Structural and optical investigation of sputter deposited hydrophobic chromium oxynitride films

Nanocrystalline chromium oxynitride films were deposited by reactive RF magnetron sputtering of metallic chromium target in argon and helium atmospheres. The paper deals with consequence of increase in oxygen partial pressure on structural, hydrophobic and optical properties of chromium oxynitride films. The film stoichiometry changes from CrN and Cr2O3 to only Cr2O3 with increase in oxygen partial pressure as evident from X-Ray Diffraction analysis in both cases. The average crystallite size decreases with increase in oxygen partial pressure for both gas atmospheres. The thickness calculated from transmission data and surface profilometer are in good harmony with each other. The deposited films are hydrophobic by nature and the contact angle of the films varies as a function of surface roughness. Surface energy of the films is inversely proportional to the observed contact angle values. As oxygen partial pressure increases, the optical properties: transmission and band gap values increases as determined by Ultraviolet–visible–Near Infrared spectrophotometer in both cases. This film can have potential applications as insulating, hydrophobic and corrosion resistant protective coatings.