Abstract: An improved apparatus and method for substrate layer deposition in which substrate layers are grown by carrier gas delivery of sequential pulses of reactants to the substrate surface. At least one of the reactants comprises excited species, e.g., radicals. In a specific embodiment, the apparatus of this invention provides sequential repeated pulses of reactants in a flow of carrier gas for reaction at a substrate surface. The reactant pulses are delivered with sufficient intervening delay times to minimize undesirable reaction between reactants in adjacent pulses in the gas phase or undesired uncontrolled reactions on the substrate surface.

Abstract: An apparatus and method is provided for manufacturing a semiconductor substrate such as web crystals. The apparatus includes a chamber and a growth hardware assembly housed within the chamber. A magnetic field system produces a vertical magnetic field within the chamber.

Abstract: A process for modifying the surface of a quartz glass crucible and a modified quartz glass crucible produced by the process, where the crucible has a transparent coated layer containing a crystallization accelerator on the surface. The process includes coating a mixed solution containing a metal salt and a partial hydrolyzate of alkoxysilane oligomer on the surface of the crucible and heating to obtain a quartz glass crucible having a transparent coated layer. The crystallization accelerator contains a metal oxide or a metal carbonate dispersed in a silica matrix.

Abstract: A low defect (e.g., dislocation and micropipe) density silicon carbide (SiC) is provided as well as an apparatus and method for growing the same. The SiC crystal, grown using sublimation techniques, is preferably divided into two stages of growth. During the first stage of growth, the crystal grows in a normal direction while simultaneously expanding laterally. Although dislocations and other material defects may propagate within the axially grown material, defect propagation and generation in the laterally grown material are substantially reduced, if not altogether eliminated. After the crystal has expanded to the desired diameter, the second stage of growth begins in which lateral growth is suppressed and normal growth is enhanced. A substantially reduced defect density is maintained within the axially grown material that is based on the laterally grown first stage material.

Abstract: A high vacuum apparatus for fabricating a semiconductor device includes a reactive chamber provided with an inlet and an outlet for a reactive gas, a suscepter installed in the reactive chamber for mounting the semiconductor thereon and a vacuum pump connected with the outlet to make the inside of the reactive chamber to put in a high vacuum state, wherein a gas injector of the reactive gas inlet is directed downward of the semiconductor device so that the initial gas flowing of the reactive gas injected from the reactive gas inlet does not directly pass the upper portion of the semiconductor substrate mounted on the suscepter. Since the reactive gas is prevented from cooling and condensing at the upper surface of the semiconductor substrate, defective proportion of the semiconductor device can be remarkably reduced.

Abstract: In a process for producing a planar body of an oxide single crystal with a &mgr; pulling-down method, a shoulder portion having a larger width is grown without any polycrystal regions, cracks or crystal deteriorations in a central portion of the planar body. A raw material of the oxide single crystal is melted in a crucible. A seed crystal is contacted to a melt of the raw material near an opening of a nozzle 13 of the crucible. Then, the melt 18 is drawn from the opening by pulling down the seed crystal to form a planar body 14A. A temperature distribution of the nozzle 13 in a direction perpendicular to the drawing direction B is controlled by supplying heat to the nozzle 13 and/or by removing heat from the nozzle 13.

Abstract: An improved apparatus and method for substrate layer deposition in which substrate layers are grown by carrier gas delivery of sequential pulses of reactants to the substrate surface. At least one of the reactants comprises excited species, e.g., radicals. In a specific embodiment, the apparatus of this invention provides sequential repeated pulses of reactants in a flow of carrier gas for reaction at a substrate surface. The reactant pulses are delivered with sufficient intervening delay times to minimize undesirable reaction between reactants in adjacent pulses in the gas phase or undesired uncontrolled reactions on the substrate surface.

Abstract: The invention relates to a method for growing large-volume monocrystals with a uniform orientation and consisting of a melt of crystal raw material, in a device comprising a sealable housing (10) in which a melting vessel (20) with side walls (22), a bottom (24), a top opening (26) facing said bottom (24) and optionally a lid (28) are located; and at least one heating element (50, 50′). According to said method, a crystal raw material in the melting vessel (20) is heated with heating elements (50, 50′) to a temperature above the melting point until a melt with a surface is formed. A monocrystal is then formed on the bottom of the melting vessel by lowering the temperature to at least the crystallisation point. Said monocrystal forms a solid/liquid interphase with the melt and grows towards the melt surface on said interphase, in a direction that is perpendicular to the interphase.

