Influence of reaction temperature on the formation process of ZnO quantum dots and the optical properties

ZnO quantum dots (QDs)with the sizes of 3.0–5.6 nm are synthesized by solution-phase method at different temperatures. We find that temperature has great influence on the size of ZnO QDs. The growth process is the most sensitive to temperature, and the process is well explained by Lifshitz-Slyozov-Wagner (LSW) model. By photoluminescence (PL) spectra of the quantum dots at different temperatures and reactive time, we come to a conclusion that ultraviolet emission is mainly due to surface defects, and the origination of green visible emission comes from the transition between the bottom of the conduction band and the level of O _i. The work has been supported in part by National Natural Science Foundation of China(Grant No. 60877029), in part by the Tianjin Natural Science Foundation (Grant No. 07JCYBJC06400 06TXTJJC14600), and in part by the Subject of Science and Technology Development Fund at University of Tianjin (Grant No. 20071207)