Ferroelectric lanthanum-substituted Bi4Ti3O12 thin films fabricated on p-type Si(100) substrates by a sol-gel method

Bi3.25La0.75Ti3O12 (BLT) thin films have been successfully fabricated on p-type Si(100) substrates by a sol-gel spin-coating method. The microstructures and surface morphologies of the BLT thin films on p-type Si(100) substrates annealed at 700 degreesC for 30 min in oxygen atmosphere were examined by an X-ray diffractometer and a scanning electron microscope, respectively. The BLT/p-type Si(100) capacitors annealed at 700 degreesC for 30 min exhibit good capacitance-voltage (C-V) characteristics and large memory window of approximately 6 V with a sweep voltage of +/- 16 V From the frequency dependency of C-V characteristics of the BLT/p-type Si(100) capacitors, the fixed charge density (N-fc) at the interface of BLT/p-type Si(100) was calculated as approximately 1.24 x 10(12)/cm(2). The humps and valleys observed in C-V curves were interpreted by introducing the electron charge injection and barrier-lowering effect at the interface of BLT/p-type Si(100). Based on the voltage and the frequency dependent C-V measurements, the memory windows of BLT/p-type Si(100) capacitor are significantly influenced by the electron charge injection and polarization reverse. (C) 2004 Published by Elsevier B.V.