Nonlinear electron transport in an asymmetric microjunction: A ballistic rectifier

An asymmetric artificial scatterer in a semiconductor microjunction is shown to dramatically affect the nonlinear transport of ballistic electrons. The chosen device geometry, defined in a GaAs-AlGaAs heterostructure, successfully guides carriers in a predetermined spatial direction, independent of the direction of the input current I. From the nonlinear current-voltage characteristic we obtain unusual symmetry relations for the four-terminal resistances with R-ij,R-kl(I) approximate to -R-ij,R-kl(-I) and R-ij,R-kl(B) much greater than R-kl,R-ij(-B) even at zero magnetic field B. The ballistic rectifier thus realized relies on a new kind of rectification mechanism entirely different from that of an ordinary diode.