References of "Nguyen, Ngoc Duy"
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See detailInfluence of ZnO Surface Modification on the Photocatalytic Performance of ZnO/NiO Thin Films
Periyannan, Shanmugapriya ULiege; Manceriu, Laura ULiege; Nguyen, Ngoc Duy ULiege et al

in Catalysis Letters (2019)

Charge carrier separation is considered as a key factor in enhancing the photocatalytic process and can be maximized by mitigating surface recombination. Following this idea, the surface of zinc oxide ... [more ▼]

Charge carrier separation is considered as a key factor in enhancing the photocatalytic process and can be maximized by mitigating surface recombination. Following this idea, the surface of zinc oxide (ZnO) was modified by thermal treatment and nickel oxide (NiO) deposition. The influence of the ZnO thermal treatment and NiO deposition conditions on the ZnO surface chemistry and heterostructure interface properties were investigated by in situ X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) and correlated to the dye photodegradation efficiency. The XPS analysis confirmed a change of doping of ZnO after thermal treatment, which mainly influenced the developed band bending, and has led to an improved photocatalytic activity. For the same reason, the heterostructures based on the surface cleaned ZnO surface had higher photocatalytic efficiency than the ones based on non-cleaned ZnO. The temperature input during NiO deposition had negligible effect on the heterostructure interface properties. The photocatalytic efficiency did not follow the band bending evolution because of a dominant contribution of charge recombination across the NiO layer as indicated by PL analysis. [less ▲]

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See detailResilience of Cuprous Oxide under Oxidizing Thermal Treatments via Magnesium Doping
Resende, Joao; Chaix-Pluchery, Odette; Rovezzi, Mauro et al

in Journal of Physical Chemistry C (2019), 123(14), 8663-8670

This study reports the influence of magnesium incorporation into cuprous oxide (Cu2O) on its transformation into cupric oxide (CuO). Thermal treatments under oxidizing conditions are performed on undoped ... [more ▼]

This study reports the influence of magnesium incorporation into cuprous oxide (Cu2O) on its transformation into cupric oxide (CuO). Thermal treatments under oxidizing conditions are performed on undoped and magnesium-doped cuprous oxide thin films, Cu2O and Cu2O:Mg respectively, deposited by aerosol-assisted metal–organic chemical vapor deposition. The oxidation kinetics of these films shows a slower rate in the Cu2O:Mg system, since the complete oxidation into CuO occurs at a higher temperature when compared with undoped Cu2O. The increased stability of Cu2O:Mg can be explained by the inhibition of the formation of split copper vacancies, the defect most frequently associated with the CuO nucleation. Annealing treatments performed on Cu2O thin films provide new insights on the dopant influence on the mechanism to generate simple and split copper vacancies as well as the transformation of Cu2O into CuO. [less ▲]

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See detailPhysics and applications of silver nanowire networks
Papanastasiou, Dorina Theodora; Sannicolo, Thomas; Resende, Joao et al

in Zhu, J; Jin, A; Zhu, D (Eds.) et al Advances toward the development of nanotechnology: current challenges and new frontiers in materials, processes, devices, and applications (2019)

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See detailNanostructured metallic networks as window electrodes for photovoltaic devices
Nguyen, Ngoc Duy ULiege

Conference (2018, November)

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See detailZnO/CuCrO2 Core–Shell Nanowire Heterostructures for Self-Powered UV Photodetectors with Fast Response
Cossuet, Thomas; Resende, Joao; Rapenne, Laetita et al

in Advanced Functional Materials (2018)

An original self-powered UV photodetector integrating ZnO/CuCrO2 core–shell nanowire heterostructures is fabricated using low-cost and scalable chemical deposition techniques operating at moderate ... [more ▼]

An original self-powered UV photodetector integrating ZnO/CuCrO2 core–shell nanowire heterostructures is fabricated using low-cost and scalable chemical deposition techniques operating at moderate temperatures. A 35 nm thick delafossite phase CuCrO2 shell is formed with high uniformity by aerosol-assisted chemical vapor deposition over an array of vertically aligned ZnO nanowires grown by chemical bath deposition. The CuCrO2 shell consists of columnar grains at the top of ZnO nanowires as well as nanograins with some preferential orientations on their vertical sidewalls. The ZnO/CuCrO2 core–shell nanowire heterostructures exhibit significant diode behavior, with a rectification ratio approaching 1.2 × 104 at ±1 V, as well as a high optical absorptance above 85% in the UV part of the electromagnetic spectrum. A high UV responsivity at zero bias under low-power illumination of up to 3.43 mA W−1 under a 365 nm UV lamp, and up to 5.87 mA W−1 at 395 nm from spectrally resolved measurements, alongside a high selectivity with a UV-to-visible (395–550 nm) rejection ratio of 106 is measured. The short rise and decay times of 32 and 35 μs, respectively, both measured at zero bias, further establish these devices as promising candidates for cost-efficient, all-oxide self-powered UV photodetectors. [less ▲]

