Optimization Of TCO Thin Films

Transparent conductive oxide films are widely used in modern optical and electricaldevices due to their high transparencies and good conductivities. Aluminum doped zincoxide （AZO） attracts many researchers because of its environment friendly, low cost, wideband gap, high transparency and good conductivity. Multi-component oxides with thespecial functions are noticed by researchers as well. In this project, AZO films wereprepared on glass substrates by RF magnetron sputtering from powder targets. Theexperimental was according to Tanguchi design by changing sputtering power, thedistance between target and substrate and deposition pressure. Then the films wereannealed at400oC in vacuum. Also, tin oxide, zinc oxide and cadmium oxide powderwere mixed by their atomic ratios to be targets. Sn_xZn_yCd_1-x-yO films then prepared onpolyimide and glass substrates at the same time. The structure and properties of AZO andSn_xZn_yCd_1-x-yO films were investigated.The structures of the films were analyzed by X-ray diffraction （XRD）, transmittanceelectron microscopy （TEM） and atomic force microscopy （AFM）. Auger electronspectrometry （AES） was used to test the distribution of the compositions throughthickness. The resistivities, concentrations and mobilities of the charge carriers of thefilms were measured by four point probes and Hall-effect measurement, transmittance ofthe films by a UV-VIS optical sepctrametry. The structures of the films were grown incolumnar clusters, which were composed by columnar nano-crystalline in （002） preferredorientation. The average transmittance of AZO films within visible wavelength wereabout85%, and the resisitivties as low as10^-3.cm. Tanguchi experimental showedsputtering power was the key parameter to affect the structures and properties, thedistance between target and substrate was the second factor and pressure, the last. Theresistivities of the Sn_xZn_yCd_1-x-yO films on PI substrates were about10Ω·cm,3ordershigher than those on glass slides. The concentrations of the charge carriers of themulti-component oxide films were about10¹⁷cm^-3, and the mobility was up to31cm².V^-1.s^-1for the films with highest Cd ratio. The effect of the metallic atoms on theproperties of the multi-component oxide films were in the order of Cd, Sn and Zn.