The Preparation And Optoelectronic Properties Of ZnO Thin Films Doped With Aluminum

ZnO has attracted much attention in recent years, it is a new generation of ultraviolet excitation emission and laser device. With the continuous development of semiconductor devices in the world, two critical problems also appear. They are p-type doping and band gap engineering problems. ZnO activation layer is double heterojunction excitation light material, the research of p-type doping and p-n junction device has made great progress in recent years. Recent research has focused on p-ZnO conductivity and ZnO-based p-n binding substrate.There are many methods to prepare aluminum doped zinc oxide, such as magnetron sputtering, molecular beam epitaxy, chemical vapor deposition (CVD), metal organic chemical vapor deposition (MOCVD), sol-gel and spray pyrolysis, etc. Spray pyrolysis equipment is relatively simple and more convenient to prepare precursor solution, its parameter is easy to adjust, so it is possible to prepare large area coating and be used for large-scale industrial production.In this experiment, Zinc acetate solution was used as a precursor solution and aluminum nitrate as the source of Al for ultrasonic spray pyrolysis system. Pure ZnO thin films and aluminum doped ZnO thin films were prepared on quartz substrate and silicon substrate. XRD (X-ray diffraction), SEM (scanning electron microscope), PL (photoluminescence spectrum), UV-Vis Spectrometer (ultraviolet-visible Spectrometer) and Hall tester were used to characterize the structure, surface morphology and optoelectronic properties of the samples. According to the test results in the different experimental parameters, such as change of substrate temperature, concentration of the precursor solution, deposition time and annealing conditions, the effect of parameters on optoelectronic properties of the samples were studied detailedly.The aluminum doped ZnO thin films prepared by spray pyrolysis method owned preferable optoelectronic properties. From the PL spectrum, the films deposited on silicon substrate had a strong near-edge ultraviolet light emitting peak. From the XRD spectrum, the films deposited on quartz substrate appeared obvious C axis preferred orientation. Experimental results showed that the optimum conditions for the preparation of aluminum doped ZnO thin films was that the substrate temperature was at470℃, the atomic ratio of nZn:nAl was1:0.04. Hall tests showed that the samples deposited with nZn:nAl=1:0.04and480℃owned p-type conductivity.