Microwave-induced DC currents in mesoscopic structures

We report the power (P) dependence of microwave (MW)-induced current (Iph) of a 1‐μm sized mesoscopic structure fabricated from two-dimensional electron gas in the GaAs/AlGaAs heterostructure at temperature of 1.4 K. MW signals were fed onto the sample through a loop antenna nearby and Iph is measured from a pair of ohmic contacts. We found that Iph is proportional to P at low-P limit; this dependence has been predicted for diffusion-limited electron transport in mesoscopic systems. By contrast, for large P, the dependence is extremely non-monotonous and complicated; even though its physical origin is still not clear so far, our data suggest it is related to the scattering processes from boundaries and impurities in the mesoscopic structure. We also investigated the symmetry properties against reversal of magnetic field (B) and found that the field-symmetric part of Iph(B) is consistent with the variation of magnetoresistance; there exists also an anti-symmetric part, which should be related to time-reversal-symmetry-breaking scattering mechanisms in the channel.