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Amador-Mendez N, Kochetkov FM, Hernandez R, Neplokh V, Grenier V, Finot S, Valera L, Duraz J, Fominykh N, Parshina EK, Deriabin KV, Islamova RM, Herth E, Bouchoule S, Julien F, Abraham M, Das S, Jacopin G, Krasnikov DV, Nasibulin A, Eymery J, Durand C, Mukhin IS, Tchernycheva M. UV-A Flexible LEDs Based on Core-Shell GaN/AlGaN Quantum Well Microwires. ACS APPLIED MATERIALS & INTERFACES 2024; 16:51000-51009. [PMID: 39258764 DOI: 10.1021/acsami.4c06181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2024]
Abstract
Nanostructured ultraviolet (UV) light sources represent a growing research field in view of their potential applications in wearable optoelectronics or medical treatment devices. In this work, we report the demonstration of the first flexible UV-A light emitting diode (LED) based on AlGaN/GaN core-shell microwires. The device is based on a composite microwire/poly(dimethylsiloxane) (PDMS) membrane with flexible transparent electrodes. The electrode transparency in the UV range is optimized: namely, we demonstrate that single-walled carbon nanotube electrodes provide a stable electrical contact to the membrane with high transparency (70% at 350 nm). The flexible UV-A membrane demonstrating electroluminescence around 345 nm is further applied to excite Zn-Ir-BipyPDMS luminophores: the UV-A LED is combined with the elastic luminophore-containing membrane to produce a visible amber emission from 520 to 650 nm. The obtained results pave the way for flexible inorganic light-emitting diodes to be employed in sensing, detection of fluorescent labels, or light therapy.
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Grimes M, Atlan C, Chatelier C, Bellec E, Olson K, Simonne D, Levi M, Schülli TU, Leake SJ, Rabkin E, Eymery J, Richard MI. Capturing Catalyst Strain Dynamics during Operando CO Oxidation. ACS NANO 2024. [PMID: 39009584 DOI: 10.1021/acsnano.4c04127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/17/2024]
Abstract
Understanding the strain dynamic behavior of catalysts is crucial for the development of cost-effective, efficient, stable, and long-lasting catalysts. Using time-resolved Bragg coherent diffraction imaging at the fourth generation Extremely Brilliant Source of the European Synchrotron (ESRF-EBS), we achieved subsecond time resolution during operando chemical reactions. Upon investigation of Pt nanoparticles during CO oxidation, the three-dimensional strain profile highlights significant changes in the surface and subsurface regions, where localized strain is probed along the [111] direction. Notably, a rapid increase in tensile strain was observed at the top and bottom Pt {111} facets during CO adsorption. Moreover, we detected oscillatory strain changes (6.4 s period) linked to CO adsorption during oxidation, where a time resolution of 0.25 s was achieved. This approach allows for the study of adsorption dynamics of catalytic nanomaterials at the single-particle level under operando conditions, which provides insight into nanoscale catalytic mechanisms.
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Chatelier C, Atlan C, Dupraz M, Leake S, Li N, Schülli TU, Levi M, Rabkin E, Favre L, Labat S, Eymery J, Richard MI. Unveiling Core-Shell Structure Formation in a Ni 3Fe Nanoparticle with In Situ Multi-Bragg Coherent Diffraction Imaging. ACS NANO 2024; 18:13517-13527. [PMID: 38753950 DOI: 10.1021/acsnano.3c11534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Solid-state reactions play a key role in materials science. The evolution of the structure of a single 350 nm Ni3Fe nanoparticle, i.e., its morphology (facets) as well as its deformation field, has been followed by applying multireflection Bragg coherent diffraction imaging. Through this approach, we unveiled a demixing process that occurs at high temperatures (600 °C) under an Ar atmosphere. This process leads to the gradual emergence of a highly strained core-shell structure, distinguished by two distinct lattice parameters with a difference of 0.4%. Concurrently, this transformation causes the facets to vanish, ultimately yielding a rounded core-shell nanoparticle. This final structure comprises a Ni3Fe core surrounded by a 40 nm Ni-rich outer shell due to preferential iron oxidation. Providing in situ 3D imaging of the lattice parameters at the nanometer scale while varying the temperature, this study─with the support of atomistic simulations─not only showcases the power of in situ multireflection BCDI but also provides valuable insights into the mechanisms at work during a solid-state reaction characterized by a core-shell transition.
