Abstract: The purpose of diffusion assisted crystal hydrothermal growth is to facilitate a greatly increased crystal growth rate that would save time that is precious in such a material and manpower costly process. The assisted crystal growth itself requires the utilization of a piezoelectric shaker connected to the autoclave in which most industrial hydrothermal crystals are grown. The waveform can be modulated to induce transport of nutrient in a singular direction, customized to the topology of the apparatus. As it stands currently, the growth of most crystals that require autoclaves for their production can take anywhere from 3 months to up to 2 years, and accordingly carries many costs, particularly electricity and supervision of the autoclave(s), and other issues that may arise during the growth. While the product of this labor results in high-quality crystals, in reality, these are not at all what is needed outside of the laboratory environment.

Abstract: An apparatus for processing materials at high temperatures comprises a high strength enclosure; a plurality of high strength radial segments disposed adjacent to and radially inward from the high strength enclosure; a liner disposed adjacent to and radially inward from the radical segments; a chamber defined interior to the liner; a heating device disposed within the chamber; and a capsule disposed within the chamber, the capsule configured to hold a supercritical fluid. The apparatus may be used for growing crystals, e.g., GaN, under high temperature and pressure conditions.

Abstract: An earth-boring tool includes a cutting element comprising a hard material and at least one of a signal generator configured to provide an electromagnetic or acoustic signal to an interface between a surface of the hard material and a surface of a subterranean formation, and a sensor configured to receive an electromagnetic or acoustic signal from the interface. A method of forming a wellbore includes rotating the earth-boring tool within a wellbore and cutting formation material with a cutting element, transmitting a signal through the cutting element to an interface between the cutting element and the formation material, and measuring a response received at a sensor. A cutting element includes a transmitter oriented and configured to dispense a signal to an interface between the cutting surface and a surface of a formation and a sensor oriented and configured to measure a signal from the interface.

Abstract: Provided is a high-pressure reactor suitable for a high-pressure process using supercritical ammonia grow bulk crystal of group III nitride having lateral dimension larger than 2 inches or to form various transition metal nitrides. The reactor has nutrient distributed along the reactor's longitudinal axis and seed material positioned at the reactor's inner wall and along the reactor's longitudinal axis. Nutrient diffuses through supercritical ammonia from the reactor's longitudinal axis and deposits on the seed material positioned by the reactor's inner wall. Both the nutrient and seed material are heated by the same heater. Material growth can primarily be due to material diffusion through supercritical ammonia. This configuration and methodology reduce convective movement of supercritical ammonia due to temperature differential, providing a more quiescent environment in which group III nitride or transition metal nitride is formed.

Abstract: A method of growing high-quality, group-III nitride, bulk single crystals. The group III-nitride bulk crystal is grown in an autoclave in supercritical ammonia using a source material or nutrient that is a group III-nitride polycrystals or group-III metal having a grain size of at least 10 microns or more and a seed crystal that is a group-III nitride single crystal. The group III-nitride polycrystals may be recycled from previous ammonothermal process after annealing in reducing gas at more then 600° C. The autoclave may include an internal chamber that is filled with ammonia, wherein the ammonia is released from the internal chamber into the autoclave when the ammonia attains a supercritical state after the heating of the autoclave, such that convection of the supercritical ammonia transfers source materials and deposits the transferred source materials onto seed crystals, but undissolved particles of the source materials are prevented from being transferred and deposited on the seed crystals.

Abstract: A multi-layer structure in a reaction cell for a diamond growth is provided. The multi-layer structure includes: a diamond seed; a first metal catalyst layer provided on the diamond seed, the first metal catalyst layer containing a first concentration of carbon; a second metal catalyst layer provided on the first metal layer, the second metal catalyst layer containing a second concentration of carbon that is higher than the first concentration; and a carbon source layer provided on the second metal layer.

Abstract: An apparatus for processing materials at high temperatures comprises a high strength enclosure; a plurality of high strength radial segments disposed adjacent to and radially inward from the high strength enclosure; a liner disposed adjacent to and radially inward from the radical segments; a chamber defined interior to the liner; a heating device disposed within the chamber; and a capsule disposed within the chamber, the capsule configured to hold a supercritical fluid. The apparatus may be used for growing crystals, e.g., GaN, under high temperature and pressure conditions.

