Barrier tuning of atomic layer deposited Ta2O5 and Al2O3 in double dielectric diodes

The performance of ultrathin atomic layer deposited dielectrics of low (Al2O3) and high (Ta2O5) electron affinity (v) is investigated in metal- insulator-(insulator)-metal [MI(I) M] diodes. The conduction mechanisms in 4 nm thick atomic layer deposited Al2O3 and Ta2O5 single barrier MIM diodes are first studied to show the dominance of tunneling and thermally activated Poole-Frenkel emission, respectively, in these oxides. Varying the layer thickness of Ta2O5 with a 1 nm thick layer of Al2O3 shows evidence for resonant tunneling in double barrier MIIM structures and is correlated with the simulated bound states in the quantum well formed between the two dielectrics. These findings demonstrate experimental work on barrier tuning of resonant tunneling diodes with sufficient rectifying capability at a turn-on voltage as low as 0.32V enabling their potential use in terahertz applications. (C) 2017 American Vacuum Society.