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September 1999 - present
September 1999 - present
January 2004 - present
Publications
Publications (361)
Class A shot-noise limited operation is achieved in an electrically pumped vertical external cavity surface emitting laser (VECSEL), opening the way for integration of such peculiar noiseless laser oscillation in applications where low power consumption and footprint are mandatory. The quantum well active medium is grown on an InP substrate to enab...
We present the first demonstration of a vertical cavity surface emitting laser (VCSEL) based on InAs quantum dots (QDs) on InP. A very high density of 10
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The shape of InAs nanostructures formed by molecular beam epitaxy on a (001) InP substrate in the Stranski-Krastanow growth mode is studied. A transition from wires to round-shaped islands is observed as a function of the amount of InAs deposited. It is attributed to the non-equivalent energies of the A and B facets existing in zinc blende material...
Here, we experimentally and theoretically clarify III-V/Si crystal growth processes. Atomically-resolved microscopy shows that mono-domain 3D islands are observed at the early stages of AlSb, AlN and GaP epitaxy on Si, independently of misfit. It is also shown that complete III-V/Si wetting cannot be achieved in most III-V/Si systems. Surface/inter...
In common photovoltaic devices, the part of the incident energy above the absorption threshold quickly ends up as heat, which limits their maximum achievable efficiency to far below the thermodynamic limit for solar energy conversion. Conversely, the conversion of the excess kinetic energy of the photogenerated carriers into additional free energy...
Taking advantage of low production costs and large integration scale, silicon photonics is a promising way to improve on-chip data routing and reduce electronic consumption. The small lattice mismatch between Si and GaP promotes the latter as a good candidate for III-V pseudomorphic integration, but questions remain on the interest of this platform...
In this work, we investigate the impact of growth parameters on surface morphology, doping levels and dopant activation in AlGaP epilayers grown on GaP substrate by solid source molecular beam epitaxy. Atomic Force Microscopy analysis reveals that a smooth surface can be obtained only in the [580-680]°C growth temperature range for a sufficiently l...
Here, we study the growth of n- and p-doped AlGaP alloys on GaP substrate, in view of their use in laser devices. The impact of growth temperature and growth rate on structural and electrical properties is studied with atomic force microscopy, C(V), Hall effect measurements, SIMS analysis and deep level transient spectroscopy (DLTS). Typical struct...
Room temperature electroluminescence of a GaP-based LED on Si and photoluminescence of (In,Ga)As quantum dots (QDs) located at 200nm of the III-V/Si interface were obtained, illustrating the good structural quality of the GaP/Si template used. The last step towards room temperature lasing on Si is thus reaching the direct bandgap emission. In this...
We evidence the influence of the quality of the starting Si surface on the III-V/Si interface abruptness and on the formation of defects during the growth of III-V/Si heterogeneous crystal, using high resolution transmission electron microscopy and scanning transmission electron microscopy. GaP layers were grown by molecular beam epitaxy on vicinal...
This study is carried out in the context of III–V semiconductor monolithic integration on silicon for optoelectronic device applications. X-ray diffraction is combined with atomic force microscopy and scanning transmission electron microscopy for structural characterization of GaP nanolayers grown on Si. GaP has been chosen as the interfacial layer...
We investigated a semiconductor heterostructure based on InGaAsP multi quantum wells
(QWs) using optical characterizations and demonstrate its potential to work as a hot carrier
cell absorber. By analyzing photoluminescence spectra, the quasi Fermi level splitting Δμ and the carrier temperature are quantitatively measured as a function of the excit...
Epitaxie cohérente de composés GaP et GaAsPN à azote dilué sur substrats de Si pour l’élaboration de cellules PV tandem III-V/Si
GaAsPN semiconductors are promising material
for the development of high-efficiency tandem solar cells
on silicon substrates. GaAsPN diluted-nitride alloy is studied
as the top-junction material due to its perfect lattice
matching with the Si substrate and its ideal bandgap
energy allowing a perfect current matching with the Si
bottom cell. The GaP...
