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Total result(s) found: 43
  •  “Surface Passivation of III-Nitride Nanowires for Enhanced Photoelectrochemical Water-Splitting”  Purushothaman Varadhan, Davide Priante, Hui-Chun Fu, Jose Ramon Duran Retamal, Chao Zhao, Mohamed Ebaid, Tien Khee Ng, Idirs Ajia, Somak Mitra, Iman S. Roqan, Boon S. Ooi, and Jr-Hau He, Nano letters (2017), accepted (DOI: 10.1021/acs.nanolett.6b04559)
Keywords:
III-Nitrides; nanowires; photoelectrochemical water-splitting; solar fuel; surface passivation
  • Double Charged Surface Layers in Lead Halide Perovskite Crystals"Double Charged Surface Layers in Lead Halide Perovskite Crystals", Mohammed Omar, Sarmah Smritakshi, Burlakov Victor, Yengel Emre, Murali Banavoth, Alarousu Erkki, Yang Chen, El-Zohry Ahmed, Alias Mohd, Zhumekenov Ayan, Saidaminov Makhsud, Cho Namchul, Wehbe Nimer, Mitra Somak, Ajia. Idris, Dey Sukumar, Mansour Ahmed E., Abdelsamie Maged, Amassian Aram, Roqan Iman, Ooi Boon, Goriely Alain, Bakr Osman, Nano letters (2017), accepted.
     
Keywords:
Lead halide Peroviskite Crystals
  • " Epitaxially-grown Gallium Nitride on Gallium Oxide substrate for photon pair generation in visible and telecomm wavelengths” K. M. Awan, K. Dolgaleva, M.M. Muhammed, I.S. Roqan. Photonics North, PN 2016 7537934 (2016)
Keywords:
nonlinear optics; integrated photonic circuits; four-wave mixing; all-optical wavelength conversion; photon pair generation; GaN epitaxial growth
  • “Nature of low dimensional structural modulations and relative phase stability in RexMo(W)1-xS2 transition metal dichalcogenide alloys” Rajib Sahu , Usha Bhat , Nitin M. Batra , Horta Sharona , Badri Vishal , Sumanta Sarkar , S Assa Aravindha , Sebastian C Peter , Iman S. Roqan , Pedro Costa , Ranjan Datta, J appl. Phys. (2016), accepted
Keywords:
dichalcogenidealloys
  •  
    “Droop-Free, Reliable, and High-Power InGaN/GaN Nanowire Light-Emitting Diodes for Monolithic Metal-Optoelectronics”, Chao Zhao Tien Khee Ng, Rami T. ElAfandy, Aditya Prabaswara, Giuseppe Bernardo Consiglio, Idris A. Ajia, Iman S. Roqan, Bilal Janjua, Chao Shen, Jessica Eid, Ahmed Y. Alyamani, Munir M. Eldesouki, and Boon S. Ooi,Nano Lett., 16, 4616–4623 (2016)
Keywords:
efficiency droop; light-emitting diode; molecular beam epitaxy; Quantum-disks-in-nanowire
  • ​A close examination of the structure and dynamics of HC(NH2)2PbI3 by MD simulations and group theory, M. A. Carignano, Y. Saeed, S. Assa Aravindh, I. S. Roqan, J. Even and C. Katan. 2016, PCCP, DOI: 10.1039/c6cp02917e​
Keywords:
Perovskite
  • ''High-quality III-nitride films on conductive, transparent (201)-oriented -Ga2O3 using a GaN buffer layer'', M.M. Muhammed, M.A. Roldan, Y. Yamashita, S.-L. Sahonta
  • , I. A. Ajia, K. lizuka, A. kuramata,  C. J. Humphrey
  • , & I. S. Roqan. 2016, 6:29747, Scientific Reports.

