X-ray diffraction and Raman characterization of β-Ga2O3 single crystal grown by edge-defined film-fed growth method
Yongzhao Yao, Yukari Ishikawa, and Yoshihiro Sugawara
Journal of Applied Physics 126, 205106 (2019); https://doi.org/10.1063/1.5129226
The crystallinity and wafer uniformity of (2¯01) and (010) oriented β-Ga2O3 substrates grown by edge-defined film-fed growth (EFG) were investigated by laboratory X-ray diffraction (XRD), synchrotron XRD, polarized Raman spectroscopy, and Raman mapping. XRD results indicated that the EFG substrates had superior crystallinity and high uniformity. Position-dependent XRD ω-rocking curves recorded across a 50.8-mm-diameter substrate had small standard deviations of δF = 1.6% for the full width at half maximum and δP = 2.8% for the peak intensity. The radius of curvature was measured to be 37.7 m for the (2¯01) substrate and 16.4 m for the (010) substrate. The results of synchrotron XRD with various beam sizes suggested that the curving of crystal planes was mainly along the  growth direction rather than along the  direction. Raman spectra showed that Sn doping up to 3.3 × 1018 cm−3 did not give rise to a notable Raman peak shift. The strain distribution evaluated by Raman mapping implied the high uniformity of both (2¯01) and (010) substrates. From these results, it was concluded that β-Ga2O3 ingots grown by EFG have high crystallinity and can be treated as three-dimensionally uniform bulk crystals in the cases of both undoped and Sn-doped growth.
Gallium oxide, crystalline structure, edge-defined film-fed growth, semi-conductor