Accession Number : ADA295504

Title :   Long Term Stability in Thin Film Ferroelectric Memories.

Descriptive Note : Final rept. 1 Apr 91-30 Jun 94,

Corporate Author : LEHIGH UNIV BETHLEHEM PA WHITAKER LAB

Personal Author(s) : Smyth, D. M. ; Harmer, M. P.

PDF Url : ADA295504

Report Date : 15 JUN 1995

Pagination or Media Count : 43

Abstract : The three main goals of the project have been accomplished: (1) a self-consistent model for the defect chemistry of Pb(Zr(1/2)Ti(1/2)O3 (PZT) was established, (2) the effect of doping on the degradation of the switchable remanent polarization ("fatigue") was determined, and (3) a field stage for the transmission electron microscope was designed and constructed so that dynamic domain switching can be observed and recorded on video tape. It was determined that the concentration of trapped holes exceeds that of free holes in PZT even at the temperatures of equilibration, and that the hole mobility is thermally-activated. It appears that electron-trapping is also extensive. The ac, bulk conductivity of quenched PZT is dominated by ionic conduction. The transport properties of PZT have been correlated with electron paramagnetic resonance results and theoretical band calculations done elsewhere. Polarization fatigue is enhanced by acceptor-doping, and suppressed by donor-doping in both thinned, bulk samples of BaTiO3 and PZT thin films. jg

Descriptors :   *MEMORY DEVICES, *FERROELECTRIC MATERIALS, *THIN FILM STORAGE DEVICES, POLARIZATION, STABILITY, DEGRADATION, MODELS, CONDUCTIVITY, DYNAMICS, ELECTRON MICROSCOPES, HOLES(ELECTRON DEFICIENCIES), TRAPPING(CHARGED PARTICLES), BULK MATERIALS, TRANSMITTANCE, CHEMISTRY, TRANSPORT PROPERTIES, FATIGUE, ELECTRON DONORS, LEAD COMPOUNDS, DOPING, ELECTRON ACCEPTORS, SWITCHING, BARIUM, TITANATES, ELECTRON PARAMAGNETIC RESONANCE, IONIC CURRENT, VIDEO TAPES, DEFECT ANALYSIS.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Computer Hardware
      Electricity and Magnetism
      Atomic and Molecular Physics and Spectroscopy
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE