dc electrical conduction in thin Ta2O5 films. I. Bulk-limited conduction

Abstract

Experimental measurements on the electrical conduction characteristic of thin Ta2O5 films are reported. The measured slope of the log (I) -E1/2 plot corresponds well with the calculated Schottky slope for very thin films. However, by two independent tests it is shown that the conduction process cannot be electrode limited, even if interface states or other interface irregularities are postulated to exist. From measurements on heat-treated samples, transition from a modified Poole-Frenkel slope to a Poole-Frenkel slope is observed, thus providing direct evidence that conduction in Ta2O5 films is bulk limited. It is further shown that the presence of water in the film is a necessary ingredient for the occurrence of the modified Poole-Frenkel slope.