Electrical modeling of InAs/GaSb superlattice mid-wavelength infrared pin photodiode to analyze experimental dark current characteristics

Dark current characteristics of 7 Monolayers (ML) InAs/ 4 ML GaSb SL pin photodiodes are simulated using ATLAS software. Using appropriate models and material parameters, we obtain good agreement between the simulated and the experimental dark current curves of photodiodes grown by molecular beam epitaxy. The n-type non-intentionally-doped (nid) SL samples exhibit a dependence of the lifetime with temperature following the T−12 law, signature of Shockley-Read-Hall (SRH) Generation-Recombination current. We also studied the dependence of the dark current with the absorber doping level. It appears that the absorber doping level must not exceed a value of 2 × 1015 cm−3, above this value the dark current is increasing with increased doping level. However for this doping value, a dark current as low as 5 × 10−9 A/cm2, at 50 mV reverse bias at 77 K can be obtained

Multiphysic FEMLAB modelling to evaluate mid-infrared photonic detector performances

National audienceInfrared photo detectors operating in the mid infrared region find application in pollution monitoring, high speed infrared imaging systems and free space telecommunications. Currently the dominant infrared detector technology are based on HgCdTe or InSb photovoltaic devices. Because of their narrow band gap these devices show at room temperature (RT) high dark reverse current and small R0.A product, which significantly restrict the getting of high ambient performances. To reduce the darkness current and increase R0.A product, we suggested studying structures with large band gap energy. The objective of the photo detector structures modelling presented in this paper is double. It allows first to simulate and to estimate the theoretical performances of previously introduced large band gap components. As such we shall calculate, the product R0.A and the quantum efficiency to end in the specific detectivity D*. It is also a support to help in the understanding and in the interpretation of the made photo detectors characterizations

Application of laser diodes and photodetectors on multiple-quantum wells at the hot-metal pyrometry

In the paper,the method of relative spectroreflectometry at using the infra-red photodetectors with a wide diapason of the spectral photosensitivity is suggested.Methodical errors at exponential and power dependencies of the emissivity of an object on the wavelength are analysed. Possible design of a pyrometer for measurements of temperature of hot metals is described and attractiveness of quantum-well laser diodes and superlattice photodetectors based on the GaSb compounds is discussed. Keywords: pyrometry, spectroreflectometry, near-infrared range, photodetector, laser diode, methodical erro

Electrical properties of short period InAs/GaSb superlattice

International audienc

Residual fixed pattern noise and random telegraph signal noise of a MWIR T2SL focal plane array

International audienceStability over time has recently become a figure of merit of major importance to compare the performances of infrared focal plane arrays (FPA) of different technologies. Indeed, this parameter dictates how often the calibration of operational electro-optical systems has to be done, and thus reflects the availability of the system during an operational mission. The stability over time is generally estimated through fixed pattern noise (FPN) and residual fixed pattern noise (RFPN) measurements after a two-point correction. However, each laboratory or industrial has its own protocols and criteria, such that published results cannot be easily compared. Recent studies also showed that random telegraph signal (RTS) noise, which leads to flickering pixels, can strongly affect the image quality, so the question arises as to wether these RTS pixels have an effect on RFPN. In this paper, we describe our experimental protocol to evaluate the stability over time of an FPA and to count up/classify flickering pixels. We then present the results obtained on a T2SL MWIR Integrated Detector Dewar Cooler Assembly (IDDCA) provided by IRnova. Our measurements show that the stability over time of the T2SL MWIR IDDCA are excellent: first, in terms of FPN/RFPN; then, in terms of RTS noise with only a few blinking pixels. We also show that the RTS pixels having an effect on the RFPN are fully detected by the algorithm used to rule out defective pixels before calculating RFPN

MTF measurements of a type-II superlattice infrared focal plane array sealed in a cryocooler

International audienceIn operational electro-optical systems, infrared focal plane arrays (IR FPA) are integrated in cryocoolers which induce vibrations that may strongly affect their modulation transfer function (MTF). In this paper, we present the MTF measurement of an IR FPA sealed in its cryocooler. The method we use to measure the MTF decorrelates operational constraints and the technological limitations of the IR FPA. The bench is based on the diffraction properties of a continuously self imaging grating (CSIG). The 26 µm pixel size extracted from the MTF measurement is in good agreement with the expected value

Hot Carrier Solar Cell: From Simulation to Devices

International audienceSingle 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. Previous modelling and experiments have shown the interest of Multiple Quantum Wells heterostructures in the antimonide system and the importance of very thin structures. 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 device

Identification of a limiting mechanism in GaSb-rich superlattice midwave infrared detector

GaSb-rich superlattice (SL) p-i-n photodiodes grown by molecular beam epitaxy were studied theoretically and experimentally in order to understand the poor dark current characteristics typically obtained. This behavior, independent of the SL-grown material quality, is usually attributed to the presence of defects due to Ga-related bonds, limiting the SL carrier lifetime. By analyzing the photoresponse spectra of reverse-biased photodiodes at 80 K, we have highlighted the presence of an electric field, breaking the minibands into localized Wannier-Stark states. Besides the influence of defects in such GaSb-rich SL structures, this electric field induces a strong tunneling current at low bias which can be the main limiting mechanism explaining the high dark current density of the GaSb-rich SL diode

Signa et tituli

La spécialisation de plus en plus grande et le cloisonnement de nos domaines de recherche (histoire, histoire de l’art, archéologie...) conduisent le plus souvent à étudier et à publier séparément, malgré leur complémentarité, les sources épigraphiques et les sources iconographiques. Des salles de nos musées aux rayons de nos bibliothèques, documents sculptés et documents inscrits forment des ensembles "disjoints". Or, statuaire et épigraphie, signa et tituli, étaient dans l’Antiquité des éléments conçus ensemble, comme les deux volets d’un même message, indissociables dès la première formulation. Cette conjonction d’un texte et d’une image définit précisément le monumentum si caractéristique de la pratique commémorative romaine. Cet ouvrage, centré sur la question du monumentum romain, regroupe les communications présentées lors du colloque "Signa et tituli. Monuments et espaces de représentation en Gaule méridionale sous le regard croisé de la sculpture et de l’épigraphie" (Aix-en-Provence, 26-27 novembre 2009). À la suite d’une approche méthodologique, l’ouvrage propose une série d’études sur différents lieux de la société romaine où se croisent données iconographiques et épigraphiques : les espaces civiques de représentation, les espaces et monuments funéraires, les espaces de la religion