Percolation at v=1 in the 2D electron system oF e −beam irradiated AlGaAs/GaAs heterostructures

Abstract

We report on the low temperature AC and DC magneto transport properties of e −-beam irradiated AlGaAs/GaAs heterojunctions. This work has been motivated by earlier investigations of the cyclotron resonance (CR) which show a spectacular difference between the AC and DC mobility. While the DC transport in such irradiated samples reflects a very low mobility of the carriers, the CR linewidth is very small for high frequencies and at magnetic fields corresponding to the extreme quantum limit of single Landau level occupation, suggesting a high mobility of the carriers. We show that at low temperature the longitudinal resistance strongly increases when the system is in this quantum limit of an apparent high mobility CR. This discrepancy between AC and DC behaviour is attributed to a percolation of the 2D electron system.