Sub-wavelength waveguide properties of 1D and surface-functionalized SnO₂ nanostructures of various morphologies

One-dimensional (1D) SnO₂ sub-wavelength waveguides are a critical contribution to advanced optoelectronics. Further understanding of the surface defects and role of morphology in 1D SnO₂ nanowires can help to better utilize these nanostructures more efficiently. For this purpose, three different nanowires (NWs), namely belts, cylindrical- and square-shaped structures were grown using SnO₂ quantum dots as a precursor material. The growth process of these NWs is discussed. The nanobelts were observed to grow up to 3 mm in length. Morphological and structural studies of the nanostructures were also carried out. All NWs showed waveguide behavior with visible photoluminescence (PL) upon excitation with a 325 nm laser. This behavior was also demonstrated in tapered and surface-functionalized SnO₂ NWs. While the tapered waveguide can allow for easy focusing of light, the simple surface chemistry offers selective light propagation by tuning the luminescence. Defect-related PL in NWs is studied using temperature-dependent measurements and a band diagram is proposed.