We have demonstrated that electron and vacancies can mediate the thermal conductivity of Dy doped CdO. More specifically, our results suggest that the enhancement in thermal conductivity in CdO at low Dy concentrations is dominated by an increase in the electron mobility due to a decrease in oxygen vacancy concentration. Furthermore, we find that at intermediate doping concentrations, the subsequent decrease in thermal conductivity can be ascribed to a large reduction in phononic thermal transport due to both point defect and cation- vacancy scattering. With these results, we gain insight into the complex dynamics driving phonon scattering and resulting thermal transport in functional oxides. This work, in which Brian Donovan was the first author, was recently published in Applied Physics Letters (Applied Physics Letters 108, 021901 (2016)), and was in collaboration with Professor J.P. Maria’s group at N.C. State University.
We appreciate the funding from the Office of Naval Research under Grant No. N00014-15-12769.
Abstract
Understanding the impact and complex interaction of thermal carrier scattering centers in functional oxide systems is critical to their progress and application. In this work, we study the interplay among electron and phonon thermal transport, mass-impurity scattering, and phonon- vacancy interactions on the thermal conductivity of cadmium oxide. We use time domain thermore- flectance to measure the thermal conductivity of a set of CdO thin films doped with Dy up to the saturation limit. Using measurements at room temperature and 80 K, our results suggest that the enhancement in thermal conductivity at low Dy concentrations is dominated by an increase in the electron mobility due to a decrease in oxygen vacancy concentration. Furthermore, we find that at intermediate doping concentrations, the subsequent decrease in thermal conductivity can be ascribed to a large reduction in phononic thermal transport due to both point defect and cation- vacancy scattering. With these results, we gain insight into the complex dynamics driving phonon scattering and resulting thermal transport in functional oxides.
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