DIELECTRIC PROPERTIES OF LANTHANUM FLUORIDE THIN-FILMS

The dielectric properties of LaF3 films evaporated by electron beam have been studied in the audio-frequency range (0.1-30 kHz) at different temperatures (300- 490 K). The capacitance was found to be dependent on both frequency and temperature, but to remain almost constant for all frequencies at room temperature. The plot of tan δ versus temperature exhibited a pronounced maximum which was shifted to the high frequency region with the rise of temperature. The activation energy calculated for the loss peak was 0.42 eV. The dielectric relaxation process was ascribed to the formation of dipoles within the film structure. The conduction process was explained on the basis of the diffusion of F- ions through vacancies in the film. The temperature coefficient of capacitance and dielectric field strength were also estimated. © 1979.