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Atlan C, Chatelier C, Martens I, Dupraz M, Viola A, Li N, Gao L, Leake SJ, Schülli TU, Eymery J, Maillard F, Richard MI. Imaging the strain evolution of a platinum nanoparticle under electrochemical control. NATURE MATERIALS 2023:10.1038/s41563-023-01528-x. [PMID: 37095227 DOI: 10.1038/s41563-023-01528-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 03/09/2023] [Indexed: 05/03/2023]
Abstract
Surface strain is widely employed in gas phase catalysis and electrocatalysis to control the binding energies of adsorbates on active sites. However, in situ or operando strain measurements are experimentally challenging, especially on nanomaterials. Here we exploit coherent diffraction at the new fourth-generation Extremely Brilliant Source of the European Synchrotron Radiation Facility to map and quantify strain within individual Pt catalyst nanoparticles under electrochemical control. Three-dimensional nanoresolution strain microscopy, together with density functional theory and atomistic simulations, show evidence of heterogeneous and potential-dependent strain distribution between highly coordinated ({100} and {111} facets) and undercoordinated atoms (edges and corners), as well as evidence of strain propagation from the surface to the bulk of the nanoparticle. These dynamic structural relationships directly inform the design of strain-engineered nanocatalysts for energy storage and conversion applications.
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Beutier G, Eymery J, Dupraz M, Richard M, Wartelle A, Verdier M, De Boissieu M, Collins S, Bellec E, Favre-Nicolin V, Leake S. Coherent diffraction imaging at space-group forbidden reflections. ACTA CRYSTALLOGRAPHICA SECTION A FOUNDATIONS AND ADVANCES 2022. [DOI: 10.1107/s2053273322094372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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Atlan C, Chatelier C, Viola A, Dupraz M, Leake S, Eymery J, Maillard F, Richard M. Operando potential-induced strain heterogeneity of a breathing Pt nanoparticle. ACTA CRYSTALLOGRAPHICA SECTION A FOUNDATIONS AND ADVANCES 2022. [DOI: 10.1107/s2053273322090180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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7
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Richard M, Dupraz M, Chatelier C, Atlan C, Bellec E, Li N, Labat S, Schülli T, Rabkin E, Thomas O, Eymery J, Leake S. Structural evolution of nanoparticles under realistic conditions observed with Bragg coherent X-ray imaging. ACTA CRYSTALLOGRAPHICA SECTION A FOUNDATIONS AND ADVANCES 2022. [DOI: 10.1107/s2053273322095869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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Purushottam Raj Purohit R, Tardif S, Castelnau O, Eymery J, Guinebretière R, Robach O, Micha J. LaueNN: neural network based hkl recognition of Laue spots and its application to polycrystalline materials. ACTA CRYSTALLOGRAPHICA SECTION A FOUNDATIONS AND ADVANCES 2022. [DOI: 10.1107/s2053273322094815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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Chatelier C, Atlan C, Dupraz M, Li N, Rabkin E, Labat S, Eymery J, Richard M. In situ 3D observations of a core–shell volume transition in an Ni 3Fe nanocrystal using Bragg coherent X-ray diffraction imaging. ACTA CRYSTALLOGRAPHICA SECTION A FOUNDATIONS AND ADVANCES 2022. [DOI: 10.1107/s2053273322090192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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Richard MI, Labat S, Dupraz M, Li N, Bellec E, Boesecke P, Djazouli H, Eymery J, Thomas O, Schülli TU, Santala MK, Leake SJ. Bragg coherent diffraction imaging of single 20 nm Pt particles at the ID01-EBS beamline of ESRF. J Appl Crystallogr 2022; 55:621-625. [PMID: 35719306 PMCID: PMC9172036 DOI: 10.1107/s1600576722002886] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/15/2022] [Indexed: 11/24/2022] Open
Abstract
Electronic or catalytic properties can be modified at the nanoscale level. Engineering efficient and specific nanomaterials requires the ability to study their complex structure-property relationships. Here, Bragg coherent diffraction imaging was used to measure the three-dimensional shape and strain of platinum nanoparticles with a diameter smaller than 30 nm, i.e. significantly smaller than any previous study. This was made possible by the realization of the Extremely Brilliant Source of ESRF, The European Synchrotron. This work demonstrates the feasibility of imaging the complex structure of very small particles in three dimensions and paves the way towards the observation of realistic catalytic particles.