  • ​​​
Keywords:
Inorganic LEDs, thin films
  • The origin of room temperature ferromagnetism mediated by Co-VZn complexes in the ZnO grain boundary, S.Assa Aravindh and Iman Roqan, RSC Advances, 2016.DOI: 10.1039/C6RA11607H
Keywords:
Dilute magnetic semiconductor materials, ferromagnetism, ZnO
  • ​''The magnetic ordering in high magnetoresistance Mn-doped ZnO thin films'', S. Venkatesh, A. Baras, J.-S. Lee, and I. S. Roqan, AIP Advances, Volume 6 Number 3, 035019 (2016); doi: 10.1063/1.4944954
Keywords:
Zinc oxide films, Magnetoresistance, Polarons, Percolation
  • ''Identifying the influence of the intrinsic defects in Gd-doped ZnO thin-films''. T. H. Flemban, M. C. Sequeira, Z. Zhang, S. Venkatesh, E. Alves, K. Lorenz, and I. S. Roqan, Journal of Applied Physics, Volume 119, Issue 6, 2016.​
Keywords:
Zinc, Zinc Oxide Films, Lattice Constants, Doping
  • Defect-band mediated ferromagnetism in Gd-doped ZnO thin films", S. Venkatesh, J. B. Franklin, M. P. Ryan, J. S. Lee, H. Ohldag, M. A. McLachlan, N. M. Alford, I. S. Roqan, J Appl Phys. 117 (1), 013913 (2015).
Keywords:
Thin films
  • ''Defect induced d0 ferromagnetism in a ZnO grain boundary'',Sasikala Devi Assa Aravindh, Udo Schwingenschloegl, and Iman S Roqan, Journal of Chemical Physics, Volume 143, Number 22, 2015. Doi: 10.1063/1.4936659 ​​
Keywords:
Zinc, Vacancies, Ferromagnetism, Zinc oxide films
  • ''Defect-impurity complex induced long-range ferromagnetism in GaN nanowires'', Assa Aravindh Sasikala Devi and  Iman S. Roqan, IOP Materials Research Express, Volume 2, Number 12, Oct. 2015.
Keywords:
GaN nanowire, density functional theory, magnetism, electronic structure
  • ''Homogeneous vertical ZnO nanorod arrays with high conductivity on an in situ Gd nanolayer'', Tahani H. Flemban, Venkatesh Singaravelu, Assa Aravindh Sasikala Devi and Iman S. Roqan​, RSC Advances, 5, 94670, 2015. DOI: 10.1039/c5ra19798h​​
Keywords:
ZnO, Nanorods
  • ​I. S. Roqan, M. M. Muhammed ''(-201) [beta]- Gallium oxide substrate for high quality GaN materials'', 2015, Proc. SPIE 9364, Oxide-based Materials and Devices VI, 93641K ; DOI: 10.1117/12.2076475
Keywords:
GaN, Ga2O3, LED, high efficiency, optical properties
  • Iman S. Roqan, S Venkatesh , Z Zhang , S Hussain , I Bantounas , J , T Flemban , B Zou , J-S Lee , U Schwingenschlogl , P Krastev Petrov , M P Ryan , N M. Alford, Obtaining strong ferromagnetism in diluted Gd-doped ZnO thin films through controlled Gd-defect complexes, Journal of Applied Physics, Volume 117, Issue 7, 2015. Doi: 10.1063/1.4908288
Keywords:
Zinc oxide films, Doping, Magnetic films, Zinc
  • ​"Thin Film growth and characterization of Ti doped ZnO by RF/DC magnetron sputtering", M. B. Haider, M. F. Al-Kuhaili, S. M. A. Durrani, S. Venkatesh, I. S. Roqan, Proceedings MRS Fall, Symposium O, 1731 (2014).
Keywords:
Ti doped ZnO
  • S. Assa Aravindh, Udo Schwingenschloegl, and Iman S. Roqan, Ferromagnetism in Gd doped ZnO nanowires: A first principles study, Journal of Applied Physics 116, 233906 (2014); DOI: 10.1063/1.4904860
Keywords:
Gd doped ZnO
  • I. Bantounas, V. Singaravelu, I. S. Roqan and Udo Schwingenschlogl, Structural and magnetic properties of Gd-doped ZnO, J. Mater.Chem.C2,10331 (2014). DOI: 10.1039/c4tc01237b
Keywords:
Gd doped ZnO, Density Functional Theory
  • Zhenkui Zhang, Udo Schwingenschlögl, and Iman S. Roqan." Vacancy complexes induce long-range ferromagnetism in GaN". Journal of Applied Physics, 2014 (Vol.116, Issue 18).
Keywords:
Vacancies, III-V semiconductors, Ferromagnetism, Density functional , Antiferromagnetism
  • Zhenkui Zhang, Udo Schwingenschlögl and Iman S. Roqan. Possible mechanism for d0 ferromagnetism mediated by intrinsic defects. RSC Advances, 2014, 4, 50759. DOI: 10.1039/c4ra06237j.
