Quantum lifetimes in antidot arrays

Magnetotransport in GaAs/Ga 1− x Al x As heterostructures with a square array of antidots has been investigated. Quantum lifetimes τ q are estimated from the amplitudes of Shubnikov–de Haas oscillations and two values of τ q are found at low and high magnetic fields. The critical field at which τ q changes corresponds to the magnetic field where the cyclotron diameter 2 R c is almost equal to the effective constriction length L c between two antidots. This suggests that the influence of scattering from antidots on τ q is different in the regions where 2 R c > L c and where 2 R c L c .