A promising path towards creating these ultrafast diodes has been in the form of "geometric diodes".[14] Graphene geometric diodes have been reported to rectify terahertz radiation.[15] In April 2020, geometric diodes were reported in silicon nanowires.[16] The wires were shown experimentally to rectify up to 40 GHz, but that was instrument limited, and theoretically may be able to rectify signals in the THz region as well.