  A highly sensitive charge detector is realized for a quantum dot in an InAs
nanowire. We have developed a self-aligned etching process to fabricate in a
single step a quantum point contact in a two-dimensional electron gas and a
quantum dot in an InAs nanowire. The quantum dot is strongly coupled to the
underlying point contact which is used as a charge detector. The addition of
one electron to the quantum dot leads to a change of the conductance of the
charge detector by typically 20%. The charge sensitivity of the detector is
used to measure Coulomb diamonds as well as charging events outside the dot.
Charge stability diagrams measured by transport through the quantum dot and
charge detection merge perfectly.
