Design and analysis of a nano-rectenna based on multi-insulator tunnel barrier for solar energy harvesting

In this paper, a rectangular spiral nano-antenna (NA) design coupled to rectifier diode to harvest the solar energy is designed and analyzed. The metal insulator metal (MIM) tunnel diode with single and double insulator was taken as rectifier diode in the rectenna. The rectifier diode is realized by overlapping the NA arms and sandwiching metal oxide layer in between to benefit from high localized fields intensity at the gap. Full-wave time domain numerical method, finite integration technique, FIT, is employed to simulate the nano-rectenna performance where the radiation efficiency, directivity and radiation pattern are calculated at the wavelength of 500 nm. The proposed designs of NAs with single insulator, MIM diode, and double insulator, MIIM diode, present roughly the same results of radiation efficiency of 99.2%, 22.9 maximum directivity at the wavelength of 500 nm and 98.40% total harvesting efficiency, respectively. In addition, the MIM diode achieves resistance of 43.6 kΩ, high responsivity of − 7.73 A/W and large asymmetry of 45, both at zero bias, respectively. Furthermore, MIIM diode increased the zero bias voltage responsivity to 18.9 A/W, maximum responsivity to − 168.9 A/W, nonlinearity to 6.5 and asymmetry to 100 at zero bias voltage. This enhancement is due to the use of multi-insulators between the dissimilar metals with different work functions.