Two-dimensional electron gas as a sensitive noise detector

The dc voltage observed at low-temperatures in a 2D electron sample $without$ external excitation is accounted by the Schottky contact rectification of the noise generated in the measuring circuit. The rectified voltage is shown to depend on the asymmetry of the contact pair. The dependence of the rectified voltage on the noise amplitude first follows the trivial quadratic law, then exhibits a nearly linear behavior, and, finally, levels-off.