References of "Nguyen, Ngoc Duy"
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See detailElectrical modelling of interface traps in GeSn MOS structures
Baert, Bruno ULg; Cerica, Delphine; Schmeits, Marcel ULg et al

Conference (2014, November 13)

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See detailClassical analogy for the deflection of flux avalanches by a metallic layer
Brisbois, Jérémy ULg; Vanderheyden, Benoît ULg; Colauto, Fabiano et al

in New Journal of Physics (2014), 16(10), 103003

Sudden avalanches of magnetic flux bursting into a superconducting sample undergo deflections of their trajectories when encountering a conductive layer deposited on top of the superconductor. Remarkably ... [more ▼]

Sudden avalanches of magnetic flux bursting into a superconducting sample undergo deflections of their trajectories when encountering a conductive layer deposited on top of the superconductor. Remarkably, in some cases the flux is totally excluded from the area covered by the conductive layer. We present a simple classical model that accounts for this behaviour and considers a magnetic monopole approaching a semi-infinite conductive plane. This model suggests that magnetic braking is an important mechanism responsible for avalanche deflection. [less ▲]

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See detailImpact of traps on the electrical characteristics of GeSn/Ge diodes
Baert, Bruno ULg; Gupta, Somya; Gencarelli, Federica et al

Poster (2014, September 15)

Germanium-tin alloys are currently receiving a lot of attention as materials for high performance MOSFET devices. Much interest is focused on the direct band gap for Sn concentrations above 8-10% and the ... [more ▼]

Germanium-tin alloys are currently receiving a lot of attention as materials for high performance MOSFET devices. Much interest is focused on the direct band gap for Sn concentrations above 8-10% and the achievement of high mobility values, which can be further increased by the strain due to the lattice mismatch with Ge or Si. GeSn is therefore expected to play a key role in the development of either source and drain stressors for Ge p-MOSFETs or for GeSn channel MOSFETs. However, despite recent tremendous progress in the growth of such materials, the impact of defects at the interface between Ge and GeSn has not been completely characterized. As the processing of diodes contains many of the steps necessary to the fabrication of MOSFET devices, we have investigated the effect of traps on the electrical characteristics of p-GeSn/n-Ge diodes, made from GeSn layers grown by CVD on Ge and in-situ doped with Boron. Using temperature-dependent current-voltage (I-V) and capacitance- voltage (C-V) measurements, we have calculated the ideality factor of the diodes, the activation energy of the reverse saturation current and the carrier concentration of the Ge substrate. In this work, based on the comparison with results obtained from numerical simulations, we discuss these characteristics in view of assessing the extent to which electronic trap states in these heterostructures affect their electrical properties. [less ▲]

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See detailElectrical characterization of pGeSn/nGe diodes
Baert, Bruno ULg; Gupta, Somya; Gencarelli, Federica et al

Conference (2014, June 03)

I-V characteristics of pGeSn/nGe diodes have been measured and show very good properties. Simulations of the same structure are able to reproduce most of the observed behavior and point to the ... [more ▼]

I-V characteristics of pGeSn/nGe diodes have been measured and show very good properties. Simulations of the same structure are able to reproduce most of the observed behavior and point to the predominating influence of parameters such as the band gap energy of the GeSn layer. C-V characteristics showing little frequency dependence have also been measured, and their analysis for the determination of the carrier concentration is confirmed by simulations. More investigations, including the effect of temperature and other defects at the interface or in the bulk of either layers are still required in order to explain some of the observed behaviors, notably the reverse saturation current. [less ▲]

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See detailTransparent electrodes composed of silver nanowire networks: physical properties and potential applications
Langley, Daniel ULg; Lagrange, Mélanie; Munoz-Rojas, David et al

Conference (2014)

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See detailTransparent electrodes composed of silver nanowire networks for photovoltaic applications
Langley, Daniel ULg; Lagrange, Mélanie; Munoz-Rojas, David et al

Conference (2014)

Research is increasingly being dedicated towards replacing rare earth elements in Transparent Conductive Materials (TCMs). In this work we present the investigation of silver nanowire (AgNW) networks as ... [more ▼]

Research is increasingly being dedicated towards replacing rare earth elements in Transparent Conductive Materials (TCMs). In this work we present the investigation of silver nanowire (AgNW) networks as transparent electrodes for solar cell applications. Metallic nanowire networks can be deposited via low cost deposition techniques and exhibit very interesting electrical, optical and mechanical properties. Experimental and simulation approaches aim at improving their physical properties. Indeed, we show that a thermal annealing can drastically improve transport properties of the nearly transparent networks. We also explore the optimization of the network density. These percolating networks exhibit excellent properties (i.e. sheet resistances (Rs) of about 10 Ω/sq and optical transparency of approximately 90%) compatible with solar applications requirements. This makes them very appropriate for future uses in low cost, large area and flexible solar and display technologies. A comprehensive understanding of the main physical properties of this promising nanostructured network and its integration with solar cells will then be presented [less ▲]

