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22 results on '"Jithesh Kuyyalil"'

1. Structural and electronic properties of thermally evaporated V2O5 epitaxial thin films

Author

Bethany Lamoureux, V. R. Singh, Jithesh Kuyyalil, Kevin E. Smith, Ting-Yi Su, and Vedran Jovic

Subjects
Materials science, Absorption spectroscopy, Photoemission spectroscopy, Metals and Alloys, Analytical chemistry, 02 engineering and technology, Surfaces and Interfaces, Substrate (electronics), 021001 nanoscience & nanotechnology, Epitaxy, 01 natural sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Crystal, Transition metal, 0103 physical sciences, Materials Chemistry, Surface roughness, Thin film, 010306 general physics, 0210 nano-technology
Abstract

This study investigated the physicochemical properties of a V2O5 thin film deposited on c-plane sapphire through thermal evaporation at a relatively high pressure. Using atomic force microscopy (AFM), X-ray diffraction (XRD) and a suite of X-ray spectroscopic techniques, it was shown that a high quality epitaxial V2O5 thin film was achieved. AFM step height analysis demonstrated that the film thickness was ~ 50 nm with a surface roughness of 1.5 A, as determined by root mean square roughness measurements. XRD analysis verified that the film was highly crystalline with a (0001) orientation on the substrate. Vanadium was predominantly in the 5 + oxidation state, with contributions from V4 + states at the surface, shown by X-ray photoemission spectroscopy analysis X-ray absorption spectroscopy further confirmed the predominant presence of V5 + in an octahedral crystal field. The existence with bulk V4 + states was shown through V L-edge X-ray emission spectroscopy which demonstrated the presence of d-d crystal field transitions in an otherwise d0 transition metal oxide. The data suggests that by increasing the partial pressure of oxygen in the vacuum chamber during growth, thermal evaporation can be used as a cheap and efficient way of growing stoichiometric V2O5 thin films.

Published
2016
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2. Vacancy assisted SrO formation on La0.8Sr0.2Co0.2Fe0.8O3−δ surfaces—A synchrotron photoemission study

Author

Jude Laverock, D. Newby, Deniz Cetin, Yang Yu, Soumendra N. Basu, Jithesh Kuyyalil, Karl F. Ludwig, and Kevin E. Smith

Subjects
Materials science, Photoemission spectroscopy, Analytical chemistry, Synchrotron radiation, Surfaces and Interfaces, Condensed Matter Physics, Synchrotron, law.invention, Surfaces, Coatings and Films, X-ray photoelectron spectroscopy, Chemical physics, law, Vacancy defect, Phase (matter), Materials Chemistry, Molecule, Thin film
Abstract

We present a systematic synchrotron radiation photoemission spectroscopy study of the interaction of O2 with defective La0.8Sr0.2Co0.2Fe0.8O3 − δ(100) surfaces at low temperatures. First, the surface chemical evolution during low energy Ar+ ion sputtering is investigated and is found to create oxygen vacancies. Subsequently, the interaction of the O2 molecules with La0.8Sr0.2Co0.2Fe0.8O3 − δ(100) surface is observed to create an insulating phase. We performed a detailed core-level peak-fitting analysis to identify the chemical nature of this phase and to probe the role of vacancies in the formation of this phase.

Published
2015
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3. Surface evolution of lanthanum strontium cobalt ferrite thin films at low temperatures

Author

Karl F. Ludwig, Uday B. Pal, Kevin E. Smith, Jacob N. Davis, D. Newby, Jude Laverock, Jithesh Kuyyalil, Yang Yu, Srikanth Gopalan, and Soumendra N. Basu

Subjects
Strontium, Argon, Materials science, Annealing (metallurgy), Inorganic chemistry, Metals and Alloys, Analytical chemistry, chemistry.chemical_element, Surfaces and Interfaces, Partial pressure, Electron spectroscopy, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, chemistry.chemical_compound, Lanthanum strontium cobalt ferrite, chemistry, X-ray photoelectron spectroscopy, Physics::Atomic and Molecular Clusters, Materials Chemistry, Thin film
Abstract

The ultra-high vacuum surface preparation of heteroepitaxial lanthanum strontium cobalt ferrite thin films has been studied using soft X-ray photoelectron spectroscopy. Specifically, the effect of annealing the films at low temperatures in low partial pressures of oxygen and argon has been investigated. We find that atmospheric surface carbon contamination of the films can be removed in select anneal temperature regimes in argon, but remains bound to the surface with oxygen annealing at any temperature. Irrespective of the gas used, an insulating phase transition occurs near 300 °C due to strontium segregation at the surface. The surface develops more insulating character if annealed with oxygen. Different species are proposed to be responsible for the discrepancy in insulating character.

