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1. Indepth doping assessment of thick doped GaAs layer by scanning spreading resistance microscopy.

Author

Qiang, Lanpeng, Chereau, Emmanuel, Regreny, Philippe, Avit, Geoffrey, Trassoudaine, Agnès, Gil, Evelyne, André, Yamina, Bluet, Jean-Marie, Albertini, David, and Brémond, Georges

Subjects
MOLECULAR beam epitaxy, SECONDARY ion mass spectrometry, AUDITING standards, MOLECULAR structure, THICK films, GALLIUM arsenide
Abstract

Scanning spreading resistance microscopy (SSRM) measurements were performed on GaAs thick films grown by hydride vapor phase epitaxy technology under different growth conditions to evaluate their carrier concentrations. For this purpose, a calibration curve was established based on a multilayer staircase structure grown by molecular beam epitaxy. The dopant calibration range measured by secondary ion mass spectrometry is from 5 × 1016 to 1019 cm−3. An abnormal phenomenon in the calibration process was explained by taking into account the parasitic parallel resistance of the calibration samples. Finally, the calibration curve was used to quantitatively analyze the carriers inside the Zn doping p-type GaAs film from 4 × 1016 to 1018 cm−3 range. We demonstrate here the applicability of SSRM to the in-depth analysis of thick epilayers, providing new inputs for the control of thick film technologies. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Charge and spin transport over record distances in GaAs metallic n-type nanowires : I photocarrier transport in a dense Fermi sea

Author

Hijazi, Hadi, Paget, Daniel, Monier, Guillaume, Grégoire, Gabin, Leymarie, Joël, Gil, Evelyne, Cadiz, Fabian, Robert-Goumet, Christine, and André, Yamina

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter
Abstract

We have investigated charge and spin transport in n-type metallic GaAs nanowires (~ 10^17 cm^-3 doping level), grown by hydride vapor phase epitaxy (HVPE) on Si substrates. This was done by exciting the nanowire by tightly-focussed circularly-polarized light and by monitoring the intensity and circular polarization spectrum as a function of distance from the excitation spot. The spin-polarized photoelectrons give rise to a well-defined feature in the nearbandgap spectrum, distinct from the main line due to recombination of the spin-unpolarized electrons of the Fermi sea with the same minority photoholes. At a distance of 2 (micro)m, only the main line remains, implying that photoelectrons have reached a charge thermodynamic equilibrium with the Fermi sea. However, although no line is present in the intensity spectrum at the corresponding energy, the circular polarization is still observed at the same energy in the spectrum, implying that photoelectrons have preserved their spin orientation and that the two spin reservoirs remain distinct. Investigations as a function of distance to the excitation spot show that, depending on excitation power, a photoelectron spin polarization of 20% can be transported over a record distance of more than 20 (micro)m. This finding has potential applications for long distance spin transport in n-type doped nanowires.

Published
2020
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3. Limitation of simple np-n tunnel junction based LEDs grown by MOVPE

Author

Robin, Yoann, Bournet, Quentin, Avit, Geoffrey, Pristovsek, Markus, André, Yamina, Trassoudaine, Agnès, and Amano, Hiroshi

Subjects
Physics - Applied Physics, Condensed Matter - Materials Science
Abstract

We show evidence that tunnel junctions (TJs) in GaN grown by metal-organic vapor phase epitaxy are dominated by trap-assisted (Poole-Frenkel) tunneling. This stems from observations of the careful optimized doping for the TJs. Especially the p$^{++}$ and the n$^{++}$ layers are far from ideal. The n$^{++}$ layer induces 3D growth, which can be seen by a rising oxygen signal in Secondary Ions Mass Spectroscopy (SIMS). Furthermore, Mg segregation observed by SIMS indicates a depletion region of more than 10 nm. Still, we could realize TJ based LEDs with a low penalty voltage of 1.1 V and a specific differential resistance of about 10$^{-2}$ $\Omega$.cm$^2$ at 20 mA without using an InGaN interlayer.

Published
2020
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4. Control of SAG-GaN at the Nanoscale.

Author

Semlali, Elias, Gil, Evelyne, Avit, Geoffrey, André, Yamina, Sauvagnat, Arthur, Jridi, Jihen, Moskalenko, Andriy V., Shields, Philip A., Rochat, Névine, Grenier, Adeline, and Trassoudaine, Agnès

Published
2024
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5. Selective Area HVPE of InGaAs Nanowires with Widely Tunable Composition on Si Substrates for Nanoscale Device Integration on Si Platforms.

