COMPOSITION-CONTROLLED GROWTH OF PBTIO3 ON SRTIO3 BY ORGANOMETALLIC CHEMICAL VAPOR-DEPOSITION

PbTiO3 thin films have been grown on (001)SrTiO3 by organometallic chemical vapour deposition (OMCVD) using the precursors tetra-ethyl-lead (TEL) and tetra-isopropoxy-titanium (TIP). The kinetics of the growth process have been studied as a function of the substrate temperature and the partial pressures of TEL, TIP and oxygen. At temperatures of 700-degrees-C and higher, the composition of the layers corresponds to stoichiometric PbTiO3, independent of the deposition temperature, oxygen partial pressure and the ratio of TEL and TIP partial pressures, which was varied between 0.2 and 1.7. This independency of growth conditions can be explained by a mechanism involving the competition between the desorption of PbO and a fast formation of PbTiO3 by the reaction of PbO with TiO2. At 700-degrees-C the growth rate of PbTiO3 is proportional to the TIP partial pressure, but decreases with increasing TEL partial pressure, indicative of a competitive adsorption of Pb- and Ti-containing species. The growth rate is limited by the supply of TIP. Under optimal growth conditions, layers are obtained having a Rutherford backscattering channeling minimum yield as low as 3%.