Zusammenfassung

We have investigated the microwave photoconductivity of 100-ìm- and 50-ìm-wide Hall bars fabricated from GaAs/AlxGa1-xAs heterostructures. We found resonant responses at frequencies fres with fres2(B) =fres2(B=0)+fc2, where fc is the cyclotron frequency of the two-dimensional electron gas in the perpendicularly applied magnetic field B. This shows that the photoresponse is dominated by collective plasmon excitations confined within the width of the Hall structure.