The role of geometry in nanoscale rectennas for rectification and energy conversion

We have surveyed developments related to the fabrication and theoretical understanding of our proposed nanoscale rectennas. These rectenna devices, based on the geometricallyasymmetric tunnel junction, can collect and rectify electromagnetic radiation, from the infrared through the visible regimes. Studies of electron transversal time and RC response time demonstrate that tunnel junctions formed with a sharp tip (early examples of which are the whisker diode and the STM probe) are capable of operating into the UV regime. Recent efforts to construct nanoscale antennas reveal a wealth of promising geometries and fabrication techniques. Other recent experimental work confirms that nanorectennas are capable of not just receiving, but also rectifying, signals through the visible regime. A number of past and recent ongoing simulation studies not only demonstrate the viability of the geometrically-asymmetric tunnel junction, but also establish the importance of certain design parameters (choice of geometry and materials) that will be crucial in efforts to optimize such devices.