Single-particle relaxation times in antidot arrays

Magnetotransport in GaAs/Ga1-xAlxAs heterostructures with a square array of antidots has been investigated. Single-particle relaxation times tau(s) are estimated from the amplitudes of Shubnikov-de Haas oscillations and two values of tau(s) are found at low and high magnetic fields. The critical field at which tau(s) changes corresponds to the magnetic field where the cyclotron diameter 2R(c) is almost equal to the effective constriction length L-c between two antidots. This suggests that the influence of scattering from antidots on tau(s) is different in the region where 2R(c) > L-c and where 2R(c) < L-c. (C) 2000 Elsevier Science Ltd. All rights reserved.