Bulk Rutile‐GeO 2 Single Crystals and Epi‐Ready Wafers

ABSTRACT Undoped and Sb‐doped rutile‐GeO 2 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 K 2 CO 3 + Na 2 CO 3 solution and [001] growth direction. Epi‐ready wafers with (100), (001), (110), and (111) surface orientations, and sizes of 5 × 5 and 10 × 10 mm 2 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‐GeO 2 wafers are well suited for homo‐ and heteroepitaxial growth of r‐GeO 2 , as well as r‐Ge x Sn 1‐x O 2 and r‐Ge y Si 1‐y O 2 films, respectively, and electronic power device fabrication.