Ohmic contact spike arrays for nanostructure device fabrication: spike distribution and geometrical scattering of the electron-wave current

We examine the ohmic contact-semiconductor interface and the process of current injection in a high mobility GaAs/AlGaAs Corbino device. Magneto-transport measurements demonstrate that weak localisation processes occur within the region of the 2DEG penetrated by the spike array formed on annealing of the ohmic contacts. These studies indicate that patterned ohmic contacts can provide a useful alternative to gated or etched sub-micron structures for fundamental mesoscopic physics investigations.