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

Abstract

The lead titanate (PbTiO 3 ) thin films were deposited on a Si(100) substrate with cerium oxide (CeO 2 ) and yttrium oxide (Y 2 O 3 ) buffer layers by the pulsed laser deposition technique. The CeO 2 /Si and Y 2 O 3 /Si thin films fabricated at 760°C in an oxygen pressure of 0.04 Torr showed CeO 2 (200) and Y 2 O 3 (222) preferential orientation, respectively. The C–V and J–E analyses of Au/CeO 2 /Si, Au/Y 2 O 3 /Si, Au/PbTiO 3 /CeO 2 /Si and Au/PbTiO 3 /Y 2 O 3 /Si thin films were carried out. The analyses results indicated that the dielectric constant of the PbTiO 3 layer increased with the thickness of buffered CeO 2 and Y 2 O 3 . The threshold voltage change ( V th ) was about 3.6 V and 5 V for Au/PbTiO 3 (150 nm)/CeO 2 (100 nm)/Si and Au/PbTiO 3 (150 nm)/Y 2 O 3 (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 PbTiO 3 (80 nm)/CeO 2 (20 nm)/Si and PbTiO 3 (80 nm)/Y 2 O 3 (20 nm)/Si thin films, respectively. The densities of surface states of Au/CeO 2 (100 nm)/Si and Au/Y 2 O 3 (100 nm)/Si interfaces estimated at 1 MHz were 6.6×10 11 /cm 2 eV and 3.7×10 11 /cm 2 eV, respectively.