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See detailInnovative Electrodes for Dye Sensitized Solar Cells
Langley, Daniel ULg; Giusti, Gael; Zhang, Shanting et al

Conference (2014)

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See detailInterplay between defects in metallic nanowire networks and their physical properties: a modeling and experimental approach
Lagrange, Mélanie; Langley, Daniel ULg; Munos-Rojas et al

Conference (2014)

The use of random metallic nanowire networks as transparent conductive materials (TCMs) is increasing rapidly. These materials can be used in flexible/stretchable electronics, flexible displays, touch ... [more ▼]

The use of random metallic nanowire networks as transparent conductive materials (TCMs) is increasing rapidly. These materials can be used in flexible/stretchable electronics, flexible displays, touch screens, photovoltaics or as transparent heaters. Metallic nanowire networks can be deposited by using low-cost and scalable deposition techniques and exhibit very interesting electrical, optical, thermal and mechanical properties. In addition to usual material defects (such as grain-boundaries) any deviation from a “perfect” infinite network (i.e. nanowire length distributions, finite device size or nanowire curvature for instance) play a prominent role in the physical properties of the resulting percolating network. Using Monte Carlo simulations, and based on experimental available wires the effects of these defects are explored. Experimental work is focused on the influence of nanowire density as well as defects within the nanostructured network such as the inhomogeneity of the network, the grain-boundary along a nanowire, the morphological nanowire instabilities… The influence of these defects on the physical properties of this promising nanostructured network will be presented [less ▲]

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See detailMetallic nanowire networks for energy applications: experimental and modelling approaches
Langley, Daniel ULg; Lagrange, Mélanie; Munoz-Rojas, David et al

Conference (2014)

Research is increasingly being dedicated towards finding emerging materials aiming at playing a prominent role in energy issues. Transparent electrodes are a key component of devices such as solar cells ... [more ▼]

Research is increasingly being dedicated towards finding emerging materials aiming at playing a prominent role in energy issues. Transparent electrodes are a key component of devices such as solar cells or efficient lighting (such as OLED). Among emerging transparent conductive materials, metallic nanowire networks appear to be a very promising solution. This work aims at designing and optimizing metallic nanowire networks based on both experimental and modelling approaches. The influence on the networks physical properties of several key parameters such as the metal/alloy used, thermal annealing, network density, device size, etc. are explored. These percolating networks exhibit excellent properties (sheet resistances and optical transparency of about 10 Ω/ sq and 90%, respectively) fulfilling the requirements for solar or efficient opto-electronic applications. This makes them very appropriate for future uses involving large area and flexible photovoltaics or efficient lighting display technologies. A comprehensive understanding of the design and main physical properties of these promising nanostructured networks will be presented [less ▲]

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See detailThermal properties of silver nanowire networks
Sorel, Sophie; Lagrange, Mélanie; Langley, Daniel ULg et al

Conference (2014)

Silver nanowire (AgNW) networks have recently been the focus of intense research due to their potential use as transparent electrodes in solar cells, flat panel displays or transparent heaters. Metallic ... [more ▼]

Silver nanowire (AgNW) networks have recently been the focus of intense research due to their potential use as transparent electrodes in solar cells, flat panel displays or transparent heaters. Metallic nanowire networks can be deposited using low-cost and scalable deposition techniques on flexible substrates. For improving the transport properties (thermal and electrical) and optical transmittance in the visible range, an optimum nanowire density should be considered. In the present contribution we investigate the thermal behaviour of AgNW networks based on two aspects. The first one shows that a thermal annealing can drastically improve transport properties. The second approach investigates the physical properties of the network when used to generate heat. Experimental observation shows that AgNW networks exhibit the properties of a very efficient transparent heater, making them appropriate for future uses compatible with large area and flexible display technology. A comprehensive understanding of the thermal properties of this promising transparent nanostructured network will be presented. [less ▲]

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See detailHighly Diffuse Fluorine-doped SnO2 Thin Films for Photovoltaic Applications
Giusti, Gael; Consonni, Vincent; Langley, Daniel ULg et al

Conference (2014)

