A single-electron transistor includes a projecting feature, such as a
pyramid, that projects from a face of a substrate. A first electrode is
provided on the substrate face that extends onto the projecting feature.
A second electrode is provided on the substrate face that extends onto
the projecting feature and that is spaced apart from the first electrode.
Accordingly, the geometric configuration of the projecting feature can
define the spacing between the first and second electrodes. At least one
nanoparticle is provided on the projecting feature between the first and
second electrodes. The single-electron transistors may be fabricated by
forming a projecting feature on a substrate that projects from a face
thereof, forming a first electrode on the substrate face that extends
onto the projecting feature, forming a second electrode on the substrate
face that extends onto the projecting feature and that is spaced apart
from the first electrode, and placing at least one nanoparticle on the
projecting feature between the first and second electrodes. The
single-electron transistor fabricated in this way may be used as a
detector for biomolecular reactions by attaching a probe molecule to the
surface of the nanoparticle and measuring changes in the electronic
signal obtained from the device.