Etude de l'amélioration de la luminescence observée dans des réseaux de nanofils de ZnO élaborés de manière optimisée par voie hydrothermale

International audienceWe report for the first time the elaboration of an original ZnO nanowire (NW) architecture entirely based on a soft chemistry approach and its thorough assessment through optical measurements and electromagnetic simulations. This architecture relies on the photo-imprinting of a sol-gel ZnO-based photosensitive seed layer combined with the subsequent localized hydrothermal growth of ZnO NWs. We firstly show how optimization of the elaboration protocol leads to uniform and reproducible linear and periodic gratings of ZnO NWs with a width / pitch of 2 µm / 4 µm. For reference, full-covered samples (NWs coating) have also been elaborated from a non-imprinted seed layer. It has been evidenced through morphological study that NW gratings present a peculiar profile similar to a hedgehog. Standard and angle-resolved photoluminescence measurements performed on both kinds of samples are then presented. These optical characterizations demonstrate that ZnO NW visible emission is strongly modified by the presence of NW gratings and that its red part is directionally extracted and increased by a factor up to 2. We present finally electromagnetic simulations performed for both samples which highlight the role of the gratings acting as coupled microcavities that boost the ZnO emission thanks to light localization and diffractive mechanisms. It enables the extraction of the resonant photons towards some specific angles and at given wavelengths