Author

Chereau, Emmanuel, Dubrovskii, Vladimir G., Diak, Ethan, Semlali, Elias, Avit, Geoffrey, Trassoudaine, Agnès, Gil, Evelyne, LaPierre, Ray, and André, Yamina

Abstract

Nanowires (NWs) are promising for the integration of III–V compound-based electrical and optical devices on Si. Selective area growth (SAG) of InxGa1–xAs NWs with compositions x varying from 0.34 to 0.90 is achieved. NWs are grown on patterned Si(111) substrates by hydride vapor phase epitaxy (HVPE) at temperatures around 690 °C. The composition is measured using EDX profiles along their lengths and found to be quite homogeneous. Theoretical analysis revealed that the NW composition is kinetically controlled and well-fit by the one-parametric Langmuir–McLean formula, with no thermodynamic factors influencing the compositional trend. This study highlights the capability of catalyst-free HVPE SAG to grow highly uniform InGaAs NW arrays with a widely tunable composition on Si substrates. [ABSTRACT FROM AUTHOR]

Published
2024
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6. VLS-HVPE growth of ultra-long and defect-free GaAs nanowires investigated by ab initio simulation coupled to near-field microscopy

Author

Andre, Yamina, Lekhal, Kaddour, Hoggan, Philip, Avit, Geoffrey, Cadiz, Fabian, Rowe, Alistair, Paget, Daniel, Petit, Elodie, Leroux, Christine, Trassoudaine, Agnes, Ramdani, Reda, Monier, Guillaume, Colas, David, Ajib, Rabih, Castelluci, Dominique, and Gil, Evelyne

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

High aspect ratio, rod-like and single crystal phase GaAs nanowires (NWs) were grown by gold catalyst-assisted hydride vapor phase epitaxy (HVPE). High resolution transmission electron microscopy (HRTEM) and micro-Raman spectroscopy revealed polytypism-free zinc blende NWs over lengths of several tens of micrometers for diameters ranging between 50 and 150 nm. Micro-photoluminescence studies of individual NWs showed linewidths smaller than those reported elsewhere which is consistent with the crystalline quality of the NWs. HVPE makes use of chloride growth precursors of which high decomposition frequency, after adsorption onto the catalyst particle, favors a direct and rapid introduction of the Ga atoms from the vapor phase into the catalyst liquid droplet. This yields high axial growth rate (more than 100 micron/h) of NWs. The fast diffusion of the Ga atoms in the droplet towards the interface between the liquid and the solid nanowire was investigated by using density functional theory calculations. The diffusion coefficient of Ga atoms was estimated to be 3x10-9 m2/s, which matches the experimental observations., Comment: This paper has been withdrawn by the author due to several corrections, including new calculation results and update experimentle calculations

Published
2013

7. Long indium-rich InGaAs nanowires by SAG-HVPE.

Author

Chereau, Emmanuel, Grégoire, Gabin, Avit, Geoffrey, Taliercio, Thierry, Staudinger, Philipp, Schmid, Heinz, Bougerol, Catherine, Trassoudaine, Agnès, Gil, Evelyne, LaPierre, Ray R, and André, Yamina

Subjects
NANOWIRES, INDIUM gallium arsenide, ENERGY dispersive X-ray spectroscopy, ELECTRON energy loss spectroscopy, TRANSMISSION electron microscopy
Abstract

We demonstrate the selective area growth of InGaAs nanowires (NWs) on GaAs (111)B substrates using hydride vapor phase epitaxy (HVPE). A high growth rate of more than 50 μ m h−1 and high aspect ratio NWs were obtained. Composition along the NWs was investigated by energy dispersive x-ray spectroscopy giving an average indium composition of 84%. This is consistent with the composition of 78% estimated from the photoluminescence spectrum of the NWs. Crystal structure analysis of the NWs by transmission electron microscopy indicated random stacking faults related to zinc-blende/wurtzite polytypism. This work demonstrates the ability of HVPE for growing high aspect ratio InGaAs NW arrays. [ABSTRACT FROM AUTHOR]

Published
2024
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8. Importance of As and Ga Balance in Achieving Long GaAs Nanowires by Selective Area Epitaxy

