GROWTH AND CHARACTERIZATION OF FERROELECTRIC BAMGF4 FILMS

Experimental data are presented that confirm ferroelectric thin films of BaMgF4 can be grown by ultrahigh vacuum (UHV) sublimation on semiconductor and metallized substrates at temperatures below 500-degrees-C. Hysteresis properties of the films are shown to be qualitatively consistent with those measured on thinned single-crystal samples cut perpendicular to the ferroelectric (orthorhombic) a axis. Loops from weakly oriented films on Si (100) display a P(r)/P(s) ratio of approximately 0.84, with P(s) = 1.6-mu-C/cm2 and E(C) = 150 kV/cm. These values are explained on the basis of the film orientation and the measured properties for the bulk crystals. Metal-insulator-semiconductor structures formed with fluoride layers grown on lightly doped Si substrates yielded C-V switching properties indicating their suitability for use in high-performance ferroelectric field-effect transistor memory structures. In particular, switching attributable to polarization charge reversal inside the ferroelectric layer, rather than by tunnel injection of carriers from the Si into the ferroelectric, has been achieved for the first time with this material.