Titanate Nanosheets as High Refractive Layer in Vertical Microcavity Incorporating Semiconductor Quantum Dots

The use of titanium dioxide as the high refractive index component in optical structures is very attractive because of its optical properties. In this work, we developed a novel synthesis of colloidal layered titanate consisting of nanosheets of titanium oxide. A colloidal solution of titanate nanosheets was deposited by spin coating and treated by thermal annealing and UV irradiation, obtaining high refractive index thin films. Transmission electron microscopy, X-ray diffraction, and spectroscopic ellipsometry were used to characterize titanate powders and the evolution of titanate films under the employed treatments. The developed low temperature UV-assisted titanate processing was found to be suitable in the fabrication of multilayer dielectric Bragg mirrors, which can be used in a vertical optical microcavity incorporating CdSe@ZnS quantum dots (QDs) in the defect layer. The developed fabrication procedure did not result in the loss of QDs emission properties, allowing for optical characterization of the coupling between QDs emission and the cavity. The compatibility between the processing of high refractive index materials and QDs functionality is very promising for novel strategies in the fabrication of optically active photonic structures.