Spontaneous Formation of Nanogap Electrodes by Self-Peeling Adhesion Lithography

Adhesion lithography (a-lith) is a simple method for forming nanoscale gaps between dissimilar metals. In its usual form, a metal is patterned on a substrate, and conformally coated with an alkyl-functionalized self-assembled monolayer, rendering it nonadhesive to other metals; a second metal is then deposited uniformly over the full area of the substrate; finally, the parts of the second metal that are in contact with the self-assembled monolayer are stripped away using an adhesive tape or film, leaving the first and second metals side-by-side on the substrate, with a nanoscale spacing between them. It is shown here that, by depositing onto the second metal an adhesive film with high internal strain, it is possible to induce spontaneous delamination of the peeling layer without the need for any applied force. The modified procedure simplifies implementation and eliminates external stresses that can cause unwanted widening of the gap. The resultant electrode separations of approximate to 10 nm are amongst the smallest values achieved to date using adhesion lithography.