Giant microwave photoresistance of two-dimensional electron gas

We measure microwave frequency (4-40 GHz) photoresistance at low magnetic f ield B, in high mobility two-dimensional electron gas samples, excited by s ignals applied to a transmission line fabricated on the sample surface. Osc illatory photoresistance vs B is observed. For excitation at the cyclotron resonance frequency, we find a giant relative photoresistance DeltaR/R of u p to 250%. The photoresistance is apparently proportional to the square roo t of applied power, and disappears as the temperature is increased. (C) 200 1 American Institute of Physics.