Resumen de Nanoestructuras híbridas para aplicaciones en fotónica.: Dispositivos fotovoltaicos y sensores de luz
Subwavelength nanostructures are of great interest for the manipulation of the effective refractive index of the materials used in photonic and plasmonic devices. In the current work, we decided to explore the use of nanostructured porous silicon (nanoPS) and hybrid nanostructures aiming at enhancing the optoelectronic properties of photonic devices based on silicon. First, we fabricated nanoPS and hybrid nanostructures of nanoPS combined with Ag metallic nanoparticles (nanoPS+AgNPs) onto silicon substrates. The optical characteristics as functions of the wavelength, angle of incidence, and polarization state of incident light were studied. The experimental results show a broadband optical absorption characteristic of the hybrid layers, which will be useful in light-harvesting devices. In addition, an accurate determination of the electrical properties of Si-based metal–insulator–semiconductor (MIS) Schottky barrier diodes was carried out. The results show a remarkable improvement in the performance of the MIS Schottky barrier diodes upon the addition of hybrid nanoPS layers with embedded Ag nanoparticles, opening the way to their use as photovoltaic devices. The key performance parameters of the MIS Schottky-junction solar cells were determined. A remarkable enhancement in the overall performance of the solar cells upon the addition of nanoPS and AgNPs layers to the basic structure is observed.
From another perspective, hybrid organic-inorganic self-powered photodetectors with three different configurations were fabricated and their optoelectronic performance was determined. In these devices, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is the organic layer and the inorganic layer is based on Si. The performance of the devices was greatly improved by modifying the structure of the active layer to be Si+nanoPS micro-arrays instead of single nanoPS layers or flat Si layers. This improved behavior is associated to the combined effect of an effective reduction of the reflectance due to the presence of nanoPS and an improvement of the electrical conduction given by the presence of heavily-doped Si regions.
