Non-equilibrium transport in GaAs/AlGaAs Quantum Dots

Over the past several years, studies of transport in semiconductor quantum dots have focused primarily on the near-equilibrium regimes. Far from equilibrium measurements of GaAs/AlGaAs dots with overlapping gate geometry structures were reported by Wu et al.(S.M. Goodnick, J.C. Wu, M.N. Wybourne, and Doran Smith, Phys. Rev. B. 48), 9150 (1993) in which negative conductance was observed. In these structures, transport through the dot was assumed to be dominated by inelastic carrier-carrier scattering resulting in strong carrier heating of the dot electrons. Here, we present measurements on GaAs/AlGaAs quantum dots with different geometries, including non-invasive voltage probes. Near equilibrium transport measurements through the dot exhibit clear Coulomb blockade oscillations. For large source-drain bias applied across the dot, nonlinear behavior is evident. The far from equilibrium charcteristics are also measured under a magnetic field applied in the transverse direction to transport, in which increased path length due to the field results in longer traversal times through the dot.