Dielectric Properties of PbTiO3Thin Films on CeO2/Si(100) and Y2O3/Si(100)

The lead titanate (PbTiO3) thin films were deposited on a Si(100) substrate with cerium oxide (CeO2) and yttrium oxide (Y2O3) buffer layers by the pulsed laser deposition technique. The CeO2/Si and Y2O3/Si thin films fabricated at 760°C in an oxygen pressure of 0.04 Torr showed CeO2(200) and Y2O3(222) preferential orientation, respectively. TheC–VandJ–Eanalyses of Au/CeO2/Si, Au/Y2O3/Si, Au/PbTiO3/CeO2/Si and Au/PbTiO3/Y2O3/Si thin films were carried out. The analyses results indicated that the dielectric constant of the PbTiO3layer increased with the thickness of buffered CeO2and Y2O3. The threshold voltage change (Vth) was about 3.6 V and 5 V for Au/PbTiO3(150 nm)/CeO2(100 nm)/Si and Au/PbTiO3(150 nm)/Y2O3(100 nm)/Si MIS capacitors, respectively. For the same current density of 100 nA/cm2, the applied fields were about 380 kV/cm and 400 kV/cm for PbTiO3(80 nm)/CeO2(20 nm)/Si and PbTiO3(80 nm)/Y2O3(20 nm)/Si thin films, respectively. The densities of surface states of Au/CeO2(100 nm)/Si and Au/Y2O3(100 nm)/Si interfaces estimated at 1 MHz were 6.6×1011/cm2eV and 3.7×1011/cm2eV, respectively.