency solar cell” The 14 th International Conference on Modulated Semiconductor Structures, Mo-mP50, Kobe (2009)

Ryuji Oshima, Ayami Takata, Yasushi Shoji, and Yoshitaka Okada
“The effect of spacer layer thickness on the properties of quantum dot solar cells” 18th International Photovoltaic Science and Engineering Conference, Kolkata (2009) (Paper award 受賞)

Yasushi Shoji, Ryuji Oshima, Ayami Takatai, Akira Uedono, and Yoshitaka Okada 
“Fabrication of InGaAs/GaNAs strain-compensated quantum dot solar cell on GaAs (311)B substrate” 18th International Photovoltaic Science and Engineering Conference, 6-3p-023, Kolkata (2009)

Naoya Miyashita, Shuhei Ichikawa, and Yoshitaka Okada
“Characteristics of GaInNAsSb Solar Cells Grown by Atomic Hydrogen-Assisted Molecular Beam Epitaxy”, 2009 18th International Photovoltaic Science and 
Engineering Conference & Exhibition, 5-1o-014, Kolkata (2009)

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-2008-

Ryuji Oshima, Yasushi Shoji, Ayami Takata, and Yoshitaka Okada
“Growth of InGaAs/GaNAs strain-compensated quantum dot superlattice on GaAs (311)B by molecular beam epitaxy” 15th International Conference on Molecular Beam Epitaxy, Vancouver, Canada (2008)

Ayami Takata, Ryuji Oshima, Yasushi Shoji and Yoshitaka Okada 
“Optical studies on InAs/InGaAs/GaNAs strain compensated quantum dots grown on GaAs(001) by molecular beam epitaxy” 15th International Conference on Molecular Beam Epitaxy, Vancouver, Canada (2008)

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-2007-

Ryuji Oshima, Ayami Takata, and Yoshitaka Okada 
“Increased photoabsorption in strain-compensated quantum dot solar cells” 17th International Photovoltaic Science and Engineering Conference, Fukuoka (2007)

Ayami Takata, Ryuji Oshima and Yoshitaka Okada “Growth of GaNAs films with As2 source in atomic hydrogen-assisted molecular beam epitaxy” International Conference on Solid State Devices and Materials, Tsukuba (2007)

Ryuji Oshima, Yuta Nakamura, Ayami Takata, and Yoshitaka Okada, 
“Multi-stacked InAs/GaNAs strain-compensated quantum dot solar cells” 22nd European Photovoltaic Solar Energy Conference and Exhibition, Milano (2007)

Naoya Miyashita, Yukiko Shimizu, and Yoshitaka Okada
“Effect of increasing N composition on the performance of GaAs/GaInNAs heterojunction solar cells”, 2007 22nd European Photovoltaic Solar Energy Conference and Exhibition, 1CV.2.5, Milano, (2007)

Ryuji Oshima, Yuta Nakamura, Ayami Takata, and Yoshitaka Okada, 
“Optical properties of multi-stacked InAs/GaNAs strain-compensated quantum dots” 15th International Conference on Crystal Growth, Salt lake City (2007)

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著書


Yoshitaka Okada, Katsuhisa Yoshida and Yasushi Shoji, "Quantum Dot Solar Cells", Advanced Solar Cell Materials, Technology, Modeling and Simulation, edited by Laurentiu Fara and Masafumi Yamaguchi (2013 IGI Global, USA)

岡田 至崇
「量子ドット太陽電池 変換効率50%以上を目指す、革新的太陽電池技術」
(工業調査会, 2010年7月)

岡田 至崇,八木 修平, 大島 隆治,
「解説:量子ドット超格子による高効率太陽電池の 開発」
応用物理, 79, pp. 206-212 (2010)

岡田 至崇,大島 隆治「解説:量子ナノ構造を導入した次世代太陽電池」
応用物理, 76, pp. 50-53 (2007)

岡田 至崇,「解説:自己組織化量子ドット超格子と高効率太陽電池への応用」
日本結晶成長学会誌, 33, pp. 89-93 (2006)

岡田 至崇,「解説:半導体量子ドットを用いた高効率太陽電池」
電気学会誌,124, pp. 782-785 (2004)

A. Yariv著,多田 邦雄,神谷 武志 監訳,「光エレクトロニクス-展開編」
(丸善,2000年11月)

A. Yariv著,多田 邦雄,神谷 武志 監訳,「光エレクトロニクス-基礎編」
(丸善,2000年3月)

応用物理学会編,「応用物理用語大事典」
(オーム社,1998年4月)

田中 俊一,末松 安晴,大越 孝敬 共編,「オプトエレクトロニクス用語事典」
(オーム社,1996年11月)

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