ZnO-In2O3-SnO2 Thin Film Transparent Heaters: Tunable Electrothermal Properties Through Substrate Temperature and Postgrowth Annealing

Abstract

Amorphous thin films of ZnO-In2O3-SnO2 (a-ZITO) were manufactured using magnetron sputtering technique for the applications of thin film transparent heaters (TFTHs). For this purpose, a custom-made 3” sputtering target was prepared with a specific composition in terms of the atomic percentages (at.%) of Zn, In, and Sn cations. The impact of varying substrate temperatures on the characteristics of the samples investigated by depositing the films on glass substrates maintained at room temperature, 150 °C, and 250 °C. To improve the optical and electrical properties, post-growth annealing was carried out under forming gas atmosphere at 400 °C. Structural, morphological, optical, and electrical properties of the samples were thoroughly examined. Electrothermal characterization was performed on samples at room temperature and -40 °C to evaluate response time, saturation temperature, thermal homogeneity, stability, recyclability, thermal resistance, and the defogging/deicing capability of the produced TFTHs. The films produced at 150 °C demonstrated an exceptional electrothermal response, with the thermal resistance calculated to be 181.7 °C·cm²/W under 12 V input. With a measured power density of 0.4635 Watt/cm², this heater was able to melt all ice and evaporate water droplets on the surface within 173 s, indicating a promising performance for commercial defogging/deicing applications.