Keywords:
Zn vacancies, ZnS nanostructures, intrinsic defects, density functional theory
  • Ajia, Idris A. and Edwards, P. R. and Liu, Z. and Yan, J. C. and Martin, R. W. and Roqan, I. S. (2014) Excitonic localization in AlN-rich AlxGa1−xN/AlyGa1−yN multi-quantum-well grain boundaries. Applied Physics Letters, 105 (12). ISSN 0003-6951
Keywords:
Multiple quantum wells, Grain boundaries, Photoluminescence, Excitons
  • M. M. Muhammed, M. Peres, Y. Yamashita, Y. Morishima, S. Sato, N. Franco, K. Lorenz, A. Kuramata and I. S. Roqan, High optical and structural quality of GaN epilayers grown on ( 201) beta-Ga2O3, Applied Physics Letters 105, 042112, 2014.
Keywords:
III-V semiconductors, Epitaxy, X-ray diffraction, Photoluminescence
  • L.-C. Gerhardt, K. L. Widdows, M. M. Erol, A. Nandakumar, I. S. Roqan, T. Ansari, A.R. Boccaccini, Neocellularization and neovascularization of nanosized bioactive glass-coated decellularized trabecular bone scaffolds, Journal of Biomedical Materials Research, 101A, 827, 2013.
Keywords:
decellularized bone, scaffold, bioactive glass, angiogenesis, coating, vascular endothelial growth factor, stereology, vascularization
  • Fred P.M. Jjunju, Abraham K. Badu-Tawiah, Anyin Li, Santosh Soparawalla, Iman S. Roqan, R. Graham Cooks, Hydrocarbon analysis using desorption atmospheric pressure chemical ionization, International Journal of Mass Spectrometry, 345–347, 80, 2013.
Keywords:
Ambient ionization mass spectrometry, Petroleum constituents, Charge exchange, Ion-molecule reactions, Polynuclear aromatics, Fuels
  • Fred. P. M. Jjunju, Anyin Li, Abraham Badu-Tawiah, Pu Wei, Linfan Li, Zheng Ouyang, Iman S. Roqan, R. Graham Cooks, In situ analysis of corrosion inhibitors using a portable mass spectrometer with paper spray ionization, Analyst, 138, 3740, 2013.
Keywords:
Mass spectrometer, Corrosion inhibitor
  • S. M. C. Miranda, P. R. Edwards, K. P. O'Donnell, M. Boćkowski, E. Alves, I.S. Roqan, A. Vantomme, and K. Lorenz, Sequential multiple-step europiumion implantation and annealing of GaN, Phys. Status Solidi C 11, 253, 2013.
Keywords:
gallium nitride, ion implantation, crystal quality, europium
  • K. Lorenz, S. M. C. Miranda, E. Alves, I. S. Roqan, K. P. O’Donnell, and M. Boćkowski High pressure annealing of Europium implanted GaN, Proc. of SPIE Vol. 8262, 82620C-1 (2012).
Keywords:
GaN, rare earth doping, europium, ion implantation, Rutherford Backscattering Spectrometry, X-ray
  • Vasily A. Melnikov, Iman S. Roqan, Lineshape Engineering in an All-Pass Ring Resonator with Backreflection Coupled to a Symmetrical Fabry–Perot Resonator, Latin America Optics and Photonics Technical Digest, OSA, LT4B.(2012).
Keywords:
Coupled-mode theory (CMT), Transfer functions, Resonator
  • K.P. O’Donnell, I.S. Roqan, Ke Wang, K. Lorenz, E. Alves, M. Bockowski, The photoluminescence/excitation (PL/E) spectroscopy of Eu-implanted GaN, Optical Materials 33, 1063 (2011).
Keywords:
Gallium nitride, Europium, Ion implantation, Photoluminescence, Excitation mechanism
  • L-C. Gerhardt , K. L. Widdows , M. M. Erol , C. W. Burch , José, A. Sanz- Herrera , I. Ochoa, R. Stämpfli, I. S. Roqan, S. Gabe, T. Ansari, A. R. Boccaccini, The pro-angiogenic properties of multi-functional bioactive glass composite scaffolds, Biomateria, 2011
Keywords:
Angiogenesis, Bioactive glass, Composite scaffold, Vascular endothelial growth factor, Bone, Vascularisation
  • Ioannis Bantounas, Souraya Goumri-Said, Mohammed Benali Kanoun, Aure´lien Manchon, I. S. Roqan, and Udo Schwingenschlogl, Ab initio investigation on the magnetic ordering in Gd doped ZnO, J Appl Phys 109, 083929 (2011).