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See detailPhysical modeling of the percolation onset in conducting nanowire networks
Nguyen, Ngoc Duy ULiege

Conference (2018, September)

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See detailSpin-injection in a Ge-based thin film device : theoretical study of geometrical aspects
Fourneau, Emile ULiege; Avila Osses, Jonathan ULiege; Silhanek, Alejandro ULiege et al

Poster (2018, May 28)

We present a two-dimensional (2D) model of spin injection/extraction from a ferromagnetic (FM) germanide Mn5Ge3 into Ge in a geometry similar to real devices. Our model addresses the challenges of ... [more ▼]

We present a two-dimensional (2D) model of spin injection/extraction from a ferromagnetic (FM) germanide Mn5Ge3 into Ge in a geometry similar to real devices. Our model addresses the challenges of describing current line distributions, barrier interface nonlinearity (thermionic emission and tunnel effect), the formation of a depletion region and the influence of the detection method (spin valves, Hanle precession). Results show the impact of confinement effects due to a scaling-down of injector electrode width, channel thickness and channel length. We highlight the importance of current crowding and depletion area on the spin injection ratio and spin lifetime and we determine the existence of an optimal current density for efficient spin-injection. Finally, we demonstrate that the spin diffusion length is impacted by current lines distribution and intensity, limiting the coherence of spin transport. [less ▲]

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See detailZnO / CuCrO2 Core-Shell Nanowire Heterostructures for Self-Powered UV Photodetectors
Cossuet, Thomas; Resende, Joao; Rapenne, Laetitia et al

Conference (2018, April 06)

Detailed reference viewed: 59 (1 ULiège)
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See detailFlexible Transparent Electrodes based on Silver Nanowire Networks: Nanoscale Characterisation, Electrical Percolation, and Integration into Devices
Sannicolo, Thomas; Nguyen, Viet Huong; AghazadehChors, Sara et al

Conference (2018, April 03)

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See detailAg-Nanowire/Metal Oxide Composite—A Printable Transparent Electrode for Applications in Optoelectronic Devices
Nguyen, Viet Huong; AghazadehChors, Sara; Masse de la Huerta, Cesar et al

Conference (2018, April 03)

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See detailPercolation in networks of 1-dimensional objects: comparison between Monte Carlo simulations and experimental observations
Langley, Daniel; Lagrange, Mélanie; Nguyen, Ngoc Duy ULiege et al

in Nanoscale Horizons (2018)

Planar networks composed of 1-dimensional nanometer scale objects such as nanotubes or nanowires have been attracting growing interest in recent years. In this work we directly compare the percolation ... [more ▼]

Planar networks composed of 1-dimensional nanometer scale objects such as nanotubes or nanowires have been attracting growing interest in recent years. In this work we directly compare the percolation threshold of silver nanowire networks to predictions from Monte Carlo simulations, focusing particularly on understanding the impact of real world imperfections on the percolation onset in these systems. This work initially determines the percolation threshold as calculated from an ideal system using Monte Carlo methods. On this foundation we address the effects of perturbations in length, angular anisotropy and radius of curvature of the 1- dimensional objects, in line with those observed experimentally in purposely fabricated samples. This work explores why twodimensional stick models in the literature currently underestimate the percolation onset in real systems and identifies which of the network’s features play the most significant role in that deviation. [less ▲]

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See detailStability enhancement of silver nanowire networks with conformal ZnO coatings deposited by atmospheric pressure spatial atomic layer deposition
Khan, Afzal; Nguyen, Viet Huong; Munoz-Rojas, David et al

in ACS Applied Materials and Interfaces (2018), 10

Silver nanowire (AgNW) networks offer excellent electrical and optical properties and have emerged as one of the most attractive alternatives to transparent conductive oxides to be used in flexible ... [more ▼]

Silver nanowire (AgNW) networks offer excellent electrical and optical properties and have emerged as one of the most attractive alternatives to transparent conductive oxides to be used in flexible optoelectronic applications. However, AgNW networks still suffer from chemical, thermal and electrical instabilities which in some cases can hinder their efficient integration as transparent electrodes in devices such as solar cells, transparent heaters, touch screens or organic light emitting diodes (OLEDs). We have used atmospheric pressure spatial atomic layer deposition (AP-SALD) to fabricate hybrid transparent electrode materials in which the AgNW network is protected by a conformal thin zinc oxide layer. The choice of AP-SALD allows to maintain the low-cost and scalable processing of AgNW based transparent electrodes. The effects of the ZnO coating thickness on the physical properties of AgNW networks are presented. The composite electrodes show a drastic enhancement of both thermal and electrical stabilities. We found that bare AgNWs were stable only up to 300 °C when subjected to thermal ramps while the ZnO coating improved stability up to 500 °C. Similarly, ZnO coated AgNWs exhibited an increase of a 100 % in electrical stability with respect to bare networks, withstanding up to 18 V. A simple physical model shows that the origin of the stability improvement is the result of hindered silver atomic diffusion thanks to the presence of the thin oxide layer and the quality of the interfaces of hybrid electrodes. The effects of ZnO coating on both the network adhesion and optical transparency are also discussed. Finally, we show that the AP-SALD ZnO-coated AgNW networks can be effectively used as very stable transparent heaters. [less ▲]

