Characterization of metal-ferroelectric-semiconductor structure using ferroelectric polymer polyvinylidene fluoride-trifluoroethylene (pvdf-trfe) (51/49)

In this work, we fabricated metal-ferroelectric-semiconductor (MFS) diodes with polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) (51/49) thin films for application to one transistor-type (1T-type) ferroelectric random access memories (FeRAMs). The thin films, with various thicknesses, were prepared on a silicon substrate by using a spin-coating method. The phase crystallinity and the grain size of the PVDF-TrFE increased as the film-thickness increased. Typical ferroelectric hysteresis loops were obtained from the capacitance-voltage (C-V) curves. These loops might be considered to be due to the ferroelectric nature of the PVDF-TrFE films. The values of the memory window width for 50-nm-, 150-nm-, and 350-nm-thick PVDF-TrFE films were about 1.4, 2.0, and 3.5 V for a bias sweeping from -5 V to 5 V, respectively. The values of the leakage current density, at a sweeping range of 5 V, were about 2.7 10-5 A/cm2, 1.1 10-5 A/cm2, and 5.6 10-6 A/cm2 for 50-nm-, 150-nm-, and 350-nm-thick films, respectively. These results are useful and promising for realizing 1T-type FeRAMs operating at a low voltage.