Effect of sputtering pressure on structural and optical properties of silver oxide thin films; Kramers–Kronig method

Abstract

Silver oxide nano layers were prepared by RF magnetron sputtering on amorphous SiO2 substrates. O2 pressure in chamber was varied from 1 to 4 and 7 mTorr during growth process. The effects of different O2 pressure on structural, morphological and optical properties of the films were investigated by means of X-ray diffraction, scanning electron microscopy, atomic force microscopy and UV–Vis spectroscopy analyses. Optical reflectance measured in the wavelength of 350–950 nm by spectroscopy. Other optical properties and optical band gaps were calculated using Kramers–Kronig relations. The X-ray diffraction measurements showed change in crystalline structure with increasing O2 pressure. Preferred orientation has been changed to another growth orientation at 4 mTorr O2 pressure. The Atomic force microscope images showed increasing in roughness consistently by increasing oxygen pressure. The thickness of the thin films decreases (from 217 to 180 nm) with increasing O2 pressure. Optical results revealed that the highest optical band gap of 3.1 eV and the highest transmittance of ~ 80% were achieved at lower O2 pressure (1 mTorr).