Hot-electron bend resistance in a ballistic GaAs/AlGaAs cross junction

Abstract

Nonlinear bend resistance is studied in a six-terminal mesoscopic ballistic junction in the hot-electron regime. Non-equilibrium electrons are generated by a voltage drop across a quantum point contact (QPC) embedded in the current lead of an orthogonal cross junction. The barrier height of the QPC constriction is tuned by a large-area top gate electrode which covers junction and leads. The junction enables to study the ballistic bend voltage in local and remote configuration. In local configuration the ballistic voltage is detected between the voltage probes opposed to the orthogonal current leads. Independent from the current polarity a negative bend resistance verifies the ballistic motion of electrons. For small gate voltages, i.e. a high QPC barrier, the absolute value of the bend resistance is enhanced if the electrons are injected through the constriction. We attribute this nonlinearity to the current-polarity-dependent excess energy gained in the negatively biased current lead. If the transfer voltage is detected between two remote orthogonal voltage probes ballistic effects are observed only for small excess energies. The remote configuration implies that the electron ballistic mean-free path decreases at high excess energies.