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 $R_{ij,kl}\left(I\right)\approx {-R}_{ij,kl}(-I)$ and $R_{ij,kl}\left(B\right)\gg R_{kl,ij}(-B)$ 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.