Published
2015
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4. In induced reconstructions of Si(111) as superlattice matched epitaxial templates for InN growth

Author

Malleswararao Tangi, Jithesh Kuyyalil, and S. M. Shivaprasad

Subjects
Diffraction, Materials science, business.industry, Band gap, Mechanical Engineering, Superlattice, chemistry.chemical_element, Condensed Matter Physics, Epitaxy, Full width at half maximum, Optics, chemistry, Mechanics of Materials, X-ray crystallography, Surface roughness, Optoelectronics, General Materials Science, business, Indium
Abstract

Indium induced surface reconstructions of Si(1 1 1)-7 × 7 are used as templates to grow high quality InN. We grow InN on Si(1 1 1)-7 × 7, Si(1 1 1)-4 × 1-In and Si(1 1 1)-1 × 1-In reconstructed surfaces and study the quality of the films formed using complementary characterization tools. InN grown on Si(1 1 1)-1 × 1-In reconstruction shows superior film quality with lowest band-edge emission having a narrow full width at half maximum, intense and narrow 0 0 0 2 X-ray diffraction, low surface roughness and carrier concentration an order lower than other samples. We attribute the high quality of the film formed at 300 °C to the integral matching of InN and super lattice dimensions, we also study the reasons for the band gap variation of InN in the literature. Present study demonstrates the proposed Superlattice Matched Epitaxy can be a general approach to grow good quality InN at much lower growth temperature on compatible In induced reconstructions of the Si surface.

Published
2013
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5. A superstructural 2D-phase diagram for Ga on the Si(111)- 7x7 system

Author

S. M. Shivaprasad, Jithesh Kuyyalil, Mahesh Kumar, and Praveen Kumar

Subjects
Auger electron spectroscopy, Adsorption, Low-energy electron diffraction, Chemistry, Phase (matter), Electron energy loss spectroscopy, Ultra-high vacuum, Materials Chemistry, Analytical chemistry, General Chemistry, Substrate (electronics), Condensed Matter Physics, Phase diagram
Abstract

The structural modifications of an Si(111)- 7x7 reconstructed surface and the evolution of growth induced by Ga adsorption in the submonolayer regime at various substrate temperatures ranging from room temperature (RT) to 600 °C, with a low Ga flux rate of 0.1 ML/min (1 ML∼6.8×1014 atoms/cm2) have been studied in-situ in Ultra High Vacuum (UHV) using Auger Electron Spectroscopy (AES), Low Energy Electron Diffraction (LEED) and Electron Energy Loss Spectroscopy (EELS) as characterization probes. Ga grows in the Stranski–Krastanov (SK) growth mode for temperatures ranging from RT to 350 °C, where 3D-islands form after one and two flat monolayers of Ga adsorption, while for higher temperatures ranging from 450 to 550 °C, Ga grows in the Volmer–Weber (VW) growth mode. A comprehensive 2D-phase diagram for this Ga/Si(111) system for adsorption, which provides pathways to attain the observed superstructural phases, viz., √3x√3-R30°, 6.3x6.3, 6.3√3x6.3√3-R30° and 11x11, has been investigated. The characteristic EELS spectrum for each superstructural phase is also reported in this study.

Published
2011
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6. Clustering and layering of In adatoms on low and high index silicon surfaces: A comparative study

Author

S. M. Shivaprasad, Jithesh Kuyyalil, Govind, and Mahesh Kumar

Subjects
Auger electron spectroscopy, Low-energy electron diffraction, Chemistry, Ultra-high vacuum, Thermal desorption, Nanowire, Analytical chemistry, Surfaces and Interfaces, Condensed Matter Physics, Surfaces, Coatings and Films, Overlayer, Adsorption, Chemical physics, Desorption, Materials Chemistry
Abstract

Using the morphological differences of low and high index surfaces as templates for metal growth, several low dimensional overlayer structures with novel structural and electronic properties can be formed. We present here a first report on submonolayer adsorption and residual thermal desorption studies of In adatoms on reconstructed high index Si (5 5 12)−2 × 1 surface and compare it with the observations on planar Si (111)−7 × 7 surface. The study is done by using in-situ Ultra High Vacuum surface sensitive probes like Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED). These conventional wide area techniques provide an understanding of atomistic issues involved in the evolution of the interface. We have observed an anomalous growth mode during adsorption at room temperature (RT) above 2ML, which includes adatom layering and clustering on Si (111) surface. This is also manifested during the desorption experiments on both surfaces, and the subtle differences on the two surfaces are discussed. The observation of LEED pattern during the adsorption process shows formation of different superstructural phases on Si (111)−7 × 7 surface. On Si (5 5 12) 2 × 1 surface we observe the sequential 2× (225), 2× (337) and 2× (113) facet formation during adsorption/desorption, which include quasi 1D-nanowire/chain structures. A combination of lattice strain effects, presence of step-edge barrier and quantum size effects are employed to speculate the differences in adsorption and desorption.