Keywords:
Ferromagnetism, Magnetic semiconductors
  • K. Lorenz, E. Alves, I. S. Roqan, K. P. O’Donnell, A. Nishikawa, Y. Fujiwara, and M. Boćkowski, Lattice site location of optical centers in GaN:Eu light emitting diode material grown by organometallic vapor phase epitaxy, Appl. Phys. Lett. 97, 111911(2010).
Keywords:
Photoluminescence, Doping, Light emitting diodes, III-V semiconductors
  • Roqan, I.S. and O'Donnell, K.P. and Martin, R.W. and Edwards, P.R. and Song, S.F. and Vantomme, A. and Lorenz, K. and Alves, E. and Boćkowski, M. (2010) Identification of the prime optical center in GaN:Eu3+. Physical Review B, 81 (1). 085209. ISSN 10
Keywords:
optics, GaN, Eu3+, Physics
  • ​K. Lorenz, I.S. Roqan, N. Franco, K. P. O’Donnell, V. Darakchieva, E. Alves, C.Trager-Cowan, R.W. Martin, D.J. As, M. Panfilova, “Eu Doping of Zincblende GaN by Ion Implantation” J Appl. Phys. 105, 113507 (2009).
Keywords:
III-V semiconductors, Rutherford backscattering, X-ray diffraction, cathodoluminescence, europium, gallium compounds, ion implantation, lattice constants, wide band gap semiconductors
  • ​I.S. Roqan, K.P. O’Donnell, C. Trager-Cowan, V. Matias, A. Vantomme, ”Optical and Structural Properties of Eu-implanted InxAl1-xN” J. Appl. Phys.106, 083508 (2009)
Keywords:
Photoluminescence, III-V semiconductors, Ion implantation, Linewidths, Rutherford backscattering
  • K Lorenz, N P Barradas, E Alves, I S Roqan, E Nogales, R W Martin, K. P. O’Donnell, F. Gloux and P Ruterana, Structural and optical characterization of Eu-implanted GaN, J. Phys. D: Appl. Phys. 42,165103 (2009).
Keywords:
ion implantation, excitation mechanism, europium, luminescence, photoluminescence, gallium nitride, photoluminescence/excitation , PL/E, spectroscopy, Eu-implanted GaN , Physics, Electronic, Optical and Magnetic Materials, Atomic and Molecular Physics
  • ​"Luminescence spectroscopy of Eu implanted zincblende GaN” I. S. Roqan, K. P. O’Donnell, C. Trager-Cowan, B. Hourahine, R.W. Martin, K. Lorenz, M. Panfilova, D.J. As, I.M. Watson, E. Alves,  Phys. Stat. Sol. (a), 245, 170 (2008).
Keywords:
Spectroscopy
  • ​"Rare earth doping of III-nitride alloys by ion implantation," K. Lorenz, E. Alves, I. S. Roqan, R. W. Martin, C. Trager-Cowan, K. P. O’Donnell, and I. M. Watson, Phys. Stat. sol. (a)205, 34 (2008).
     
Keywords:
Rare earth luminescence, wide band gap, AlGaN, AlInN, GaN
  • “The effect of growth temperature on the luminescence and structural properties of rare earth doped MBE GaN”, I. S. Roqan, E. Nogales, K. P. O’Donnell, C. Trager-Cowan, R. W. Martin, G. Halambalakis, O. Briot, J. Crystal Growth, 310, 4069 (2008).
Keywords:
Atomic Force Microscopy, Molecular beam epitaxy
  • “A microspectroscopic study of cap damage in annealed RE-doped AlN-capped GaN” E. Nogales, K. Wang, I. S. Roqan, R.W. Martin, K.P. O'Donnell, Materials Research Society Symposium Proceedings, 892, 625 (2006).
Keywords:
AlN nanocaps, annealing
  • “Characterization of the blue emission of Tm/Er co-implanted GaN” I.S. Roqan, Trager-Cowan, B. Hourahine, K. Lorenz, E. Nogales, K.P. O'Donnell, R.W. Martin, E. Alves, S. Ruffenach, O. Briot, Materials Research Society Symposium Proceedings, 892, 599, 2006
Keywords:
PL, GaN
  • Blue cathodoluminescence from thulium implanted AlGaN and InAlN” I. S. Roqan, K. Lorenz, K.P. O’Donnell, C. Trager-Cowan, R.W. Martin, I.M. Watson, E. Alves, Superlattices Microstruct. 40, 445 (2006).
Keywords:
Rare earth; GaAlN; InAlN; Implantation; Cathodoluminescence