  Advancement of molecular devices will critically depend on the approach to
establish electrical connections to the functional molecule(s). We produced a
molecular device strategy which is based on chemically attaching of molecules
between the two magnetic/nonmagnetic metallic electrodes along the multilayer
edge(s) of a prefabricated tunnel junction. Here, we present the fabrication
methodology for producing these multilayer edge molecular
electronics/spintronics devices (MEMEDs/MEMSDs) and details of the associated
challenges and their solutions. The key highlight of our MEMED/MEMSD approach
is the method of producing exposed side edge(s) of a tunnel junction for
hosting molecular conduction channels by a simple liftoff method. The liftoff
method ensured that along the tunnel junction edges, the minimum gap between
the two metal electrodes equaled the thickness of the tunnel barrier. All of
the tunnel junction test beds used a ~2 nm alumina (AlOx) tunnel barrier. We
successfully bridged the magnetic organometallic molecular clusters and
non-magnetic alkane molecules across the AlOx insulator along the exposed
edges, to transform the prefabricated tunnel junction into the molecular
electronics or spintronics devices. Tunnel junction test beds were fabricated
with a variety of metal electrodes, such as NiFe, Co, Ni, Au, Ta, Cu and Si.
Stability of ultrathin thin AlOx varied with the type of bottom metal
electrodes used for making MEMED/MEMSD. Additionally, molecular solution used
for bridging molecular channels in a MEMED was not compatible with all the
metal electrodes; molecular solution resistant ferromagnetic electrodes were
developed for the fabrication of MEMSDs. MEMSD approach offers an open platform
to test virtually any combination of magnetic electrodes and magnetic
molecules, including single molecular magnets.
