of the tip to the surface. Therefore, a decrease in the thickness of the insulator results in an increase in tunneling current.
4.7.1 Metal–insulator-Metal diodes
The MIM diode is a quantum-tunneling device, not based on semiconductors. It consist of two metal plates separated by an insulating layer of the order of few nanometers. To improve the rectenna efficiency, the diode must satisfied several parameters [41]: