We use a combination of e-beam lithography, in the Nanomaterials Rapid Prototyping Facility, and Focused Ion Beam induced deposition to contact nanowires freed from templates. With our e-beam system we are capable of writing contacts with a width of 200nm with a seperation of 150nm allowing us to contact wires which are only 200nm long with two contacts and make four contact measurements on 1 micron long nanowires. We can place the contacts on drop cast nanowires with a precision of better than 50nm. We have access to a wide range of thin film deposition systems and can make contacts from almost any metal and indium tin oxide. For longer wires we also use direct write optical lithography which has the advantage of increased speed and simplicity.
Using these techniques we have developed a molecular electronics test bed from nanowires which are formed with a self-assembled monolayer or controlled number of monolayers to form a gaps in the range 1.8nm-10nm. After the wires have been contacted we then used thermal desorption or UV cleaning to remove the molecules from the gap allowing other molecules access.
Development of a nanowire-based test bed device for molecular electronics applications
CE Gardiner, MA Ghanem, JW Wilson, and DC Smith
Analytical Chemistry 78 (3), 951-955 (2006).