Abstract: The apparatus has a crucible for storing a solution; an inner container for storing a crucible; a heating container for storing the inner container, the heating container including heating elements, a container body provided with the heating elements and a lid combined with the container body; and a pressure vessel for storing the heating container and for charging an atmosphere comprising at least nitrogen gas. The lid also has a fitting surface to the container body that is inclined to a horizontal plane.

Abstract: There is provided a novel method for producing a nitride single crystal with both a rapid crystal growth rate and high crystal quality, as well as a novel autoclave that can be used in the method. The invention provides a method for producing a Ga-containing nitride single crystal by an ammonothermal method, comprising introducing at least a starting material, an acidic mineralizer and ammonia into an autoclave, and then growing a Ga-containing nitride single crystal under conditions wherein the temperature (T1) at the single crystal growth site is 600° C. to 850° C., the temperature (T1) at the single crystal growth site and the temperature (T2) at the starting material feeder site are in the relationship T1>T2, and the pressure in the autoclave is 40 MPa to 250 MPa, as well as an autoclave that can be used in the method.

Abstract: A method of growing high-quality, group-III nitride, bulk single crystals. The group III-nitride bulk crystal is grown in an autoclave in supercritical ammonia using a source material or nutrient that is a group III-nitride polycrystals or group-III metal having a grain size of at least 10 microns or more and a seed crystal that is a group-III nitride single crystal. The group III-nitride polycrystals may be recycled from previous ammonothermal process after annealing in reducing gas at more then 600° C. The autoclave may include an internal chamber that is filled with ammonia, wherein the ammonia is released from the internal chamber into the autoclave when the ammonia attains a supercritical state after the heating of the autoclave, such that convection of the supercritical ammonia transfers source materials and deposits the transferred source materials onto seed crystals, but undissolved particles of the source materials are prevented from being transferred and deposited on the seed crystals.

Abstract: Reactor designs for use in ammonothermal growth of group-III nitride crystals. Internal heating is used to enhance and/or engineer fluid motion, gas mixing, and the ability to create solubility gradients within a vessel used for the ammonothermal growth of group-III nitride crystals. Novel baffle designs are used for control and improvement of continuous fluid motion within a vessel used for the ammonothermal growth of group-III nitride crystals.

Abstract: Reactor designs for use in ammonothermal growth of group-III nitride crystals. Internal heating is used to enhance and/or engineer fluid motion, gas mixing, and the ability to create solubility gradients within a vessel used for the ammonothermal growth of group-III nitride crystals. Novel baffle designs are used for control and improvement of continuous fluid motion within a vessel used for the ammonothermal growth of group-III nitride crystals.

Abstract: Boron-containing compounds, gasses and fluids are used during ammonothermal growth of group-III nitride crystals. Boron-containing compounds are used as impurity getters during the ammonothermal growth of group-III nitride crystals. In addition, a boron-containing gas and/or supercritical fluid is used for enhanced solubility of group-III nitride into said fluid.

Abstract: To provide a production method for a nitride crystal, where a nitride crystal can be prevented from precipitating in a portion other than on a seed crystal and the production efficiency of a gallium nitride single crystal grown on the seed crystal can be enhanced. In a method for producing a nitride crystal by an ammonothermal method in a vessel containing a mineralizer-containing solution, out of the surfaces of said vessel and a member provided in said vessel, at least a part of the portion coming into contact with said solution is constituted by a metal or alloy containing one or more atoms selected from the group consisting of tantalum (Ta), tungsten (W) and titanium (Ti), and has a surface roughness (Ra) of less than 1.80 ?m.

Abstract: A semiconductor crystal is produced through crystal growth in the presence of a solvent in a supercritical and/or subcritical state in a reactor, wherein at least a part of the surface of the reactor and the surface of the member to be used inside the reactor is coated with a platinum group-Group 13 metal alloy coating film.

Abstract: Boron-containing compounds, gasses and fluids are used during ammonothermal growth of group-Ill nitride crystals. Boron-containing compounds are used as impurity getters during the ammonothermal growth of group-Ill nitride crystals. In addition, a boron-containing gas and/or supercritical fluid is used for enhanced solubility of group-Ill nitride into said fluid.

