  The thermal gradient along indium-arsenide nanowires was engineered by a
combination of fabricated micro- trenches in the supporting substrate and
focused laser irradiation. This allowed local control of thermally activated
oxidation reactions of the nanowire on the scale of the diffraction limit. The
locality of the oxidation was detected by micro-Raman mapping, and the results
were found consistent with numerical simulations of the temperature profile.
Applying the technique to nanowires in electrical devices the locally oxidized
nanowires remained conducting with a lower conductance as expected for an
effectively thinner conducting core.
