Lateral V/VO$_{x}$/V Tunnel Junctions Formed by Anodic Oxidation

Anodization has been found to be a simple and cost effective technique to produce oxide films of many transition metals. In this work, we have used anodic oxidation as a means of fabricating lateral V/VO$_{x}$/V junctions. Vanadium wires grown by ion beam deposition were patterned by lithography and an active working window was defined on the wire. VO$_{x}$ was then grown under galvanostatic control in a two electrode electrochemical micro-cell. A droplet of oxygen rich saturated Boric acid was used as the electrolyte to electrically connect the Vandium working electrode to a Platinum wire counter electrode. A constant current of approximately 100 $\mu $A/cm$^{2}$ was maintained through the cell for various amounts of time. Electrical measurements of the resulting V/VO$_{x}$/V junctions indicate a metal to insulator transition (MIT) near 340 $^{o}$K that is similar to the structural phase transition and accompanied MIT of VO$_{2}$ which occurs at this temperature. A 4-fold change in resistance is observed in the junctions. Below this transition temperature a typical junction behavior is observed with a dramatic change in resistance state from high to low with increasing applied current. This non-linear IV characteristic on the junction with a size of 5 $\mu $m by 15 $\mu $m suggests that the anodized VO$_{x}$ film behaves like a tunneling barrier.