247 research outputs found
Numerical simulation of InGaN Schottky solar cell
The Indium Gallium Nitride (InGaN) III-Nitride ternary alloy has the
potentiality to allow achieving high efficiency solar cells through the tuning
of its band gap by changing the Indium composition. It also counts among its
advantages a relatively low effective mass, high carriers\^a mobility, a high
absorption coefficient along with good radiation tolerance.However, the main
drawback of InGaN is linked to its p-type doping, which is difficult to grow in
good quality and on which ohmic contacts are difficult to realize. The Schottky
solar cell is a good alternative to avoid the p-type doping of InGaN. In this
report, a comprehensive numerical simulation, using mathematically rigorous
optimization approach based on state-of-the-art optimization algorithms, is
used to find the optimum geometrical and physical parameters that yield the
best efficiency of a Schottky solar cell within the achievable device
fabrication range. A 18.2% efficiency is predicted for this new InGaN solar
cell design
Robust Design by Antioptimization for Parameter Tolerant GaAs/AlOx High Contrast Grating Mirror for VCSEL Application
A GaAs/AlOx high contrast grating structure design which exhibits a 99.5%
high reflectivity for a 425nm large bandwidth is reported. The high contrast
grating (HCG) structure has been designed in order to enhance the properties of
mid-infrared VCSEL devices by replacing the top Bragg mirror of the cavity. A
robust optimization algorithm has been implemented to design the HCG structure
not only as an efficient mirror but also as a robust structure against the
imperfections of fabrication. The design method presented here can be easily
adapted for other HCG applications at different wavelengths.Comment: (c) 2013 IEEE. Personal use of this material is permitted. Permission
from IEEE must be obtained for all other users, including
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work
Simulation study of a new InGaN p-layer free Schottky based solar cell
On the road towards next generation high efficiency solar cells, the ternary
Indium Gallium Nitride (InGaN) alloy is a good passenger since it allows to
cover the whole solar spectrum through the change in its Indium composition.
The choice of the main structure of the InGaN solar cell is however crucial.
Obtaining a high efficiency requires to improve the light absorption and the
photogenerated carriers collection that depend on the layers parameters,
including the Indium composition, p-and n-doping, device geometry.. .
Unfortunately, one of the main drawbacks of InGaN is linked to its p-type
doping, which is very difficult to realize since it involves complex
technological processes that are difficult to master and that highly impact the
layer quality. In this paper, the InGaN p-n junction (PN) and p-in junction
(PIN) based solar cells are numerically studied using the most realistic
models, and optimized through mathematically rigorous multivariate optimization
approaches. This analysis evidences optimal efficiencies of 17.8% and 19.0% for
the PN and PIN structures. It also leads to propose, analyze and optimize
player free InGaN Schottky-Based Solar Cells (SBSC): the Schottky structure and
a new MIN structure for which the optimal efficiencies are shown to be a little
higher than for the conventional structures: respectively 18.2% and 19.8%. The
tolerance that is allowed on each parameter for each of the proposed cells has
been studied. The new MIN structure is shown to exhibit the widest tolerances
on the layers thicknesses and dopings. In addition to its being player free,
this is another advantage of the MIN structure since it implies its better
reliability. Therefore, these new InGaN SBSC are shown to be alternatives to
the conventional structures that allow removing the p-type doping of InGaN
while giving photovoltaic (PV) performances at least comparable to the standard
multilayers PN or PIN structures.Comment: Superlattices and Microstructures, Elsevier, 201
The theory of photorefractive resonance for localized beams in two-carrier photorefractive systems
This paper extends the existing theory of two carrier photorefractivity
resonance, which is generally applied to Iron doped Indium Phosphide (InP:Fe),
to the case of low non-harmonic illumination. The space charge field profile is
computed, and the variations of its amplitude, width and position are
determined as functions of the background intensity. The effect of
photorefractive resonance on these quantities is evidenced, contributing to the
understanding of published experimental results in InP:Fe.Comment: Physical Review A: Atomic, Molecular and Optical Physics Accepted
(2009) To be publishe
Cellular Computing and Least Squares for partial differential problems parallel solving
The pre-print archived version is not the one that is published, as the editor does not formally allow it.International audienceThis paper shows how partial differential problems can be solved thanks to cellular computing and an adaptation of the Least Squares Finite Elements Method. As cellular computing can be implemented on distributed parallel architectures, this method allows the distribution of a resource demanding differential problem over a computer network
Microsecond infrared beam bending in photorefractive iron doped indium phosphide
International audienceA time resolved study of the behavior of a single beam in photorefractive iron doped indium phosphide is provided down to the microsecond range, showing that infrared beam bending does occur on the microsecond time scale for moderate beam intensities. Two distinct time scales are evidenced, the behavior of which are the sign of two different photorefractive mechanisms
Optique Ondulatoire
Utiliser la version "slides" du cours pour la projeter avec n'importe quel lecteur de PDF (type Acrobat Reader), en ayant auparavant distribué la version "handout" imprimée..; http://moodle.univ-metz.fr/course/view.php?id=770Licence / L2Cours d'Optique Ondulatoire adapté à une vidéo-projection, associé à un manuel, de niveau Licence deuxième anné
Experimental control of steady state photorefractive self-focusing in InP:Fe at infrared wavelengths
International audienceThis paper reports an experimental study of the self-focusing process in iron doped indium phosphide at an 1.06 micron wavelength, identifying the influence of temperature, beam intensity and background illumination \RefereeOne{for two different iron dopings}. We point out that the iron ionization ratio is at the origin of different qualitative behavior previously reported and we show that it is possible to reproduce the said behaviors in the same crystal by applying a uniform illumination, allowing their eventual control for dynamic wave-guiding
SLALOM: Open-source, portable, and easy-to-use solar cell optimizer. Application to the design of InGaN solar cells
International audienceThe design and optimization of novel structures is an essential part of the next-generation solar cells development. Indeed, the technological steps involved in the development of high-performance solar cells involve a huge set of interdependent physical and geometrical parameters: layers thicknesses, dopings, compositions, and defect characteristics. In this work, we propose a new open-source and free solar cell optimizer: SLALOM À for SoLAr ceLl multivariate OptiMizer À that implements a rigorous multivariate approach, which improves from the one-parameter-at-a-time procedure that is traditionally used in the field to a state-of-the-art multivariate approach. Applied to indium gallium nitride (InGaN) solar cells, it shows its potential to become a useful tool for the development of novel solar cells. SLALOM is implemented to be extended to any semiconductor simulation engine. Several models for solar cells have been implemented in SLALOM, including, for instance, InGaN. One can adapt these models to any solar cell technology by changing the parameter set, the here proposed generic code structure remaining unchanged
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