Energy relaxation of two-dimensional electrons in the quantum Hall effect regime

The mm-wave spectroscopy with high temporal resolution is used to measure t he energy relaxation times tau(e) of 2D electrons in GaAs/AlGaAs heterostru ctures in magnetic fields B = 0-4 T under quasi-equilibrium conditions at T = 4.2 K. With increasing B, a considerable increase in tau(e) from 0.9 to 25 ns is observed. For high B and low values of the filling factor nu, the energy relaxation rate tau(e)(-1) oscillates. The depth of these oscillatio ns and the positions of maxima depend on the filling factor nu. For nu > 5, the relaxation rate tau(e)(-1) is maximum when the Fermi level lies in the region of the localized states between the Landau levels. For lower values of nu, the relaxation rate tau(e)(-1) is maximum at half-integer values of nu when the Fermi level is coincident with the Landau level. The character istic features of the dependence tau(e)(-1)(B) are explained by different c ontributions of the intralevel and interlevel electron-phonon transitions t o the process of the energy relaxation of 2D electrons. (C) 2000 MAIK "Nauk a/Interperiodica".