DIELECTRIC-RELAXATION IN AMORPHOUS THIN-FILMS OF SRTIO3 AT ELEVATED-TEMPERATURES

Temperature and frequency dispersion of dielectric permittivity was investigated on thin amorphous films of SrTiO3 prepared by a sputtering method using neutralized argon-ion beams. The amorphous SrTiO3 films deposited on glass substrates exhibited a marked dielectric relaxation at temperatures 500-800 K in a frequency range 0.1-50 kHz. This behavior was explained based on a dipolar relaxation of the Cole-Cole type with the static dielectric constant epsilon(s)'congruent to 380, the constant at high frequency epsilon(infinity)'congruent to 35, and the distribution parameter of the relaxation time beta congruent to 0.8. The analysis of the temperature dependence of relaxation time gave the activation energy for the relaxation of about 1.08 eV and the characteristic relaxation time of the order of 10(-12) s. In the temperature range where strong relaxation occurred, a semiconductor-type conduction having the activation energy of about 0.84 eV became dominant. A correlation between the mechanisms of the dielectric relaxation and the thermally activated motions of ionized defects in the amorphous structure is discussed. (C) 1995 American Institute of Physics.