Time-resolved far-infrared spectroscopy of quantum Hall systems

We have performed time-resolved measurements of the far-infrared photoconductivity of the two-dimensional electron system in GaAs/AlGaAs heterostructures in the integer quantum Hall regime (near filling factor ν=2) by the application of a p–Ge laser radiation. We have found, that the photoresponse (PR) signal has two components, a bolometric component with a decay time not longer than 1–View the MathML source, and a cyclotron resonance-related component of opposite polarity with a decay time of about 4–View the MathML source. We have observed a strong dependence of the PR signal on the filling factor, sample current and laser intensity. Surprisingly, no pronounced dependence of the PR decay times on these parameters and on the electron mobility was found. Accordingly, we have found a decreasing influence of the mobility on the critical drift length of the quantum Hall effect breakdown with increasing amplitude when applying short electric pulses.