Three-dimensional analysis of the rectifying properties of geometrically asymmetric metal-vacuum-metal junctions treated as an oscillating barrier

We study the rectification properties of geometrically asymmetric metal-vacuum-metal junctions treated as an oscillating barrier. In particular, we focus on systems in which an oscillating bias is established between a cathode characterized by a hemispherical protrusion and a flat anode. We propose a quantum-mechanical approach of this problem by using a transfer-matrix methodology, with developments that enable the time dependence of the external bias to be accounted for explicitly. This study extends the quasistatic analysis presented in our previous work. In particular, we study how the rectification properties of these junctions depend on the frequency and the amplitude of the oscillating barrier. We also determine the power this device could provide to an external load and the efficiency, with which the energy of an incident radiation can be converted into a useful dc. It is demonstrated that rectification of optical frequencies is possible by using the nanoscale device discussed in this paper.