In the last decades, polycrystalline fluorine-doped SnO2 (FTO) thin films have received increasing interest due to their promising application in a wide variety of devices such as gas sensors, coatings ... [more ▼]

In the last decades, polycrystalline fluorine-doped SnO2 (FTO) thin films have received increasing interest due to their promising application in a wide variety of devices such as gas sensors, coatings and electrodes for solar cells. FTO thin films exhibit good electro-optical properties and other important physical properties such as a high work function, good thermal stability… FTO thin films have already been shown to act as an efficient transparent electrode in solar cells. In this work, FTO thin films were grown by ultrasonic spray pyrolysis on glass and flexible polymer substrates. The structural, electronic and optical properties of these FTO layers were thoroughly investigated. Our work focuses on a better understanding of their electro-optical properties, in terms for instance of electron scattering. We show that FTO layers (when combined with ZnO nanoparticles) exhibit haze factor as high as 60%, whilst maintaining very good electro-optical properties. The integration into solar cells is also presented. [less ▲]

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See detailPhysical properties of silver nanowire networks: effects of percolation and thermal annealing
Langley, Daniel ULg; Lagrange, Mélanie; Giusti, Gael et al

Conference (2014)

Silver nanowire networks have recently been a heavily researched subject due to their potential use as transparent electrodes in solar cells or flat panel displays. Currently, the most commonly used ... [more ▼]

Silver nanowire networks have recently been a heavily researched subject due to their potential use as transparent electrodes in solar cells or flat panel displays. Currently, the most commonly used material for such applications (Tin-doped Indium oxide) suffers from two major drawbacks: indium scarcity and brittleness. However, metallic nanowire networks can be deposited by low cost deposition techniques and exhibit simultaneously very promising optical, electrical and electro-mechanical properties. To enhance these properties, nanowire density should be considered. For a given nanowire aspect ratio, lower nanowire densities result in higher optical transparency but demonstrate lower electrical conductivity. As the density of nanowires is increased the relationship is reversed, resulting in high electrical conductivity but low optical transparency. Numerical Montecarlo simulations on stick percolation shed light on the percolative nature of these 2D networks. Relations between simulation and experimental observations are discussed. We also show that thermal annealing can efficiently improve the electrical properties without significantly changing the optical response2. However, above a certain temperature threshold, morphological instabilities occur and induce a cancelling out of the beneficial effects. The physical mechanisms involved in thermal annealing of Ag nanowire networks are addressed as well as their effects on electro-optical properties. Finally the potential integration of Ag nanowire networks into devices is evaluated. [less ▲]

Detailed reference viewed: 54 (0 ULg)
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See detailStick Percolation: Models for Real Systems
Langley, Daniel ULg; Lagrange, Mélanie; Nguyen, Ngoc Duy ULg et al

Conference (2014)

Detailed reference viewed: 13 (1 ULg)
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See detailStudy of the energy distribution of the interface trap density in a GeSn MOS structure by numerical simulation of the electrical characteristics
Baert, Bruno ULg; Schmeits, Marcel ULg; Nguyen, Ngoc Duy ULg

in Applied Surface Science (2014), 291

Using a custom-made numerical simulation tool, we performed a systematic study of the energy distribution of the interface trap density in a GeSn MOS structure and of their effect on the electrical ... [more ▼]

Using a custom-made numerical simulation tool, we performed a systematic study of the energy distribution of the interface trap density in a GeSn MOS structure and of their effect on the electrical characteristics such as C–V and impedance spectra. Interface traps with various densities of states and energies in the bandgap have been investigated and the application of the conductance method was assessed. Based on a theoretical analysis, we obtained, as key results, direct connections between microscopic parameters of the structures and experimentally accessible features of the simulated macroscopic quantities. A straightforward relationship between the interface state density and the peaks in the conductance response is also highlighted. The dependence of the peak characteristics on the trap states was identified, as well as the effects of traps extending over large energy ranges in the bandgap. [less ▲]

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See detailStability of templated and nanoparticles dye-sensitized solar cells : photovoltaic and electrochemical investigation of degradation mechanisms at the photoelectrode interface
Dewalque, Jennifer ULg; Nguyen, Ngoc Duy ULg; Colson, Pierre ULg et al

in Electrochimica Acta (2014), 115(1), 478-486

A key issue in the commercialization of dye-sensitized solar cells is to maintain high efficiency and long lifetime. As reported in the literature, dye-sensitized solar cells are stable under visible ... [more ▼]

