Fabrication of nano-gap electrodes using a focused ion beam for measuring electrical properties of molecular scale transistors

Abstract

Molecular electronics, in which a molecule having some nanometers of conjugation length is used as an active element, requires the ability to interface the molecule to macroscopic electronic circuits. For this application, the focused ion beam (FIB) is proposed out of various nano-scale patterning techniques because of its simplicity, minimum time and efforts needed for fabrication of large number of devices. We patterned I-pads with bridge thickness (<10μm) using photolithography and used FIB milling to fabricate contact electrodes separated by hundreds of nanometer. The approach was tested by device fabrication with pentacene deposition on patterned gold pads. We were able to successfully fabricate and demonstrate saturation in large number of organic thin film transistors with channel length in order of 200-300nm by this approach.