Enhanced Optical Absorbance Of Hydrophobic Ti Thin Film: Role Of Surface Roughness

Abstract

In the present work, structural, morphological, optical and wettability properties of DC magnetron sputtered titanium (Ti) thin films have been investigated. The nanostructured Ti thin films were deposited on glass and silicon substrates at various deposition angles, θD = 0°, 30°, 45° and 60°. HCP structure of Ti thin films with preferred peak orientations (100) and (002) were revealed from XRD. It was observed that as the deposition angle increases, film thickness (~260 - 100 nm) as well as average crystallite size (~27 - 11 nm) of Ti thin films decrease. Significant changes in topography of the films, with change in deposition angle, have been observed. The optical and wettability results suggested that transmission, reflection, absorption and water contact angle of Ti thin films are strongly influenced by deposition angle due to change in its surface roughness. The large near infrared (NIR) absorbance (~ 66 - 75%) was found for the sample deposited at θD = 30°, which exhibited hydrophobic (~ 94.6°) nature with high surface roughness (~ 28 nm).