RETENTION AND IMPRINT PROPERTIES OF FERROELECTRIC THIN-FILMS

The retention and imprint properties of ferroelectric Pb(Zr0.53Ti0.47)O-3 (PZT) and SrBi2Ta2O9 (SBT) thin films are studied. A simple characterization technique which consists of four measurement pulses is used to differentiate the retention and imprint effects. The high concentration of oxygen vacancies in PZT capacitors results in longer screening lengths and higher depolarization fields that worsen etention properties. A c-axis preferred oriented SBT thin film deposited on Pt(100)/MgO(100) substrate contains a higher concentration of 180 degrees domains and results in better retention properties due to the minimum ferroelastic effect. Ferroelectric SBT thin films with symmetric P-E hysteresis loops are chosen to study the imprint effect. The imprint process changes the symmetry of P-E hysteresis loop, which indicates the imprint process builds up an internal field within the ferroelectric thin films. Electrical charges trapped at electrode-ferroelectric interfaces during the imprint stress are responsible for internal field build-up and screen the spontaneous polarization internally.