Published
2010
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7. Abrupt GaP/Si hetero-interface using bistepped Si buffer

Author

Charles Cornet, Antoine Létoublon, Mounib Bahri, Karine Tavernier, M.F. da Silva, T. Nguyen Thanh, Anne Ponchet, Rozenn Bernard, Ronan Tremblay, Y. Ping Wang, A. Le Corre, Samy Almosni, Olivier Durand, T. Rohel, Gilles Patriarche, Jithesh Kuyyalil, Julien Stodolna, Ludovic Largeau, César Magén, Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), Centre d'élaboration de matériaux et d'études structurales (CEMES), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Surfaces, Interfaces et Nano-Objets (CEMES-SINanO), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Laboratoire de photonique et de nanostructures (LPN), Centre National de la Recherche Scientifique (CNRS), University of Zaragoza - Universidad de Zaragoza [Zaragoza], ANR-12-BS03-0002,OPTOSI,Intégration par épitaxie de composants optoélectroniques III-V sur Si(2012), ANR-11-PRGE-0007,MENHIRS,Intégration monolithique de cellules solaires III-V à haut rendement sur substrats de silicium(2011), ANR-14-CE26-0014,ANTIPODE,Analyse approfondie de la nucléation III-V/Si pour les composants photoniques hautement intégrés(2014), European Project: 312483,EC:FP7:INFRA,FP7-INFRASTRUCTURES-2012-1,ESTEEM 2(2012), Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse)

Subjects
Materials science, Physics and Astronomy (miscellaneous), Silicon, business.industry, chemistry.chemical_element, Heterojunction, Epitaxy, Crystallography, chemistry, Transmission electron microscopy, Scanning transmission electron microscopy, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, High-resolution transmission electron microscopy, business, Vicinal, Molecular beam epitaxy
Abstract

International audience; We evidence the influence of the quality of the starting Si surface on the III-V/Si interface abruptness and on the formation of defects during the growth of III-V/Si heterogeneous crystal, using high resolution transmission electron microscopy and scanning transmission electron microscopy. GaP layers were grown by molecular beam epitaxy on vicinal Si (001). The strong effect of the Si substrate chemical preparation is first demonstrated by studying structural properties of both Si homoepitaxial layer and GaP/Si heterostructure. It is then shown that choosing adequate chemical preparation conditions and subsequent III-V regrowth conditions enables the quasi-suppression of micro-twins in the epilayer. Finally, the abruptness of GaP/Si interface is found to be very sensitive to the Si chemical preparation and is improved by the use of a bistepped Si buffer prior to III-V overgrowth.

Published
2015
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8. Enhanced electron correlations at theSrxCa1−xVO3surface

Author

Bo Chen, Joseph C. Woicik, Kevin E. Smith, Ravi Pratap Singh, Jude Laverock, B. A. Karlin, Geetha Balakrishnan, and Jithesh Kuyyalil

Subjects
Materials science, Photoemission spectroscopy, Binding energy, Fermi level, Photoionization, Electronic structure, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, symbols.namesake, Ab initio quantum chemistry methods, Content (measure theory), symbols, Strongly correlated material, Atomic physics
Abstract

We report hard x-ray photoemission spectroscopy measurements of the electronic structure of the prototypical correlated oxide ${\mathrm{Sr}}_{x}{\mathrm{Ca}}_{1\ensuremath{-}x}{\mathrm{VO}}_{3}$. By comparing spectra recorded at different excitation energies, we show that 2.2 keV photoelectrons contain a substantial surface component, whereas 4.2 keV photoelectrons originate essentially from the bulk of the sample. Bulk-sensitive measurements of the O $2p$ valence band are found to be in good agreement with ab initio calculations of the electronic structure, with some modest adjustments to the orbital-dependent photoionization cross sections. The evolution of the O $2p$ electronic structure as a function of the Sr content is dominated by $A$-site hybridization. Near the Fermi level, the correlated V $3d$ Hubbard bands are found to evolve in both binding energy and spectral weight as a function of distance from the vacuum interface, revealing higher correlation at the surface than in the bulk.

