DIELECTRIC-CONSTANT DEPENDENCE OF POOLE-FRENKEL POTENTIAL IN TANTALUM OXIDE THIN-FILMS

A change of more than five orders of magnitude of leakage current density has been observed in tantalum oxide films with a dielectric constant ranging from 20 to 45. The films were deposited by a simple DC reactive sputtering technique. The measured leakage current density dependence on the film's dielectric constant can be explained by the Poole-Frenkel potential barrier model in which the barrier height is inversely proportional to the dielectric constant of the material. This intrinsic dielectric constant dependence of the trap barrier may give a limit on the lowest leakage current density that one can obtain in a high dielectric constant film.