Magnetic field dependence of the photoresponse time of GaAs/AlGaAs quantum Hall effect device
The characteristic time of far IR response of a quantum Hall effect (QHE) detector in a GaAs/AlGaAs heterostructure has been investigated versus the magnetic field around the even values of the Landau level filling factor ν = 2, 4. The response time is shown to have a dip minimum in the center of a QHE plateau and two sharp maxima at either side of the plateau. Outside the QHE plateau the response time drop seems to result from the rise of the equilibrium population of Landau level over/below the Fermi energy with electrons/holes which increases the probability of photoexcited carrier recombination. The minimum at the QHE plateau center is due to the vanishing of screening of the random potential. The length scale of the potential fluctuations has been estimated.