Photoluminescence Spectroscopy Of Impurities And Defects In Single Crystalline ZnO

In order to develope ZnO-based optoelectronic devices, the preparation of p-ZnO with good optical and electrical properties is essential. Deep insights into the behavior of the intrinsic defects and impurities in ZnO are the key point for the acquisition of high-performance p-ZnO. Photoluminescence (PL) is one of the most effective methods to study the behavior of impurity and defect in ZnO. High quality single-crystal ZnO is the basis of carrying out the high resolution PL study. In this thesis, we take ZnO nanorods and ZnO film as the study objects, respectively. We realized in situ Na doped ZnO nanorods by hydrothermal method and ion implantation of single crystal ZnO, and then discussed the photoluminescence of the ZnO (ZnO:Na) nanorods in detail. The primary results are described in the following:(1) ZnO nanorod arrays were grown by CVD, and then exposed to rapid thermal annealing in O2. We found that the annealing improved the crystal quality and induced a strong biexcitonic emission at3.357eV, moreover resulted in obvious changes in the peak energy and lineshape of the A line.The A line in the as-grown nanorods likely implied the competition between FA and FX-LO. The phonon replica of free exciton was suggested as the origin of A line in the ZnO nanorods.(2) We found the structured green emission (SGE) in undoped ZnO nanorods grown by CVD. SGE is usually known as the emission from Cu impurities, but we have not observed the correspondence between the SGE and Cu impurities content. The SGE shows the negative temperature quenching effect, a128meV trap energy level and a deep level acceptor impurity-370meV was extracted. An energy diagram is proposed to interpret the experimental results.(3) We analyzed the low temperature (LT) PL of ZnO:Na nanorods grown by hydrothermally, and found a DAP recombination emission at3.23eV, corresponding to a Na acceptor level of170meV. We also found that the rapid thermal annealing is more benefit to Na doping in ZnO.(4) We analyzed the LT PL Na ion implantated ZnO thin films by MBE. We found a DAP recombination at-3.1eV, and deduced a Na relative acceptor level at-300meV.(5) We carried out the surface SIMS scanning to analyze the unintentionally doped impurities of ZnO grown by CVD method and the evolution of the impurities after rapid thermal annealing.