Atmospheric pressure MOCVD of TiO2 thin films using various reactive gas mixtures

TiO2 thin films were deposited under atmospheric pressure by chemical vapor deposition using metal organic precursors (AP-MOCVD) in the temperature range 350–700 °C on Si(100) and stainless steel substrates. Titanium tetraisopropoxide (TTIP) was used as metal source. The influence on the growth process of an oxidant co-reagent (O2 and H2O) has been investigated. TTIP mole fraction and the substrate temperature are the major parameters which permit a good control of the morphology, the microstructure, the composition and the growth rate of these functional oxide thin films. Addition of O2 in the input gas phase does not change significantly the main features of the layers. By contrast, TTIP/H2O gas mixtures exhibit a higher reactivity leading to the deposition of TiO2 at lower temperature and with a higher growth rate. For instance, the deposition rate at 450 °C is approximately 440 and 90 nm/min with and without H2O vapor, respectively. Single-phased (anatase or rutile) and bi-phased coatings with a controlled composition can be deposited depending on the temperature and the TTIP mole fraction.