Thorough structural and optical analyses of GaP-based heterostructures monolithically grown on silicon substrates for photonics on Si applications: toward the laser on silicon and high efficiency photovoltaics on silicon
In this paper, we present a comprehensive study of high efficiencies tandem solar cells monolithically grown on a silicon substrate using GaAsPN absorber layer. InGaAs(N) quantum dots and GaAsPN quantum wells have been grown recently on GaP/Si susbstrate for applications related to light emission. For photovoltaic applications, we consider the GaAs...
Development of GaAsPN alloy for its integration in III-V/Si tandem solar cell
We investigated a semiconductor heterostructure based on InGaAsP multi quantum wells using optical and electrical characterizations. The optical analysis allows us to probe the potential of such a structure in the scope of hot carrier solar cell device. Using different photoluminescence techniques, the quasi Fermi level splitting Δμ and the carrier...
Advanced concepts of III-V-based Solar Cells heterostructures: towards III-V/Si CPV on Si substrates and hot-carrier solar cells on InP substrates
The nature of the ground optical transition in (In, Ga)As/GaP quantum dots is thoroughly investigated through k·p calculations and a supercell tight-binding simulation. Quantum dot morphology is deduced from scanning-tunneling-microscopy images. The strain field has a strong influence on the conduction band states. Indeed, for a pure GaAs QD, the w...
Lattice-matched GaAsPN/GaP single junction solar cell for high-efficiency tandem solar cells on silicon
Optimisation des propriétés structurale de l’interface GaP/Si et des propriétés électroniques de cellules solaires GaAsPN/GaP pour la fabrication de cellule tandem
Here we report for the first time a passive mode-locking of single section Fabry-Perot (FP) lasers based on InAs quantum dots(QDs) grown on (113)B InP substrate. Devices under study are a 1 and 2 mm long laser diodes emitting around 1.58 µm. Self-starting pulses with repetition rates around 23 and 39 GHz and pulse widths down to 1.5 ps are observed...
Analyse quantitative de la perfection cristalline de nanocouches épitaxiales GaP/Si
Abstract
We report on the association of Ultra High Vaccum Chemical Vapor Deposition (UHVCVD) and Molecular Beam Epitaxy (MBE) to achieve III–V (GaP) integration on Si/Si(100) substrates. We first demonstrate that a very good flatness (0.3 nm) can be obtained when growing directly GaP on a chemically prepared Si substrate. X-ray diffraction pole fi...
We report an InP based vertical cavity surface emitting laser (VCSEL) achieving a lasing operation between 1529 and 1646 nm. This optically-pumped VCSEL includes a wide-gain bandwidth active region based on InAs quantum dashes and wideband dielectric Bragg mirrors. Based on a wedge microcavity design, we obtain a spatial dependence of the resonant...
We report on the quantitative study of microtwins (MT) defects in the GaP/Si(0 0 1) thin film grown by Molecular Beam Epitaxy and the optical properties of GaAsP(N)/GaP(N) quantum wells grown on top of the GaP/Si pseudo-substrates. A 780 nm photoluminescence at room temperature from the GaAsPN quantum wells is measured on silicon. Time-resolved pho...
Raman spectroscopy was used to investigate the residual strain in thin GaP layers deposited on Si substrates by molecular beam epitaxy. Different growth conditions were used to obtain a clean GaP-Si interface, including migration enhanced epitaxy. The strain induced Raman shifts of the longitudinal and the transverse optical GaP lattice modes were...
AlGaP alloy and InGaAs/GaP quantum dots are studied toward possible solutions for the cladding layers and the active zone of a pseudomorphic laser structure on silicon. Coherent growth of AlGaP layers on GaP substrate is carefully analysed by X-ray reciprocal space mapping. The influence of Al content on refractive index is studied by spectroscopic...
In the context of III-V monolithic integration on silicon, synchrotron X-ray diffraction has been employed in this study using a bi-dimensional large area hybrid pixel detector (XPAD third generation) to characterize defects in the GaP layers. Despite a very coherent interface (low plastic relaxation) of GaP/Si, 2 types of defect are detected. Micr...
GaAsPN compounds for Si photonics
Intégration optique par croissance directe de nanostructures III-V sur silicium
We report on an optically excited InAs quantum dash vertical cavity surface
emitting lasers (VCSEL) on InP substrate. By introducing a wedge microcavity design, we
obtain a spatial dependence of the resonant wavelength along the wafer, enabling us to
monitor the gain material bandwidth. In this paper we show a continuously variable VCSEL
emission f...
