Effects of additive elements on improvement of the dielectric properties of Ta2O5 films formed by metalorganic decomposition

Ta2O5-based composite thin films formed by metalorganic decomposition have been investigated with respect to their dielectric properties. The dielectric and insulating properties of composite (1-x)Ta2O5-xTiO(2) and (1-x)Ta2O5-xWO(3) thin films are found to be improved compared to those of pure Ta2O5 thin films. In particular, thin films with x=0.08 composition of additive TiO2 or WO3 to Ta2O5 exhibited superior dielectric and insulating properties. The maximum dielectric constant and charge storage density of composite films are about 20 and 53.6 fC/mum(2), respectively, higher than those of pure Ta2O5 films (about 13 and 34.5 fC/mum(2)). The temperature coefficient of the dielectric constant of composite films dramatically decreases from 65 ppm/degreesC for pure Ta2O5 to less than 11 ppm/degreesC. The leakage current density of composite films is lower than 1x10(-9) A/cm(2) up to an applied electric field of 3 MV/cm. The dominant conduction is Poole-Frenkel conduction in the films according to the measurement temperature dependence of the I-V characteristics. (C) 2003 American Institute of Physics.