In the process for growing single crystals including the steps of placing material in a crucible, heating the crucible to above the melting point of the material, and thereafter solidifying the melted material by extracting heat from a central portion of the bottom of the crucible, that improvement wherein the temperature of the side walls of the crucible is maintained at temperatures above the melting point of the material until substantially all the material within the crucible has been solidified.
A process that, without doping of PBN crucibles, produces semi-insulating GaAs having low, or essentially no, dislocation density; and in which the crystal may be in situ annealed after growth. The process is a variant of the Heat Exchanger Method (HEM) disclosed in U.S. Pat. No. 3,898,051. Crack-free, semi-insulating GaAs crystals having low dislocation density are grown from presynthesized undoped GaAs meltstock in sealed quartz (vitreous silica) crucibles, without the need for an encapsulant. One aspect of the invention features seeded growth of <100> orientation crystals having a dislocation density 1-2 orders of magnitude less than that of the seed; in another aspect, crystals having fewer than 500 dislocations/cam.sup.2 in their center column are grown without a seed.
An apparatus for growing a silicon ingot including a graphite crucible in which a quartz crucible is placed, a driving axis connected to a lower part of the graphite crucible to revolve and move the graphite crucible up and down so as to support the graphite crucible, a heating element to heat the graphite crucible, and an insulating wall to protect and thermally isolate the graphite crucible, heating means, and driving axis in part from the external environment. The driving axis includes a hollow axis part having a hollow inside, an insulating axis part attached to the bottom of the hollow axis part to inhibit heat transfer, and a cylindrical axis part attached to the bottom of the insulating axis part. The construction of the driving axis reduces a temperature gradient in the molten silicon, improving uniform heat distribution for increased silicon ingot quality.
The invention relates to the growth of nickel manganese oxide monocrystals having a cubic spinel geometry. Methods of their growth and sensors constructed with same are also described.
A method is provided to liquify and then freeze a crystallizable stoichiometric compound so that a large well defined interface between simultaneous liquid and solid phases moves at a preprogrammed rate through the compound without moving the compound or the vessel in which it is contained.
The invention provides a method for growth of single crystals from the melt by directional solidification in vertical bottom seeded crucibles. The crucible confining the melt is insulated radially and from above. The heat is supplied to the melt by a heater submerged in the melt or an auxiliary heater above the crucible containing the melt. A small portion of the melt is enclosed between the submerged heater and the growing crystal. The confined melt in this region is thermally stratified and therefore stagnant.
