  Recent experiments on symmetry-broken mesoscopic semiconductor structures
have exhibited an amazing rectifying effect in the transverse current-voltage
characteristics with promising prospects for future applications. We present a
simple microscopic model, which takes into account the energy dependence of
current-carrying modes and explains the rectifying effect by an interplay of
fully quantized and quasi-classical transport channels in the system. It also
suggests the design of a ballistic rectifier with an optimized rectifying
signal and predicts voltage oscillations which may provide an experimental test
for the mechanism considered here.
