  Temperature dependent photoluminescence (PL) is used to study the electronic
properties of single CdS nanowires. At low temperatures, both near-band edge
(NBE) photoluminescence (PL) and spatially-localized defect-related PL are
observed in many nanowires. The intensity of the defect states is a sensitive
tool to judge the character and structural uniformity of nanowires. As the
temperature is raised, the defect states rapidly quench at varying rates
leaving the NBE PL which dominates up to room temperature. All PL lines from
nanowires follow closely the temperature-dependent band edge, similar to that
observed in bulk CdS.
