Investigation On Photoluminescence Properties Of Na-doped Single Crystalline ZnO

Zinc oxide (ZnO) has drawn much attention over the years due to its great potential for a variety of applications in many fields. However, high-quality and reproducible p-type ZnO has not been obtained yet, seriously hampering the development of ZnO based optoelectronic devices. Group I elements such as Na have been reported as possible shallow acceptors. We mainly explore the role of Na played in ZnO by photoluminescence. For a clear environment, we choose ZnO nanorods grown by metalorganic chemical vapor deposition (MOCVD) and ZnO single crystal grown by hydrothermal method as the substrates. The main work could be summarized as following:1. We demonstrate the successful growth of Na-doped ZnO nanorods array by MOCVD. Unlike the undoped ZnO nanorods, the low temperature PL spectrum of Na-doped sample is dominated by excitons bound to ionized donors (D+X), suggesting the formation of Na acceptors and high compensation between the donors and acceptors. The formation of Na acceptors is supported by the shift of Fermi level toward the valence band.2. Na+ ion-implanted c-plane (0001) and a-plane (1120) ZnO single crystal was prepared with different implantation energies and dose. After annealing at 650 ℃, the low temperature PL spectrum is dominated by excitons bound to neutral acceptor (A0X), indicating the formation of Na acceptors. The tracking test of donor-acceptor-pair PL spectra suggest that NaZn is not stable. And the impact of different implantation energies, dose and crystal orientation on the formation of Na acceptors is studied, the results show that Na doping is regulated by the crystal polarity.