The Research Of Conductive And Transparent Properties Of SnO₂:F Thin Films Prepared By Magnetron Sputtering

Transparent conductive oxide (TCO) thin films is a kind of distinctivelyfunctional thin film material with excellent conductivity and high transparency in thevisible region simultaneously. TCO films has been widely used in various applicationfields such as lighting emitting diodes, flat panel displays, thin film solar cells,electronic glasses, etc. SnO2:F (FTO) thin film have attracted broad attention due toit’s outstanding superiorities of non-toxin to human body, high stability, cheaper rawmaterials price, compared with other TCO materials. At present the chemical synthesismethods of FTO thin films mainly include spray pyrolysis, chemical vapor deposition,sol-gel, etc. However, there are few literature about FTO films prepared by magnetronsputtering.In this paper, magnetron sputtering was employed to prepare FTO thin films onsoda-lime glasses with pure Ar atmosphere and mixed atmosphere respectively. Servalanalytical techniques such as Hall measurements and ultraviolet-visible (UV-Vis)spectrophotometer were used to characterize the electrical-optical properties of FTOthin films. The effects of sputtering power, substrate temperature and sputteringpressure with pure Ar atmosphere during the deposition processes on the electricaltransport and optical properties of FTO thin films have been studied and discussedrespectively. We also discussed the effects of O2flux with Ar/O2mixed atmosphere,and H2flux, sputtering power, sputtering pressure and sputtering time with Ar/H2mixed atmosphere on the transparent conductive properties of FTO films. Furthermore,the paper has studied the effects of annealing temperature, annealing atmosphere andannealing time on the electrical-optical properties of FTO films.The results showed that the effects of sputtering power, pressure and substratetemperature were highly related to the crystalline of FTO films and concentration ofdonor impurity. H2injection could reduce the resistivity of FTO films during thedeposition process. A certain flux of H2could increase the concentration of oxygen `vacancies. However, a large amount of H2should deteriorate the crystalline of FTOfilms and generate SnO phase in films, which increased the resistivity of FTO films.The optimized deposition parameters were carried out at power of90W, substratetemperature of150℃and H2flux of3Sccm，and the transparent and conductiveproperties of FTO films reach the minimum resistivity of1.09×10-2· cm with carrierconcentration of8.63×1019cm-3and mobility of6.64cm2/V·s as well as averagetransmittance of91%. The results of post-annealing experiments showed that theresistivity of FTO thin films emerged different decreasing trends as function ofannealing temperature with air, vacuum and Ar/H2atmosphere, which was related tothe adsorbed oxygen content of grain boundary in FTO films.