Opportunities of Semiconducting Oxide Nanostructures as Advanced Luminescent Materials in Photonics.

The luminescence properties of semiconductors are key to the development of photonics. In recent years, the targeted semiconductor materials have shifted from narrow-bandgap to wide- and ultra-wide-bandgap ones, which means spanning the domains of operation for devices beyond those possible with conventional semiconductors in the fields of high-power devices and deep-ultraviolet photodetectors. Furthermore, materials nanostructures with one or more dimensions at the nanoscale drive additional novelties in their optical properties, boosting innovative features. The next step in advanced materials necessarily goes through the quantum - photonic link, in which electromagnetic waves and electronic quantum states display all possible degrees of freedom. To achieve effective advances in this field, both innovative research in materials science and the development of suitable strategies to assess the quantum signatures in the material systems under study are required. This work reviews the fascinating light emission and confinement in wide and ultra-wide bandgap semiconducting oxides of technological interest in nanostructured form, focusing on their luminescence and the key role they can play in future quantum photonic technologies, such as single photon sources and quantum sensing. Finally, an outlook on future avenues in research is outlined.