A key issue in the commercialization of dye-sensitized solar cells is to maintain high efficiency and long lifetime. As reported in the literature, dye-sensitized solar cells are stable under visible light soaking but thermal stress and UV exposure lead to efficiency degradation. However, all the stability studies published so far have been performed on cells whose TiO2 electrodes were prepared by tape casting or screen printing of nanoparticle pastes/inks. The present study concerns cells based on highly porous templated TiO2 electrodes, whose larger surface area could enhance the negative effects of thermal stress, light soaking and UV exposure. The long-term stability of these cells is compared with a classical nanoparticle-based cell using current-voltage measurements (I-V curves) and electrochemical impedance spectroscopy. Due to their higher active interface, templated cells are more sensitive than nanoparticle cells to UV illumination, although this can be easily solved in both cases by the use of a UV filter. The templated cells are as stable as the nanoparticle cells under visible light soaking (UV filtered). However, we showed that templated cells are more stable under thermal stress. Moreover, as evidenced by electrochemical impedance spectroscopy, templated cells show lower transfer resistance, as well as lower recombination resistance compared to nanoparticle cells. The crystallite connectivity promoted by the templating route seems to favor the electron transfers inside the porous layer. Using templated films in dye-sensitized solar cells is therefore really promising because higher conversion efficiencies are reached without promoting cell degradation. [less ▲]

Detailed reference viewed: 88 (17 ULg)
See detailNumerical simulation of the electrical characteristics of CIGS/CdS/ZnO solar cell heterostructures
Amand, Julien ULg; Nguyen, Ngoc Duy ULg

Poster (2013, December 03)

The electrical characteristics of CIGS-based solar cell heterostructure have been simulated by numerically solving the basic semiconductor equations by means of a finite differences method based on a ... [more ▼]

The electrical characteristics of CIGS-based solar cell heterostructure have been simulated by numerically solving the basic semiconductor equations by means of a finite differences method based on a Scharfetter-Gummel discretization scheme. The electric potential, electric field, carrier concentrations, current densities and recombination rates are obtained as function of the space coordinate and the bias voltage. Starting with the analysis of a single absorber layer structure sandwiched between two metal electrodes, we subsequently studied the properties of the CIGS/ZnO pn heterojunction and the influence of the buffer layer thickness in the CIGS/CdS/ZnO on the cell electrical response. A special focus was also given to the influence of grain boundaries in the bulk of CIGS depending on the defects nature and concentration. Electrical measurements including admittance spectroscopy were performed on samples for comparison to be further lead. Motivations This research is part of the project IQuaReS (Innovative in-line Quality control for Renewable Solar solutions) that aims to develop an in-line quality control tool for manufactured CIGS-based solar cells, based on electrical and optoelectrical, preferably non-invasive measurement methods. Exploratory simulations aim to isolate signature patterns that could be sought in experimental measurements . [less ▲]

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See detailNumerical simulation of the electrical characteristics of CIGS/CdS/ZnO solar cell heterostructures
Amand, Julien ULg; Nguyen, Ngoc Duy ULg

Poster (2013, September 17)

The electrical characteristics of CIGS-based solar cell heterostructure have been simulated by numerically solving the basic semiconductor equations by means of a finite differences method based on a ... [more ▼]

The electrical characteristics of CIGS-based solar cell heterostructure have been simulated by numerically solving the basic semiconductor equations by means of a finite differences method based on a Scharfetter-Gummel discretization scheme. The electric potential, electric field, carrier concentrations, current densities and recombination rates are obtained as function of the space coordinate and the bias voltage. Starting with the analysis of a single absorber layer structure sandwiched between two metal electrodes, we subsequently studied the properties of the CIGS/ZnO pn heterojunction and the influence of the buffer layer thickness in the CIGS/CdS/ZnO on the cell electrical response. A special focus was also given to the influence of grain boundaries in the bulk of CIGS depending on the defects nature and concentration. [less ▲]

Detailed reference viewed: 109 (20 ULg)
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See detailSilver nanowire network : physical properties and effects of thermal treatments
Lagrange, Mélanie; Langley, Daniel ULg; Giusti, Gael et al

Conference (2013, September 16)

Detailed reference viewed: 30 (1 ULg)
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See detailTheoretical and experimental investigation of the GeSn bandgap
Shimura, Yosuke; Wang, Wei; Gencarelli, Federica et al

Conference (2013, September)

Detailed reference viewed: 42 (0 ULg)
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See detailElectrical Activity of Threading Dislocations and Defect Complexes in GeSn Epitaxial Layers
Gupta, Somya; Simoen, Eddy; Asano, Takanori et al

Conference (2013, June 04)

Detailed reference viewed: 109 (15 ULg)