Low-Temperature Fabrication of Highly Transparent Zr-Doped In2O3 Thin Films by Pulsed Laser Deposition

The In ₂ O ₃ and Zr-doped In ₂ O ₃ transparent nanostructured films were made by depositing the materials on glass using Pulsed Laser Deposition (PLD) at ambient temperature and then annealing them at 250°C. Three compositions were investigated: undoped In ₂ O ₃ (F1), In ₂ O ₃ : 2 at. % Zr (F2), and In ₂ O ₃ : 5 at.% Zr (F3). XRD patterns confirmed the formation of nanocrystalline bixbyite In2O3 with broadened peaks, indicating limited crystallinity. The size of the crystallites varied from 10.3 nm (F1) to 11.77 nm (F2) and then down to 9.69 nm (F3) as a result of lattice strain at increasing doping levels. FESEM images revealed uniform, compact, crack free surfaces composed of closely packed nanograins, with improved grain connectivity at 2% Zr. Optical measurements showed a gradual reduction in absorbance and absorption coefficient with increasing Zr content, indicating enhanced transparency in the visible region. The tauc analysis revealed a blue shift of the absorption edge and an increase of the optical band gap from approximately 2.9 eV (F1) to 3.0 eV (F2) and 3.1 eV (F3), all of which can be accounted for by the Burstein Moss effect. The film thickness was estimated to be within 200–230 nm. These results indicate that moderate Zr doping (2%) optimizes the balance between crystallinity, morphology, and optical transparency, making these films promising for transparent conducting oxide and optoelectronic applications compatible with low temperature glass processing.