Published
2015
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9. Simultaneous Spectroscopic, Diffraction and Microscopic Study of the Metal-Insulator Transition of VO2

Author

Salinporn Kittiwatanakul, Alexei Zakharov, Jiwei Lu, Bo Chen, Stuart A. Wolf, Kevin E. Smith, Yuran Niu, Jithesh Kuyyalil, and Jude Laverock

Subjects
Metal, Diffraction, Materials science, Electron diffraction, Chemical physics, Rutile, visual_art, Phase (matter), visual_art.visual_art_medium, Electron, Electronic structure, Metal–insulator transition
Abstract

We present a simultaneous photoemission spectroscopic, low-energy electron diffraction and low-energy electron microscopic study of the metal-insulator transition of strained VO2. The fraction of rutile structure is extracted from the microscopic measurements throughout the transition, and compared with the fraction of the metallic electrons from photoemission data. We find that at intermediate temperatures, while the system is predominantly monoclinic-like in structure, the electronic component of the transition is much further advanced. Our results provide direct evidence for a monoclinic-like metallic phase of VO2 that is easily accessible at ambient temperatures and pressures.

Published
2015
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10. Evolution of correlated electron behavior from the surface to the bulk in SrxCa1-xVO3

Author

Ruimin Qiao, Ravi Pratap Singh, Johan Adell, Bo Chen, Jude Laverock, Joseph C. Woicik, Geetha Balakrishnan, Jithesh Kuyyalil, B. A. Karlin, Kevin E. Smith, and Wanli Yang

Subjects
Surface (mathematics), chemistry.chemical_compound, Materials science, chemistry, Spectral weight, Binding energy, Energetics, Oxide, Electronic structure, Electron, Emission spectrum, Molecular physics
Abstract

We present a detailed depth-sensitive study of the evolution in correlated electron behavior from the surface of the prototypical correlated oxide, SrxCa1-xVO3, to its bulk. Photoemission measurements of varying surface sensitivity are employed to directly compare both the spectral weight and energetics of the correlated electron features, and resonant soft x-ray emission spectroscopy is used as a bulk-sensitive reference. The surface component, which still contributes significantly to photoemission at 2.2 keV, is characterized by a transfer of spectral weight into the incoherent lower Hubbard band and the corresponding shift of these states towards lower binding energy.

Published
2015
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11. Defects limitation in epitaxial GaP on bistepped Si surface using UHVCVD-MBE growth cluster

Author

Samy Almosni, Charles Cornet, S. Loualiche, O. Dehaese, Jithesh Kuyyalil, N. Chevalier, Antoine Létoublon, T. Nguyen Thanh, Nathalie Boudet, Nicolas Bertru, Jean-François Berar, Olivier Durand, Tony Rohel, Thomas Quinci, A. Le Corre, K. Tavernier, Jacky Even, Y. Ping Wang, Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), CRG & Grands instruments (NEEL - CRG), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-Télécom Bretagne, CRG et Grands Instruments (CRG), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)

Subjects
010302 applied physics, Materials science, Silicon, business.industry, chemistry.chemical_element, 02 engineering and technology, Chemical vapor deposition, Substrate (electronics), Pole figure, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Epitaxy, 01 natural sciences, Crystallographic defect, Inorganic Chemistry, Optics, chemistry, 0103 physical sciences, Materials Chemistry, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, 0210 nano-technology, business, Layer (electronics), Molecular beam epitaxy
Abstract

International audience; We report on the association of Ultra High Vaccum Chemical Vapor Deposition (UHVCVD) and Molecular Beam Epitaxy (MBE) to achieve III-V (GaP) integration on Si/Si(100) substrates. We first demonstrate that a very good flatness (0.3 nm) can be obtained when growing directly GaP on a chemically prepared Si substrate. X-ray diffraction pole figure however demonstrates that a residual amount of micro-twins originating from the hetero-interface still remains. Silicon homoepitaxial buffer layer is then optimized in the UHVCVD chamber on different Si substrates misorientation (+/-0.15-6°-off) . A flat, clean and bistepped Si surface is achieved during the homoepitaxial growth on 6°-off silicon substrates. Samples are then transferred under UHV conditions to the MBE chamber to perform GaP overgrowth. Keeping the same III-V overgrowth conditions, influence of silicon homoepitaxial buffer layer on micro-twins generation is determined quantitatively using Synchrotron X-Ray Diffraction. We finally demonstrate that growing a flat, clean and bistepped silicon buffer layer on a 6°-off substrate, and transferring it under UHV to the MBE chamber for GaP overgrowth reduces significantly the amount of anisotropic defects generated in the GaP epilayers.

