Evaluation of the Oxidation of TiO 2 Films during Reactive Evaporation of Ti 3 O 5 and during Exposure of the Films to the Atmosphere

A surplus amount of oxygen is needed to produce titanium dioxide films by reactive electron-beam evaporation of Ti3 O5 . We investigated the ratio of the rates at which oxygen molecules and TiOx molecules impinge upon substrates at 25 (degree) and 250 (degree)C to produce TiO2 films that show no optical absorption in the visible spectral region. On unheated substrates the ratio was 49, and at 250 (degree)C it was 26, provided that the substrates had been exposed to air after being coated at the given substrate temperature. Higher ratios were required if the TiO2 film was covered with a SiO2 film, which impeded further oxidation. Furthermore, the postdeposition oxidation behavior of these films was studied.