ABSTRACT Evaluating the performances of infrared photodetectors requires both electrical and optical measurements, including a detailed analysis of the noise behavior. Indeed, in such detectors, noise can arise from the absorbing layer... more
ABSTRACT Evaluating the performances of infrared photodetectors requires both electrical and optical measurements, including a detailed analysis of the noise behavior. Indeed, in such detectors, noise can arise from the absorbing layer (Schottky noise due to photonic and dark currents, thermal noise, low frequency noise due to technological imperfections) as well as from the read-out integrated circuit (ROIC) or from the analog to digital converter (ADC). Therefore, it is of great importance to carry out noise measurements on single elements (without ROIC and ADC) as well as on focal plane arrays. In this paper, we present noise measurements on single detectors and on a large format focal plane array, both suitable to address the 3-5μm spectral range. The single detectors are InAs/GaSb superlattice pin photodiodes which already proved to be a very promising emerging technology, whereas the focal plane array relies on the well established, high performance InSb technology.
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HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad,... more
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et a ̀ la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Hot carrier solar cells allow potential efficiency close to the thermodynamical limit in ideal conditions. However, the feasability of such devices has not been clearly stated so far and only ideal cells were considered in previous... more
Hot carrier solar cells allow potential efficiency close to the thermodynamical limit in ideal conditions. However, the feasability of such devices has not been clearly stated so far and only ideal cells were considered in previous studies. Here we develop a model with realistic energy selective contacts, carrier thermalization and absorptivity. The requirements in term of contact selectivity is investigated, showing that semi-selective contacts are not incompatible with high efficiencies. Candidates for absorbing material were synthesized and the required thermalization properties are obtained. Specific structures were designed to enhance absorption of concentrated sunlight in a small material thickness, allowing high carrier density in the absorber.
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Infrared photodetectors based on type-II InAs/GaSb superlattice (T2SL) material has been given a lot of attention this past decade, in particular by U.S. laboratories. Among the advantages of this material system, one can cite the... more
Infrared photodetectors based on type-II InAs/GaSb superlattice (T2SL) material has been given a lot of attention this past decade, in particular by U.S. laboratories. Among the advantages of this material system, one can cite the possibility to span a large Infrared (IR) range (3μm to 30 μm) by tailoring the band-gap independently from the lattice constant, allowing addressing many applications by the same fabrication process and the realization of multi-color IR sensors for high performance imaging systems. Recently, the maturity of the growth of the quantum structure by molecular beam epitaxy (MBE) and progress on the processing resulted in the demonstration of high-performance mega-pixel focal plane arrays (FPA) in both the mid-wavelength (MWIR) and the long-wavelength (LWIR) infrared spectral bands [1]. Consequently, InAs/GaSb T2SL photodetector can be now considered as a new infrared technology which can be complementary to InSb, MCT or QWIPs technologies. After some reminders...
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In this paper, results from the development of LWIR and VLWIR InAs/GaSb type-II infrared photodetector arrays are presented. Dark currents comparable to the HgCdTe benchmark (Rule07) have been observed and the quantum efficiencies of the... more
In this paper, results from the development of LWIR and VLWIR InAs/GaSb type-II infrared photodetector arrays are presented. Dark currents comparable to the HgCdTe benchmark (Rule07) have been observed and the quantum efficiencies of the detectors exceed 30 %. Bias and temperature dependencies of the QE have been studied showing very low turn on bias (~-25mV) and no variation of the peak QE value with temperature. These results show that there are no unintentional barriers in the detector structures and that the diffusion lengths are long enough to provide efficient collection of carriers. Initial results from the extension of the cut-off wavelength from 11 μm to 14 μm are also presented as well as initial results from photodiodes with thicker absorbers to enhance the QE.
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ABSTRACT Symmetric and asymmetric mid-wavelength infrared (MWIR) InAs/GaSb superlattice (SL) pin photodiode were fabricated by Molecular Beam Epitaxy (MBE) on p-type GaSb substrate and characterized as a function of temperature. The... more
ABSTRACT Symmetric and asymmetric mid-wavelength infrared (MWIR) InAs/GaSb superlattice (SL) pin photodiode were fabricated by Molecular Beam Epitaxy (MBE) on p-type GaSb substrate and characterized as a function of temperature. The symmetric SL structure was made of 8 InAs monolayers (MLs) and 8 GaSb MLs and exhibits at 80K a cut-off wavelength (lambdac) of 4.5mum, while the asymmetric SL design was composed of 7.5 InAs MLs and 3.5 GaSb MLs for lambdac = 5.5mum at 80K. Optical characterizations made of photoluminescence as a function of temperature and room temperature absorption spectra were performed on these two kinds of structures. Several electrical characterizations including dark current and capacitance-voltage measurements were also carried out on single detectors in the temperature range [77K-300K]. Results obtained were compared and analyzed in order to define optimized SL structure design for the high performance in the MWIR domain.
