Electrical characterization and Auger depth profiling of nanogap electrodes fabricated by I2-assisted focused ion beam

Iodine (I-2)-assisted, 30 keV Ga+ focused ion beam (FIB) has been employed to fabricate nanogap Au electrodes and has been compared to conventional FIB milling. Electrical characterization shows that I-2 assistance improves insulation resistance from 300-400 G Omega to 20-50 T Omega. Auger depth profiling reveals that the Ga concentration profile in FIB-milled samples has a peak value of 25 at. % at 7 nm and extends, with a decreasing Gaussian tail, down to 40 nm, whereas in I-2-processed samples Ga concentration is reduced below 5 at. %. I-2 assistance is found to increase minimum gap size from 8 to 16 nm and to markedly roughen Au surface morphology. (c) 2006 American Institute of Physics.