摘要： Metal–insulator–metal (MIM) diodes are among the most promising candidates for applications in the high frequency regime. Owing to the tunneling dominant current conduction mechanism, they facilitate femtosecond fast switching time, which has drawn great research attention for many potential high-speed applications and especially as a rectifier in rectenna based energy harvesting. Since its advent in the early 1960s, a lot of development has occurred in various aspects of design, fabrication and characterization of MIM diodes for rectenna applications. In this work, a detailed study on MIM diodes is conducted emphasizing the advancements in design and fabrication of MIM diodes and future challenges from the point of view of their application in rectennas. In addition, the fabrication and characterization of a graphene (Gr) based Al/AlOx/Gr MIM diode are also presented herein, exhibiting highly asymmetric current–voltage characteristics with large current density and a good degree of nonlinearity. An asymmetricity exceeding 2500 and the corresponding current density up to (cid:2) 1 A/cm2 were obtained at a voltage bias of 1 V. The peak nonlinearity was (cid:2) 3.8, whereas the zero bias resistance was as low as (cid:2) 600 X. These performance metrics are highly desirable for rectification operation and hence the as-fabricated Al/AlOx/Gr MIM diode holds great promise for its potential use as a rectifying element in rectennas.