Breakdown of the quantum Hall effect in periodic and aperiodic antidot arrays

We have studied the breakdown of the quantum Hall effect in GaAs/Al_xGa_1-xAs heterostructures with antidot arrays as a function of the density and distribution of antidots. For periodic arrays (lithographic antidot diameter 100 nm) and periods from 400 to 1000 nm, the breakdown current is systematically reduced with increasing antidot density and determined by the peak value of the local current density. In aperiodic arrays, the breakdown current is markedly lower than in periodic arrays of the same antidot density due to higher local current densities at the same total current.