Influence of post‐deposition annealing on electrical and optical properties of ZnO‐based TCOs deposited at room temperature

Abstract

The post‐deposition modification of ZnO‐based transparent conductive oxides (TCOs) can be the key to produce thin films with optoelectronic properties similar to indium tin oxide (ITO), but at a much lower cost. Here, we present electro‐optical results achieved for post‐deposition annealing of Al–Zn–O (AZO), AZO:H, Ga–Zn–O:H (GZO:H), and Zn–O:H (ZNO:H) thin films deposited by RF sputtering at room temperature. These studies comprise results of thermal annealing at atmospheric pressure, vacuum, forming gas, H2 and Ar atmospheres, and H2 and Ar plasmas, which lead to significant enhancement of their electro‐optical properties, which are correlated to morphological and structural improvements. The post‐deposition annealing leads to an enhancement in resistivity above 40% for AZO, AZO:H, and GZO:H, reaching ρ ≈ 2.6–3.5 × 10−4 Ωcm, while ZnO:H showed a lower improvement of 13%. The averaged optical transmittance in the visible region is about 89% for the investigated TCOs. Such results match the properties of state‐of‐art ITO (ρ ≈ 10−4 Ωcm and transmittance in VIS range of 90%) employing much more earth‐abundant materials.