Publications by Jacques Levrat

Related publications (30)

Generic picture of the emission properties of III-nitride polariton laser diodes: Steady state and current modulation response

Nicolas Grandjean, Raphaël Butté, Jacques Levrat, Georg Rossbach, Marlene Glauser, Munise Nevin Cobet

The main emission characteristics of electrically driven polariton lasers based on planar GaN microcavities with embedded InGaN quantum wells are studied theoretically. The polariton emission dependence on pump current density is first modeled using a set ...

Amer Physical Soc2012

Field test and electrode optimization of electrodynamic cleaning systems for solar panels

Christophe Ballif, Aïcha Hessler-Wyser, Matthieu Despeisse, Nicolas Würsch, Antonin Faes, Jacques Levrat

Soiling is the major cause of power loss of photovoltaics (PV) and concentrated solar power (CSP) in desert areas. Electrodynamic cleaning system (EDS) is an automatic and water-free integrated cleaning system for mirrors or solar panels, which uses pulsed ...

WILEY2019

The impact of silicon solar cell architecture and cell interconnection on energy yield in hot & sunny climates

Christophe Ballif, Stefaan De Wolf, Matthieu Despeisse, Jacques Levrat, Johannes Peter Seif, Jan Haschke, Jean Cattin, Yannick Samuel Riesen, Andrea Tomasi

Extensive knowledge of the dependence of solar cell and module performance on temperature and irradiance is essential for their optimal application in the field. Here we study such dependencies in the most common high-efficiency silicon solar cell architec ...

Royal Soc Chemistry2017

Tailoring the strong coupling regime in III-nitride based microcavities for room temperature polariton laser applications

Nicolas Grandjean, Jean-François Carlin, Eric Feltin, Raphaël Butté, Gabriel Christmann, Jacques Levrat

We report on the properties of III-nitride based microcavities (MCs) operating in the strong coupling regime (SCR) up to room temperature. We first discuss why this class of materials is well suited to investigate the physics of cavity polaritons, which ar ...

Wiley-Blackwell2009

Q-factor of (In,Ga)N containing III-nitride microcavity grown by multiple deposition techniques

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Jacques Levrat, Gatien Cosendey, Georg Rossbach, Marlene Glauser

A 3 lambda/2 (In,Ga)N/GaN resonant cavity, designed for similar to 415nm operation, is grown by molecular beam epitaxy and is sandwiched between a 39.5-period (In,Al)N/GaN distributed Bragg reflector (DBR), grown on c-plane GaN-on-sapphire pseudo-substrate ...

Amer Inst Physics2013

Light-induced performance increase of silicon heterojunction solar cells

Christophe Ballif, Stefaan De Wolf, Matthieu Despeisse, Sylvain Nicolay, Jacques Levrat, Gabriel Christmann, Antoine Descoeudres

Silicon heterojunction solar cells consist of crystalline silicon (c-Si) wafers coated with doped/intrinsic hydrogenated amorphous silicon (a-Si:H) bilayers for passivating-contact formation. Here, we unambiguously demonstrate that carrier injection either ...

American Institute of Physics2016

Quantifying and modeling the impact of interconnection failures on the electrical performance of crystalline silicon photovoltaic modules

Christophe Ballif, Antonin Faes, Jacques Levrat, Alessandro Francesco Aldo Virtuani, Matthieu Despeisse, Fanny Sculati-Meillaud, Eleonora Annigoni

Failures in the metallic interconnections are among the main degradation modes for photovoltaic modules. Fatigue accumulation due to thermomechanical stresses can result in deterioration of the solder joints or in broken ribbons. In this paper, we first qu ...

2019

Stress tolerance of lightweight glass-free PV modules for vehicle integration

Kléber Nicolet-dit-Félix, Christophe Ballif, Matthieu Despeisse, Aïcha Hessler-Wyser, Jacques Levrat, Antonin Faes, Gianluca Cattaneo, Umang Bhupatrai Desai, Fahradin Mujovi

Electric vehicles (EVs) currently dominate the sales in the automotive market. A big leap in this market can be made by developing a photovoltaic product that can be integrated to an EV, as it can boost the driving range of the EV while reducing the chargi ...

Edp Sciences S A2024

Intrinsic dynamics of weakly and strongly confined excitons in nonpolar nitride-based heterostructures

Nicolas Grandjean, Benoît Marie Joseph Deveaud, Jean-Daniel Ganière, Jacques Levrat, Pierre Michel Corfdir

Both weakly and strongly confined excitons are studied by time-resolved photoluminescence in a nonpolar nitride-based heterostructure grown by molecular beam epitaxy on the a-facet of a bulk GaN crystal, with an ultralow dislocation density of 2 × 105 cm-2 ...

2011

Condensation phase diagram of cavity polaritons in GaN-based microcavities: Experiment and theory

Nicolas Grandjean, Jean-François Carlin, Eric Feltin, Raphaël Butté, Jacques Levrat

The evolution of the polariton condensation threshold (P-thr) under incoherent optical pumping is investigated both theoretically and experimentally over a wide range of temperatures (4-340 K) and exciton-cavity photon detunings (-120-0 meV) in a multiple ...

