Modélisation et Réalisation de Réseaux Sub-Longueur d'Onde :
Application au Contrôle de la Réflectivité Large Bande, Large Incidence.

摘要

Antireflective surface coatings allow increasing the efficiency of photovoltaic cells, increasing the sensitivity of photodetectors or improving the light extraction from LEDs. Traditionally, antireflective coatings are obtained using thin-film stacks. We have studied an alternative technique based on the micro-structuration of the air/substrate interface. More precisely, we have focused our efforts on the modelization and the fabrication of bi-periodic micro-structured surfaces on silicon and germanium. Such microstructured surface on Si and Ge exhibit efficient antireflection properties in the infrared bands II and III respectively. These structures need a rigorous description of light propagation phenomena. The influence of opto-geometrical parameters is studied using the photonic crystal theory and photonic band diagrams. To fabricate these structures, low cost processing techniques are proposed using wet anisotropic etching of crystalline semiconductors through a mask obtained by photolithography. On silicon, we have experimentally obtained a reflectance lower than 4% on the entire IR II band. A very good agreement between calculated and experimental results enables the validations of previously obtained numerical results.