High frequency conductivity of the high-mobility two-dimensional electron gas

We measure the real and imaginary conductivity sigma(k=0,omega) of a high-m obility two-dimensional electron gas (2DEG) system at frequencies below and above the momentum scattering rate. The imaginary part of the 2DEG impedan ce is observed to be inductive, consistent with the Drude model. Using this kinetic inductance, we construct a transmission line by capacitively coupl ing the 2DEG to an Al Schottky barrier gate separated by 5000 Angstrom from the 2DEG. The measured wave velocity and temperature-dependent damping of this transmission line are in good agreement with a simple Drude model. Exc iting these modes is equivalent to exciting a 2D plasma mode strongly modif ied by the interaction between the 2DEG and the gate. (C) 2000 American Ins titute of Physics. [S0003-6951(00)01906-9].