Inverse thermal anisotropy in CdMgO measured using photothermal infrared radiometry and thermoreflectance

This study elucidates the intriguing phenomenon of inverse thermal anisotropy in cadmium magnesium oxide (CdMgO) thin films, characterized by cross-plane thermal conductivity being greater than in-plane thermal conductivity, essential for optimizing thermal management in next-generation optoelectronic devices. Herein, we utilized Photothermal Radiometry and Frequency Domain Thermoreflectance to precisely determine the thermal conductivity and diffusivity across various concentrations of magnesium in CdMgO alloys, thereby providing essential insights into thermophysical behavior. Atomic force microscopy and X-ray diffraction revealed a direct correlation between increasing magnesium content and progressive structural evolution within plasma-assisted molecular beam epitaxy-derived CdMgO alloys. Furthermore, heat transport mechanism, analyzed using Callaway and Abeles models, indicated key phonon interactions. This comprehensive investigation provides a framework for the precise control of CdMgO thin film thermal properties, paving the way for scalable fabrication strategies to optimize performance in high-power thermal management applications.