Author

Chereau, Emmanuel, primary, Dubrovskii, Vladimir G., additional, Grégoire, Gabin, additional, Avit, Geoffrey, additional, Staudinger, Philipp, additional, Schmid, Heinz, additional, Bougerol, Catherine, additional, Coulon, Pierre-Marie, additional, Shields, Philip A., additional, Trassoudaine, Agnès, additional, Gil, Evelyne, additional, LaPierre, Ray R., additional, and André, Yamina, additional

Published
2023
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10. Selective Area Growth of GaAs Nanowires and Microplatelet Arrays on Silicon by Hydride Vapor-Phase Epitaxy

Author

Zeghouane, Mohammed, primary, Grégoire, Gabin, additional, Chereau, Emmanuel, additional, Avit, Geoffrey, additional, Staudinger, Philipp, additional, Moselund, Kirsten E., additional, Schmid, Heinz, additional, Coulon, Pierre-Marie, additional, Shields, Philip, additional, Isik Goktas, Nebile, additional, LaPierre, Ray R., additional, Trassoudaine, Agnès, additional, André, Yamina, additional, and Gil, Evelyne, additional

Published
2023
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11. List of Contributors

Author

Amano, Hiroshi, primary, André, Yamina, additional, Asahi, Hajime, additional, Ayers, John E., additional, Aziz, Michael J., additional, Bansal, Bhavtosh, additional, Bhattacharya, Arnab, additional, Biefeld, Robert M., additional, Bol, A.A., additional, Brown, April S., additional, Cadoret, Robert, additional, Cederberg, Jeffrey G., additional, Chen, Xiaogang, additional, Cobas, Enrique D., additional, Coleman, James J., additional, Dadgar, Armin, additional, Evans, Paul G., additional, Fornari, Roberto, additional, Fujioka, Hiroshi, additional, Gaskill, D. Kurt, additional, Gil, Evelyne, additional, Goorsky, Mark S., additional, Johnson, Brett C., additional, Kessels, W.M.M., additional, Kim, Jeong Dong, additional, Kimoto, Tsunenobu, additional, Knoops, H.C.M., additional, Koblmüller, G., additional, Koleske, Daniel D., additional, Krost, Alois, additional, Kuech, Thomas F., additional, Lang, J.R., additional, Li, Hongdong, additional, Li, Xiuling, additional, Losurdo, Maria, additional, Matsukura, Fumihiro, additional, Mauk, Michael G., additional, McCallum, Jeffrey C., additional, McCreary, Kathleen M., additional, Miao, Xin, additional, Nakatsuka, Osamu, additional, Newman, Nathan, additional, Nishinaga, Tatau, additional, Ohno, Hideo, additional, Potts, S.E., additional, Ptak, Aaron J., additional, Redwing, Joan M., additional, Robinson, Zachary R., additional, Schmucker, Scott W., additional, Simbrunner, Clemens, additional, Sitter, Helmut, additional, Skowronski, Marek, additional, Spalenka, Josef W., additional, Speck, J.S., additional, Stolz, Wolfgang, additional, Suhir, E., additional, Talalaev, Roman, additional, Tanaka, Hidekazu, additional, Trassoudaine, Agnès, additional, Vahidi, Mahmoud, additional, Volz, Kerstin, additional, Young, E.C., additional, and Zaima, Shigeaki, additional

Published
2015
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13. Selective Area Growth by Hydride Vapor Phase Epitaxy and Optical Properties of InAs Nanowire Arrays

Author

Grégoire, Gabin, primary, Zeghouane, Mohammed, additional, Goosney, Curtis, additional, Goktas, Nebile Isik, additional, Staudinger, Philipp, additional, Schmid, Heinz, additional, Moselund, Kirsten E., additional, Taliercio, Thierry, additional, Tournié, Eric, additional, Trassoudaine, Agnès, additional, Gil, Evelyne, additional, LaPierre, Ray R., additional, and André, Yamina, additional

Published
2021
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16. Long catalyst-free InAs nanowires grown on silicon by HVPE

Author

Grégoire, Gabin, primary, Gil, Evelyne, additional, Zeghouane, Mohammed, additional, Bougerol, Catherine, additional, Hijazi, Hadi, additional, Castelluci, Dominique, additional, Dubrovskii, Vladimir G., additional, Trassoudaine, Agnès, additional, Goktas, Nebile Isik, additional, LaPierre, Ray R., additional, and André, Yamina, additional

Published
2021
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17. Optical and structural analysis of ultra-long GaAs nanowires after nitrogen-plasma passivation

