Dielectric anomaly in Li-doped zinc oxide thin films grown by sol-gel route

Abstract

Sol-gel route was employed to grow polycrystalline thin films of Li-doped ZnO thin films (Zn_1-xLi_xO, x=0.15). Polycrystalline films were obtained at a growth temperature of 400-500 °C. Ferroelectricity in Zn_0.85Li_0.15O was verified by examining the temperature variation of the real and imaginary parts of dielectric constant, and from the C-V measurements. The phase transition temperature was found to be 330 K. The room-temperature dielectric constant and dissipation factor were 15.5 and 0.09 respectively, at a frequency of 100 kHz. The films exhibited well-defined hysteresis loop, and the values of spontaneous polarization (P_s) and coercive field were 0.15 µ C/cm² and 20 kV/cm, respectively, confirming the presence of ferroelectricity.