Fabrication of highly conducting ZnO/Ag/ZnO and AZO/Ag/AZO transparent conducting oxide layers using RF magnetron sputtering at room temperature

Abstract

Sputter deposition of multilayer ZAZ (ZnO/Ag/ZnO) and AAA (AZO/Ag/AZO) TCO coatings has been done using a magnetron sputtering system. The deposition has been performed by moving the substrate under the desired target (ZnO or AZO and Ag) using a movable arm. This movable arm allows the substrate movement in the required order through a controller in a forward or reverse direction. Using this arrangement, the fabrication of ZAZ and AAA multilayer TCOs has been done on glass substrates at room temperature and the layer properties are found to be comparable with the properties of commercial ITO film. The fabricated ZAZ and AAA multilayers (with thickness around 70 nm) exhibit better electrical properties as compared to the commercial ITO film. The electrical resistivities of the ZAZ 2 and AAA 2 layers are 3.78 × 10−5 and 3.71 × 10−5 Ω cm, respectively which are much lower than the ITO resistivity of 4.56 × 10−4 Ω cm. The sheet resistances of ZAZ 2, AAA 2 and commercial ITO layers are 5.4, 5.3 and 16.8 Ω/□, respectively. The figure of merit (FoM) for AAA 2 multilayer is 45.5 × 10−3 Ω−1, much higher than commercial ITO film (23.7 × 10−3 Ω−1). The high-temperature annealing shows almost stable optical and electrical properties of the fabricated TCO layers up to 200 °C. Therefore, these TCOs can be used as electrodes for the solar cell fabrication where high-temperature annealing is required.