Geometrical rectifying properties of metal-vacuum-metal junctions

Point-contact diodes are among the devices used for the selective detection and mixing of infrared radiations [1]. In these devices a sharp tip terminates in a MVM or MIM barrier. However, in contrast to a linear MIM rectifier, rectification can here be due to the geometrical asymmetry of the tip [1,2]. Current efforts aim at reducing the characteristic response times and improving the sensitivity of these systems. Fundamental properties and potential applications of metal-vacuum-metal junctions exhibiting a geometrical asymmetry are still open to investigation. We report on the rectification properties of geometrically asymmetric metal-vacuum-metal (MVM) junctions. Our model is a planar cathode metal that supports a hemispherical protrusion. Using a transfer matrix methodology, we compute the forward and backward currents. The currents enable the calculation of the rectification ratio of the device in the limit of quasistatic fields.