RAMAN-SPECTROSCOPY STUDY OF PBTIO3 THIN-FILMS GROWN ON SI SUBSTRATES BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Raman spectra have been investigated in PbTiO3 thin films grown on Si by metalorganic chemical vapor deposition. A large grazing-angle scatt ering technique was taken to measure the temperature dependence of Ram an spectra below room temperature. All Raman modes in the thin films a re assigned and compared with those in the bulk single crystal, a new A(1)(TO) soft mode at 104 cm(-1) was recorded which satisfies the Curi e-Weiss relation omega(2) = A(T-c - T). Intensities of the A(1)(1TO) a nd E(1TO) modes were anomalously strengthened with increasing temperat ure. Raman modes for the thin films exhibit remarkable frequency downs hift and upshift which is related to the effect of internal stress.