LiNbO3 ferroelectric properties on high-and moderate-doped Si substrates

Abstract

Ferroelectric LiNbO3 thin film properties in MFS structures have been evaluated using degenerated Si wafers with elimination of the depletion layer capacitance influence in the substrates surface. Significant ferroelectric properties could be obtained only after the films were annealed above 750 degreesC. The capacitance on highly doped Si wafer shows hysteresis behavior like a butterfly shape and this result indicates clearly that the dielectric films have ferroelectric properties. The typical measured remnant polarization (2P(r)) and coercive filed (E-C) values were about 1.2 muC/cm(2) and 120 kV/cm, respectively, in an applied electric field of 300 kV/cm. In case of fatigue, there was no loss in switched polarization tip to 10(11) cycles using 1 MHz square wave form at 300 kV/cm with platinum electrode. The extracted switching time (t(sw)) was less than 20 ns. Switching charge density, Q(sw), which was calculated by the integral of the difference between the switching current and non-switching current, was about 1.6 muC/cm(2) for the positive amplitude of the pulse of 300 kV/cm. The switching charges degraded only by 10 % of their initial values after 4 days at room temperature.