The Preparation And Study Of Al-doped ZnO Thin Films By Magnetron Sputtering

Al-doped zinc oxide(AZO)transparent conductive film is a new wide-band-gap semiconductor material with high transmittance and low resistivity characteristics,which is widely used in optoelectronic devices.The AZO transparent conductive films were prepared by RF magnetron sputtering method and the influence of process parameters on the structures and optical and electrical properties of the films was studied.In addition,the effects of ultraviolet(UV)radiation on the structures and properties of AZO films deposited on quartz glass substrates and PET flexible substrates were studied for the first time.The main results are as follows:The process parameters,such as RF power,Ar gas pressure,deposition time,deposition temperature and substrate rotation speed,were changed in the experiments,the effects of process parameters on the structures and properties of the AZO films were investigated by XRD,SEM,XPS,UV-vis and four-probe tester.All samples with different process parameters and different substrate materials have obvious c-axis preferred orientation near 2? = 34.4 °.When the RF power was 120 W,the film had the highest transmittance nearly 75% and maximum grain size of 26.8nm.The crystal quality of the films increased first and then decreased with the increase of Ar gas pressure.When the Ar pressure was 0.8Pa,the crystal quality of AZO film was the best with lowest sheet resistance of 8.2?/?.The prolonged deposition time had a great improvement on the crystal quality of the films.When the deposition time was less than 90 min,the visible light transmittance of the films was more than 85%.The higher temperature had positive effect on the crystallization of the AZO films,the greatest crystal quality was obtained at 250 ?,in the temperature range of 150~250?,the deposition temperature had little effect on the transmittance.The crystallization of the films decreased with the increase of substrate rotation speed,the film was denser and the conductivity was the best at the rotation speed of 0 rpm.Based on the optimization of the process parameters,the transmittances of AZO films on quartz glass substrates were more than 85% and sheet resistance was 21?/?,the transmittances of AZO films on PET substrates were more than 75% and sheet resistance of 36.2?/? were obtained.At this time,the RF power was 120 W,the Ar pressure was 0.8Pa,the deposition time was 90 min,the deposition temperature was 250 ?(quartz glass substrates)and 100 ?(PET substrates)and the substrate rotation speed was 0 rpm.The effect of 168 hours UV radiation on the structure and properties of AZO thin films was studied for the first time.The results showed that long time UV radiation had a significant effect on the structure and properties of AZO films,whether quartz glass substrates or PET flexible substrates.After UV radiation,the grain sizes of the films were reduced and the diffraction angle shifted to a larger angle,the crystal quality was deteriorated,resulting in the increase of the sheet resistance and the decrease in the visible light transmittance of the films.