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Segura-Ruiz J, Salomon D, Rogalev A, Eymery J, Alén B, Martínez-Criado G. Spatially and Time-Resolved Carrier Dynamics in Core-Shell InGaN/GaN Multiple-Quantum Wells on GaN Wire. NANO LETTERS 2021; 21:9494-9501. [PMID: 34762425 DOI: 10.1021/acs.nanolett.1c02760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Time-resolved cathodoluminescence is a key tool with high temporal and spatial resolution. However, optical spectroscopic information can be also extracted using synchrotron pulses in a hard X-ray nanoprobe, exploiting a phenomenon called X-ray excited optical luminescence. Here, with 20 ps time resolution and 80 nm lateral resolution, we applied this time-resolved X-ray microscopy technique to individual core-shell InGaN/GaN multiple quantum well heterostructures deposited on GaN wires. Our findings suggest that the m-plane related multiple quantum well states govern the carrier dynamics. Likewise, our observations support not only the influence of In incorporation in the recombination rates, but also carrier localization phenomena at the hexagon wire apex. In addition, our experiment calls for further investigations of the spatiotemporal domain on the underlying mechanisms of optoelectronic nanodevices. Its great potential becomes more valuable when time-resolved X-ray excited optical luminescence microscopy is used in operando with other methods, such as X-ray absorption spectroscopy.
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Guan N, Amador-Mendez N, Kunti A, Babichev A, Das S, Kapoor A, Gogneau N, Eymery J, Julien FH, Durand C, Tchernycheva M. Heat Dissipation in Flexible Nitride Nanowire Light-Emitting Diodes. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2271. [PMID: 33207755 PMCID: PMC7696961 DOI: 10.3390/nano10112271] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/10/2020] [Accepted: 11/12/2020] [Indexed: 01/05/2023]
Abstract
We analyze the thermal behavior of a flexible nanowire (NW) light-emitting diode (LED) operated under different injection conditions. The LED is based on metal-organic vapor-phase deposition (MOCVD)-grown self-assembled InGaN/GaN NWs in a polydimethylsiloxane (PDMS) matrix. Despite the poor thermal conductivity of the polymer, active nitride NWs effectively dissipate heat to the substrate. Therefore, the flexible LED mounted on a copper heat sink can operate under high injection without significant overheating, while the device mounted on a plastic holder showed a 25% higher temperature for the same injected current. The efficiency of the heat dissipation by nitride NWs was further confirmed with finite-element modeling of the temperature distribution in a NW/polymer composite membrane.