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Page 1. A theoretical study of laser structures based on dilute-nitride InAsN for mid-infrared operation This article has been downloaded from IOPscience. ... doi:10.1088/0268-1242/24/8/085010 A theoretical study of laser structures based... more
Page 1. A theoretical study of laser structures based on dilute-nitride InAsN for mid-infrared operation This article has been downloaded from IOPscience. ... doi:10.1088/0268-1242/24/8/085010 A theoretical study of laser structures based on dilute-nitride InAsN for ...
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... H. Aït-Kaci, J. Nieto, JB Rodriguez, P. Grech, F. Chevrier, A. Salesse, A. Joullié, and P. Christol* Centre d'Électronique et de Micro-optoélectronique de Montpellier (CEM2), Unité Mixte de Recherche CNRS n°5507,... more
... H. Aït-Kaci, J. Nieto, JB Rodriguez, P. Grech, F. Chevrier, A. Salesse, A. Joullié, and P. Christol* Centre d'Électronique et de Micro-optoélectronique de Montpellier (CEM2), Unité Mixte de Recherche CNRS n°5507, Université de Montpellier II, Sciences et Techniques du ...
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ABSTRACT In this paper, the electro-optical properties of InAs/GaSb superlattice (SL) midwave infrared photodiodes with different periods were investigated. Three devices with different SL periods, but the same cut-off wavelength at 5 µm... more
ABSTRACT In this paper, the electro-optical properties of InAs/GaSb superlattice (SL) midwave infrared photodiodes with different periods were investigated. Three devices with different SL periods, but the same cut-off wavelength at 5 µm at 77 K, were grown by molecular beam epitaxy on p-type GaSb substrates. The optical and electrical behaviours were characterized and analysed. Our investigations show strong influence of the SL composition on both the material properties and photodetector performances, such as the background doping concentration, shape of the response spectra and the dark current behaviours.
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ABSTRACT A midwave infrared pin photodiode based on a type II InAs/GaSb superlattice (SL) was fabricated, and electrical measurements under dark conditions were performed as a function of temperature. The SL structure exhibits... more
ABSTRACT A midwave infrared pin photodiode based on a type II InAs/GaSb superlattice (SL) was fabricated, and electrical measurements under dark conditions were performed as a function of temperature. The SL structure exhibits photoluminescence emission at 4.55 μm at 77 K. Deduced from current density–voltage (J–V) measurements, a zero-bias resistance–area product R 0A greater than 1 × 106 Ω cm2 at 77 K was measured. Additional noise measurements show no presence of intrinsic 1/f noise above 20 Hz, and the photodiode presents Schottky-limited behavior below −600 mV. All these results confirm the potential for such SL InAs/GaSb superlattice pin photodiodes operating in the midwave infrared domain.
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Recombination through quantum dots (QDs) is a major factor that limits efficiency of QD intermediate-band (IB) solar cells. Our proposal for a new IB solar cell based on type-II GaSb QDs located outside the depletion region of a GaAs... more
Recombination through quantum dots (QDs) is a major factor that limits efficiency of QD intermediate-band (IB) solar cells. Our proposal for a new IB solar cell based on type-II GaSb QDs located outside the depletion region of a GaAs p-n-junction aims to solve this problem. The important advantage of proposed heterostructure appears due to the outside location of IB. Such IB does not assist generation of additional leakage current flow through the depletion region. Carriers cannot escape from outside QDs through the buffer layer and the depletion region into GaAs substrate by tunneling because QDs are far from the depletion layer. Only solar photon or thermal assistance may enable electron escape from QDs. Such type-II QD IB solar cell concept promises an efficiency enhancement relative to that of GaAs solar cells.
