Fabrication and current–voltage characteristics of NiOx/ZnO based MIIM tunnel diode

Highlights: • Fabrication of single and bilayer tunnel diodes by sputter deposition. • Current–voltage characteristics study. • Enhanced asymmetry and non-linearity. • Study of tunneling mechanism. - Abstract: Enhanced asymmetric and non-linear characteristics of Ni–NiOx based MIM diode has been reported by the addition of a second insulator layer ZnO to form MIIM configuration. These properties are required for applications like energy-harvesting devices, terahertz electronics, macro electronics, etc. In this work, single insulator layer Ni–NiOx–Cr and double insulator Ni–NiOx–ZnO–Cr tunnel diodes were fabricated and their I–V characteristics were studied. A significant increase by one order of magnitude in asymmetry has been observed in case of bilayer NiOx/ZnO dielectric configuration at low voltages. The sensitivity of the NiOx and NiOx/ZnO dielectric configuration in MIM stack was 11 V⁻¹ and 16 V⁻¹. The improved performance of the bilayer insulator diode is due to the second insulator which enables resonant tunneling or step-tunneling. Resonant tunneling was found to be dominant through trap assisted tunneling in the NiOx/ZnO diode