Global Optimization of Rectennas for IR Energy Harvesting at 10.6μm

The impedance mismatch between a rectenna's two components, the antenna and the rectifying diode, represents a serious impediment to improving the rectenna's efficiency. Also, the diode's capacitance and the device equivalent resistance determine the rectenna's cutoff frequency. For the detection of the terahertz-frequency signals, ultrafast rectifying metal-insulator- metal diodes are feasible rectifiers. Here, we investigate the global optimization of the rectenna's efficiency working at 10.6 μm by taking the diode materials' properties into consideration. Our proposed objective function considers the impedance matching between antenna and diode, the device cutoff frequency, and the diode responsivity which governs the rectification efficiency. The optimal parameter set reveals a 5.5% coupling efficiency and a zero-bias responsivity of 6.4 A/W. The desirable material properties and geometry are prescribed. The fabrication of Ti-TiO2/ZnO-Al metal-insulator-insulator-metal diode based on the optimal results is carried out and characterized.