Modulation of morphology and optical characteristics of TiO₂ grown into porous silicon by an easy approach

In this work, a straightforward solvothermal approach to growing titanium dioxide (TiO₂) structures into porous silicon substrates was developed. It was possible to modulate the morphology and optical characteristics of TiO₂ by varying the concentration of the precursor and the kind of solvent. It was determined that these parameters strongly influence the morphology, photoluminescent response, bandgap, and structural characteristics of TiO₂. The morphology of the TiO₂ particles deposited on the walls of porous Si can be modulated from elongated particles to nanoflakes by increasing the precursor concentration. On the other hand, their morphology is flake-like, semi-spherical, and sea urchin-like, for methanol, ethylene glycol, and acetone, respectively. The particle size also varies with the precursor concentration; the size is smaller for lower concentrations, producing that the bandgap and emission energy increase. The variety of TiO₂ structures presented in this work, with different properties, can find potential applications in photocatalysis, solar cells, and sensing devices.