Cyclotron study of 2DES incorporating QD layer

We have investigated the magneto-transport property and the cyclotron resonance (CR) of a two-dimensional electron system (2DES) separated by a thin barrier from a layer of InAs self-assembled quantum dots (QDs) in the quantum Hall regime. The magnetoresistance (ρxx) and Hall resistance (ρxy) were suppressed significantly at ν<1 when a positive voltage was applied to the front gate. On the other hand, clear two absorption lines of CR of the GaAs 2DES were observed, indicating coexistence of free-like-electrons and electrons trapped by the local potential minima in the 2DES. Since the CR of the trapped electrons appears when the suppression of ρxx and ρxy occurs, we assigned it to the CR of the electrons which are induced in the 2DES by the function of the QDs as a floating gate.