(Ta1-xNbx)2O5 films produced by atomic layer deposition:: Temperature dependent dielectric spectroscopy and room-temperature I-V characteristics

Temperature dependent ac dielectric spectroscopy and room-temperature I-V characterization were performed on atomic layer deposited (Ta1-xNbx)(2)O-5 films. The high frequency permittivity, as well as the dc conductivity of the films, were found to increase with increasing Nb content. The conduction mechanism in the mixed Ta-Nb oxide films was of the Poole-Frenkel type, while the high field conduction in pure Ta2O5 was space-charge limited. The activation energy for dc conduction was higher in mixed Ta-Nb oxides compared to pure Ta2O5 and Nb2O5 films. Irreversible changes in the conduction mechanism took place upon heat treatment above a certain irreversibility temperature. This temperature was higher for the mixed oxides than for the binary ones. (C) 2001 American Institute of Physics.