Tunable Density-of-States in Chromium Oxide Thin Films via Room Temperature Laser Ablation

Chromium oxide thin films were deposited at room temperature, via reactive laser ablation under varying O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> pressures and analyzed using in-situ X-ray Photoelectron Spectroscopy. Cr 2p spectra exhibited spin-orbit splitting, with peak separations ranging from 9.2 to 9.5 eV. Cr<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup>,Cr<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4+</sup> and Cr<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6+</sup> states were identified, with 2p<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3/2</sub> binding energies between 576.8 and 582.5 eV. Quantitative analysis confirmed that lower O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> pressures favored Cr<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> growth, while higher pressures promoted CrO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>. Near-Fermi-level spectra revealed significant Density-Of-States modulation, with the Valence Band Maximum shifting from 1.25 to 3.3 eV. A direct correlation between O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> pressure and electronic structure was established.