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Grenier V, Finot S, Jacopin G, Bougerol C, Robin E, Mollard N, Gayral B, Monroy E, Eymery J, Durand C. UV Emission from GaN Wires with m-Plane Core-Shell GaN/AlGaN Multiple Quantum Wells. ACS APPLIED MATERIALS & INTERFACES 2020; 12:44007-44016. [PMID: 32894670 DOI: 10.1021/acsami.0c08765] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The present work reports high-quality nonpolar GaN/Al0.6Ga0.4N multiple quantum wells (MQWs) grown in core-shell geometry by metal-organic vapor-phase epitaxy on the m-plane sidewalls of c̅-oriented hexagonal GaN wires. Optical and structural studies reveal ultraviolet (UV) emission originating from the core-shell GaN/AlGaN MQWs. Tuning the m-plane GaN QW thickness from 4.3 to 0.7 nm leads to a shift of the emission from 347 to 292 nm, consistent with Schrödinger-Poisson calculations. The evolution of the luminescence with temperature displays signs of strong localization, especially for samples with thinner GaN QWs and no evidence of quantum-confined Stark effect, as expected for nonpolar m-plane surfaces. The internal quantum efficiency derived from the photoluminescence (PL) intensity ratio at low and room temperatures is maximum (∼7.3% measured at low power excitation) for 2.6 nm thick quantum wells, emitting at 325 nm, and shows a large drop for thicker QWs. An extensive study of the PL quenching with temperature is presented. Two nonradiative recombination paths are activated at different temperatures. The low-temperature path is found to be intrinsic to the heterostructure, whereas the process that dominates at high temperature depends on the QW thickness and is strongly enhanced for QWs larger than 2.6 nm, causing a rapid decrease in the internal quantum efficiency.
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Li N, Labat S, Leake SJ, Dupraz M, Carnis J, Cornelius TW, Beutier G, Verdier M, Favre-Nicolin V, Schülli TU, Thomas O, Eymery J, Richard MI. Mapping Inversion Domain Boundaries along Single GaN Wires with Bragg Coherent X-ray Imaging. ACS NANO 2020; 14:10305-10312. [PMID: 32806035 DOI: 10.1021/acsnano.0c03775] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Gallium nitride (GaN) is of technological importance for a wide variety of optoelectronic applications. Defects in GaN, like inversion domain boundaries (IDBs), significantly affect the electrical and optical properties of the material. We report, here, on the structural configurations of planar inversion domain boundaries inside n-doped GaN wires measured by Bragg coherent X-ray diffraction imaging. Different complex domain configurations are revealed along the wires with a 9 nm in-plane spatial resolution. We demonstrate that the IDBs change their direction of propagation along the wires, promoting Ga-terminated domains and stabilizing into {11̅00}, that is, m-planes. The atomic phase shift between the Ga- and N-terminated domains was extracted using phase-retrieval algorithms, revealing an evolution of the out-of-plane displacement (∼5 pm, at maximum) between inversion domains along the wires. This work provides an accurate inner view of planar defects inside small crystals.
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Kapoor A, Finot S, Grenier V, Robin E, Bougerol C, Bleuse J, Jacopin G, Eymery J, Durand C. Role of Underlayer for Efficient Core-Shell InGaN QWs Grown on m-plane GaN Wire Sidewalls. ACS APPLIED MATERIALS & INTERFACES 2020; 12:19092-19101. [PMID: 32208628 DOI: 10.1021/acsami.9b19314] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Different types of buffer layers such as InGaN underlayer (UL) and InGaN/GaN superlattices are now well-known to significantly improve the efficiency of c-plane InGaN/GaN-based light-emitting diodes (LEDs). The present work investigates the role of two different kinds of pregrowth layers (low In-content InGaN UL and GaN UL namely "GaN spacer") on the emission of the core-shell m-plane InGaN/GaN single quantum well (QW) grown around Si-doped c̅-GaN microwires obtained by silane-assisted metal organic vapor phase epitaxy. According to photo- and cathodoluminescence measurements performed at room temperature, an improved efficiency of light emission at 435 nm with internal quantum efficiency >15% has been achieved by adding a GaN spacer prior to the growth of QW. As revealed by scanning transmission electron microscopy, an ultrathin residual layer containing Si located at the wire sidewall surfaces favors the formation of high density of extended defects nucleated at the first InGaN QW. This contaminated residual incorporation is buried by the growth of the GaN spacer and avoids the structural defect formation, therefore explaining the improved optical efficiency. No further improvement is observed by adding the InGaN UL to the structure, which is confirmed by comparable values of the effective carrier lifetime estimated from time-resolved experiments. Contrary to the case of planar c-plane QW where the improved efficiency is attributed to a strong decrease of point defects, the addition of an InGaN UL seems to have no influence in the case of radial m-plane QW.
