Ellipsometry, transmission, and photoluminescence characterization of Mn-doped ITO thin films deposited by DC magnetron sputtering

Abstract

Manganese-doped indium tin oxide (ITO) thin films (0–12.8 at% Mn) were deposited by DC magnetron sputtering. The structural, electrical, and optical properties of the films were studied. Optical characterization was emphasized and included ellipsometry, transmission, and photoluminescence (PL) measurements. Features of the energy band structure of ITO and Mn-ITO were extracted from PL spectra and Tauc analyses of absorption data. We concluded that the fundamental bandgap of ITO is ∼2.8 eV. A separate deep valence band, ∼0.8 eV below the valence band maximum, was confirmed to be involved in higher energy optical absorption and emission transitions. Both of these observations were consistent with recent published theoretical studies and spectroscopic measurements (XPS, XES, etc). Mn addition was found to result in a decrease of the transition energies. Additionally, Burstein–Moss shifts were observed.