Abstract: Materials of a nitride single crystal of a metal belonging to III group and a flux are contained in a crucible, which is contained in a reaction container, the reaction container is contained in an outer container, the outer container is contained in a pressure container, and nitrogen-containing atmosphere is supplied into the outer container and melt is generated in the crucible to grow a nitride single crystal of a metal belonging to III group. The reaction container includes a main body containing the crucible and a lid. The main body includes a side wall having a fitting face and a groove opening at the fitting face and a bottom wall. The lid has an upper plate part including a contact face for the fitting face of the main body and a flange part extending from the upper plate part and surrounding an outer side of said side wall.

Abstract: A method and apparatus for growing crystals in a reactor vessel, wherein the reactor vessel uses carbon fiber containing materials as a structural element to contain the materials for growing the crystals as a solid, liquid or gas within the reactor vessel, such that the reactor vessel can withstand pressures or temperatures necessary for the growth of the crystals. The carbon fiber containing materials encapsulate at least one component of the reactor vessel, wherein stresses from the encapsulated component are transferred to the carbon fiber containing materials. The carbon fiber containing materials may be wrapped around the encapsulated component one or more times sufficient to maintain a desired pressure differential between an exterior and interior of the encapsulated component.

Abstract: A high pressure apparatus and related methods for processing supercritical fluids is described. The apparatus includes a capsule, a heater, at least one ceramic ring with one or more scribe marks and/or cracks present. The apparatus optionally has a metal sleeve containing each ceramic ring. The apparatus also has a high-strength enclosure, end flanges with associated insulation, and a power control system. The apparatus is capable of accessing pressures and temperatures of 0.2-2 GPa and 400-1200° C., respectively.

Abstract: Alkaline-earth metals are used to reduce impurity incorporation into a Group-III nitride crystal grown using the ammonothermal method.

Abstract: To provide a production method for a nitride crystal, where a nitride crystal can be prevented from precipitating in a portion other than on a seed crystal and the production efficiency of a gallium nitride single crystal grown on the seed crystal can be enhanced. In a method for producing a nitride crystal by an ammonothermal method in a vessel containing a mineralizer-containing solution, out of the surfaces of said vessel and a member provided in said vessel, at least a part of the portion coming into contact with said solution is constituted by a metal or alloy containing one or more atoms selected from the group consisting of tantalum (Ta), tungsten (W) and titanium (Ti), and has a surface roughness (Ra) of less than 1.80 ?m.

Abstract: A semiconductor crystal is produced through crystal growth in the presence of a solvent in a supercritical and/or subcritical state in a reactor, wherein at least a part of the surface of the reactor and the surface of the member to be used inside the reactor is coated with a platinum group-Group 13 metal alloy coating film.

Abstract: A high pressure apparatus and related methods for processing supercritical fluids is described. The apparatus includes a capsule, a heater, at least one ceramic ring with one or more scribe marks and/or cracks present. The apparatus optionally has a metal sleeve containing each ceramic ring. The apparatus also has a high-strength enclosure, end flanges with associated insulation, and a power control system. The apparatus is capable of accessing pressures and temperatures of 0.2-2 GPa and 400-1200° C., respectively.

Abstract: A high pressure apparatus and related methods for processing supercritical fluids. In a specific embodiment, the present apparatus includes a capsule, a heater, at least one ceramic ring but can be multiple rings, optionally, with one or more scribe marks and/or cracks present. In a specific embodiment, the apparatus optionally has a metal sleeve containing each ceramic ring. The apparatus also has a high-strength enclosure, end flanges with associated insulation, and a power control system. In a specific embodiment, the apparatus is capable of accessing pressures and temperatures of 0.2-2 GPa and 400-1200° C., respectively.

Abstract: A method for ammonothermally growing group-III nitride crystals using an initially off-oriented non-polar and/or semi-polar growth surface on a group-III nitride seed crystal. Group-III-containing source materials and group-III nitride seed crystals are placed into a vessel, wherein the seed crystals have one or more non-polar or semi-polar growth surfaces. Group-III nitride crystals are ammonothermally grown by filling the vessel with a nitrogen-containing solvent for dissolving the source materials and transporting a fluid comprised of the solvent with the dissolved source materials to the seed crystals for growth of the group-III nitride crystals on the seed crystals. The growth surfaces are initially off-oriented growth surfaces, wherein the growth surfaces are off-oriented m-plane or highly vicinal m-plane growth surfaces. The growth surfaces of the seed crystals may be created by cutting group-III nitride crystals at a desired angle with respect to an m-plane.

