Patent ID: 8512470

Claim:
A method of growing high-resistivity single crystals, comprising: placing a raw material in a vacuum-sealable ampoule, wherein the raw material comprises polycrystalline Group III-V material, Group II-VI material, or Group IV material, wherein the raw material comprises moisture and impurities that include oxide compounds and carbon; capping an open end of the vacuum-sealable ampoule while leaving an air channel between the cap and the rim of the open end of the vacuum-sealable ampoule, wherein the cap includes a bulb connected to the opening of the cap with a neck; heating the raw material in the vacuum-sealable ampoule to vaporize the moisture in the raw material; exhausting the vaporized moisture from the vacuum-sealable ampoule; fusing the cap to the rim of the open end of the vacuum-sealable ampoule to vacuum seal the vacuum-sealable ampoule; heating the raw material in the vacuum-sealable ampoule to vaporize the oxide compounds in the raw material; cooling at least a portion of the bulb to produce condensed oxide compounds on an inner surface of the bulb; fusing the neck of the bulb to isolate the condensed oxide compounds from the vacuum-sealable ampoule; breaking the neck to remove the bulb and the condensed oxide compounds from the vacuum-sealable ampoule; and placing the vacuum-sealable ampoule comprising the raw material in a crystal growth apparatus to grow a high-resistivity crystal from the raw material.