Hydrophobicity and high-temperature mechanical behaviour of hard and optically transparent nanocomposite Al–Si–N thin films

Nanocomposite Al–Si–N thin films were deposited on SS 304, silicon and quartz substrates through magnetron sputtering. Silicon addition in AlN has transformed the coating structure from a single-phase coating into a nanocomposite structured film. It affected the phase formation and interband electronic transition in the Al–Si–N thin film. XPS study suggests the formation of Al–N, Si–N and composite Al–Si–N phases in the Al–Si–N film. The Urbach energy increases from 535 to 763 meV with addition of Si, for nanocomposite Al–Si–N film. No significant change in hardness and microstructure were observed up to 400 °C. The Al–Si–N film showed good hydrophobicity on both SS 304 and quartz substrates along with high hardness values. Low wettability and high strength make them a potential candidate for protective optical coatings as they are optically transparent too.Graphical abstract