X-ray photoelectron spectroscopy study of chromium and magnesium doped copper ferrite thin film
Thiha Soe, Arthit Jityen, Teerakorn Kongkaew, Kittitat Subannajui, Asawin Sinsarp, Tanakorn Osotchan
Abstract
X-ray photoelectron spectroscopy (XPS) is a surface-sensitive quantitative spectroscopic technique that measures the elemental composition, empirical formula, chemical state and electronic state of the elements. Moreover, XPS is also widely used in semiconductor applications as the main characterization technique. In this work, chromium and magnesium doped copper ferrite thin films were prepared on the glass substrates by spin-coating technique at room temperature. The stoichiometry 1:2 ratio was used for copper (II) acetate monohydrate and iron (III) nitrate nonahydrate with different doping percentages from 5%, 10%, 15% to 20% of chromium and magnesium. After spin-coated, the films were annealed at 120°C, 200°C, 300°C and 400°C in air. The surface properties of the post-annealed thin films can be characterized by XPS technique due to their surface sensitivities. Therefore, the surface properties of different doped amounts of chromium and magnesium thin films were systematically investigated for different annealing temperatures. For varying anneal temperatures, the oxidation numbers of copper and iron ions were different. At low temperature, the oxidation number of copper was Cu+ and iron was a mixture of Fe2+ and Fe3+ while at high-temperature, the copper and iron ions showed Cu2+ and iron Fe3+ characteristics, respectively. After etching, the oxidation number of copper and iron ions at the surface shifted to lower oxidation state.