Lorentzian noise in the two-dimensional electron gas of AlxGa1-xAs/GaAs quantum wells

Current noise spectra S-I(omega) are reported on samples grown by the molecular beam epitaxy technique, with current-carrying contacts, acting as source and drain, and two probes extending into the two-dimensional electron gas (2DEG) of the AlGaAs/GaAs quantum well, in the range 77-295 K for frequencies of 10 Hz to 1 MHz. The time constants are almost independent of temperature and the current dependence is close to linear. The noise is interpreted as Lorentzian-modulated shot noise of the 2DEG current. (C) 1999 American Institute of Physics. [S0021-8979(99)08323-1].