Published
2013
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12. Synchrotron X-ray diffraction analysis for quantitative defect evaluation in GaP/Si nanolayers

Author

E. Giudicelli, M. Danila, Thomas Quinci, A. Le Corre, Antoine Létoublon, T. Nguyen Thanh, Jithesh Kuyyalil, Anne Ponchet, Nathalie Boudet, Cedric Robert, Nicolas Bertru, Olivier Durand, Charles Cornet, Samy Almosni, Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), CRG et Grands Instruments (CRG), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Centre d'élaboration de matériaux et d'études structurales (CEMES), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), National Institute for Research and Development in Microtechnologies - IMT, Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), CRG & Grands instruments (NEEL - CRG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Diffraction, Planar defects, Materials science, Silicon, chemistry.chemical_element, Context (language use), GaP, 02 engineering and technology, 01 natural sciences, law.invention, Synchrotron, Optics, law, 0103 physical sciences, Materials Chemistry, Specular reflection, 010302 applied physics, business.industry, Scattering, Metals and Alloys, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, Crystallographic defect, Semimetal, Antiphase domains, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, X-ray diffraction, chemistry, Microtwins, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Si, 0210 nano-technology, business
Abstract

original title in E-MRS Spring 2012 - Symposium W : "Synchrotron X-ray diffraction complementary peak analysis for quantitative defect evaluation in GaP/Si nanolayers"; International audience; In the context of III-V monolithic integration on silicon, synchrotron X-ray diffraction has been employed in this study using a bi-dimensional large area hybrid pixel detector (XPAD third generation) to characterize defects in the GaP layers. Despite a very coherent interface (low plastic relaxation) of GaP/Si, 2 types of defect are detected. Micro-twins contributions are evidenced and quantitatively evaluated from additional reflections analysis. Antiphase domains are evidenced using the Williamson-Hall-like plot method applied to transverse scans extracted directly from single XPAD images taken on specular GaP reflections.

Published
2013
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13. Structural and optical properties of (In,Ga)As/GaP quantum dots and (GaAsPN/GaPN) diluted-nitride nanolayers coherently grown onto GaP and Si substrates for photonics and photovoltaics applications

Author

Abdallah Sakri, Clotilde Des Robert, N. Bertru, Christophe Levallois, Jean-Marc Jancu, Jithesh Kuyyalil, Mircea Modreanu, Antoine Létoublon, A. Le Corre, Laurent Pedesseau, Andrea Balocchi, Slimane Loualiche, Xavier Marie, Anne Ponchet, Olivier Durand, Nathalie Boudet, Laurent Lombez, Mathieu Perrin, Jacky Even, Charles Cornet, Samy Almosni, Thomas Quinci, T. Nguyen Thanh, Pierre Rale, Jean-François Guillemoles, S. Tricot, Pascal Turban, Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), CRG & Grands instruments (NEEL - CRG), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Centre d'élaboration de matériaux et d'études structurales (CEMES), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Surfaces, Interfaces et Nano-Objets (CEMES-SINanO), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut de Recherche et Développement sur l'Energie Photovoltaïque (IRDEP), Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT), Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Tyndall National Institute, Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-Télécom Bretagne, CRG et Grands Instruments (CRG), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC), Institut National des Sciences Appliquées (INSA), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Photoluminescence, Silicon, chemistry.chemical_element, quantum dots, 02 engineering and technology, Substrate (electronics), 7. Clean energy, 01 natural sciences, 010309 optics, monolithic integration, Photovoltaics, 0103 physical sciences, GaP/Si, business.industry, Heterojunction, electroluminescence and photoluminescence, 021001 nanoscience & nanotechnology, photonics on silicon, quantum wells, chemistry, Quantum dot, solar cells, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, Light emission, Photonics, 0210 nano-technology, business, TEM and XRD
Abstract

San Francisco, California, United States; International audience; Lattice-matched GaP-based nanostructures grown on silicon substrates is a highly rewarded route for coherent integration of photonics and high-efficiency photovoltaic devices onto silicon substrates. We report on the structural and optical properties of selected MBE-grown nanostructures on both GaP substrates and GaP/Si pseudo-substrates. As a first stumbling block, the GaP/Si interface growth has been optimised thanks to a complementary set of thorough structural analyses. Photoluminescence and time-resolved photoluminescence studies of self-assembled (In,Ga)As quantum dots grown on GaP substrate demonstrate a proximity of two different types of optical transitions interpreted as a competition between conduction band states in X and Γ valleys. Structural properties and optical studies of GaAsP(N)/GaP(N) quantum wells coherently grown on GaP substrates and GaP/Si pseudo substrates are reported. Our results are found to be suitable for light emission applications in the datacom segment. Then, possible routes are drawn for larger wavelengths applications, in order to address the chip-to-chip and within-a-chip optical interconnects and the optical telecom segments. Finally, results on GaAsPN/GaP heterostructures and diodes, suitable for PV applications are reported