Abstract: To grow a highly pure nitride crystal having a low oxygen concentration efficiently by an ammonothermal method. A process for producing a nitride crystal, which comprises bringing a reactant gas reactive with ammonia to form a mineralizer, and ammonia into contact with each other to prepare a mineralizer in a reactor or in a closed circuit connected to a reactor; and growing a nitride crystal by an ammonothermal method in the presence of the ammonia and the mineralizer.

Abstract: Reactor designs for use in ammonothermal growth of group-III nitride crystals. Internal heating is used to enhance and/or engineer fluid motion, gas mixing, and the ability to create solubility gradients within a vessel used for the ammonothermal growth of group-III nitride crystals. Novel baffle designs are used for control and improvement of continuous fluid motion within a vessel used for the ammonothermal growth of group-III nitride crystals.

Abstract: A production method is provided in which Group-III-element nitride single crystals that have a lower dislocation density and a uniform thickness and are transparent, high quality, large, and bulk crystals can be produced with a high yield. The method for producing Group-III-element nitride single crystals includes: heating a reaction vessel containing at least one metal element selected from the group consisting of an alkali metal and an alkaline-earth metal and at least one Group III element selected from the group consisting of gallium (Ga), aluminum (Al), and indium (In) to prepare a flux of the metal element; and feeding nitrogen-containing gas into the reaction vessel and thereby allowing the Group III element and nitrogen to react with each other in the flux to grow Group-III-element nitride single crystals, wherein the single crystals are grown, with the flux being stirred by rocking the reaction vessel, for instance.

Abstract: A method of operating a high pressure system for growth of gallium nitride containing materials. The method comprises providing a high pressure apparatus comprising a growth region and feedstock region. The high pressure reactor comprises a high pressure enclosure and is configured within a primary containment structure. The method includes operating an exhaust system coupled to the primary containment structure. The exhaust system is configured to remove ammonia gas derived from at least 0.3 liters of ammonia liquid.

Abstract: A method for charging with liquefied ammonia comprising sequentially a feeding step of feeding gaseous ammonia in a condenser, a liquefaction step of converting the gaseous ammonia into a liquefied ammonia in the condenser, and a charging step of feeding the liquefied ammonia formed in the condenser to a vessel to thereby charge the vessel with the liquefied ammonia wherein a cooling step of feeding the liquefied ammonia formed in the condenser to the vessel and cooling the vessel by the latent heat of vaporization of the liquefied ammonia and a circulation step of feeding the gaseous ammonia formed through vaporization of the liquefied ammonia in the previous cooling step to the condenser are carried out between the liquefaction step and the charging step.

Abstract: When a group III nitride crystal is grown in a pressurized atmosphere of a nitrogen-containing gas from a melt 50 including at least a group III element, nitrogen and an alkali metal or an alkali earth metal, a melt-holding vessel 160 that holds the above-described melt 50 is swung about two axes different in direction from each other such as an x-axis and a Y-axis.

Abstract: A method for producing Group-III-element nitride crystals by which an improved growth rate is obtained and large high-quality crystals can be grown in a short time, a producing apparatus used therein, and a semiconductor element obtained using the method and the apparatus are provided. The method is a method for producing Group-III-element nitride crystals that includes a crystal growth process of subjecting a material solution containing a Group III element, nitrogen, and at least one of alkali metal and alkaline-earth metal to pressurizing and heating under an atmosphere of a nitrogen-containing gas so that the nitrogen and the Group III element in the material solution react with each other to grow crystals.

Abstract: The present disclosure proves for new design of reactors used for ammonothermal growth of III nitride crystals. The reactors include a region intermediate a source dissolution region and a crystal growth region configured to provide growth of high quality crystals at rates greater than 100 ?m/day. In one embodiment, multiple baffle plates having openings whose location is designed so that there is no direct path through the intermediate region, or with multiple baffle plates having differently sized openings on each plate so that the flow is slowed down and/or exhibit greater mixing are described. The disclosed designs enables obtaining high temperature difference between the dissolution region and the crystallization region without decreasing conductance through the device.

