High-temperature thermal expansion of ScAlMgO4 for substrate application of GaN and ZnO epitaxial growth

High-temperature powder X-ray diffraction measurements for ScAlMgO 4 ( in space group) grown by Czochralski method were carried out from 303 to 1473 K. The obtained temperature-dependent unit cell parameters were expressed as for the a -axis and for the c -axis, where T is temperature in kelvin. The axial thermal expansion coefficients for the a -axis estimated from the unit cell parameters were comparable to those of GaN and ZnO. A c -plane ScAlMgO 4 substrate can be easily obtained with using cleavage plane along c -plane, which is parallel to a -axis. Thus, ScAlMgO 4 is one of the promising substrates for c -plane epitaxial growth of GaN and ZnO. High temperature X-ray single crystal structural analysis of ScAlMgO 4 demonstrated the mechanism of the nonlinear variation of the obtained cell parameters as a function of temperature.