Thermal conductivity and Seebeck coefficients of icosahedral boron arsenide films on silicon carbide

The thermal conductivity of icosahedral boron arsenide (B12 As₂) films grown on (0001) 6H-SiC substrates by chemical vapor deposition was studied by the 3ω technique. The room temperature thermal conductivity decreased from 27.0 to 15.3 W/m K as the growth temperature was decreased from 1450 to 1275 °C. This is mainly attributed to the differences in the impurity concentration and microstructure, determined from secondary ion mass spectrometry and high resolution transmission electron microscopy, respectively. Callaway's theory was applied to calculate the temperature-dependent thermal conductivity, and the results are in good agreement with the experimental data. Seebeck coefficients were determined as 107 μV/K and 136 μV/K for samples grown at 1350 °C with AsH₃ / B₂ H₆ flow ratio equals to 1:1 and 3:5, respectively.