Abstract: Disclosed herein is a cooling system for a chamber of an ingot growth apparatus. In the present invention, guide blades (180) are provided in a base plate (100) at positions adjacent to unevenly curved parts of a guide line (170), which is the base plate (100), and along which cooling water flows. Furthermore, guide blades (360) are provided in a lid (300) at positions adjacent to ports, which are provided in the lid (300) and interfere with the flow of cooling water. As such, in the present invention, the guide blades are provided in the base plate (100) and the lid (300), which define the chamber, at positions at which cooling water creates stationary vortices, thus solving a problem of water stagnation, thereby increasing a cooling effect.

Abstract: An apparatus and associated method for large-scale manufacturing of gallium nitride is provided. The apparatus comprises a large diameter autoclave and a raw material basket. Methods include metered addition of dopants in the raw material and control of the atmosphere during crystal growth. The apparatus and methods are scalable up to very large volumes and are cost effective.

Abstract: An apparatus and associated method for large-scale manufacturing of gallium nitride is provided. The apparatus comprises a large diameter autoclave and a raw material basket. Methods include metered addition of dopants in the raw material and control of the atmosphere during crystal growth. The apparatus and methods are scalable up to very large volumes and are cost effective.

Abstract: An apparatus and associated method for large-scale manufacturing of gallium nitride. The apparatus comprises a large diameter autoclave or internally-heated high pressure vessel, a seed rack, and a raw material basket. Methods include effective means for utilization of seed crystals. The apparatus and methods are scalable up to very large volumes and are cost effective.

Abstract: In one embodiment of the present invention, an assembly for HPHT processing comprises a can with an opening. A powder mixture is disposed within the opening. A substrate is disposed within the opening adjacent the powder mixture. Paint is coated on a surface within the opening and opposite the powder mixture with respect to the substrate. A meltable sealant is disposed within the opening and opposite the substrate with respect to the surface and a cap is covering the opening. In another embodiment of the present invention, an assembly for HPHT processing comprises a can with an opening, a powder mixture is disposed within the opening, a substrate disposed within the opening adjacent and above the powder mixture, a formable sealant barrier is disposed within the opening above the substrate, a meltable sealant is disposed within the opening above the formable sealant barrier, and a cap covers the opening.

Abstract: A high pressure apparatus and related methods for processing supercritical fluids. In a specific embodiment, the present apparatus includes a capsule, a heater, at least one ceramic ring but can be multiple rings, optionally, with one or more scribe marks and/or cracks present. In a specific embodiment, the apparatus optionally has a metal sleeve containing each ceramic ring. The apparatus also has a high-strength enclosure, end flanges with associated insulation, and a power control system. IN a specific embodiment, the apparatus is capable of accessing pressures and temperatures of 0.2-2 GPa and 400-1200° C., respectively.

Abstract: A growth apparatus is used having a plurality of crucibles 10 each for containing the solution, a heating element for heating the crucible, and a pressure vessel for containing at least the crucibles and the heating element and for filling an atmosphere comprising at least nitrogen gas. One seed crystal is put in each of the crucibles to grow the nitride single crystal on the seed crystal.

Abstract: An object of the present invention is to manufacture single crystals of high quality on an industrial production scale by preventing impurities from being mixed in single crystals when the single crystals are produced by the solvothermal method. A pressure vessel body 1, in which a supercritical state is maintained, is made of heat resistant alloy, a portion of the pressure vessel body is open, a corrosion-resistant mechanical lining 5 is provided on an inner face of the pressure vessel and on an entire outer circumferential edge of the opening, and the opening is sealed by an airtight mating face formed out of a corrosion-resistant mechanical lining, which is formed on the outer circumferential edge of the opening, and by an airtight mating face of the corrosion-resistant mechanical lining cover 6 on an inner face of the cover 3 through a corrosion-resistant gasket member.

Abstract: A nitride single crystal is produced using a growth solution 7 containing an easily oxidizable material. A crucible 1 for storing the growth solution 7, a pressure vessel for storing the crucible and charging an atmosphere containing at least nitrogen, and an oxygen absorber 14, 15 disposed inside the pressure vessel and outside the crucible 1 are used to grow the nitride single crystal.

Abstract: A method for manufacturing a single crystal includes the steps of: flowing a raw material gas toward a seed crystal in a reactive chamber so that the single crystal grows from the seed crystal; controlling the raw material gas by a gas flow control member having a cylindrical shape; passing the raw material gas through a clearance between the seed crystal and an inner wall of the gas flow control member; and flowing a part of the raw material gas to bypass the seed crystal. The method provides the single crystal having good quality.

