Insight into structural and electronic properties of low cost oxygen-deficient alumina films

Abstract

Current trends in materials science are focused on two main branches: lowering costs and enhancing performance. A new, cost-efficient synthesis of the sol-gel-based spin-coat fabrication of oxygen-deficient alumina thin films is presented, achieving Al/O molar ratio of approximately 1.0. This technology produces approximately 50 nm-thick smooth layers even at low spin rates, reducing manufacturing costs while maintaining high-quality layers. Moreover, the spin rate is shown to control grain size (c.a. 2 nm) effectively, influencing the surface topography, as well as the chemical and electronic properties of the layers. The analysis of the above properties was done by mutually comprehensive experimental techniques: photoelectron spectroscopies in UV and X range, as well as atomic force microscopy and spectroscopic ellipsometry. The XPS data were cross-checked with density functional theory calculations to ensure accurate interpretation. Oxygen vacancies were identified as crucial in tuning the electronic structure, highlighting their importance for wide-bandgap semiconductor applications.