Nonlocal versus local rectification in multiply connected electron waveguide structures

We report on a novel nanoscale four-terminal ballistic rectifier fabricated from a high-mobility GaAs/AlGaAs heterostructure using electron-beam lithography and wet etching. The geometry of the rectifier corresponds to a ψ-shaped cross junction consisting of a straight electron waveguide “stem” providing voltage probes and two waveguide branches as current injectors, which oppositely lead into the stem under an angle φ. Current–voltage (I–V) characteristics measured in four-terminal (non-local) configuration point out that the mechanism of rectification completely differs from that one obtained in a three-terminal (local) configuration. Local rectification mainly issues from different mode population in the injection leads, whereas non-local rectification can be explained in a simple billiard-like pure ballistic picture. Our device geometry enables a straight separation of both rectification mechanisms.