Abstract: A manufacturing apparatus of Group III nitride crystals and a method for manufacturing Group III nitride crystals are provided, by which high quality crystals can be manufactured. For instance, crystals are grown using the apparatus of the present invention as follows. A crystal raw material (131) and gas containing nitrogen are introduced into a reactor vessel (120), to which heat is applied by a heater (110), and crystals are grown in an atmosphere of pressure applied thereto. The gas is introduced from a gas supplying device (180) to the reactor vessel (120) through a gas inlet of the reactor vessel, and then is exhausted to the inside of a pressure-resistant vessel (102) through a gas outlet of the reactor vessel. Since the gas is introduced directly to the reactor vessel (120) without passing through the pressure-resistant vessel (102), the mixture of impurities attached to the pressure-resistant vessel (102) and the like into the site of the crystal growth can be prevented.

Abstract: An apparatus including a crucible, an energy source, and a controller is provided. The crucible may be sealed to a nitrogen-containing gas, and may be chemically inert to at least ammonia at a temperature in a range of about 400 degrees Celsius to about 2500 degrees Celsius. The energy source may supply thermal energy to the crucible. The controller may control the energy source to selectively direct sufficient thermal energy to a predefined first volume within the crucible to attain and maintain a temperature in the first volume to be in a range of from about 400 degrees Celsius to about 2500 degrees Celsius. The thermal energy may be sufficient to initiate, sustain, or both initiate and sustain growth of a crystal in the first volume. The first temperature in the first volume may be controllable separately from a second temperature in another volume within the crucible. The first temperature and the second temperature differ from each other. Associated methods are provided.

Abstract: A seed crystal fixing apparatus for fixing the seed crystal on the seed crystal setting part of a reaction vessel with interposition of the adhesive, has a chamber configured to place the seed crystal setting part and form a hermetic atmosphere within the chamber; and a pressure part placed within the chamber for uniformly applying a pressure on the entire surface of the seed crystal.

Abstract: A crystal growth method of a group III nitride includes the steps of forming a melt mixture of an alkali metal and a group III element in a reaction vessel, and growing a crystal of a group III nitride formed of the group III element and nitrogen from the melt mixture in the reaction vessel, wherein the step of growing the crystal of the group III nitride is conducted while controlling an increase rate of degree of supersaturation of a group III nitride component in the melt mixture in a surface region of the melt mixture.

Abstract: A large semiconductor crystal has a diameter of at least 6 inches and a low dislocation density of not more than 1×104 cm?2. The crystal is preferably a single crystal of GaAs, or one of CdTe, InAs, GaSb, Si or Ge, and may have a positive boron concentration of not more than 1×1016 cm?3 and a carbon concentration of 0.5×1015 cm?3 to 1.5×1015 cm?3 with a uniform concentration throughout the crystal. Such a crystal can form a very thin wafer with a low dislocation density. A special method and apparatus for producing such a crystal is also disclosed.

Abstract: A very-high pressure generator of construction such that the lower and upper guide blocks of the generator are each configured so as to form a pyramidal recess on the bottom surface and an upside-down pyramidal recess on the top surface accurately symmetrically, their pyramidal slopes given one and the same angle of inclination and are prevented from being deformed under high pressure not by enlarging the guide blocks and the press, but by making the support conditions of all the anvils of the generator uniform, the positions of the anvils can easily be adjusted and therefore the generator is capable of pressurizing a pressure transmitting medium into the shape of the desired cube accurately. Each of the lower and upper guide blocks has a pyramidal recess in its bottom surface and an upside-down pyramided recess in its top surface and us symmetric with respect to its horizontal center plane. Each of lower and upper base blocks has a lower upside-down pyramidal portion and an upper pyramidal portion.

Abstract: A large semiconductor crystal is produced by charging a raw material into a crucible in a reactor tube, sealing the reactor tube with a flange on an open end of the tube, pressurizing the interior of the tube to an elevated pressure with an inert gas, heating the tube with an externally arranged heater to melt the raw material to form a raw material melt in the crucible, and solidifying the raw material melt to grow the semiconductor crystal. A second raw material such as a group V element can be introduced as a vapor from a reservoir into the melt in the crucible to form a compound semiconductor material. The flange is sealed to the tube by an elastic seal member, of which the temperature is maintained below 400° C. throughout the process, to protect its elastic sealing properties.