Zinc oxide (ZnO) was incorporated into metal-insulator-semiconductor (MIS) structures featuring high dielectric constant (high-kappa) barium tantalate (BaTa(2)O(6))or alumina (Al(2)O(3))as the insulator, and the structures were electrically evaluated for potential applications in transparent thin film transistors. The ZnO films were deposited by radio-frequency magnetron sputtering at 100 degrees C whereas the dielectric films were deposited by the same method at room temperature. The leakage currents of both the BaTa(2)O(6) and Al(2)O(3) structures were on the order of 10(-7)A/cm(2). The trap density and trapped charge concentration at the BaTa(2)O(6)/ZnO interface were determined to be 6.18 x 10(11) eV(-1) cm(-2)and 5.82 x 10(11) cm(-2) from conductance-voltage and capacitance-voltage measurements. At the Al(2)O(3)/ZnO interface the trap density and trapped charge were more than an order of magnitude smaller at 1.09 x 10(10) eV(-1) cm(-2)and 1.04 x 10(10) cm(-2) respectively. The BaTa(2)O(6) structures had significantly larger frequency dispersions due to the larger number of interface traps. Chemical analysis using X-ray photoelectron spectroscopy with depth profiling indicates that acceptor type defects associated with a deficiency of oxygen are related to the observed electron trapping in the BaTa(2)O(6)MIS structure. Overall, the results indicate that Al(2)O(3) would be better suited for transparent thin film transistors deposited at low temperature or without substrate heating. (C) 2011 Elsevier B.V. All rights reserved.