Coefficients of thermal expansion of single crystalline β-Ga2O3 and in-plane thermal strain calculations of various materials combinations with β-Ga2O3

The coefficients of thermal expansion (CTEs) of single crystalline, monoclinic β-Ga2O3 were determined by employing high-resolution X-ray diffraction measurements. This work reports the CTE measurements on a single crystalline β-Ga2O3 substrate. The CTE values along the “a,” “b,” and “c” axes are 3.77 × 10−6 °C−1, 7.80 × 10−6 °C−1, and 6.34 × 10−6 °C−1, respectively, and the CTE of the angle β (the angle between the “a” and “c” axes) is determined to be 1.31 × 10−4 ° K−1. All CTE values reported here are linear under the temperature regime between room temperature and 1000 °C. All measurements were performed in a controlled nitrogen gas environment, and no surface degradation was observed after these measurements. Thermal strain calculations with different material combinations involving β-Ga2O3 are also presented relevant to both epitaxial and wafer bonding applications for Si, InP, 3C–SiC, 6H–SiC, GaN, and sapphire.