The Preparation And Optical Properties Of ZnO Thin Films Co-doped With Na-Mg By Ultrasonic Spray Pyrolysis Method

ZnO (Zinc Oxide) is Ⅱ-Ⅵmaterial, which has a wide bandgap semiconductor. Itsforbidden band width is3.37eV and it has high exciton binding energy at roomtemperature,which can reach60mev. Because of its excellent photoelectric, piezoelectric,pyroelectric features, ZnO has a broad application prospect in LED, LCD, solar cells, gassensor, varistor, surface acoustic wave devices and other fields. Researches have found thatZnO materials with more excellent performance can be prepared by doping.In this thesis, the crystal structure and the properties of ZnO and its application inintegrated optics are introduced in detail at the first place. Then ultrasonic spray pyrolysis(USP) method is used to prepare pure ZnO thin films and Na-Mg doped ZnO thin films insilicon and quartz glass substrate with zinc acetate as the precursor solution for the former andwith zinc acetate, magnesium nitrate and sodium acetate as the precursor solution for the latter,respectively. The samples are characterized by SEM, XRD and PL spectrum lastly. What’smore, the crystal structure, surface morphology, crystal quality and band gap width areanalyzed.The results show that Na and Mg co-doping can improve the C axis preferredorientation of ZnO thin film growth. By changing the concentration of the doping, theconcentration of Na+0.02has more excellent crystal and optical performance. A highintensity violet emission peak can be clearly observed in the PL spectra. And its emissionpeak intensity is increased nearly7times compared with the pure ZnO thin films, whichproves that the concentration of Na+0.02has more excellent optical performance.Experimental results show that the optimum conditions for the preparation of Na and Mgco-doping ZnO thin films are that the concentration of Na+is0.02, the substrate temperatureis at500℃,the distance of nozzle to substrate is5cm and the oxygen flow rate is1.8L/min.