An oblique angle radio frequency sputtering method to fabricate nanoporous hydrophobic TiO2 film

• Porous nano-columnar array of TiO2 thin film
• Transition of hydrophilic to hydrophobic surface
• Correlation of optical property with porosity

In this work, we investigate growth of ordered arrays of amorphous TiO2 nano-columns by using radio frequency sputter deposition technique. The as-prepared thin films were characterized by atomic force microscopy, field emission scanning electron microscopy, X-ray diffraction, and ultraviolet–visible spectroscopy. The nano-columnar films are found to be porous in nature which results from glancing angle sputter deposition. In fact, porosity has a linear relationship with increasing deposition angle. Reflectance of the thin films is also studied as a function of porosity. In addition, contact angle measurements demonstrate the roughness dependent transition from a hydrophilic to a hydrophobic TiO2 surface.