Undoped and Sb‐doped rutile‐GeO2 single crystals of diameter up to 18 mm and length up to 25 mm were grown by the top‐seeded solution growth (TSSG) method using a K2CO3 + Na2CO3 solution and 001 growth direction. Epi‐ready wafers with (100), (001), (110), and (111) surface orientations, and sizes of 5 × 5 and 10 × 10 mm2 were prepared by chemical‐mechanical polishing. The full width at half maximum (FWHM) of the rocking curves for all orientations was confined between 13–26 arcsec, while the root mean square (RMS) roughness was between 100–150 pm. Wafer annealed in air at temperatures 600–900°C revealed that the RMS roughness could be further decreased to 70 pm for the (001) surface orientation. The prepared r‐GeO2 wafers are well suited for homo‐ and heteroepitaxial growth of r‐GeO2, as well as r‐GexSn1‐xO2 and r‐GeySi1‐yO2 films, respectively, and electronic power device fabrication.
Galazka et al. (Tue,) studied this question.