Thermal conductivity of yttria-stabilized zirconia thin films grown by plasma-enhanced atomic layer deposition |
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Authors: | Sung Il Park Byung Chan Yang Jihyun Kim Jaeyoon Ko Gyung-Min Choi Jihwan An Jungwan Cho |
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Affiliation: | 1. School of Mechanical Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do, Republic of Korea;2. Department of Nano-IT Fusion Engineering, Seoul National University of Science and Technology, Seoul, Republic of Korea;3. Department of Energy Science, Sungkyunkwan University, Suwon, Gyeonggi-do, Republic of Korea;4. Department of Manufacturing Systems and Design Engineering, Seoul National University of Science and Technology, Seoul, Republic of Korea |
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Abstract: | Zirconia doped with yttrium, widely known as yttria-stabilized zirconia (YSZ), has found recent applications in advanced electronic and energy devices, particularly when deposited in thin film form by atomic layer deposition (ALD). Although ample studies reported the thermal conductivity of YSZ films and coatings, these data were typically limited to Y2O3 concentrations around 8 mol% and thicknesses greater than 1 μm, which were primarily targeted for thermal barrier coating applications. Here, we present the first experimental report of the thermal conductivity of YSZ thin films (∼50 nm), deposited by plasma-enhanced ALD (PEALD), with variable Y2O3 content (0–36.9 mol%). Time-domain thermoreflectance measures the effective thermal conductivity of the film and its interfaces, independently confirmed with frequency-domain thermoreflectance. The effective thermal conductivity decreases from 1.85 to 1.22 W m−1 K−1 with increasing Y2O3 doping concentration from 0 to 7.7 mol%, predominantly due to increased phonon scattering by oxygen vacancies, and exhibits relatively weak concentration dependence above 7.7 mol%. The effective thermal conductivities of our PEALD YSZ films are higher by ∼15%–128% than those reported previously for thermal ALD YSZ films with similar composition. We attribute this to the relatively larger grain sizes (∼23–27 nm) of our films. |
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Keywords: | Doping Plasma-enhanced atomic layer deposition (PEALD) Thermal conductivity Thermoreflectance Yttria-stabilized zirconia (YSZ) |
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