The Thermal Conductivity Tensor of β-Ga2O3 from 300 to 1275 K

Abstract

Laser-flash measurements of the thermal conductivity (Formula presented.) of Czochralski-grown β-Ga2O3 single crystals are reported perpendicular to four independent crystallographic lattice planes (Formula presented.), (010), (001), and (100) between room temperature and 1200 K. λ is represented by a symmetric tensor of rank 2 and has four independent components. Tensor components (Formula presented.) W m−1 K−1 and (Formula presented.) W m−1 K−1 (values for 300 K) can be directly measured. (Formula presented.) W m−1 K−1 and (Formula presented.) W m−1 K−1, instead, are obtained by combining (Formula presented.) W m−1 K and (Formula presented.) W m−1 K. The crystallographic (Formula presented.) -axis is the direction with the highest thermal conductivity, λ22. The thermal conductivity assumes its lowest value (11.73 W m−1 K−1) in a direction close to the crystallographic (Formula presented.) -axis. However, this direction does not coincide with (Formula presented.), and changes with temperature.