Transmission tunnel assistée par défaut dans un détecteur infrarouge à multipuits quantiques

Session AffichesNational audienceOn étudie l'influence d'un défaut profond sur la transmission tunnel dans la zone à multipuits quantiques d'un photo-détecteur infrarouge. Dans le cadre d'un formalisme matriciel, le défaut est assimilé à une singularité de Dirac du potentiel

Interface roughness transport in THz quantum cascade detectors

Infrared Detectors based on a Quantum Cascade have been proposed to suppress the dark current which is identified as a limiting factor in Quantum Well Infrared Photodetectors. Those detectors have been mostly designed for the 3-5um and 8-12um range of wavelength. For detector operating in the THz range a complete change of regime of transport is expected since the photon energy is lower than the Longitudinal Optical (LO) phonon energy. Using a two dimensional code of transport we have identified Interface Roughness (IR) as the key interaction in such a structure. We have used scanning transmission electron microscopy (STEM) to evaluate the IR parameters (magnitude of the roughness and mean distance between defects) instead of the classical mobility measurements. Finally, we used these parameters to study their influence on the resistance of the 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

15{\mu}m Quantum well infrared photodetector for thermometric imagery in cryogenic windtunnel

Quantum Well Infrared Photodetector (QWIP) usually suffer from a too moderate quantum efficiency and too large dark current which is often announced as crippling for low flux applications. Despite this reputation we demonstrate the ability of QWIP for the low infrared photon flux detection. We present the characterization of a state of the art 14.5\mu m QWIP from Alcatel-Thales 3-5 Lab. We developed a predictive model of the performance of an infrared instrument for a given application. The considered scene is a Cryogenic Wind Tunnel (ETW), where a specific Si:Ga camera is currently used. Using this simulation tool we demonstrate the QWIP ability to image a low temperature scene in this scenario. QWIP detector is able to operate at 30K with a NETD as low as 130mK. In comparison to the current detector, the temperature of use is three times higher and the use of a QWIP based camera would allow a huge simplification of the optical part

: Orientation of emerging technologies for infrared detection

This manuscript presents an overview of my research activities dedicated to the orientation of emerging technologies for infrared detection. It begins with a brief description of the context, followed by a presentation of the five experimental test benches and the three modelling tools that were developed under my supervision. Then, the concrete example of the InAs/GaSb type-II superlattice technology is described into detail, since I had the opportunity to drive the orientation of this emerging technology from the very beginning, ten years ago.This mission allowed me to put in place a long-term scientific approach, based on a fruitful collaboration with the Institut d’Electronique et des Systèmes (IES) from university of Montpellier. The results we obtained allow us to rule on the potential of this emerging technology to address the 3 - 5 µm spectral band and to define new axes of research for the years to come. To finish with, my teaching activities, which also focus on infrared detection, are described.Ce mémoire présente l’essentiel de mes travaux de recherche sur l’orientation des filières émergentes en détection infrarouge. Après une brève présentation du contexte, je présente les outils que j’ai contribué à développer au travers des travaux de thèse ou de post-doc que j’ai encadrés : en l’occurrence, cinq bancs de tests et trois modèles. Je prends ensuite l’exemple concret de la filière super-réseaux, dont je pilote l’orientation à l’ONERA depuis dix ans maintenant.Cette mission m’a permis de mettre en place une démarche scientifique sur le long terme, qui s’articule autour de la collaboration nouée avec l’Institut d’Electronique et des Systèmes (IES) de l’université de Montpellier. Les résultats obtenus me permettent de conclure sur le potentiel de cette filière émergente dans la bande spectrale 3 - 5µm et de définir de nouveaux axes de recherche pour les années à venir. Je termine ce mémoire par la description des activités d’enseignement que j’ai menées en parallèle de mon travail de recherche, elles aussi centrées sur la détection infrarouge

Transmission tunnel assistée par défaut dans un détecteur infrarouge à multipuits quantiques

Session AffichesNational audienceOn étudie l'influence d'un défaut profond sur la transmission tunnel dans la zone à multipuits quantiques d'un photo-détecteur infrarouge. Dans le cadre d'un formalisme matriciel, le défaut est assimilé à une singularité de Dirac du potentiel

Quantum scattering engineering of quantum well infrared photodetectors in the tunneling regime

International audienceDark current is shown to be significantly reduced in quantum well infrared photodetectors in the tunneling regime, i.e., at very low temperature, by shifting the dopant impurity layers away from the central part of the wells. This result confirms that the interwell tunneling current is dominated by charged impurity scattering in usual structures. The experimental results are in good quantitative agreement with the proposed theory. This dark current reduction is pushing further the ultimate performances of quantum well infrared photodetectors for the detection of low infrared photon fluxes. Routes to further improvements are briefly sketched