Preparations And Properties Of Sn-Al Co-doped ZnO Thin Films By Magnetron Sputtering

Transparent conductive oxide（TCO） thin films are widely used inoptoelectronic industry as conducting electrode applications, such as solar cells,liquid crystal displays （LCDs）, and light emitting diodes （LEDs） owing to theirdesirable electrical conductivity and optical transparency. Recently, indium tinoxide has been well researched and widely utilized as TCO material. However,indium is a kind of rare metal material which is expensive and toxic. It has to bereplaced by another new kind of materials. Because of its lower cost andavailability and environmental protection, doped ZnO thin films with good opticaland electrical properties may replace the ITO materials in transparent conductingelectrode applications.Ceramic targets were sintered by SnO₂, Al₂O₃, ZnO mixed powder in differentmass fraction. Sn-Al co-doped ZnO thin films（ZATO） were deposited by RFmagnetron sputtering. By XRD, AFM, XPS, SEM, UV-visible spectrophotometer,four-probe meter and multi-function film surface properties instrument, the filmstructure and optoelectronics performance were characterized. The influences ofpressure, RF power, O2and Ar pressure ratio on the ZATO thin film structure,surface roughness and photoelectric properties were investigated. The influences ofannealing atmosphere, temperature, time and the doped amount of Sn on theproperties mentioned above were also investigated.The best mass fraction ratio of SnO₂, Al₂O₃, ZnO in the target is3:1:96. TheZATO film deposited by this target has a lower resistivity that is7.46×10-3·cm andits average transmittance between400nm-760nm is88.6%. The binding force of ZATO thinfilm on glass is33N. The best process parameters of RF magnetron sputtering are as below:sputtering pressure is1.0Pa, RF power is120W, O2and Ar pressure ratio is0.2:20.ZATO thin film annealed at450℃for60minutes under Ar ambience shows betterfilm structure and photoelectric properties.