Published
2013
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14. Nitrogen-phosphorus competition in the molecular beam epitaxy of GaPN

Author

A. Le Corre, Tony Rohel, Charles Cornet, Jithesh Kuyyalil, Nicolas Bertru, Samy Almosni, Antoine Létoublon, Olivier Durand, T. Nguyen Thanh, Thomas Quinci, Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-Télécom Bretagne

Subjects
010302 applied physics, Materials science, Phosphorus, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, Plasma, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Decomposition, Nitrogen, Inorganic Chemistry, chemistry, Desorption, 0103 physical sciences, Materials Chemistry, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Growth rate, 0210 nano-technology, Luminescence, Molecular beam epitaxy
Abstract

International audience; In this work, we study the nitrogen-phosphorus competition during the molecular beam epitaxial growth of GaPN alloy with N content ranging from 0 to 6%. N2 decomposition in the valved RF plasma cell is first optimized through the spectroscopic analysis of the plasma luminescence. Strain relaxation process and determination of N content in GaPN layers are then clarified using a reciprocal space mapping around the (224) Bragg reflection. Influence of growth temperature and phosphorus beam equivalent pressure (BEP) on the nitrogen incorporation is finally studied. It is demonstrated that nitrogen incorporation is mainly governed by temperature and phosphorus BEP, through the nitrogen-phosphorus competition. A good control of the nitrogen content is achieved when the temperature is low enough to avoid irreproducibility due to N or N2 desorption, and the phosphorus BEP high enough to limit the effects of nitrogen-phosphorus competition. Finally, a good accuracy on the nitrogen content control is achieved for a wide range of nitrogen composition, using effects of growth rate and valve opening.

Published
2013
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15. Evaluation of InGaPN and GaAsPN materials lattice-matched to Si for multi-junction solar cells

Author

Philippe Barate, Mathieu Perrin, N. Bertru, Christophe Levallois, Thomas Quinci, Charles Cornet, Jithesh Kuyyalil, Samy Almosni, Jacky Even, Olivier Durand, Cedric Robert, Xavier Marie, A. Le Corre, Laurent Pedesseau, Jean-Marc Jancu, Antoine Létoublon, T. Nguyen Thanh, Andrea Balocchi, Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), CEA Grenoble, DRT/DPTS/SCPIO/LCPO (CEA GRENOBLE), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)

Subjects
Solar cells, Photoluminescence, Materials science, Silicon, Band gap, General Physics and Astronomy, chemistry.chemical_element, Tight-binding model, 02 engineering and technology, Epitaxy, 01 natural sciences, 7. Clean energy, Gallium arsenide, chemistry.chemical_compound, Photovoltaics, 0103 physical sciences, Thermodynamic states and processes, 010302 applied physics, business.industry, Wide-bandgap semiconductor, 021001 nanoscience & nanotechnology, X-ray diffraction, chemistry, Chemical elements, PACS: 88.40.Jp, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Optoelectronics, Activation energies, 0210 nano-technology, business, Molecular beam epitaxy
Abstract

International audience; We compare the potentiality of bulk InGaPN and GaAsPN materials quasi-lattice-matched to silicon (Si), for multi-junction solar cells application. Bandgaps of both bulk alloys are first studied by a tight-binding model modified for nitrogen incorporation in diluted regimes. The critical thicknesses of those alloys are then calculated for various compositions. For the same lattice-mismatch and nitrogen amount, the bandgap of bulk GaAsPN is found to be closer to the targeted gap value of 1.7 eV for high efficiency tandem solar cell. GaPN and GaAsPN epilayers are then grown by molecular beam epitaxy on GaP substrate and studied by photoluminescence and X-ray diffraction. A GaAsPN bulk alloy emitting light at 1.77 eV at room temperature is obtained, demonstrating promising properties for further use in III-V/Si photovoltaic multijunction solar cells.