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See detailInjection of spin-polarized current in a Ge- based magnetic device with coplanar contacts
Fourneau, Emile ULiege; Avila Osses, Jonathan ULiege; Silhanek, Alejandro ULiege et al

Poster (2017, November 06)

Electron spin injection and spin detection in magnetic materials are key features to the functionalization of electron spin polarization as a degree of freedom for both information processing and storage ... [more ▼]

Electron spin injection and spin detection in magnetic materials are key features to the functionalization of electron spin polarization as a degree of freedom for both information processing and storage. Currently, spin-dependent tunneling in magnetic junction devices is the most common approach to achieve efficient spin injection. However, many recent studies highlighted the interesting possibility to create spin-polarized currents in structures which combine a magnetic semiconductor, e.g. magnetic alloys based on group-IV semiconductors or diluted magnetic semiconductor compounds, forming a Schottky-like rectifying junction with a metallic ferromagnet. Although theoretical works have already addressed the performance of this structure by numerical simulations of the spin drift and spin diffusion equations, taking into account various characteristics of the ferromagnet (FM) / semiconductor (SC) interface such as barrier height and boundary roughness in 1D models, correlations with experimental results are scarce. This work aims at achieving spin injection with Ge-based magnetic structures using a rectifying junction in a coplanar architecture. We performed 2D numerical calculations of the spin drift and diffusion process in the direct neighborhood of a junction consisting of a Mn5Ge3 half-metallic ferromagnet acting as the injecting contact and an n-type Ge film, forming 3- and 4-terminal devices (Fig. 1). Our results show that geometrical effects play a major role on the spin injection efficiency. Moreover, the simulations emphasize the asymmetry of spin accumulation at the FM/SC interface as well as a strong effect of the depletion layer caused by the Schottky contact junction. We report values of spin polarization related potential differences higher than 5 μV for a bias of 1 mV, in agreement with previous experimental results. [less ▲]

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See detailInfluence of the inhomogeneous properties of a superconducting film on the penetration of the magnetic flux
Burger, Loïc ULiege; Avila Osses, Jonathan ULiege; Nguyen, Ngoc Duy ULiege et al

Poster (2017, September 20)

We consider the penetration of magnetic flux perpendicular to a Nb superconducting film containing edge indentations and/or defects. The presence of such defects and indented edges forces the induced ... [more ▼]

We consider the penetration of magnetic flux perpendicular to a Nb superconducting film containing edge indentations and/or defects. The presence of such defects and indented edges forces the induced currents to change direction abruptly, which gives rise to discontinuity lines (d-lines). It has been recently shown, by magneto-optical means, that the shape of the d-lines contain information about the size and the shape of the indentations [1]. Moreover, in contrast with what is commonly assumed, thermomagnetic instabilities are not preferentially triggered near the manufactured indentations, but rather along smooth edges [1]. Such phenomena can lead to unexpected quenching of superconducting samples and considerably damage them, which must be avoided in applications. In this poster, we investigate whether inhomogeneous superconducting properties can be responsible for triggering magnetic flux avalanches. To this aim, we numerically model the flux penetration and determine the distribution of current lines and electric fields for a situation where the superconducting properties vary locally over a small region of the film. We consider the variation of the thickness of the film, the critical current density and the size of the discontinuity. The resulting shapes of the d-lines are deduced and compared to analytical critical state approximations. We also determine the location and the amplitude of the maximal electric field in the film and compare it to typical values which must be reached in order to trigger magnetic flux avalanches. We conclude that the investigated variations lead to levels of electric field which are of the same order of magnitude as those generated by artificial indentations. [less ▲]

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See detailModel for the penetration of magnetic flux in Nb superconducting films with lithographically defined indentations and defects due to inhomogeneities
Vanderheyden, Benoît ULiege; Avila Osses, Jonathan ULiege; Brisbois, Jérémy ULiege et al

Conference (2017, August 31)

We consider the penetration of magnetic flux perpendicularly to a Nb superconducting film containing edge indentations and/or defects. The induced currents undergo an abrupt change of direction around the ... [more ▼]

