Electron dynamics of a two-dimensional electron gas with a random array of InAs quantum dots

We show that the presence of InAs dots embedded in a host GaAs quantum well containing a two-dimensional electron gas dramatically modifies the cyclotron resonance (CR). Far-infrared CR measurements show two modes with different dispersions with applied magnetic field B. The lower-frequency mode, with a sublinear dependence on B, is identified as a CR at low B, developing into a skipping orbit around the dot perimeters at higher B; this has not been previously observed for a system with randomly distributed scatterers. The higher-frequency mode is identified as a magnetoplasmon localized by the confining effect of the arrays of repulsive potentials due to the dots in the well. The linewidths of these modes, despite the broad size distribution of the dots, are narrow, suggesting that Coulombic interactions are important.