Study on the technical improvement and the crystalline quality optimization of columnar β-Ga2O3 crystal growth by EFG method

High quality columnar β-Ga2O3 crystals have been successfully grown by edge-defined film-fed growth (EFG) method equipped with columnar Ir die. The effects of pulling rate and die height on the structural quality and crystal shape of β-Ga2O3 were summarized and discussed detailedly. The main problems of spiral, polycrystal and Incompletely columnar in the β-Ga2O3 crystal growth were solved successfully. The suitable growth parameters were detemined to be that the pulling rate and Ir height at range from 2-10 mm/h and 30-40 mm (0.6-0.8 longer than crucible height), respectively. At the same time, the die diameter should be 25mm (0.5 wider than crucible diameter) , to get good quality of the columnar β-Ga2O3. Furthermore, the crystalline quality of the as-grown crystal has been confirmed by high-resolution X-ray diffraction (HRXRD) with a full-width at half-maximum (FWHM) of 69.3 arcsec. The defects of β-Ga2O3 were studied by chemical etching method. Two types of etch pits: (1) triangle-shaped etch pit, and (2) quadrangle-shaped etch pit were observed. The average defect density was estimated at a lower order of magnitude -104cm−2.