Dielectric properties of PbTiO3 thin 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 rind Y2O3/Si thin films fabricated at 760 degrees C in an oxygen pressure of 0.04 Torr showed CeO2(200) and Y2O3(222) preferential orientation, respectively. The C-V and J-E analyses 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 PbTiO3 layer increased with the thickness of buffered CeO2 and Y2O3. The threshold voltage change (V-th) 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/cm(2), 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 x 10(11)/cm(2)eV and 3.7 x 10(11)/cm(2)eV, respectively.