Author

André, Yamina, primary, Isik Goktas, Nebile, additional, Monier, Guillaume, additional, Hijazi, Hadi, additional, Mehdi, Hussein, additional, Bougerol, Catherine, additional, Bideux, Luc, additional, Trassoudaine, Agnès, additional, Paget, Daniel, additional, Leymarie, Joël, additional, Gil, Evelyne, additional, Robert-Goumet, Christine, additional, and LaPierre, Ray R, additional

Published
2020
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18. Formation of voids in selective area growth of InN nanorods in SiNx on GaN templates

Author

Zeghouane, Mohammed, primary, André, Yamina, additional, Avit, Geoffrey, additional, Jridi, Jihen, additional, Bougerol, Catherine, additional, Coulon, Pierre-Marie, additional, Ferret, Pierre, additional, Castelluci, Dominique, additional, Gil, Evelyne, additional, Shields, Philip, additional, Dubrovskii, Vladimir G, additional, and Trassoudaine, Agnès, additional

Published
2020
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19. Dynamics of Gold Droplet Formation on SiO2/Si(111) Surface

Author

Hijazi, Hadi, primary, Leroy, Frédéric, additional, Monier, Guillaume, additional, Grégoire, Gabin, additional, Gil, Evelyne, additional, Trassoudaine, Agnès, additional, Dubrovskii, Vladimir G., additional, Castelluci, Dominique, additional, Goktas, Nebile Isik, additional, LaPierre, Ray R., additional, André, Yamina, additional, and Robert-Goumet, Christine, additional

Published
2020
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21. Si Doping of Vapor–Liquid–Solid GaAs Nanowires: n-Type or p-Type?

Author

Hijazi, Hadi, primary, Monier, Guillaume, additional, Gil, Evelyne, additional, Trassoudaine, Agnès, additional, Bougerol, Catherine, additional, Leroux, Christine, additional, Castellucci, Dominique, additional, Robert-Goumet, Christine, additional, Hoggan, Philip E., additional, André, Yamina, additional, Isik Goktas, Nebile, additional, LaPierre, Ray R., additional, and Dubrovskii, Vladimir G., additional

Published
2019
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22. Selective growth of ordered hexagonal InN nanorods

Author

Zeghouane, Mohammed, primary, Avit, Geoffrey, additional, Cornelius, Thomas W., additional, Salomon, Damien, additional, André, Yamina, additional, Bougerol, Catherine, additional, Taliercio, Thierry, additional, Meguekam-Sado, Ariane, additional, Ferret, Pierre, additional, Castelluci, Dominique, additional, Gil, Evelyne, additional, Tournié, Eric, additional, Thomas, Olivier, additional, and Trassoudaine, Agnès, additional

Published
2019
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23. Vapor liquid solid-hydride vapor phase epitaxy (VLS-HVPE) growth of ultra-long defect-free GaAs nanowires: Ab initio simulations supporting center nucleation.

Author

André, Yamina, Lekhal, Kaddour, Hoggan, Philip, Avit, Geoffrey, Cadiz, Fabian, Rowe, Alistair, Paget, Daniel, Petit, Elodie, Leroux, Christine, Trassoudaine, Agnès, Réda Ramdani, M., Monier, Guillaume, Colas, David, Ajib, Rabih, Castelluci, Dominique, and Gil, Evelyne

Subjects
*CRYSTAL growth, *MOLECULAR beam epitaxy, *CRYSTALLIZATION, *CRYSTAL grain boundaries, *SEMICONDUCTOR growth, *NANOSTRUCTURED materials, *TRANSMISSION electron microscopy
Abstract

High aspect ratio, rod-like and single crystal phase GaAs nanowires (NWs) were grown by gold catalyst-assisted hydride vapor phase epitaxy (HVPE). High resolution transmission electron microscopy and micro-Raman spectroscopy revealed polytypism-free zinc blende (ZB) NWs over lengths of several tens of micrometers for a mean diameter of 50 nm. Micro-photoluminescence studies of individual NWs showed linewidths smaller than those reported elsewhere which is consistent with the crystalline quality of the NWs. HVPE makes use of chloride growth precursors GaCl of which high decomposition frequency after adsorption onto the liquid droplet catalysts, favors a direct and rapid introduction of the Ga atoms from the vapor phase into the droplets. High influxes of Ga and As species then yield high axial growth rate of more than 100 μm/h. The diffusion of the Ga atoms in the liquid droplet towards the interface between the liquid and the solid nanowire was investigated by using density functional theory calculations. The diffusion coefficient of Ga atoms was estimated to be 3 × 10-9 m2/s. The fast diffusion of Ga in the droplet favors nucleation at the liquid-solid line interface at the center of the NW. This is further evidence, provided by an alternative epitaxial method with respect to metal-organic vapor phase epitaxy and molecular beam epitaxy, of the current assumption which states that this type of nucleation should always lead to the formation of the ZB cubic phase. [ABSTRACT FROM AUTHOR]

