Structural, Electrical and Optical Behaviour of RF Magnetron Sputtered Nanocrystalline Silver Oxide Films: Bias Effect

Abstract

Nanocrystalline silver oxide thin films were deposited on glass substrates by RF magnetron sputtering of metallic silver target in an oxygen partial pressure of 2×10−2 Pa and at sputtering pressure of 4 Pa under different substrate bias voltages in the range from 0 to −60 V. Influence of bias voltage on the structure, morphological, electrical and optical properties of the silver oxide films was investigated. The unbiased films formed at room temperature showed the presence of (111) reflection of Ag2O. The films formed at substrate bias voltage of −30 V showed a strong (111) texture with large sized grains of Ag2O. At higher substrate voltage of −60 V the films showed a mixed phase of Ag2O and Ag. The crystallite size of the films increased from 5.3 to 18.2 nm with increase of substrate bias voltage from 0 to −30 V. The grain size of the films increased from 71 to 230 nm with the increase of substrate bias voltage from 0 to −30 V. The electrical resistivity of the Ag2O films decreased remarkably with increase of substrate bias voltage to −30 V. At an optimum substrate bias voltage of −30 V, the Ag2O films were nanocrystalline with electrical resistivity of 1.2×10−3 Ωcm and optical band gap of 2.20 eV.