Growth and crystallinity of shaped and multiple sapphire crystals by a micro-pulling-down method
We developed a growth technique of shape-controlled and multiple crystals by a micro-pulling-down (μ-PD) method using a developed special configuration crucible. A square tube-shaped sapphire crystal was grown with a molybdenum crucible with square tube die of 4mm×4mm outer periphery and 2mm×2mm inner periphery on the bottom. In contrast, six multiple square-shaped sapphire crystals were simultaneously grown by a molybdenum crucible with six circularly arranged square-shaped dies with a size of 2×2mm2 on the bottom. Growth of six multiple square-shaped sapphire crystals indicated a single phase of α-Al2O3 and almost same lattice parameters by X-ray diffraction measurement. Crystallinities of the six crystals were high in all positions of crystals comparable to the crystals grown by the Czochralski method.