A novel fabrication technique developed by UConn engineering professor Brian Willis could provide the breakthrough technology scientists have been looking for to vastly improve today’s solar energy systems.

The potential breakthrough lies in a novel fabrication process called selective area atomic layer deposition (ALD) that was developed by Willis, an associate professor of chemical, materials, and biomolecular engineering and the previous director of UConn’s Chemical Engineering Program. Willis joined UConn in 2008 as part of an eminent faculty hiring initiative that brought an elite team of leaders in sustainable energy technology to the University. Willis developed the ALD process while teaching at the University of Delaware, and patented the technique in 2011.

It is through atomic layer deposition that scientists can finally fabricate a working rectenna device. In a rectenna device, one of the two interior electrodes must have a sharp tip, similar to the point of a triangle. The secret is getting the tip of that electrode within one or two nanometers of the opposite electrode, something similar to holding the point of a needle to the plane of a wall. Before the advent of ALD, existing lithographic fabrication techniques had been unable to create such a small space within a working electrical diode. Using sophisticated electronic equipment such as electron guns, the closest scientists could get was about 10 times the required separation. Through atomic layer deposition, Willis has shown he is able to precisely coat the tip of the rectenna with layers of individual copper atoms until a gap of about 1.5 nanometers is achieved. The process is self-limiting and stops at 1.5 nanometer separation.