We consider the penetration of magnetic flux perpendicularly to a Nb superconducting film containing edge indentations and/or defects. The induced currents undergo an abrupt change of direction around the indentations and the defects, giving rise to discontinuity lines (d-lines). It has recently been shown, by means of magneto-optical imaging and numerical models, that the detailed structure of the d-lines generated with lithographically-defined micro-indentations carry information about their size and shape, and vary with temperature [1]. In this talk, we describe the models which can be used to describe the d-lines and discuss the effects of temperature, demagnetization, and flux creep, as well as the influence of a field-dependent critical current density on the distribution of the magnetic field. We extend the model to discontinuities produced by defects arising from inhomogeneous properties of the film and discuss the information contained in the resulting d-line structure. Last, in contrast to what has been repeatedly predicted in the literature, artificial indentations were not observed to act as preferred nucleation spots for flux avalanches [1]. To investigate this result, we estimate the levels of electric field strengthening arising near indentations and defects, and compare with the levels necessary for triggering thermomagnetic instabilities. [less ▲]

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See detailIntegration of CuCrO2 thin film grown by Aerosol-Assisted MOCVD in core shell ZnO nanowire heterostructure for UV photodetectors
Resende, Joao; Cossuet, Thomas; Appert, Estelle et al

Poster (2017, June 12)

Detailed reference viewed: 36 (1 ULiège)
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See detailA novel ZnO / CuCrO2 core shell nanowire heterostructure for UV photodetectors
Resende, Joao; Cossuet, Thomas; Appert, Estelle et al

Conference (2017, May 23)

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See detailStraightforward prediction of the Ni1−xO layers stoichiometry by using optical and electrochemical measurements
Manceriu, Laura ULiege; Colson, Pierre ULiege; Maho, Anthony ULiege et al

in Journal of Physics: D Applied Physics (2017), 50

In this study, we propose a straightforward method for x determination in sub-stoichiometric nickel oxide (Ni1−xO) films prepared by ultrasonic spray pyrolysis on fluor-tin oxide (FTO) substrates by ... [more ▼]

In this study, we propose a straightforward method for x determination in sub-stoichiometric nickel oxide (Ni1−xO) films prepared by ultrasonic spray pyrolysis on fluor-tin oxide (FTO) substrates by varying the post-deposition thermal treatment. The Ni3+ concentration, the flat band potential (Φfb) and the open circuit potential (Voc) were determined by electrochemical impedance analysis in aqueous media and correlated to the transmission of Ni1−xO films. An x-ray photoelectron spectroscopy study was also performed to quantify the amount of Ni3+ in the films and compare it with the one determined by electrochemical analysis. The electrochromic behavior of the Ni1−xO films in non-aqueous electrolyte was investigated as well. With increasing Ni3+ concentration the films became more brownish and more conductive, both Voc and Φfb values increased. Calibration curves of transmission at 550 nm or open circuit potential versus carrier concentration were plotted and allowed the prediction of x in an unknown Ni1−xO sample. The Ni1−xO films characterized by the highest Ni3+ concentration have a darker colored state but lower transmission modulation, due to their reduced specific surface and increased crystallinity. [less ▲]

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See detailTransparent Electrodes Based on Silver Nanowire Networks: From Physical Considerations towards Device Integration
Bellet, Daniel; Lagrange, Mélanie; Sannicolo, Thomas et al

in Materials (2017), 10

The past few years have seen a considerable amount of research devoted to nanostructured transparent conducting materials (TCM), which play a pivotal role in many modern devices such as solar cells ... [more ▼]

The past few years have seen a considerable amount of research devoted to nanostructured transparent conducting materials (TCM), which play a pivotal role in many modern devices such as solar cells, flexible light-emitting devices, touch screens, electromagnetic devices, and flexible transparent thin film heaters. Currently, the most commonly used TCM for such applications (ITO: Indium Tin oxide) suffers from two major drawbacks: brittleness and indium scarcity. Among emerging transparent electrodes, silver nanowire (AgNW) networks appear to be a promising substitute to ITO since such electrically percolating networks exhibit excellent properties with sheet resistance lower than 10 Ω/sq and optical transparency of 90%, fulfilling the requirements of most applications. In addition, AgNW networks also exhibit very good mechanical flexibility. The fabrication of these electrodes involves low-temperature processing steps and scalable methods, thus making them appropriate for future use as low-cost transparent electrodes in flexible electronic devices. This contribution aims to briefly present the main properties of AgNW based transparent electrodes as well as some considerations relating to their efficient integration in devices. The influence of network density, nanowire sizes, and post treatments on the properties of AgNW networks will also be evaluated. In addition to a general overview of AgNW networks, we focus on two important aspects: (i) network instabilities as well as an efficient Atomic Layer Deposition (ALD) coating which clearly enhances AgNW network stability and (ii) modelling to better understand the physical properties of these networks. [less ▲]

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