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Abstract In this paper, a comparison of quantum efficiency and dark current densities of shallow etched and deep etched InAs/GaSb type-II superlattice photodiodes is presented. The detectors were tailored for space applications with... more
Abstract In this paper, a comparison of quantum efficiency and dark current densities of shallow etched and deep etched InAs/GaSb type-II superlattice photodiodes is presented. The detectors were tailored for space applications with measured cut-off wavelengths around 11.2 µm. Bias and temperature dependencies of the QE have been studied showing very low turn on bias (>−25 mV) and very small variation of the peak QE value with temperature. At 70 K, peak quantum efficiencies of shallow and deep etched devices were deduced to 34% and 30%, respectively (without antireflection coating). The difference was attributed to a larger collection area of shallow etched devices, with a collection range of approximately 22 µm outside of the defined pixel area. Diffusion limited dark currents were observed down to 60 K for both shallow and deep etched devices under low reverse bias (∼−200 mV) with dark current densities on the order of 1.7 × 10−5 A/cm2 at 60 K. A gradually increasing influence of generation-recombination (G-R) and trap-assisted tunneling (TAT) was observed at lower temperatures for high reverse bias. The lowest dark current densities were observed for deep etched photodiodes, on the order of 3 × 10−7 A/cm2 at 40 K (Vbias = −100 mV). Detector arrays were fabricated with deep etched 30 µm pitch pixels. Comparably low dark current densities were observed for the detector array pixels under low reverse bias as for the single pixel photodiodes, however a significant increase of the TAT dark current was observed under high reverse bias.
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Abstract In this work, we report on the determination of band discontinuities and energy band diagram of the Ga0.6Al0.4As0.034Sb0.966(p)/Ga0.6Al0.4As0.034Sb0.966(n)/InAs0.9Sb0.1 double interface at equilibrium and room temperature, by... more
Abstract In this work, we report on the determination of band discontinuities and energy band diagram of the Ga0.6Al0.4As0.034Sb0.966(p)/Ga0.6Al0.4As0.034Sb0.966(n)/InAs0.9Sb0.1 double interface at equilibrium and room temperature, by capacitance-voltage measurements (C-V). Mesa diodes, with three different diameters are characterized and physical quantities like doping concentration in the unintentionally doped (n.i.d) InAsSb material and diffusion potentials at interfaces are extracted from C-V data. Finally, the energy band diagram of the structure is drawn and experimental values of energy band offsets are deduced and compared to those obtained by a numerical simulation.
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The residual carrier concentration of GaSb and GaSb-lattice matched Ga1-xInxAsySb1-y alloys (x = 0.12-0.26 y = 0.9x) grown by liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) was studied as a function of growth temperature,... more
The residual carrier concentration of GaSb and GaSb-lattice matched Ga1-xInxAsySb1-y alloys (x = 0.12-0.26 y = 0.9x) grown by liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) was studied as a function of growth temperature, V/III ratio and alloy composition. Typical carrier concentrations p ~ 2-3×1016 cm-3 were obtained for undoped GaSb grown by MBE at 480°C, by LPE from Ga-rich melt at low temperature (400°C), and by LPE from Sb-rich melts at ~600°C. The native acceptor defect responsible of the high p-type residual doping in GaSb is reduced when the indium concentration is increased, and disappears for indium rich alloys (x = 0.23, 0.26). Tellurium compensation was used for controlled n-type doping in the (0.05-30)×1017 cm-3 range. A maximum of free carrier concentration was 1.5×1018 cm-3 for LPE layers, 2×1018 cm-3 for MBE layers grown at 1.0 mum/h, 3.5×1018 cm-3 for MBE layers grown at 0.2 mum/h. SIMS measurements showed Te concentrations of more than 1020 at/cm3, suggesting the formation of ternary GaSb1-xTex solid solution.
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ABSTRACT The paper presents an overview of semiconductor laser and detector structures for the mid-infrared wavelength range (3-5 μm). Recent progress in new laser systems are described : intersubband quantum cascade lasers (QCLs),... more
ABSTRACT The paper presents an overview of semiconductor laser and detector structures for the mid-infrared wavelength range (3-5 μm). Recent progress in new laser systems are described : intersubband quantum cascade lasers (QCLs), interband "W" lasers, and interband quantum cascade lasers (ICLs). All these laser structures employing AlSb, InAs, GaSb and related alloys have the potentiality to reach the challenges of room temperature operation in continuous wave for modern applications. The description of detector structures is focussed on intersubband transition systems based on type-II InAs/GaSb superlattices or InSb/GaSb quantum dots.
