Structural properties of titanium dioxide films deposited in an rf glow discharge

Abstract

An rf glow discharge has been used to promote the reaction between titanium tetrachloride and oxygen in order to deposit thin films of titanium dioxide at low temperatures. Structural properties of the films have been studied as functions of deposition temperature (25 to 700 °C) and of substrate material (Si, sapphire, glass, NaCl, and Ti). Films deposited onto glass substrates were amorphous at temperatures less than 300 °C, anatase at 300 and 400 °C, a mixture of anatase and rutile at 500 °C, and only rutile at 600 °C and above. Films deposited on the other substrates showed similar behavior but the temperatures for specific crystalline forms differed for each substrate material. Deposition at low power densities and 400 °C resulted in large (∼5 μm) anatase crystallites in 1–2 μm films.