Reduction of electrical damage in specimens prepared using focused ion beam milling for dopant profiling using off-axis electron holography

GaAs specimens containing p-n junctions have been prepared using focused ion beam (FIB) milling for examination using off-axis electron holography. By lowering the FIB operating voltage from 30 to 8 M we have shown a systematic reduction of the electrically 'inactive' thickness from 220 to 100 nm, resulting in a significant increase in the step in phase measured across the junctions as well as an improvement in the signal-to-noise ratio. We also show that the step in phase measured across the junctions can be influenced by the intensity of the electron beam. (c) 2007 Elsevier B.V. All rights reserved.