The Optical Properties Of NaMgZnO Thin Films Prepared By Sol-Gel Process

Zinc oxide?ZnO?is a hexagonal wurtzite structure of the VI group metal oxide.At room temperature with a width of 3.37eV direct band gap,ZnO exciton binding energy is relatively high?about 60meV?,far more than the activation energy at room temperature.Exciton can be stable at room temperature or higher temperature and will not occur the recombination process of ionization,which can be applied to ZnO optoelectronic devices.The Zn O functional material with excellent properties can be synthesized by a suitable method.In this thesis,intrinsic ZnO thin films using ethylene glycol monomethyl ether as the solvent and zinc acetate as the precursor for the system,Mg_x Zn_1-xO and Na_yMg_0.2Zn_0.8-yO composite films using magnesium acetate and sodium chloride as Mg source and Na source respectively,single Ethanol as a stabilizer for the colloidal system,were successfully prepared on glass substrate by sol-gel technique adopting spin coating process after pre-annealing and high temperature heat treatment.The optimum parameters to prepare ZnO thin films were annealing temperature of 500?and spin coating time of 5 times.The lattice parameters,structure and crystal quality,microstructure,photoluminescence and transmission properties were investigated by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,photoluminescence?PL?spectrum and UV-Vis spectrophotometer?UV?.The results show that:?1?After adding Na and Mg elements into ZnO thin films,the C-axis preferential growth is more obvious,and the grain size of the composite films is changed after the increasing of Na⁺concentration.?2?By comparing PL spectra of Mg_xZn_1-xO?x=0.01?0.02?0.03?composite films,It is speculated that the Ultraviolet Emission at 380 nm may be caused by the free exciton recombination of ZnO,and the band gap of ZnO thin film increases with the introducing of Mg element.?3?Na_0.02Mg_0.2Zn_0.78O composite films own good crystal quality and excellent optical performance,its PL spectrum has only a larger violet emission peak.The intensity of UV emission peak is enhanced obviously compared with the intrinsic ZnO,indicating that the composite films own better UV luminescence performance.