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Miskovsky N.M.,Pennsylvania State University | Miskovsky N.M.,Scitech Associates LLC | Cutler P.H.,Pennsylvania State University | Cutler P.H.,Scitech Associates LLC | And 7 more authors.
Proceedings of SPIE - The International Society for Optical Engineering

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. © 2013 SPIE. Source

Miskovsky N.M.,Pennsylvania State University | Miskovsky N.M.,Scitech Associates LLC | Cutler P.H.,Pennsylvania State University | Cutler P.H.,Scitech Associates LLC | And 5 more authors.
Journal of Nanotechnology

We present a new and viable method for optical rectification. This approach has been demonstrated both theoretically and experimentally and is the basis fot the development of devices to rectify radiation through the visible. This technique for rectification is based not on conventional material or temperature asymmetry as used in MIM (metal/insulator/metal) or Schottky diodes, but on a purely sharp geometric property of the antenna. This sharp or edge with a collector anode constitutes a tunnel junction. In these devices the rectenna (consisting of the antenna and the tunnel junction) acts as the absorber of the incident radiation and the rectifier. Using current nanofabrication techniques and the selective atomic layer deposition (ALD) process, junctions of 1nm can be fabricated, which allow for rectification of frequencies up to the blue portion of the spectrum. To assess the viability of our approach, we review the development of nanoantenna structures and tunnel junctions capable of operating in the visible region. In addition, we review the detailed process of rectification and present methodologies for analysis of diode data. Finally, we present operational designs for an optical rectenna and its fabrication and discuss outstanding problems and future work. Copyright © 2012 N. M. Miskovsky et al. Source

Lerner P.B.,Pennsylvania State University | Miskovsky N.M.,Scitech Associates LLC | Miskovsky N.M.,Pennsylvania State University | Cutler P.H.,Scitech Associates LLC | And 3 more authors.
Nano Energy

We derive thermodynamically an expression for the theoretical open circuit voltage of a rectenna device that converts high frequency ac radiation into dc power output. In addition, we obtain the conversion efficiency of an electron emission rectenna, which consists of a nano-antenna collector and a geometrically asymmetric rectifying MVM tunnel junction. This quantity plays an analogous role to the fill factor for conventional n-p semiconducting PV devices in limiting the overall efficiency. Thus, in effect, we develop a theory analogous to the Shockley-Queisser theory or limit (SHQL) for rectennas. The predicted limitations on the efficiency of the electron emission device, as in the case of the SHQL for n-p junction devices, are useful for guiding the development of practical devices based on rectennas. [1]. These are useful benchmarks for evaluating different electron emission-based schemes for energy conversion. © 2012 Elsevier Ltd. Source

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