Published
2014
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24. Highlights of the HVPE for the frowth of GaN and InGaN nanowires

Author

Trassoudaine, Agnes, André, Yamina, Avit, Geoffrey, Gil, Evelyne, Castelluci, Dominique, ZEGHOUANE, Mohammed, Leymarie, Joël, Médard, François, Bougerol, Catherine, Roche, Elissa, Institut Pascal (IP), SIGMA Clermont (SIGMA Clermont)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020]), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-SIGMA Clermont (SIGMA Clermont)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des sciences et matériaux pour l'électronique et d'automatique (LASMEA), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Nanophysique et Semiconducteurs (NPSC), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), SIGMA Clermont (SIGMA Clermont)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), and Nanophysique et Semiconducteurs (NEEL - NPSC)

Subjects
[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2017

27. Circumventing the miscibility gap in InGaN nanowires emitting from blue to red

Author

Roche, Elissa, primary, André, Yamina, additional, Avit, Geoffrey, additional, Bougerol, Catherine, additional, Castelluci, Dominique, additional, Réveret, François, additional, Gil, Evelyne, additional, Médard, François, additional, Leymarie, Joël, additional, Jean, Theo, additional, Dubrovskii, Vladimir G, additional, and Trassoudaine, Agnès, additional

Published
2018
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31. Self-catalyzed GaAs nanowires on silicon by hydride vapor phase epitaxy

Author

Dong, Zhenning, primary, André, Yamina, additional, Dubrovskii, Vladimir G, additional, Bougerol, Catherine, additional, Leroux, Christine, additional, Ramdani, Mohammed R, additional, Monier, Guillaume, additional, Trassoudaine, Agnès, additional, Castelluci, Dominique, additional, and Gil, Evelyne, additional

Published
2017
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32. GaN Rods Grown on Si by SAG-HVPE toward GaN HVPE/InGaN MOVPE Core/Shell Structures

Author

Avit, Geoffrey, primary, André, Yamina, additional, Bougerol, Catherine, additional, Castelluci, Dominique, additional, Dussaigne, Amélie, additional, Ferret, Pierre, additional, Gaugiran, Stéphanie, additional, Gayral, Bruno, additional, Gil, Evelyne, additional, Lee, Yann, additional, Ramdani, M. Reda, additional, Roche, Elissa, additional, and Trassoudaine, Agnès, additional

Published
2016
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33. Record Pure Zincblende Phase in GaAs Nanowires down to 5 nm in Radius

Author

Gil, Evelyne, primary, Dubrovskii, Vladimir G., additional, Avit, Geoffrey, additional, André, Yamina, additional, Leroux, Christine, additional, Lekhal, Kaddour, additional, Grecenkov, Jurij, additional, Trassoudaine, Agnès, additional, Castelluci, Dominique, additional, Monier, Guillaume, additional, Ramdani, Reda M., additional, Robert-Goumet, Christine, additional, Bideux, Luc, additional, Harmand, Jean Christophe, additional, and Glas, Frank, additional

Published
2014
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34. Ultralong and Defect-Free GaN Nanowires Grown by the HVPE Process

Author

Avit, Geoffrey, primary, Lekhal, Kaddour, additional, André, Yamina, additional, Bougerol, Catherine, additional, Réveret, François, additional, Leymarie, Joël, additional, Gil, Evelyne, additional, Monier, Guillaume, additional, Castelluci, Dominique, additional, and Trassoudaine, Agnès, additional

Published
2014
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35. Hydride VPE: the unexpected process for the fast growth of GaAs and GaN nanowires with record aspect ratio and polytypism-free crystalline structure

Author

André, Yamina, additional, Trassoudaine, Agnès, additional, Avit, Geoffrey, additional, Lekhal, Kaddour, additional, Ramdani, Mohammed R., additional, Leroux, Christine, additional, Monier, Guillaume, additional, Varenne, Christelle, additional, Hoggan, Philip, additional, Castelluci, Dominique, additional, Bougerol, Catherine, additional, Réveret, François, additional, Leymarie, Joël, additional, Petit, Elodie, additional, Dubrovskii, Vladimir G., additional, and Gil, Evelyne, additional

