| AVS 62nd International Symposium & Exhibition | |
| Electronic Materials and Processing | Monday Sessions |
| Session EM+AS+SS-MoM |
| Session: | Rectenna Solar Cells, MIM Diodes, and Oxide Interfaces |
| Presenter: | Garret Moddel, University of Colorado and RedWave Energy, Inc. |
| Authors: | G. Moddel, University of Colorado and RedWave Energy, Inc. S. Joshi, University of Colorado at Boulder B. Pelz, University of Colorado at Boulder A. Belkadi, University of Colorado at Boulder S. Yuan, University of Colorado at Boulder P. Brady, RedWave Energy, Inc. D. Kotter, RedWave Energy, Inc. |
| Correspondent: | Click to Email |
Optical rectennas are of interest for radiant heat and light energy harvesting, and ultra-fast detectors that work for terahertz waves up through visible-light wavelengths. The devices work under constraints that are different from those of either microwave rectennas or conventional solar cells. These antenna-coupled diodes incorporate micron-scale antennas and diodes that must operate at frequencies in the tens to hundreds of terahertz, but the antenna size and diode speed are not the most daunting challenges. The current produced by the antenna – particularly for rectennas operating at close to visible-light frequencies – samples the diode at discrete voltages described by a quantum approach instead of at continuously varying voltages described by classical electromagnetic theory – which makes for a fascinating theory of operation. The consequence is a quantum limit to the power conversion efficiency, similar to the Shockley-Queisser limit for conventional solar cells. The optical frequency and intensity determine whether the rectenna operation can be described classically or must involve a quantum analysis. Because rectennas gather current from the entire antenna, if the light is not spatially coherent cancellation occurs, resulting in reduced efficiency. This limits the amount of power received by each diode, which further limits the diode rectification efficiency. Over the last decade the number of groups investigating various parts of rectenna technology has grown from almost none to at least 50. This growing community of researchers, with innovative solutions, is needed to meet optical rectenna challenges and enable a practical technology. Some emerging solutions will be presented.