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Verheij D, Peres M, Cardoso S, Alves LC, Alves E, Durand C, Eymery J, Fernandes J, Lorenz K. Ion beam induced current analysis in GaN microwires. EPJ WEB OF CONFERENCES 2020. [DOI: 10.1051/epjconf/202023305001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
GaN is a wide bandgap semiconductor which is expected to withstand high radiation doses. Consequently, it is considered a promising material for new generation particle detectors in radiation related applications. We report on the fabrication and electrical characterization under proton irradiation of single microwire sensors based on a back-to-back Schottky contact configuration. The microwires are grown by metal-organic vapor phase epitaxy and processed into sensors by using optical lithography on dispersed wires. We investigate the impact of the contacts and the semiconductor bulk on the ion beam induced current (IBIC) by irradiating specific areas of the sensor and simultaneously measuring the change in conductivity. We observed that the contribution of the excess charge carriers generated in the depletion regions formed at the contact interfaces is of low influence when compared to the excess charge carriers generated in the microwire bulk.
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Zhou A, Ping Wang Y, Cornet C, Léger Y, Pédesseau L, Favre-Nicolin V, Chahine GA, Schülli TU, Eymery J, Bahri M, Largeau L, Patriarche G, Durand O, Létoublon A. A study of the strain distribution by scanning X-ray diffraction on GaP/Si for III–V monolithic integration on silicon. J Appl Crystallogr 2019. [DOI: 10.1107/s1600576719008537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A synchrotron-based scanning X-ray diffraction study on a GaP/Si pseudo-substrate is reported, within the context of the monolithic integration of photonics on silicon. Two-dimensional real-space mappings of local lattice tilt and in-plane strain from the scattering spot distributions are measured on a 200 nm partially relaxed GaP layer grown epitaxially on an Si(001) substrate, using an advanced sub-micrometre X-ray diffraction microscopy technique (K-Map). Cross-hatch-like patterns are observed in both the local tilt mappings and the in-plane strain mappings. The origin of the in-plane local strain variation is proposed to be a result of misfit dislocations, according to a comparison between in-plane strain mappings and transmission electron microscopy observations. Finally, the relationship between the in-plane strain and the free surface roughness is also discussed using a statistical method.
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Guan N, Amador-Mendez N, Wang J, Das S, Kapoor A, Julien FH, Gogneau N, Foldyna M, Som S, Eymery J, Durand C, Tchernycheva M. Colour optimization of phosphor-converted flexible nitride nanowire white light emitting diodes. JPHYS PHOTONICS 2019. [DOI: 10.1088/2515-7647/ab2c84] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
We demonstrate flexible nanowire white light-emitting-diodes (LEDs) with an optimized colour quality. The devices consist of flexible InGaN/GaN nanowire LEDs acting as pumps, capped with removable phosphor-doped polydimethylsiloxane membranes. Five different phosphors with tens of microns in grain size emitting from green to orange are investigated using both violet-blue and a blue-green nanowire-based LED pumps. In addition, a flexible nanowire white LED with a warm white emission is demonstrated using two layers of different phosphors. Compared to the previous realizations of flexible nanowire white LEDs, these novel LEDs improve the colour rendering index from 54 to 86 and show a colour tuneable from a bluish cool white colour to natural white and finally to warm white. The flexibility tests show that the LEDs can be bent down to 1.5 cm curvature radius without significant degradation. Therefore, the replacement of the nano-phosphors used in the previous realization by relatively inexpensive micro-phosphors does not degrade the good mechanical flexibility of the white nanowire LEDs.