Published
2013
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37. Hydride VPE: the unexpected process for the fast growth of GaAs and GaN nanowires with record aspect ratio and polytypism-free crystalline structure

Author

Friend, James, Tan, H. Hoe, André, Yamina, Trassoudaine, Agnès, Avit, Geoffrey, Lekhal, Kaddour, Ramdani, Mohammed R., Leroux, Christine, Monier, Guillaume, Varenne, Christelle, Hoggan, Philip, Castelluci, Dominique, Bougerol, Catherine, Réveret, François, Leymarie, Joël, Petit, Elodie, Dubrovskii, Vladimir G., and Gil, Evelyne

Published
2013
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38. Continuous wave and ultra-fast reflectivity studies for the determination of GaN excitonic oscillator strengths as a function of the in-plane biaxial strain

Author

O. Aoudé, Agnès Trassoudaine, A M Vasson, Yamina André, E. Aujol, Pierre Disseix, Joël Leymarie, Bernard Beaumont, Laboratoire des sciences et matériaux pour l'électronique et d'automatique (LASMEA), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), and André, Yamina

Subjects
010302 applied physics, Materials science, Condensed matter physics, Oscillator strength, business.industry, Exciton, Biaxial tensile test, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, Condensed Matter Physics, 01 natural sciences, Spectral line, Condensed Matter::Materials Science, Quality (physics), [PHYS.COND.CM-GEN] Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Femtosecond, Continuous wave, Optoelectronics, General Materials Science, Electrical and Electronic Engineering, 010306 general physics, business, Impulse response
Abstract

Up to now, many works have been dedicated to the study of the excitonic parameters of GaN by analyzing cw-spectroscopy results. In this work, time-resolved reflectivity experiments are carried out to record the impulse response of excitons at the femtosecond scale. By combining the analysis of continuous wave and time-resolved reflectivity spectra recorded on high quality GaN samples, the excitonic parameters are determined with accuracy. The oscillator strength evolutions of A, B and C free excitons are analysed versus the in-plane biaxial stress and compared with theoretical predictions.

Published
2005

39. Circumventing the ammonia-related growth suppression for obtaining regular GaN nanowires by HVPE.

Author

Semlali E, Avit G, André Y, Gil E, Moskalenko A, Shields P, Dubrovskii VG, Cattoni A, Harmand JC, and Trassoudaine A

Abstract

Selective area growth by hydride vapor phase epitaxy of GaN nanostructures with different shapes was investigated versus the deposition conditions including temperature and ammonia flux. Growth experiments were carried out on templates of GaN on sapphire masked with SiN x . We discuss two occurrences related to axial and radial growth of GaN nanowires. A growth suppression phenomenon was observed under certain conditions, which was circumvented by applying the cyclic growth mode. A theoretical model involving inhibiting species was developed to understand the growth suppression phenomenon on the masked substrates. Various morphologies of GaN nanocrystals were obtained by controlling the competition between the growth and blocking mechanisms as a function of the temperature and vapor phase composition. The optimal growth conditions were revealed for obtaining regular arrays of ∼5 μ m long GaN nanowires., (© 2024 IOP Publishing Ltd.)

Published
2024
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40. Compositional control of homogeneous InGaN nanowires with the In content up to 90.

Author

Zeghouane M, Avit G, André Y, Bougerol C, Robin Y, Ferret P, Castelluci D, Gil E, Dubrovskii VG, Amano H, and Trassoudaine A

Abstract

Homogenous InGaN nanowires with a controlled indium composition up to 90% are grown on GaN/c-Al 2 O 3 templates by catalyst-free hydride vapor phase epitaxy using InCl 3 and GaCl as group III element precursors. The influence of the partial pressures on the growth rate and composition of InGaN nanowires is investigated. It is shown how the InN mole fraction in nanowires can be finely tuned by changing the vapor phase composition. Thermodynamic calculations are presented that take into account different interconnected reactions in the vapor phase and show a good agreement with the compositional data. Energy dispersive x-ray spectroscopy profiles performed on single nanowires show a homogenous indium composition along the entire nanowire length. X-ray diffraction measurements performed on nanowires arrays confirm these data. High-resolution transmission electron microscopy analysis shows the wurtzite crystal structure with a reduced defect density for InGaN nanowires with the highest indium content.

Published
2019
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