Effect of deposition temperature on the physical properties of RF magnetron sputtered Ag–Cu–O films with various Cu to Ag ratios

Abstract

AbstractThin films of Ag–Cu–O were deposited on glass substrates held at various temperatures in the 303–523 K range by RF magnetron sputtering of Ag90Cu10, Ag80Cu20 and Ag70Cu30, and elemental copper and silver targets in an oxygen partial pressure of 2 × 10−2 Pa and sputtering pressure of 4 Pa. The deposited films were characterised by energy dispersive X‐ray analysis, X‐ray diffraction (XRD), atomic force microscopy, UV–Vis–NIR spectroscopy and employing four‐point probe method. The atomic ratio of Cu/Ag in the films formed at 303 K was in correlation with the composition of the starting sputter targets. The increase in substrate temperature induced the decomposition of the Ag–Cu–O films into a mixture of metallic silver and copper oxide. The electrical resistivities of silver oxide and copper oxide films formed at 303 K were 3 × 10−3 Ω cm and 29 Ω cm, respectively. The electrical resistivity of the films formed with Ag70Cu30 target at 303 K was 8.2 Ω cm and it decreased to 2.4 Ω cm with increase in substrate temperature to 523 K due to structural changes in the films. The optical band gap of the Ag–Cu–O films formed at 303 K increased from 1.60 to 1.95 eV with the increase of copper to silver atomic ratio from 0.10 to 0.30 in the films. The optical band gap of the films formed with Ag70Cu30 target increased from 1.95 to 2.15 eV with the increase in substrate temperature from 303 to 523 K, respectively.