2010

Exciton localization on basal stacking faults in a-plane epitaxial lateral overgrown GaN grown by hydride vapor phase epitaxy

Nicolas Grandjean, Benoît Marie Joseph Deveaud, Jean-Daniel Ganière, Denis Martin, Jacques Levrat, Pierre Michel Corfdir

We present a detailed study of the luminescence at 3.42 eV usually observed in a-plane epitaxial lateral overgrowth (ELO) GaN grown by hydride vapor phase epitaxy on r-plane sapphire. This band is related to radiative recombination of excitons in a commonl ...

American Institute of Physics2009

Physics of Polariton Condensates in GaN-based Planar Microcavities

Jacques Levrat

Since its prediction in 1996 by Imamoğlu and coworkers, the use of a non-equilibrium polariton condensate to produce an intense coherent light source referred to as a polariton laser has attracted a lot of interest in the whole physics community as it ...

EPFL2012

Impact of saturation on the polariton renormalization in III-nitride based planar microcavities

Nicolas Grandjean, Jean-François Carlin, Eric Feltin, Raphaël Butté, Jacques Levrat, Georg Rossbach

It has been widely observed that an increasing carrier density in a strongly coupled semiconductor microcavity (MC) alters the dispersion of cavity polaritons, below and above the condensation threshold. The interacting nature of cavity polaritons stems fr ...

Amer Physical Soc2013

Low-Temperature Screen-Printed Metallization for the Scale-Up of Two-Terminal Perovskite-Silicon Tandems

Christophe Ballif, Matthieu Despeisse, Sylvain Nicolay, Antonin Faes, Soo-Jin Moon, Jacques Levrat, Laura Ding, Gabriel Christmann, Bertrand Yves Paul Paviet-Salomon, Arnaud Walter, Adriana Paracchino

Tandem photovoltaic devices based on perovskite and crystalline silicon (PK/c-Si) absorbers have the potential to push commercial silicon single junction devices beyond their current efficiency limit. However, their scale-up to industrially relevant sizes ...

AMER CHEMICAL SOC2019

Pinning and Depinning of the Polarization of Exciton-Polariton Condensates at Room Temperature

Nicolas Grandjean, Jean-François Carlin, Eric Feltin, Raphaël Butté, Jacques Levrat, Marlene Glauser

A room temperature polariton condensate realized in a microcavity with embedded GaN quantum wells emits linearly polarized light at threshold with the plane of polarization pinned to one of the crystallographic axes. With increasing pumping power, a depinn ...

2010

Increasing the efficiency of silicon heterojunction solar cells and modules by light soaking

Christophe Ballif, Franz-Josef Haug, Antoine Descoeudres, Jacques Levrat, Matthieu Despeisse, Stefaan De Wolf

Silicon heterojunction solar cells use crystalline silicon (c-Si) wafers as optical absorbers and employ bilayers of doped/intrinsic hydrogenated amorphous silicon (a-Si:H) to form passivating contacts. Recently, we demonstrated that such solar cells incre ...

Elsevier Science Bv2017

One-dimensional exciton luminescence induced by extended defects in nonpolar GaN/(Al,Ga)N quantum wells

Nicolas Grandjean, Pierre Stadelmann, Raphaël Butté, Benoît Marie Joseph Deveaud, Jean-Daniel Ganière, Jacques Levrat, Denis Martin, Pierre Michel Corfdir

In this study, we present the optical properties of nonpolar GaN/(Al,Ga)N single quantum wells (QWs) grown on either a- or m-plane GaN templates for Al contents set below 15%. In order to reduce the density of extended defects, the templates have been proc ...

Institute of Physics2011

Reassessment of cell to module gains and losses: Accounting for the current boost specific to cells located on the edges

Christophe Ballif, Matthieu Despeisse, Mathieu Gérard Boccard, Jacques Levrat, Olivier Denis Dupré

The power produced by a photovoltaic module is not simply the sum of the powers of its constituents cells. The difference stems from a number of so-called “cell-to-module” (CTM) gain or loss mechanisms. These are getting more and more attention as improvem ...

2018

Polariton lasing in a hybrid bulk ZnO microcavity

Nicolas Grandjean, Raphaël Butté, Jacques Levrat, Georg Rossbach

We demonstrate polariton lasing in a bulk ZnO planar microcavity under non-resonant optical pumping at a small negative detuning (delta similar to -1/6 the 130 meV vacuum Rabi splitting) and a temperature of 120 K. The strong coupling regime is maintained ...

AIP American Institute of Physics2011

Impact of biexcitons on the relaxation mechanisms of polaritons in III-nitride based multiple quantum well microcavities

Nicolas Grandjean, Jean-François Carlin, Benoît Marie Joseph Deveaud, Eric Feltin, Raphaël Butté, Jean-Daniel Ganière, Gabriel Christmann, Jacques Levrat, Pierre Michel Corfdir, Georg Rossbach

We report on the direct observation of biexcitons in a III-nitride based multiple quantum well microcavity operating in the strong light-matter coupling regime by means of nonresonant continuous wave and time-resolved photoluminescence at low temperature. ...

2012