Published
2013
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16. Preferential incorporation of substitutional nitrogen near the atomic step edges in diluted nitride alloys

Author

T. Nguyen Thanh, A. Rambaud, Antoine Létoublon, Olivier Durand, Jithesh Kuyyalil, A. Le Corre, T. Rohel, Thomas Quinci, Samy Almosni, N. Bertru, Charles Cornet, Fonctions Optiques pour les Technologies de l'informatiON (FOTON), Université de Rennes (UR)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Télécom Bretagne-Centre National de la Recherche Scientifique (CNRS), Département des Technologies Solaires (DTS), Laboratoire d'Innovation pour les Technologies des Energies Nouvelles et les nanomatériaux (LITEN), Institut National de L'Energie Solaire (INES), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de L'Energie Solaire (INES), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), We acknowledge 'Region Bretagne' through the PONANT project including FEDER funds., Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université européenne de Bretagne - European University of Brittany (UEB)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-École Nationale Supérieure des Sciences Appliquées et de Technologie (ENSSAT)-Centre National de la Recherche Scientifique (CNRS)-Télécom Bretagne

Subjects
010302 applied physics, Materials science, Physics and Astronomy (miscellaneous), business.industry, chemistry.chemical_element, 02 engineering and technology, Nitride, 021001 nanoscience & nanotechnology, Epitaxy, 01 natural sciences, Nitrogen, Semiconductor, chemistry, Chemical physics, 0103 physical sciences, Surface roughness, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Step edges, Growth rate, 0210 nano-technology, business, Molecular beam epitaxy
Abstract

International audience; We have investigated the influence of the surface roughness on nitrogen incorporation during the molecular beam epitaxy of diluted nitrides, independently of the other growth parameters. GaPN/GaP layers grown simultaneously on surfaces displaying different roughnesses reveal a large difference in nitrogen incorporation despite the same growth temperature and growth rate. The same difference is found on quasi-lattice-matched GaAsPN demonstrating that the phenomenon is not related to any strain-induced mechanisms. The tendency is clearly confirmed when varying the growth conditions. As a direct consequence, the incorporation of substitutional nitrogen near the atomic step edges is found to be 6.7 times more probable than the in-plane nitrogen incorporation. The formation of N-Ni clusters and their stability on the surface is discussed.

Published
2012
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17. Optical bandgap and near surface band bending in degenerate InN films grown by molecular beam epitaxy

Author

S. M. Shivaprasad, Malleswararao Tangi, and Jithesh Kuyyalil

Subjects
Materials science, Condensed matter physics, Band gap, business.industry, Fermi level, General Physics and Astronomy, Charge density, eye diseases, Semimetal, Condensed Matter::Materials Science, symbols.namesake, Band bending, Semiconductor, symbols, Optoelectronics, Charge carrier, Direct and indirect band gaps, sense organs, business
Abstract

We study the surface charge accumulation on InN thin films that strongly effects mobility of charge carriers. The films are formed by MBE in the temperature range (400–470 °C) yielding films with different morphology, crystallinity, and optical properties. The band-gap values determined by optical absorption and PL studies are found to depend on the Hall carrier concentration as per the Moss-Burstein relation. The magnitude of the near surface band bending is measured on InN thin films by knowing the surface and bulk Fermi level position with respect to the valence band maximum using X-ray photoelectron spectroscopy and optical absorption measurements, respectively. The studies show that the surface charge occurs due to the In adlayer on the film causing band-bending is up to 1 eV for low band gap single crystalline films and nearly a flat band for the highly degenerate polycrystalline films. The absence of the band bending is seen to occur when the bulk carrier concentration related to the crystalline quality of the InN films, tends to equate with the surface charge density.

Published
2013
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18. Publisher's Note: 'Evaluation of InGaPN and GaAsPN materials lattice-matched to Si for multi-junction solar cells' [J. Appl. Phys. 113, 123509 (2013)]

Author

Thomas Quinci, Clotilde Des Robert, Jean-Marc Jancu, Antoine Létoublon, A. Le Corre, T. Nguyen Thanh, Andrea Balocchi, Charles Cornet, N. Bertru, Christophe Levallois, Laurent Pedesseau, Mathieu Perrin, Jithesh Kuyyalil, Samy Almosni, Olivier Durand, Philippe Barate, Xavier Marie, and Jacky Even

Subjects
Materials science, Condensed matter physics, Silicon, business.industry, Wide-bandgap semiconductor, General Physics and Astronomy, chemistry.chemical_element, Multijunction photovoltaic cell, Gallium arsenide, chemistry.chemical_compound, chemistry, Lattice (order), Optoelectronics, business
Published
2013
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19. Effect of interfacial lattice mismatch on bulk carrier concentration and band gap of InN

Author

Malleswararao Tangi, S. M. Shivaprasad, and Jithesh Kuyyalil

Subjects
Materials science, Effective mass (solid-state physics), Semiconductor, Condensed matter physics, Band gap, business.industry, Kondo insulator, Wide-bandgap semiconductor, General Physics and Astronomy, Direct and indirect band gaps, business, Semimetal, Wurtzite crystal structure
Abstract