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Richard MI, Fernández S, Eymery J, Hofmann JP, Gao L, Carnis J, Labat S, Favre-Nicolin V, Hensen EJM, Thomas O, Schülli TU, Leake SJ. Crystallographic orientation of facets and planar defects in functional nanostructures elucidated by nano-focused coherent diffractive X-ray imaging. NANOSCALE 2018; 10:4833-4840. [PMID: 29473085 DOI: 10.1039/c7nr07990g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The physical and chemical properties of nanostructures depend on their surface facets. Here, we exploit a pole figure approach to determine the three-dimensional orientation matrix of a nanostructure from a single Bragg reflection measured with a coherent nano-focused X-ray beam. The signature of any truncated (faceted) crystal produces a crystal truncation rod, which corresponds to a streak of intensity in reciprocal space normal to the surface. When two or more non-parallel facets are present, both the crystal orientation and the crystal facets can be identified. This enables facets to be rapidly indexed and uncommon facets, and planar defects, that have been difficult to study before to be identified. We demonstrate the technique with (i) epitaxial core-shell InGaN/GaN multiple quantum-wells grown on GaN nanowires, where surface facets and planar defects are determined, and (ii) single randomly oriented highly faceted tetrahedrahexal Pt nanoparticles. The methodology is applicable to a broad range of nanocrystals and provides a unique insight into the connection between structure and properties of nanomaterials.
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El Kacimi A, Pauliac-Vaujour E, Eymery J. Flexible Capacitive Piezoelectric Sensor with Vertically Aligned Ultralong GaN Wires. ACS APPLIED MATERIALS & INTERFACES 2018; 10:4794-4800. [PMID: 29338171 DOI: 10.1021/acsami.7b15649] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We report a simple and scalable fabrication process of flexible capacitive piezoelectric sensors using vertically aligned gallium nitride (GaN) wires as well as their physical principles of operation. The as-grown N-polar GaN wires obtained by self-catalyst metal-organic vapor phase epitaxy are embedded into a polydimethylsiloxane (PDMS) matrix and directly peeled off from the sapphire substrate before metallic electrode contacting. This geometry provides an efficient control of the wire orientation and an additive contribution of the individual piezoelectric signals. The device output voltage and efficiency are studied by finite element calculations for compression mechanical loading as a function of the wire geometrical growth parameters (length and density). We demonstrate that the voltage output level and sensitivity increases as a function of the wire length and that a conical shape is not mandatory for potential generation as it was the case for horizontally assembled devices. The optimal design to improve the overall device response is also optimized in terms of wire positioning inside PDMS, wire density, and total device thickness. Following the results of these calculations, we have fabricated experimental devices exhibiting outputs of several volts with a very good reliability under cyclic mechanical excitation.
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Favre-Nicolin V, Girard G, Eymery J, Leake S, Mandula O, Elzo-Aizarna M, Andrieu F, Berthelon R, Gerard JM, Claudon J. X-ray imaging of single semi-conductor nanostructures for photonics and electronics. Acta Crystallogr A Found Adv 2017. [DOI: 10.1107/s2053273317090726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Durand C, Carlin JF, Bougerol C, Gayral B, Salomon D, Barnes JP, Eymery J, Butté R, Grandjean N. Thin-Wall GaN/InAlN Multiple Quantum Well Tubes. NANO LETTERS 2017; 17:3347-3355. [PMID: 28441498 DOI: 10.1021/acs.nanolett.6b04852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Thin-wall tubes composed of nitride semiconductors (III-N compounds) based on GaN/InAlN multiple quantum wells (MQWs) are fabricated by metal-organic vapor-phase epitaxy in a simple and full III-N approach. The synthesis of such MQW-tubes is based on the growth of N-polar c-axis vertical GaN wires surrounded by a core-shell MQW heterostructure followed by in situ selective etching using controlled H2/NH3 annealing at 1010 °C to remove the inner GaN wire part. After this process, well-defined MQW-based tubes having nonpolar m-plane orientation exhibit UV light near 330 nm up to room temperature, consistent with the emission of GaN/InAlN MQWs. Partially etched tubes reveal a quantum-dotlike signature originating from nanosized GaN residuals present inside the tubes. The possibility to fabricate in a simple way thin-wall III-N tubes composed of an embedded MQW-based active region offering controllable optical emission properties constitutes an important step forward to develop new nitride devices such as emitters, detectors or sensors based on tubelike nanostructures.
