Origin of the near-band-edge photoluminescence emission in aqueous chemically grown ZnO nanorods

Abstract

The optical properties of ZnO nanorods realized by an advanced low-temperature aqueous chemical growth on both silicon and plastic substrates are presented. Systematic photoluminescence investigations in the temperature range of 4–293K reveal strong and well-resolved near-band-edge emission even for rods on plastic substrate, and a weak deep-level emission. At intermediate temperatures phonon replicas of excitonic lines are observable. The optimum molar concentration range of the solution for obtaining nanorods of good optical quality is shown to lie between 0.025M and 0.075M. The large linewidth of the near-band-edge emission (∼10meV), its temperature dependence, and the absence of sharp excitonic transitions indicate that this emission is a result of transitions from a band of donor states.