  Focused ion beam milling allows manipulation of the shape and size of
nanostructures to create geometries potentially useful for opto-electronics,
thermoelectrics, and quantum computing. We focus on using the ion beam to
control the thickness of Bi2Se3 and to create nanowires from larger structures.
Changes in the material structure of Bi2Se3 nanomaterials that have been milled
using a focused ion beam are presented. In order to characterize the effects of
ion beam processing on the samples, we use a variety of techniques including
analytical transmission electron microscopy and atomic force microscopy. The
results show that while part of the material remains intact after shaping,
amorphous regions form where the beam has been used to thin the sample. For
wires created by thinning the material down to the substrate, the sidewalls of
the wires appear intact based on diffraction images from samples cut at an
angle, but thin crystalline regions remain at the wire edges. Even with the
resulting defects, focused ion beam milling shows promise for directly
fabricating intricate nanodevices of Bi2Se3.
