Annealing-induced change of hydrogen behavior in ZnO nanorods revealed by photoluminescence

• Annealing at 1223 K removes H and greatly modifies the luminescence of ZnO nanorods.
• VZn–H complex exists in the hydrothermally grown ZnO materials.
• VZn and VZn–H complex are responsible for the different deep level emission.

We carry out a comprehensive photoluminescence (PL) study on hydrothermally grown ZnO nanorods to provide insights into the role of hydrogen impurity in ZnO materials. Annealing at 1223 K greatly modifies the PL properties of the ZnO nanorods, both for the excitonic and deep level emissions. The suppression of excitons bound to H donors as well as enhancement of deep level emission after annealing suggests the removal of H from ZnO lattice. The temperature-dependent behavior of the deep level emissions suggests the formation of VZn–Hn complexes.