Tunnel junction testbed based molecular devices

Abstract

Molecule based devices may govern the advancement of futuristic logic and memory devices for the next generation computers. Molecules are strong candidate for becoming important device elements, because chemists can mass produce a variety of molecules with unique set of optical, magnetic, and charge transport characteristics. However, the biggest challenge is to connect two metal electrodes to molecule(s) and develop a robust and versatile device fabrication technology that can be adopted for commercial scale mass production. This paper discusses the scope of utilizing tunnel junction devices as a testbed for developing molecular devices. Specifically, this paper describes the use of a tunnel junction with the exposed sides as a testbed for molecular devices. On the exposed sides of a tunnel junction molecules are successfully bridged across an insulator by chemically bonding them to two metal leads. Sequential growth of metal-insulator-metal layers ensures that separation between metal electrodes is controlled by the insulator thickness to the molecular device length scale. A number of control experiments, including reversing the effect of molecules to retain the tunnel junction testbed characteristics, were performed. TJMDs with ferromagnetic electrodes also exhibited room temperature current suppression and molecule enhanced exchange coupling. This paper will also discuss our recent Monte Carlo simulation that assist in understanding the underlying mechanisms behind the molecule induced transport and magnetic changes on a tunnel junction test bed.