Magnetotransport through an antidot lattice in GaAs-AlxGa1-xAs heterostructures

Regular two-dimensional arrays of antidots with periodicities in the range of 200--500 nm are prepared in GaAs-AlxGa1-xAs heterostructures by means of Ga-focused ion-beam implantation. Transport measurements at low magnetic fields reveal a strong negative magnetoresistance originating from the localization of the electrons in the potential valleys between antidots. The low-temperature mobilities of the carriers deduced from the B=0 resistance are in the range of 1000--30 000 cm2/V s. Under illumination mobility changes by more than a factor of 20 can be achieved. For high magnetic fields well-defined Shubnikov--de Haas oscillations and quantum Hall plateaus are observed. Close to B=0 a very small structure in the magnetoresistance occurs reflecting the commensurability of the cyclotron diameter and the periodicity of the antidot array