Influence Of Mn Doping On The Structure And Optical Properties Of ZnO Nanocrystals

Diluted magnetic semiconductor(DMS) has two major features of the charge and spin of electrons, the optoelectronic devices produced from DMS will have a significant impact for the future development of information technology. Now, numerous experimental attempts have been reported to fabricate diluted magnetic semiconductor,,such as molecular beam epitaxy(MBE), pulsed laser deposition(PLD), magnetron sputtering, sol-gel, and hydrothermal method.ZnO is a II-VI semiconductor material. It has a wide band gap and a large exciton binding energy, and they are3.37eV and60meV respectively. One-dimensional structure is the most representative of the ZnO structures, it has a fairly complex defect level,and this has great significance for the performance of the semiconductor material. So now in the field of devices, ZnO nanomaterials have extensive application.Mn and Co are currently the most widely used two elements in production of diluted magnetic semiconductor. In this paper, the Mn-doped ZnO-based diluted magnetic semiconductors are fabricated by hydrothermal process. The structure, morphology and optical properties of the prepared samples were respectively characterized by XRD, SEM and PL spectra. The main contents in this paper are summarized as follows:1. The Mn-doped ZnO nanocrystals with different doping concentrations were fabricated, and the effects of Mn doping concentration on the nanocrystals were investigated. The results show that all the samples are wurtzite structural and have c-axis preferred growth orientation. And with increasing Mn content, the lattice constant of samples increases, and the UV emission firstly red-shifts and then blue-shifts. It is also found that appropriate Mn doping can promote the radial growth of ZnO nanowires.2. The Mn-doped ZnO nanorods were fabricated on different substrates (ordinary glass and ITO glass), and the effects of the substrates on Mn doped ZnO nanocrystals were investigated. The results show that the substrate material has a great influence on the morphology and optical properties of the nanorods. and the average diameter of the nanorods is closely related to the substrate.3. The Mn-doped ZnO nanorods with different growth times were fabricated, and the effects of the growth times on the nanorods were investigated. The results show that with increasing of the growth time, the intensity of the (002) diffraction peak and the degree of crystallinity of the sample are enhanced, the diameter of the nanorods become larger, and the PL intensity of the sample increases.4. The Mn-doped ZnO nanocrystals grown at different temperatures were fabricated, and the effects of the growth temperatures on Mn doped ZnO nanocrystals were investigated. The experimental results show that with the increasing of the reaction temperature, the intensity of the (002) diffraction peak significantly is enhanced, the crystalline properties of Mn-doped ZnO nanocrystals are improved. When the growth temperature is lower, the crystalline quality of the sample is poor and the orientation of nanorods is not good, while the growth temperature is higher, the crystalline quality and the orientation will be significantly improved, the UV emission peak is stronger and the defects of Mn-doped ZnO nanocrystals are also reduced.