Conduction processes in metal–insulator–metal diodes with Ta2O5 and Nb2O5 insulators deposited by atomic layer deposition

Abstract

Metal–insulator–metal diodes with Nb2O5 and Ta2O5 insulators deposited via atomic layer deposition are investigated. For both Nb2O5 and Ta2O5, the dominant conduction process is established as Schottky emission at small biases and Frenkel–Poole emission at large biases. Fowler–Nordheim tunneling is not found to play a role in determining current versus voltage asymmetry. The dynamic dielectric constants are extracted from conduction plots and found to be in agreement with measured optical dielectric constants. Trap energy levels at ϕT ≈ 0.62 and 0.53 eV below the conduction band minimum are estimated for Nb2O5 and Ta2O5, respectively.