Cyclotron resonance absorption of 2DEG with embedded self-organized antidots

Far-infrared experiments have been performed on the two-dimensional electro n gas (2DEG) of an AlGaAs/GaAs heterojunction with additional self-organize d AlInAs antidot islands located at the interface. The electron density has been varied from 9 x 10(9) to 3 x 10(11) cm(-2) by applying a gate voltage . In addition to the CR peak we observe a narrow line which lies above the CR peak. The width of the line is as small as 0.5 cm (-1) at filling factor s less than 1. In contrast to the CR peak this line displays a considerable shift toward higher energies when the electron density is increased. We di scuss the observed features in terms of the formation of a correlated phase of electrons localized in local minima originating from the antidot potent ial and coupled via Coulomb interaction. (C) 2001 Published by Elsevier Sci ence B.V.