Growth of TiO2 thin films on Si(100) and Si(111) substrates using single molecular precursor by high-vacuum MOCVD and comparison of growth behavior and structural properties

Abstract

We have deposited titanium dioxide (TiO2) thin films on Si(100) and Si(111) substrates in the temperature range of 500-750degreesC and in the pressure range o f 3.0 X 10(-7) -5.0 x 10(-5) Torr using a single molecular precursor such as titanium (IV) iso-propoxide (Ti[OCH(CH3)(2)](4), 97%) by high-vacuum metal-organic chemical vapor deposition method. Highly oriented, stoichiometric TiO2 thin films with rutile phase were successfully deposited on both Si(100) and Si(111) substrates between 650degreesC and 750degreesC under a working pressure of 1.0 x 10(-5) Torr. X-ray diffraction results clearly showed different growth behaviors between Si(100) and Si(111) substrates. The main film growth directions are [110] on Si(100) and [200] on Si(111), respectively. Scanning electron microscope and transmission electron microscope images showed a quite smooth surface with no cracks and sharp interface between fflni layers, suggesting good adhesion and uniformity in depth. In the case of TiO2 films, grown under low temperature below 600degreesC and high pressure above 3.0 x 10(-5) Torr, transmission electron diffraction pattern showed a mixed structure with spot and ring patterns, resulting in polycrystalline film formation. By increasing the growth temperature to 650degreesC and decreasing the pressure to 3.0 x 10(-7) Torr, however, strong spot images with weak ring pattern were observed, indicating that the film crystallinity as well as growth direction was strongly affected by deposition temperature and pressure. (C) 2002 Elsevier Science B.V. All rights reserved.