Low-temperature deposition of ultrafine rutile TiO2 thin films by the hydrothermal method

Ultrafine (50 × 20 nm2) rutile TiO2 thin films (0.18 m̈m) on α-Al2O3 substrates have been prepared by hydrothermal treatment of a solution of a mixture of TiO2−4 (0.5 M) and HNO3(2.0 M) at low temperatures. Films prepared in the temperature range of 100 to 200 °C contain only the rutile phase and adhere well to the substrates. The acidity of the solution and the hydrothermal treatment time are the critical parameters determining the formation of pure rutile phase.