dc electrical conduction in thin Ta2O5 films. II. Highly imperfect films

Abstract

Experimental results on the dc conduction characteristics of highly imperfect Ta₂O₅ films are presented. Two regions with distinct conduction mechanisms have been identified. In the high‐field region the conduction mechanism is bulk limited. In the low‐voltage region the conduction mechanism is electrode limited and obeys a modified field‐emission equation. Quantitative comparison between theory and experiment is possible. As a result, the nature of the Ta₂O₅‐metal interface is identified. Based on reasonable estimates of the donor density and the effective mass of conduction electrons, the energy diagram of Ta₂O₅ can be deduced. There is also some experimental evidence which appears to be contradictory to the present interpretation. Plausible explanations for these discrepancies are discussed.