Electrical and optical properties of (In_1-xSn_x)₂O_3(1+δ) films (0.03 ≤ x ≤ 0.40, δ ≈ 0.28) grown on Si substrates using co-sputtering of In₂O₃ and SnO₂

Sn-doped In₂O₃ (ITO) films are in high demand for use as transparent electrodes in optoelectronic devices. Technological developments have improved the quality of ITO films, and a detailed investigation of their properties is desired. Therefore, we investigated the composition dependence of the electrical and optical properties of (In_1-xSn_x)₂O_3(1+δ) films (with 0.03 ≤ x ≤ 0.40 and δ ≈ 0.28) films grown on Si and glass substrates utilizing the co-sputtering of In₂O₃ and SnO₂ targets. Using X-ray diffraction, we found that the In₂O₃-like (222) phase was the dominant phase for x = 0.03. Further, the In₂Sn₂O_7+x (400) phase became the dominant phase as the Sn concentration increased. This work demonstrates that ITO films exhibit excellent transmittance properties (T ≈ 88.3%) in the visible range as well as very low resistivities (ρ ≈ 2 × 10⁻⁴ Ω cm), regardless of the Sn composition. However, ITO films with Sn = 0.11, the commercially used composition, exhibited the lowest transmittance in the near-infrared range, 73.7%, whereas other ITO films showed large transmittances in the near-infrared range: T = 90.9% at x = 0.03 and T = 85.7% at x = 0.40.