Abstract

We have developed a theory of photon-assisted quantum transport in quantum point contact devices. According to the theory, ballistic electrons in a quantum point contact can absorb an integer number of far-infrared photons via intersubband transitions. Consequently, a photon-induced drain/source current can be produced by a far-infrared radiation whose frequency is comparable to that of the intersubband spacing at the narrowest constriction of the quantum point contacts. Motivated by this theory, we have studied transport properties of an antenna-coupled quantum point contact under coherent far-infrared (285 GHz) radiation. A pronounced photon-induced drain/source current is observed. The amplitude of the photon-induced current is about 10% of that corresponding to a quantized conductance step, and it oscillates with the gate voltage. Our analysis suggests that the observed photon-induced current is mainly due to heating of the electron gas in the source and drain (a bolometric effect) rather than photon-assisted quantum transport. Further investigation reveals a photon-induced thermopower which oscillates with the gate voltage in a manner that tracks the onset of subband channels. This thermopower is a result of asymmetric heating.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.