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Jacques Levrat

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Related publications (30)

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Realization of GaInP/Si Dual-Junction Solar Cells With 29.8% 1-Sun Efficiency

Christophe Ballif, Matthieu Despeisse, Antonin Faes, Loris Barraud, Jacques Levrat, Antoine Descoeudres, Bertrand Yves Paul Paviet-Salomon, Stephanie Essig

Combining a Si solar cell with a high-bandgap top cell reduces the thermalization losses in the short wavelength and enables theoretical 1-sun efficiencies far over 30%. We have investigated the fabrication and optimization of Si-based tandem solar cells w ...

Ieee-Inst Electrical Electronics Engineers Inc2016

High quality factor two dimensional GaN photonic crystal cavity membranes grown on silicon substrate

Romuald Houdré, Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Antonino Francesco Castiglia, Kirill Atlasov, Jacques Levrat, Georg Rossbach, Ulagalandha Perumal Dharanipathy, Noelia Vico Triviño

We report on the achievement of freestanding GaN photonic crystal L7 nanocavities with embedded InGaN/GaN quantum wells grown by metal organic vapor phase epitaxy on Si (111). GaN was patterned by e-beam lithography, using a SiO2 layer as a hard mask, and ...

American Institute of Physics2012

Nonlinear emission properties of an optically anisotropic GaN-based microcavity

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

The pronounced optical in-plane anisotropy of a suitably designed nonpolar GaN-based microcavity, mainly inherited from the valence-band complexity of wurtzite semiconductors, allows the coexistence of two different light-matter coupling regimes along orth ...

Amer Physical Soc2012

Phase diagram of a polariton laser from cryogenic to room temperature

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

The signature of the strong-coupling regime is unambiguously evidenced in a GaN-based microcavity (MC) above the polariton lasing threshold P-thr at room temperature through the observation of the upper polariton branch. The MC system exhibits a renormaliz ...

2009

Impact of quantum confinement and quantum confined Stark effect on biexciton binding energy in GaN/AlGaN quantum wells

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

We report on time-resolved photoluminescence measurements carried out along the thickness gradient of two types of GaN/AlGaN quantum wells with low Al content in the barriers (5% and 9%, respectively). A reduction of the biexciton binding energy with incre ...

2008

Quantifying and Modeling the Impact of Interconnection Failures on the Electrical Performance of Crystalline Silicon Photovoltaic Modules

Christophe Ballif, Matthieu Despeisse, Antonin Faes, Alessandro Francesco Aldo Virtuani, Jacques Levrat, Eleonora Annigoni

We present an electrical model developed with LT SPICE that simulates the performance of a string of cells with disconnections in the electrical circuit. In a previous contribution, we quantified experimentally how the module performance is affected when o ...

IEEE2018

Tailoring the light-matter coupling in anisotropic microcavities: Redistribution of oscillator strength in strained m-plane GaN/AlGaN quantum wells

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

We present a comprehensive study of the anisotropic optical properties of nonpolar GaN/AlGaN multiple quantum wells intentionally designed to act as an active region of a planar microcavity operating in the strong-coupling regime. The strain induced by the ...

2011

High reflectivity airgap distributed Bragg reflectors realized by wet etching of AlInN sacrificial layers

Nicolas Grandjean, Jean-François Carlin, Eric Feltin, Raphaël Butté, Antonino Francesco Castiglia, Jacques Levrat, Alexei Altoukhov

The authors report on the achievement of a vertically oriented three pair airgap/GaN distributed Bragg reflector realized by controlled oxidation and wet-chemical etching of AlInN sacrificial layers. Microreflectivity measurements exhibit high peak reflect ...

2009

Towards room temperature electrically pumped blue vertical cavity surface emitting lasers

Nicolas Grandjean, Jean-François Carlin, Eric Feltin, Raphaël Butté, Gabriel Christmann, Antonino Francesco Castiglia, Jacques Levrat, Gatien Cosendey, Alexei Altoukhov

The authors report on strategies to achieve lasing in electrically driven vertical cavity surface emitting lasers at room temperature, namely the improvement of the quality factor of a microcavity suited for electrical injection, the use of a ZnO contact t ...

Ieee2009

Biexcitonic molecules survive excitons at the Mott transition

Nicolas Grandjean, Jean-François Carlin, Benoît Marie Joseph Deveaud, Eric Feltin, Raphaël Butté, Jean-Daniel Ganière, Gwénolé Jean Jacopin, Jacques Levrat, Georg Rossbach, Mehran Shahmohammadi

When the carrier density is increased in a semiconductor, according to the predictions of Sir Nevil Mott, a transition should occur from an insulating state consisting of a gas of excitons to a conductive electron-hole plasma. This crossover, usually refer ...

Nature Publishing Group2014