A new process for the fabrication of planar antenna coupled Ni–NiOx–Ni tunnel junction devices

Abstract

Graphical abstractDisplay Omitted Highlights? Methods to fabricate planar, geometrically asymmetric Ni-NiOx-Ni tunnel diodes are developed. ? Planar structure decreased the parasitic capacitance enabling high cut-off frequency. ? Ni electrodes provided the surface oxidation control and low band edge offset with its native oxide. ? Asymmetric geometry of the electrodes resulted in electrical asymmetry across zero bias. ? Three Ni oxidation methods are studied to build a thin, but durable oxide for the tunnel barrier. Antenna coupled metal-insulator-metal (ACMIM) tunnel junctions are fast electromagnetic wave detectors shown to respond to radiation of wavelength as short as 1.6µm. In the design and fabrication of these devices, it is crucial to keep the RC time constant of the tunnel junction small to achieve the requisite cut-off frequency and adequate rectification efficiency. Junction geometry and the properties of the insulation layer between the metal antenna parts play an important role in determining both the time constant and the rectification effectiveness. In this paper we have designed and fabricated Ni-NiOx-Ni devices and performed three oxidation processes to optimize the insulation layer. Ease of manufacture over large areas is also a requirement for successful implementation. We detail two simple and low cost processes for the fabrication of Ni-NiOx-Ni tunnel junctions. These methods allow for the large area array implementations of the antenna coupled MIMs for the application in low-cost energy harvesting.