Résumé
We present a low temperature magnetoconductance study of a submicron hall bar made from an AlGaAs/InGaAs/GaAs heterostructure. Experiments were performed at very low temperature (120 mK), with a magnetic field ranging from OT to 13.5 T. In the presence of a quantizing magnetic field, at the transition between two quantized Hall plateaus, a succession of sharp peaks is detected in the Hall signal RH and in the longitudinal resistance R-L. The peaks appearing on the high-v side of the R-L transition appear to be different from the peaks appearing on the low-v side. They mainly differ by their temperature dependence. On the high-v side of the RL transition, the temperature evolution of the peaks is typical for resonant tunneling through a single state in one of the antidots that are progressively formed when the initially occupied LL is emptied. On the low v of the transition, by contrast, the temperature dependence is different. This may be related to the asymmetry of the density of states, or to additional inelastic processes.