Tailoring Structural, Optical, and Electrical Properties of ITO Thin Films via Thickness Control, Reactive Nitrogen, and Thermal Annealing

In this study, indium tin oxide (ITO) and nitrogen-incorporated ITO (ITON) thin films with thicknesses of 57, 116, and 173 nm were deposited on glass substrates using DC magnetron sputtering. The effects of nitrogen incorporation, film thickness, and thermal annealing on the structural, optical, and electrical properties were investigated. X-ray diffraction (XRD) analysis revealed that ITON exhibited partial crystallization in the as-deposited state and influenced the preferred crystal orientation after annealing, with ITO favoring (400) and ITON favoring (222). Both materials demonstrated high optical transparency (>70%) in the visible range, with ITON exhibiting higher transmittance, particularly at thickness of 173 nm (84.79% after annealing). The optical bandgap decreased with increasing thickness but increased after annealing, with ITON maintaining consistently higher values. Electrical measures indicated a thickness-dependent resistivity trend. Un-annealed ITO showed a systematic sheet resistance decrease from 546.4 to 255.83 Ω/square, whereas annealed ITO exhibited a minimum sheet resistance of 208.5 Ω/square at 173 nm. ITON films initially displayed unmeasurable sheet resistance at lower thicknesses, but after annealing, sheet resistance decreased systematically from 1789.0 to 447.23 Ω/square. Despite the low nitrogen concentration (0.01%), its incorporation significantly influenced the structural and electrical properties of the films. These findings provide insights into optimizing ITON thin films for advanced optoelectronic applications.