| ZnO, with a band gap of 3.37 eV and a binding energy of exciton as high as 60meV at room temperature (RT) has been attracted more and more attention as a strong candidate for ultraviolet light emitting diode and lasing diode. However, there are still some unsolved problems restricting its further application in optoelectric field. The problems are as follows:(1) High quality undoped ZnO is essential for the application of ZnO in optoelectric field. However, there exists great amount of intrinsic defects and impurities in undoped ZnO, which limits the application in optoelectric field.(2) Stable and reproducible p-type ZnO plays a very important role for the application of ZnO in the optoelectric field. However, it is hard to obtain high quality p-type ZnO films due to high ionization energy of acceptor impurities, low solubility of dopants, and self-compensation effect in ZnO, which becomes another reason for limiting the application for ZnO.(3) Lacking of theoretical supervision becomes another bottleneck for the application for ZnO.According to the present research difficulties on ZnO, we concentrated on the influence of the stoichiometry for undoped ZnO, the formation mechanism of acceptor and the magnetism for p-type ZnO, the details are as follows: (1) High quality undoped ZnO thin films were fabricated on c-sapphire substrate by at various Zn/O ratios by plasma-assisted molecular beam epitaxy (P-MBE). The influence of Zn/O ratio on the structural, electrical and optical properties of the ZnO films was investigated.(2) Stable and reproducible ZnO:(Li, N) films with different Li doping concentrations were prepared on c-sapphire substrates by P-MBE with highly pure metal Zn and Li as well as NO.(3) The origin of the formation mechanism and the ferromagnetism of p-type ZnO:(Li, N) films is elucidated through the systematically investigation on the structure, optical, electrical, magnetism of p-type ZnO:(Li, N) films. |
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