The structural properties of (In,Ga)As/GaP quantum dots (QDs) are studied by plane view and cross scanning tunneling microscopy. Time-resolved and pressure dependent photoluminescence experiments show a ground optical transition of indirect type. Mixed k.p/tight-binding simulations indicate a possible indirect to direct crossover depending on indiu...
We report for the first time the passive mode-locking of single section Fabry-Perot (FP) lasers based on InAs quantum dots grown on (113)B InP substrate. Devices under study are a 1 and 2 mm long laser diodes emitting around 1.58 μm. Self-starting pulses with repetition rates around 39 and 23 GHz and pulse widths down to 1.5 ps are observed after p...
UHVCVD-MBE growth cluster for III-N-V/Si solar cells
We compare the potentiality of bulk InGaPN and GaAsPN materials quasi-lattice-matched to silicon (Si), for multi-junction solar cells application. Bandgaps of both bulk alloys are first studied by a tight-binding model modified for nitrogen incorporation in diluted regimes. The critical thicknesses of those alloys are then calculated for various co...
Enhanced incorporation of nitrogen on atomic step edges adsorption sites in diluted nitrides alloys
This paper aims to investigate the effects of the temperature on the
mode-locking capability of two section InAs/InP quantum nanostructure
(QN) passively mode locked lasers. Devices are made with multi-layers of
self-assembled InAs QN either grown on InP(100) (5 quantum dashes
(QDashes) layers) or on InP (311)B (6 quantum dots (QDs) layers). Using...
Lattice-matched GaP-based nanostructures grown on silicon substrates is
a highly rewarded route for coherent integration of photonics and
high-efficiency photovoltaic devices onto silicon substrates. We report
on the structural and optical properties of selected MBE-grown
nanostructures on both GaP substrates and GaP/Si pseudo-substrates. As a
firs...
We have investigated the influence of the surface roughness on nitrogen incorporation during the molecular beam epitaxy of diluted nitrides, independently of the other growth parameters. GaPN/GaP layers grown simultaneously on surfaces displaying different roughnesses reveal a large difference in nitrogen incorporation despite the same growth tempe...
L’intégration d’émetteurs ou d’absorbeurs optiques efficaces sur substrat de silicium est un enjeu de taille pour d’une part le développement de la photonique sur silicium (lasers intégrés) et d’autre part les cellules solaires photovoltaïques très haut rendement. Dans cette communication, les derniers résultats sur la croissance cristalline direct...
(In,Ga)As/GaP(001) quantum dots (QDs) are grown by molecular beam epitaxy and studied both theoretically and experimentally. The electronic band structure is simulated using a combination of k.p and tight-binding models. These calculations predict an indirect to direct crossover with the In content and the size of the QDs. The optical properties ar...
We study in detail self-assembled (In,Ga)As quantum dots grown on GaP substrate from the structural, theoretical, and optical points of view. Single quantum dot morphology is first determined at the atomic level using plane-view scanning tunneling microscopy. Unusual C2 symmetry properties with high-index {136} facets are demonstrated for small qua...
We report a structural study of molecular beam epitaxy-grown lattice-matched GaP/Si(0 0 1) thin layers with an emphasis on the interfacial structural properties, and optical studies of GaAsP(N)/GaP(N) quantum wells coherently grown onto the GaP/Si pseudo substrates, through a complementary set of characterization tools. Room temperature photolumine...
We report original results on GSMBE grown InAs/InP QD structures. Three single section devices show passive mode locking from 20 GHz to 83 GHz with low RF spectral width (32 kHz) and low pulse duration of 1.3 ps. We report also a double wavelength emission at high injection current, associated with degradation of mode locking properties. The real c...
Polarization controlled quantum dashes (QDHs) Vertical Cavity Surface Emitting Lasers (VCSELs) emitting at 1.6 µm grown on InP(001) are investigated and compared with a quantum well (QW) similar VCSEL. Polarization stability of optically-pumped VCSELs under a low frequency modulation is investigated. While major fluctuations of the polarization-res...
