Publications de Dobri Simeonov

Time-resolved cathodoluminescence on polychromatic light emitting (In,Ga)N quantum wells grown on (11-22) GaN facets

Jean-François Carlin, Nicolas Grandjean, Benoît Marie Joseph Deveaud, Jean-Daniel Ganière, Eric Feltin, Pierre Michel Corfdir, Dobri Simeonov

We present a low-temperature time-resolved cathodoluminescence study on (In,Ga)N/GaN quantum wells grown on the (11-22) facets of non-coalesced ELO-GaN. Taking advantage of the quantum confined Stark effect, such structures have been proposed as promising ...

V C H Publishers, Suite 909, 220 E 23Rd St, New York, Ny 10010 Usa2011

Synthesis and optical investigation of single polar GaN/AlN quantum dots

Dobri Simeonov

Over the past few decades, III-V nitrides have attracted much attention due to the possibility to realize high efficiency optoelectronic devices covering all the UV and visible part of the light spectrum. However, the device fabrication has gone much faste ...

EPFL2009

Quantum confinement dependence of the energy splitting and recombination dynamics of A and B excitons in a GaN/AlGaN quantum well

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Eric Feltin, Dobri Simeonov, Massimo Gurioli

We report the observation of well-resolved A and B excitonic resonances in the reflectivity spectra of a wedged GaN/AlGaN quantum well (QW) with 5% Al content in the barriers for different well thicknesses. For the thicker well cases, the energy splitting ...

2009

Temperature mapping of Al0.85In0.15N/AlN/GaN high electron mobility transistors through micro-photoluminescence studies

Nicolas Grandjean, Jean-François Carlin, Eric Feltin, Marcel Py, Marcus Gonschorek, Dobri Simeonov

Crack-free lattice-matched Al0.85In0.15N/GaN heterostructures were grown on sapphire substrates with barrier thicknesses up to 100 nm which exhibit very high polarization-induced electron sheet density (>2.5 x 10(13) cm(-2)) located at the heterointerface. ...

2009

Complex behavior of biexcitons in GaN quantum dots due to a giant built-in polarization field

Nicolas Grandjean, Raphaël Butté, Dobri Simeonov

In-depth optical spectroscopic studies of single polar GaN/AlN quantum dots (QDs) grown by molecular beam epitaxy are carried out by means of low-temperature microphotoluminescence. Luminescence linewidths as low as 700 mu eV are obtained allowing thorough ...

2008

High quality nitride based microdisks obtained via selective wet etching of AlInN sacrificial layers

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

The authors report a technique for selective wet chemical etching of an AlInN sacrificial layer lattice-matched to GaN for the fabrication of air-gap photonic structures. It is used to demonstrate high quality factor (Q) microdisk cavities. Whispering gall ...

2008

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

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Jacques Levrat, Eric Feltin, Dobri Simeonov, Massimo Gurioli

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

Biexciton kinetics in GaN quantum wells: Time-resolved and time-integrated photoluminescence measurements

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Eric Feltin, Dobri Simeonov, Massimo Gurioli

We report on the experimental achievement of narrow ultraviolet excitonic and biexcitonic emission from GaN/AlGaN quantum wells. The very large biexciton binding energy (up to 12 meV) inhibits thermalization between the two species allowing to study the re ...

2008

Current status of AlInN layers lattice-matched to GaN for photonics and electronics

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Julien Dorsaz, Eric Feltin, Gabriel Christmann, Antonino Francesco Castiglia, Sylvain Nicolay, Marcel Py, Marcus Gonschorek

We report on the current properties of Al1-x InxN (x approximate to 0.18) layers lattice- matched ( LM) to GaN and their specific use to realize nearly strain- free structures for photonic and electronic applications. Following a literature survey of the g ...

2007

Efficient current injection scheme for nitride vertical cavity surface emitting lasers

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Julien Dorsaz, Eric Feltin, Antonino Francesco Castiglia, Dobri Simeonov

The authors report the realization of InGaN/GaN light emitting diodes (LEDs) with an electrical injection design suitable for vertical cavity surface emitting lasers. Controlled oxidation of an AlInN interlayer lattice matched to GaN allows confining the i ...

2007