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Salomon D, Messanvi A, Eymery J, Martínez-Criado G. Silane-Induced N-Polarity in Wires Probed by a Synchrotron Nanobeam. NANO LETTERS 2017; 17:946-952. [PMID: 28103050 DOI: 10.1021/acs.nanolett.6b04291] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Noncentrosymmetric one-dimensional structures are key driving forces behind advanced nanodevices. Owing to the critical role of silane injection in creating nanosized architectures, it has become a challenge to investigate the induced local lattice polarity in single GaN wires. Thus, if axial and radial structures are well-grown by a silane-mediated approach, an ideal model to study their polar orientations is formed. By combining synchrotron X-ray fluorescence and X-ray excited optical luminescence, we show here experimental evidence of the role of silane to promote the N-polarity, light emission, and elemental incorporation within single wires. In addition, our experiment demonstrates the ability to spatially examine carrier diffusion phenomena without electrical contacts, opening new avenues for further studies with simultaneous optical and elemental sensitivity at the nanoscale.
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Zhang H, Dai X, Guan N, Messanvi A, Neplokh V, Piazza V, Vallo M, Bougerol C, Julien FH, Babichev A, Cavassilas N, Bescond M, Michelini F, Foldyna M, Gautier E, Durand C, Eymery J, Tchernycheva M. Flexible Photodiodes Based on Nitride Core/Shell p-n Junction Nanowires. ACS APPLIED MATERIALS & INTERFACES 2016; 8:26198-26206. [PMID: 27615556 PMCID: PMC5054459 DOI: 10.1021/acsami.6b06414] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Accepted: 09/12/2016] [Indexed: 05/27/2023]
Abstract
A flexible nitride p-n photodiode is demonstrated. The device consists of a composite nanowire/polymer membrane transferred onto a flexible substrate. The active element for light sensing is a vertical array of core/shell p-n junction nanowires containing InGaN/GaN quantum wells grown by MOVPE. Electron/hole generation and transport in core/shell nanowires are modeled within nonequilibrium Green function formalism showing a good agreement with experimental results. Fully flexible transparent contacts based on a silver nanowire network are used for device fabrication, which allows bending the detector to a few millimeter curvature radius without damage. The detector shows a photoresponse at wavelengths shorter than 430 nm with a peak responsivity of 0.096 A/W at 370 nm under zero bias. The operation speed for a 0.3 × 0.3 cm2 detector patch was tested between 4 Hz and 2 kHz. The -3 dB cutoff was found to be ∼35 Hz, which is faster than the operation speed for typical photoconductive detectors and which is compatible with UV monitoring applications.
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Mandula O, Elzo Aizarna M, Eymery J, Burghammer M, Favre-Nicolin V. PyNX.Ptycho: a computing library for X-ray coherent diffraction imaging of nanostructures. J Appl Crystallogr 2016. [DOI: 10.1107/s1600576716012279] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
X-ray imaging techniques have undergone a remarkable development during the past decade, taking advantage of coherent X-ray sources. Among these techniques, ptychography allows reconstruction of the specimen and the illumination probe from a series of diffraction patterns without any prior knowledge about the sample. However, the reconstruction of the ptychographic data remains challenging and the reconstruction software is often not publicly available. Presented here is an open-source library for the reconstruction of two-dimensional ptychographic data, written in Python. This library implements existing algorithms, with examples of data reconstruction on both simulated and experimental (Bragg ptychography on heterogeneous strained InAs/GaAs nanowires) data sets. It can be used for educational (simulation) purposes or experimental data analysis, and also features an OpenCL version of the ptychography algorithm for high-performance computing.
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