May 4, 2006 – Philips Research and the U. of Groningen in The Netherlands say they have fabricated arrays of molecular diodes (1.5nm thin) on standard substrates with “high yields,” targeting applications in plastic electronics requiring low temperature or low cost in-line manufacturing processes.
Work on molecular electronics utilizing self-organizational properties have been ongoing for years, and has led to the creation of functional molecules sandwiched between two metallic (e.g., gold) electrodes, and spontaneously forming a densely-packed monolayer on the bottom electrode. However, efforts to deposit a metal electrode directly onto the monolayer have run into problems — e.g., shorting caused by contacts forming between the electrodes, since the monolayer is only 1-2nm thick.
To address these issues, the scientists use monolayers confined to predefined holes in a polymer applied on top of the bottom electrode. An additional plastic electrode is deposited onto the monolayer prior to the deposition of the metallic electrode. The plastic electrode protects the monolayer, enabling a nondetrimental deposition of the gold electrode.
Bert de Boer, leader of the research team and assistant professor at the U. of Groningen’s Materials Science Centre, explained that the new process “will enable us, for the first time, to do reliable and reproducible measurements on molecular junctions, which is essential for the exploration of the potential applications of molecular electronics.”
Molecular electronics is seen as an option for manufacturing plastic electronics requiring low temperature or low cost in-line manufacturing processes, not as a replacement current silicon-based IC technologies, explained Dago de Leeuw, a Philips Research Fellow and one of the joint research team members. Using molecular electronics processes, scientists hope to fabricate elements for electronic elements in which the functionality is confined to a single molecular layer.