Ultrasmooth Mg-Doped CuCrO2 Thin Films: Optimizing Thermoelectric Performance for Energy Harvesting

초록

Driven by the need for sustainable energy harvesting, this study advances thermoelectric (TE) materials by depositing CuCr1-xMgxO2 (0.03 <= x <= 0.15) thin films with ultralow surface roughness via DC magnetron sputtering. Precise Mg doping critically influences the film's phase composition and crystal structure, controlling the formation/proportions of phases such as CuCrO2, CuO, Cu2O, and MgCr2O4. This optimization yields a record-low root-mean square roughness of 0.26 nm (10 mu m2 area) for 5 at% Mg-doped CuCrO2 thin films (approximate to 150 nm thickness), surpassing prior CuCrO2-based thin films. This smoothness reduces "trap" states, minimizing charge carrier scattering and activation energy, thereby boosting electrical conductivity. The Mg-doped film with x = 0.05 exhibits a high power factor of 120 mu W m-1 K-2 at 125 degrees C, outperforming comparable materials prepared using similar methods and measured at similar temperatures by a factor of 2-3, making it a promising candidate for TE devices. Furthermore, this work identifies the ideal Mg content and interstitial oxygen defect levels required to maximize the TE performance of Mg-doped CuCrO2 thin films. These findings illuminate a scalable route to high-performance TE materials with potential for energy harvesting, sensing, and beyond, advancing the design of multifunctional oxides.

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