HYDROTHERMAL CRYSTAL GROWING PROCESS AND APPARATUS

摘要

Large single crystals of berlinite are grown onto seed crystals by maintaining the crystals at a fixed elevated temperatutre in a pressure vessel containing a nutrient of coarse berlinite crystalline powder, held at a fixed lower temperature, and concentrated phosphoric acid. Because berlinite shows retrograde solubility, the nutrient goes into solution, and berlinite deposits on the higher-temperature growing crystal. The vessel is rocked to promote motion of saturated solution to the crystal and depleted solution to the nutrient. Large single crystals of alpha-gallium orthophoshate may be grown using the same apparatus and a similar process. The resultant crystals may be cut into wafers useful in surface acoustic wave devices.