SEMINAR LMGP - June 21, 2022 - Aubry MARTIN

Aubry MARTIN

PhD student,
Université Clermont Auvergne, Clermont Auvergne INP, CNRS, Institut de Chimie de Clermont-Ferrand (ICCF), Clermont-Ferrand, France
Université Grenoble Alpes, CNRS, LMGP, Grenoble, France

Abstract

       The main objective of the presented study is to take advantage of the specificities of Zinc Oxide (ZnO) Nanowires (NWs) array (porosity, specific surface…) for their use in LED lighting, by combining them with YAG:Ce phosphor and blue and UV LEDs. Indeed, the nanowires are expected to increase the emission intensity thanks to multi-scattering effects at the interface but also to emit in the red wavelengths domain (under UV excitation), where the YAG:Ce emission lacks intensity. The ZnO NWs were grown by hydrothermal synthesis from a ZnO seed layer directly deposited first on quartz and then on sol-gel derived Ce³⁺-doped yttrium aluminum garnet (Y₃Al₅O₁₂:Ce or YAG:Ce) coatings. ZnO NWs elaboration process was also optimized to achieve a specific structure, gratings with controlled optogeometrical properties (profile, height, width and frequency pitch). The use of NWs gratings instead of plenary array was expected to influence heterostructures features, notably their optical properties. Classical but also original techniques such as Atomic Force Microscopy (AFM) have been carried out to study the structural, morphological and optical properties of these functional coatings. In particular, the optical study showed that a resonant grating effect could be observed for certain emission angles, highly increasing the emission intensity of ZnO NWs and the YAG:Ce phosphor layer, which could lead to new LED systems for white lighting, better performing and with a reduced rare-earth content.