Thin strip crystals are grown by pulling the growing crystal from the melt, through a thin slit, the walls of which are not wetted by the melt. The stability of growth at the edges of the strip is achieved by maintaining the pressure of the melt adjacent the interface between crystal and melt above a critical level which is such as to cause the meniscus of the melt to be convex on all sides of the growing crystal. The critical pressure is defined as where S is the surface tension of the crystallizable material b is the thickness of the slit z is the density of the melt g is the acceleration due to gravity; and the depth of the slit is at least (2S/zg).sup.1/2, preferably (32S/zg).sup.1/2 to ensure that a pressure exceeding the critical pressure can be developed and maintained without the liquid spilling out of the slit. The walls of the slit can be parallel or divergent in the direction in which the crystal is pulled, this divergence being necessary with certain materials. An arrangement is disclosed containing a head of the melt for creating the required pressure. An alternative arrangement is disclosed in which actuating devices, such as hydraulic piston and cylinder arrangements, create the pressure.
An apparatus and method pulling a shaped crystalline fiber of a given crystal-forming material from a liquid reservoir of the material. The apparatus includes a vessel in which the liquid material is maintained as a liquid reservoir at a temperature above the melting point or crystal-forming temperature of the material. A die is provided having an inner-tubular surface which includes a crystal shaping portion which is tapered. The liquid flows from the reservoir through the die so that the liquid flows from the narrow end of the shaping portion to the wide end of the shaping portion. The temperature of the liquid crystal growth material is selectively lowered at the top end of the die to form crystalline material which is continually pulled from the crystal-liquid interface. The apparatus is operated to maintain the crystal-liquid interface within the crystal shaping portion of the die to provide accurate shaping of the crystal by the tubular surface and to maintain accurate alignment of the crystal fiber with the die.
According to the present invention, in the growth of an oxide single crystal or a compound semiconductor single crystal such as GaAs single crystal by the CZ method or LEC method, the tendency of concave solid-liquid interface shape at the periphery of the growing crystal can be suppressed to prevent polycrystallization without localized heating of the solid-liquid interface, while controlling the diameter of the growing crystal even when using a crucible with a larger diameter, thus improving the yield of crystal on a commercial scale. In the invention, the end of a cylindrical body having an inner diameter of larger than the predetermined diameter of straight part of the growing crystal is immersed in the raw material melt or liquid encapsulant and the crystal is pulled while preventing the shape of the solid-liquid interface from becoming concave by controlling the rotation rate of at least one of a crucible holding the raw material melt, the growing crystal and cylindrical body.
A process is disclosed for continuously producing a single crystal by drawing downwardly a melt of a single crystal raw material, wherein a single crystal body grown from the melt is continuously pulled downwardly, and a plurality of single crystal products are continuously formed by intermittently cutting the single crystal body being downwardly moved.
This invention involves a method and apparatus for drawing crystalline bodies from a melt by means of an open-ended drawing nozzle which determines the cross-sectional geometry of the crystalline body. The drawing nozzle is composed of a material which is resistant to the melt. The feed of melt proceeds from a reservoir situated at the lower end of the drawing nozzle and the melt is conveyed to the upper opening thereof by capillary action. In keeping with the present invention, there is provided a drawing nozzle which has an upper opening merging into a contoured surface such that the meniscus formed at the interface between the crystalline and molten phases is freely displaceable on the contoured surface into which the upper opening discharges.
According to the present invention, in the growth of an oxide single crystal or a compound semiconductor single crystal such as GaAs single crystal by the CZ method or LEC method, the tendency of concave solid-liquid interface shape at the periphery of the growing crystal can be suppressed to prevent polycrystallization without localized heating of the solid-liquid interface, while controlling the diameter of the growing crystal even when using a crucible with a larger diameter, thus improving the yield of crystal on a commercial scale. In the invention, the end of a cylindrical body having an inner diameter of larger than the predetermined diameter of straight part of the growing crystal is immersed in the raw material melt or liquid encapsulant and the crystal is pulled while preventing the shape of the solid-liquid interface from becoming concave by controlling the rotation rate of at least one of a crucible holding the raw material melt, the growing crystal and cylindrical body.
