Dissertation
Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials

Studies on the Prepration and Properties of (Al, Co) Co-doped ZnO Thin Films

Author HuangWenJuan
Tutor FangQingQing
School Anhui University
Course Materials Science
Keywords ZnO thin films Structure Photoluminescence Magnetic H annealing
CLC TB383.2
Type Master's thesis
Year 2011
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ZnO is a wide band gap semiconductor, with potential applications in many other areas such as photonics, spintronics and transparent electronic film. Recent studies have found that in ZnO doped with the Co 3d transition metal elements, can be prepared Curie temperature above room temperature diluted magnetic semiconductors. Such materials combined with light effects and magnetic effects, can be used to produce a spin light-emitting diodes, spin-polarized solar battery and magneto-optical switches and other devices, which will information technology to bring about revolutionary change. In this paper, the pulsed laser deposition (PLD), high c-axis oriented single crystal Si (100) substrate was prepared ZnAlCoO film study different Al, Co content of the film structure, optical and magnetic properties, and preparation process were explored to optimize the process conditions, the main contents are as follows: 1 XRD spectrum analysis showed that all ZnAlCoO film has a hexagonal structure, and along the (002) direction of preferential growth. The experimental results show that the film thickness has a great influence on the ZnO layer is crystallized, the proper thickness of the ZnO layer, the ZnO thin films of high crystal quality can be obtained. The analysis also showed that in the ZnAlCoO film, Al, there is an optimum ratio of the Co content, so that the film has preferably the crystalline quality. 2, the use of light-emitting properties of the light-induced luminescence (PL) spectroscopy have been used systematically studied sample. PL spectra analysis showed that the increase of the Co content leads to the light-emitting spectrum of the film changed significantly, defect emission peak enhancement film, In addition to the intrinsic defects VZn, Vo and ZnO thin films, but also appeared a certain concentration Zni defects. Also was found that a high concentration of Al doping, resulting in a film visible emission peak intensity enhancement VZn the ZnI of visible light-emitting peak intensity having a significantly enhanced effect. 3, magnetic measurements indicate that the defect-induced ferromagnetism at room temperature in all samples. Where, VZn Zni two defects on the magnetic properties. The analysis shows that, VZn shallow acceptor the main defect states and Co 3d electron orbital hybridization is the main reason for the formation of ferromagnetic. At the same time found that, ZnI donor defects by the number of electronic transitions between the impact and Co 3d electronic states of the magnetic impact. 4, the system H annealing on the structure and performance. XRD patterns analysis showed that, after processing of the H atmosphere, better crystal quality. PL spectrum shows, H annealing, ZnAlCoO film is enhanced UV emission peak. For the high concentration of Al-doped samples, H annealing significantly inhibited the defect peak intensity in the visible region of the spectrum. The magnetic measurements show that the sample still has a room-temperature ferromagnetism after treatment with H, H annealing treatment to reduce defects in the sample, resulting in a saturation magnetization of the sample is reduced. It was found that the impact of ZnO thin film magnetic Co-doped ZnO films, injection of H should be the formation of Co-H-Co structure key.

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