Effect of Ag layer thickness and scan line spacing during laser annealing of Ag/F-doped SnO2 bilayer composite thin films under ultrasonic vibration assistance

Abstract

To further improve electrical performance of FTO single-layer films and obtain high-performance transparent electrodes, the effects of silver (Ag) layer thickness and scan line spacing on optical and electrical properties of Ag/F-doped SnO2 (FTO) bilayer composite thin films prepared by radio frequency (RF) magnetron sputtering and ultrasonic-vibration-assisted laser annealing were investigated. The results indicate that as compared to the untreated FTO single-layer film, the Ag/FTO composite film displays a dramatic decrease in sheet resistance with even an improvement in transparency when the Ag layer thickness reaches 5 nm under the combined effect of laser annealing and ultrasonic vibration. Furthermore, the XRD and SEM analyses reveal that only using the moderate scan line spacing during ultrasonic-vibration-assisted laser annealing can contribute to the grain growth of the films. The Ag/FTO film with an Ag layer thickness of 5 nm and a scan line spacing of 20 μm shows a remarkable overall performance with an increased figure of merit of 2.13 × 10−2 Ω−1 comparing to 1.13 × 10−2 Ω−1 for the untreated FTO film. This work confirms the opportunity of combining Ag layer deposition and ultrasonic-vibration-assisted laser annealing in significantly improving both optical and electrical properties of FTO single-layer films, providing a promising alternative to the conventional ITO transparent electrodes.