The issue of ambiguous values of the band gap (0.6 to 2 eV) of InN thin film in literature has been addressed by a careful experiment. We have grown wurtzite InN films by PA-MBE simultaneously on differently modified c-plane sapphire substrates and characterized by complementary structural and chemical probes. Our studies discount Mie resonances caused by metallic In segregation at grain boundaries as the reason for low band gap values (≈ 0.6 eV) and also the formation of Indium oxides and oxynitrides as the cause for high band gap value (≈ 2.0 eV). It is observed that polycrystallinity arising from azimuthal miss-orientation of c-oriented wurtzite InN crystals increases the carrier concentration and the band gap values. We have reviewed the band gap, carrier concentration, and effective mass of InN in literature and our own measurements, which show that the Moss-Burstein relation with a non-parabolic conduction band accounts for the observed variation of band gap with carrier concentration.

Published
2012
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20. Role of native defects in nitrogen flux dependent carrier concentration of InN films grown by molecular beam epitaxy

Author

S. M. Shivaprasad, Malleswararao Tangi, and Jithesh Kuyyalil

Subjects
Materials science, business.industry, Band gap, General Physics and Astronomy, chemistry.chemical_element, Nitrogen, Electron spectroscopy, Crystallographic defect, Crystallography, Semiconductor, chemistry, Absorption edge, X-ray photoelectron spectroscopy, Chemical physics, business, Molecular beam epitaxy
Abstract

We address the carrier concentration, strain, and bandgap issue of InN films grown on c-sapphire at different N-flux by molecular beam epitaxy using x-ray diffraction and x-ray photoelectron spectroscopy. We demonstrate that the strain in InN films arises due to point defects like nitrogen interstitials and nitrogen antisites. We report minimal biaxial strain due to relaxed growth morphology and a minimal hydrostatic strain arising due to interstitial nitrogen atoms being partially compensated by nitrogen antisites. We find that the variation in absorption edge can be attributed to defect induced carrier concentration and that nitrogen interstitials and nitrogen antisites act as donors that yield the respective absorption edge and Moss-Burstein shift. Our studies are a step towards the ability to form low carrier concentration strain-relaxed films and to determine the intrinsic band gap value for this technologically important material.

Published
2012
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21. Dependence of crystal orientation and bandgap on substrate temperature of molecular-beam epitaxy grown InN on bare Al2O3 (0001)

Author

Malleswararao Tangi, Jithesh Kuyyalil, and S. M. Shivaprasad

Subjects
Materials science, Band gap, Inorganic chemistry, Sapphire, Analytical chemistry, General Physics and Astronomy, Grain boundary, Substrate (electronics), Nitride, Epitaxy, Wurtzite crystal structure, Molecular beam epitaxy
Abstract

The issue of variable bandgap values for InN films grown on c-sapphire has been addressed in this work. α-InN films have been deposited in nitrogen rich condition at different substrate temperatures on bare Al2O3 (0001) by plasma assisted molecular beam epitaxy (PA-MBE). The results of several complementary characterization techniques show that single crystalline wurtzite InN is formed, but their orientation depends on the substrate temperature. The bandgap measured on these samples (1.78 eV) is explained by Moss-Burstein shift on these degenerately n-doped samples. Our results discount effects of crystal orientation, presence of oxygen at grain boundaries and In/N stoichiometry as factors that influence the measured band-gap values.

Published
2011
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22. Ga induced superstructures as templates for lattice matched hetroepitaxial growth of GaN on Si(111) substrate

Author

Praveen Kumar, S. M. Shivaprasad, and Jithesh Kuyyalil

Subjects
Crystallography, Full width at half maximum, Photoluminescence, Lattice constant, Materials science, Physics and Astronomy (miscellaneous), Surface roughness, Crystal growth, Thin film, Epitaxy, Molecular beam epitaxy
Abstract

High quality GaN is grown by plasma assisted molecular beam epitaxy on Ga induced superstructural phases of Si(111)7×7. Three stable surface phases induced by Ga adsorption, viz., (1×1), (6.3×6.3), and (√3×√3)R30°, are employed as templates to grow epitaxial (0001) GaN thin films. GaN grown on Si(√3×√3)R30°-Ga is found to be highly crystalline with intense (0002) x-ray diffraction and photoluminescence peaks with low full width at half maximum, low surface roughness, and stoichiometric surface composition. The high quality of these GaN films formed at a low temperature of 400 °C is explained by the integral (×2) lattice matching between the unit cell of GaN and the (√3×√3) phase. The experiments demonstrate a plausible approach of adsorbate induced surface modifications as templates for III-V hetroepitaxy on Si surfaces.

Published
2010
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