  We determine the locations of unintentional quantum dots (U-QDs) in a silicon
nanowire with a precision of a few nanometers by comparing the capacitances to
multiple gates with a capacitance simulation. Because we observe U-QDs in the
same location of the wire in multiple devices, their cause is likely to be an
unintended consequence of the fabrication, not random atomic-scale defects as
is typically assumed. The locations of the U-QDs appear consistent with
conduction band modulation from strain from the oxide and the gates. This
allows us to suggest methods to reduce the frequency of U-QDs.
