Steps of the Giant Terahertz Photoconductance of a Tunneling Point Contact

The photoresponse of the conductance of a tunneling quantum point contact to irradiation in the frequency range of 0.5–1.7 THz has been simulated within the theory of photon-assisted tunneling. The simulation has shown that the dependences of the conductance on the Fermi energy exhibit steps corresponding to transitions with the absorption of one, two, or three photons to channels near the top of the tunnel barrier. Under experimentally achievable conditions, the ratio of the photoconductance to the dark value on these steps can reach several orders of magnitude.