Resistance of very small area ohmic contacts on GaAs

Very small area, alloyed ohmic contacts on n+-GaAs etched mesas have been fabricated and their resistance measured. The nominal contact size ranges from 10 down to 0.1 μm on a side. The data show an extremely large increase of the resistance spread as the contact size is reduced. Grain size effects in the alloyed contacts and dead zones due to ion etching are discussed as possible causes for the observations.