Ultrathin Ferroelectric P(VDF/TrFE) Copolymer Film in Low-Cost Non-Volatile Data Storage Applications

摘要

Ultrathin ferroelectric P(VDF/TrFE(72/28) films were used in the fabrication of metal-ferroelectric polymer-metal single bit device with special emphasis on the formation of uniform film surface, faster dipole switching time under an external electric field, and longer memory retention time. FTIR-GIRAS and AFM were used complementarily in analyzing the changes in chain orientation and surface crystalline morphology with varying sample preparation methods. It was found that the magnitudes of remnant polarization and coercive field are highly related to the degree of chain orientation along the conductive substrate surface. The cast- annealed sample showed the highest polarization and the smallest coercive field. DC-EFM technique was successfully used to write and erase the data bit on the ultrathin P(VDF/TrFE) film by applying a dc bias voltage much larger than coercive voltage with different polarities and the data bit state could be read by measuring the piezoelectric response of the cantilever with a lock-in amplifier by applying an ac modulating voltage whose Vpp is much less than the coercive voltage.