Concepts 2D et 3D de résonateurs sub-longueur d'onde pour application à la photodétection

Abstract : This work was focused on quantum detectors in the short wave infrared (SWIR). We aimed at improving the performance of these devices (spectral properties & noise sensitivity) by exploring original concepts of detectors integrating 2D or 3D nano-resonators. In order to facilitate the numerical analysis of these structures, we developed at first a new method for modelling 3D resonators, based on the Finite Integration Technique (FIT). The matrices in the modal equations are highly sparse, which enables the use of specific algorithms for faster calculation. After that, we studied two separate designs of photodetecting devices : 1. We investigated the performance of an uncooled photodetector, based on two-photon absorption (TPA) in a gallium arsenide layer. Single photons are not absorbed in the semiconductor above 900 nm, but non-linear effects enable the simultaneous absorption of photon pairs ; however, they also have a low efficiency. In our design, the semiconductor material was introduced inside a nanostructured resonant cavity. We evidenced both numerically and experimentally an increase of the TPA inside the cavity by several orders of magnitude, due to strong field enhancement. 2. In a similar approach, we worked on reducing the noise level in indium gallium arsenide photodetectors. At present, the main contributor to this noise is the dark current due to generation-recombination processes, which can be decreased by reducing the semiconductor volume. To prevent the absorption from decreasing also, we designed nanostructured cavities enabling light trapping inside the semiconductor layer. In some cases, the resonances lead to the generation of photocarriers being highly localised, an interesting concept for noise reduction which has been patented.
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Benjamin Portier. Concepts 2D et 3D de résonateurs sub-longueur d'onde pour application à la photodétection. Optique [physics.optics]. Ecole Polytechnique X, 2013. Français. ⟨pastel-00933300⟩

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