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Single junction III-V heterostructures based devices could overtake the Shockley-Queisser limit if thermalisation of photogenerated carriers can be strongly limited as in the hot carrier solar cell concept [1]. Previous modelling [2] and... more
Single junction III-V heterostructures based devices could overtake the Shockley-Queisser limit if thermalisation of photogenerated carriers can be strongly limited as in the hot carrier solar cell concept [1]. Previous modelling [2] and experiments [3] have shown the interest of Multiple Quantum Wells heterostructures in the antimonide system and the importance of very thin structures [3,4]. In this paper we report new data on the thermalisation rates in antimonide and phosphide heterostructures measured at ambient temperature. For the first time electrical control of hot carrier population is performed on hot carrier heterostructures devices.
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Aujourd'hui il n'existe aucune source laser classique a semiconducteur capable de fonctionner a temperature ambiante, et en regime continu, dans la region spectrale 3-5 μm du moyen infrarouge. Cette plage de longueurs d'onde... more
Aujourd'hui il n'existe aucune source laser classique a semiconducteur capable de fonctionner a temperature ambiante, et en regime continu, dans la region spectrale 3-5 μm du moyen infrarouge. Cette plage de longueurs d'onde est tres interessante du point de vue des applications car elle constitue une fenetre de transparence de l'atmosphere pour les transmissions optiques. Cette absence de sources tient a des limitations fondamentales liees d'une part a l'existence de recombinaisons non radiatives telles que l'effet Auger, d'autre part a la reabsorption des photons emis au sein du materiau actif par suite d'interactions avec les porteurs de charge, electrons et trous, presents dans la structure. Il est possible de contourner ces limitations en s'appuyant sur de nouveaux concepts de fonctionnement, fondes sur le controle des proprietes quantiques grâce a une ingenierie de bandes a l'echelle atomique. Cet article propose deux exemples de ces nouvelles structures laser, qui utilisent les proprietes specifiques des antimoniures, le laser interbande a puits quantiques « W» et le laser a cascade quantique InAs/AISb.
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The electronic band-structure and optical gain properties of dilute-nitride InAsN/GaSb/InAsN type-II 'W' quantum wells based mid-infrared laser diodes on InAs substrate are numerically investigated... more
The electronic band-structure and optical gain properties of dilute-nitride InAsN/GaSb/InAsN type-II 'W' quantum wells based mid-infrared laser diodes on InAs substrate are numerically investigated with an accurate 10-bands kp model. The laser diodes are designed to operate at 3.3 µm at room temperature. The dispersion relations, the optical gain and the threshold current density including computation of non-radiative Auger recombination
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We report the molecular beam epitaxy growth of a new laser structure on n-type (100) InAs substrate, which was designed for emission near 3μm at 80K and 3.3μm at room temperature. This structure employs the InAsSb/InAs/InAsSb/InAlAsSb... more
We report the molecular beam epitaxy growth of a new laser structure on n-type (100) InAs substrate, which was designed for emission near 3μm at 80K and 3.3μm at room temperature. This structure employs the InAsSb/InAs/InAsSb/InAlAsSb type-II “W” configuration in the active region, broad InAlAsSb waveguides, and AlAsSb cladding layers. Lattice-matching of In0.88Al0.12As1−xSbx quaternary alloy was obtained at a low
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ABSTRACT We present a numerical modeling of the conduction- and the valence-band diagrams of W designed Si/Si0.4Ge0.6/Si type II quantum wells. These W structures, strain-compensated on relaxed Si0.75Ge0.25 pseudo-substrates, are... more
ABSTRACT We present a numerical modeling of the conduction- and the valence-band diagrams of W designed Si/Si0.4Ge0.6/Si type II quantum wells. These W structures, strain-compensated on relaxed Si0.75Ge0.25 pseudo-substrates, are potentially interesting for emission and photo-detection around a 1.55 mu m wavelength. Two main features have been extrapolated by solving self-consistently Schrodinger and Poisson equations, taking into account the electrostatic attraction induced by carrier injection: (i) Coulomb attraction strongly modifies the band profiles and increases the electron probability density at the quantum well interfaces. (ii) The injected carrier concentration enhances the in-plane oscillator strength and the electron-hole wave-function overlap. (c) 2006 Elsevier B.V. All rights reserved.