Preparation of RF sputtered AZO/Cu/AZO multilayer films and the investigation of Cu thickness and substrate effects on their microstructural and optoelectronic properties

Highlights: • AZO/Cu/AZO multilayer films were deposited on glass and quartz substrates by RF magnetron sputter. • Effects of Cu thickness and substrate on the properties of AZO /Cu/AZO multilayer films were investigated. • XRD analyses revealed that higher crystal quality is obtained using Cu thickness of 7 nm. • For both substrates, resistivity of AZO/Cu/AZO decreases with increasing of Cu thickness. • The highest figure of merit values are obtained for both substrates with 13 nm Cu multilayer films. -- Abstract: AZO/Cu/AZO multilayer films are deposited on glass and amorphous quartz substrates by RF magnetron sputtering in confocal configuration at room temperature. The effects of Cu thickness and substrate type on the microstructure and optoelectronics properties are investigated. The results show that the properties of the tri-layer lms are strongly influenced by these parameters. For both substrates, all the lms are polycrystalline and show an obvious ZnO (002) c-axis preferential growth. No diffraction peaks related to Cu are observed through X-ray diffraction analysis. The average transmittance in the visible region is in the range of 69–83%, while the optical band gap remains constant at 3.454 eV regardless of the Cu thickness and substrate type. With the increase of Cu thickness, the electrical properties of AZO/Cu/AZO tri-layer films on glass and quartz substrates are improved. The best figure of merit obtained is 1.97 × 10^-3 Ω^-1 for a Cu thickness of 13 nm on glass substrate with a low resistivity of 2.05 10^-4 Ω cm and an acceptable average transmittance of 70%. These multilayer structures, with such good performances, are of great interest for potential thin film applications in optoelectronic devices in the visible and NIR region, in particular solar cells.