Processing optimization of SiO2-capped aluminum-doped ZnO and amorphous In-Zn-Sn-Oxide thin films for transparent heater and near-infrared reflecting applications

Can, Hilal Aybike
In this study, AZO/SiO2 and amorphous In-Zn-Sn-oxide (a-ZITO) functional coatings were developed with combinatorial approach for transparent heater and heat reflecting applications. AZO/SiO2 and amorphous In-Zn-Sn-oxide (a-ZITO) coatings were obtained via magnetron sputtering. A series of optimization steps were carried out specific to each method and coating type. The samples were produced on 75x50 mm2 glass substrates. Further, optimum post-deposition annealing conditions were identified as 400 °C and Ar+%4 H2 atmosphere to improve electrothermal properties. 750 nm thick and polycrystalline AZO/SiO2 coatings displayed impressive room-temperature electrical conductivity of nearly 3774 S/cm with a sheet resistance of 3.53 Ω/□, carrier concentration of 1.14x1021 cm-3, and Hall mobility of 20.48 cm2/Vs. These films exhibited very high optical transmittance (96%) in the visible range and reflectance (73% at 2.5 µm) in the NIR region. Electrothermal tests demonstrated that the achievable saturation temperature was 161 °C with a power density of 5981 W/m2 in case of applying 12 V. Deicing tests were performed with samples cooled to -40 °C and resulted with complete removal of ice/water only within 180 s. a-ZITO coatings were deposited using a 3” sputtering target on substrates held at 150 °C. This target was prepared within a particular oxide composition which was determined via combinatorial approach. The films were remained amorphous after the annealing step and demonstrated room-temperature electrical conductivity of 1805 S/cm, sheet resistance of 7.49 Ω/□, carrier concentration of 0.3x1021 cm-3, and Hall mobility of 36.59 cm2/Vs. The transmission in the visible range and reflectance at 2.5 µm were measured as 86% and 35%, respectively. a-ZITO coating was displayed a saturation temperature of 112 °C and a power density of 4635 W/m2 whereas defrosting within 173 s (initial temperature -40 °C) was observed with 12 V input.


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Citation Formats
H. A. Can, “Processing optimization of SiO2-capped aluminum-doped ZnO and amorphous In-Zn-Sn-Oxide thin films for transparent heater and near-infrared reflecting applications,” M.S. - Master of Science, Middle East Technical University, 2022.