High transmittance in IR region of conductive ITO/AZO multilayers deposited by RF magnetron sputtering

The widely commercial used transparent conductive oxides (TCOs), such as ITO, combine ideal transmittance in visible light region and low electrical resistivity. However, its transmittance in near infrared (NIR) region is very limited. In contrast, AZO as a promising candidate of ITO possesses better optical transmittance in NIR region but presents poor electrical properties. In order to extend the applications of TCO materials in NIR region, ITO/AZO multilayers were designed in this work. The influence of the AZO monolayer thickness on the film's optoelectronic properties in NIR region was investigated. The results show that with AZO monolayer thickness increasing, the film's electrical resistivity increases, but always lower than that of single AZO film. In addition, the film's transmittance in NIR region is greatly improved by increasing AZO monolayer thickness. In point of the figure of merit, all ITO/AZO multilayers present enhanced optoelectronic properties in NIR region with respect to single ITO film or single AZO film. When AZO monolayer thickness is about 6 nm, the optimal film is realized. Its resistivity is around 8.6 x 10(-3) Omega cm, while its average transmittance in NIR region reaches 90.0%.