Magneto transport on antidot arrays, fabricated by an atomic force microscope

A recently introduced lithographic tool employing an atomic force microscope is improved and utilized to fabricate nanometer-scale antidot arrays. The AFM periodically creates holes in a thin photoresist, covering a conventional mesa-etched GaAs-AlGaAs heterostructure. To minimize the period of produced holes in the resist we now use carbon AFM supertips, prepared in a scanning electron microscope. To create holes or lines in the resist, a mechanical force of typically 1 mu N is exerted at ambient conditions. We thus succeed in fabricating hole arrays with a periodicity down to 15 nm and a hole diameter of only few nanometers. The resist mask is transferred onto the two-dimensional electron gas either by a shallow wet chemical etch step or by an ion beam irradiation technique, respectively. In magneto-resistance studies at T = 4.2 K on antidot-devices with periods down to 85 nm, we clearly observe commensurability oscillations of the longitudinal resistance R(xx), demonstrating the successful pattern transfer to the electron system. Resistance fluctuations measured at T = 25 mK indicate a clear dependence on the period of the antidots.