Abstract: A method for producing crystals and/or crystal materials is described whereby the undesirable impurities are removed from the crystal and/or the material with the aid of a purification agent or getter. Elemental fluorine and/or a reactive fluorine-containing substance is used as the purification agent or getter. Preferred getters are XeF2 and/or carbon fluoride. Crystals obtained in this manner are suitable for use as optical components.

Abstract: An improved mechanical arrangement controls the introduction of silicon particles into an EFG (Edge-defined Film-fed Growth) crucible/die unit for melt replenishment during a crystal growth run. A feeder unit injects silicon particles upwardly through a center hub of the crucible/die unit and the mechanical arrangement intercepts the injected particles and directs them so that they drop into the melt in a selected region of the crucible and at velocity which reduces splashing, whereby to reduce the likelihood of interruption of the growth process due to formation of a solid mass of silicon on the center hub and adjoining components. The invention also comprises use of a Faraday ring to alter the ratio of the electrical currents flowing through primary and secondary induction heating coils that heat the crucible die unit and the mechanical arrangement.

Abstract: A method and apparatus for axially growing single crystal silicon carbide is provided. Utilizing the system, silicon carbide can be grown with a dislocation density of less than 104 per square centimeter, a micropipe density of less than 10 per square centimeter, and a secondary phase inclusion density of less than 10 per cubic centimeter. As disclosed, a SiC source and a SiC seed crystal of the desired polytype are co-located within a crucible, the growth zone being defined by the substantially parallel surfaces of the source and the seed in combination with the sidewalls of the crucible. Prior to reaching the growth temperature, the crucible is evacuated and sealed, either directly or through the use of a secondary container housing the crucible. The crucible is comprised of tantalum or niobium that has been specially treated.

Abstract: A crystal puller for growing monocrystalline silicon ingots includes first and second electrical resistance heaters in the crystal puller in longitudinal, closely spaced relationship with each other to radiate heat toward the ingot as the ingot is pulled upward within the housing. An adapter mounting the heaters may also be provided for adapting existing crystal pullers to incorporate the heaters.

Abstract: A device for promoting protein crystal growth (PCG) using microfluidic channels. A protein sample and a solvent solution are combined within a microfluidic channel having laminar flow characteristics which forms diffusion zones, providing for a well defined crystallization. Protein crystals can then be harvested from the device. The device is particularly suited for microgravity conditions.

Abstract: A method for making a below 200-nm wavelength optical fluoride crystal feedstock includes loading a fluoride raw material into a chamber, exposing the fluoride raw material to a flow of gaseous fluoride at a predetermined temperature, and storing the exposed fluoride raw material in a dry atmosphere.

Abstract: A method and apparatus for axially growing single crystal silicon carbide is provided. Utilizing the system, silicon carbide can be grown with a dislocation density of less than 104 per square centimeter, a micropipe density of less than 10 per square centimeter, and a secondary phase inclusion density of less than 10 per cubic centimeter. As disclosed, a SiC source and a SiC seed crystal of the desired polytype are co-located within a crucible, the growth zone being defined by the substantially parallel surfaces of the source and the seed in combination with the sidewalls of the crucible. Prior to reaching the growth temperature, the crucible is evacuated and sealed, either directly or through the use of a secondary container housing the crucible. The crucible is comprised of tantalum or niobium that has been specially treated.

Abstract: The invention describes an apparatus for chemical vapor deposition on substrates, a related method of deposition of epitaxial layers on the wafers and an assemblage for use therewith. In the apparatus of the invention, the wafers are placed directly on the surface of a heating filament. The apparatus of the invention may include a reaction chamber, a rotatable spindle, a plurality of rotatable electrodes mounted on the spindle for rotation together with the spindle and a heating filament in electrical contact with the rotatable electrodes. The heating filament may be rotated by rotating the rotatable electrodes, and heated by providing electric current to the electrodes. In one embodiment of the invention, heating filament may be detached from the rotatable electrodes to load or unload the wafers. Preferably, the heating filament is transported between a deposition position and a loading position. Alternatively, the heating filament is permanently mounted on the electrodes.

Abstract: A crystal growth vessel for growing a crystal within a main container has a crystal growth starting portion in which the crystal starts to grow, whereas the crystal growth starting portion is formed from a material having a thermal conductivity higher than that of a material of the main container.

Abstract: Disclosed are processes and reactor apparatus for rapidly producing large diameter, high-purity polycrystalline silicon rods for semiconductor applications. A.C. current, having a fixed or variable high frequency in the range of about 2 kHz to 800 kHz, is provided to concentrate at least 70% of the current in an annular region that is the outer 15% of a growing rod due to the “skin effect.

Abstract: A simple and inexpensive method and apparatus for producing crystalline silicon comprising the steps of melting silicon in a mold, then cooling the bottom of the mold is cooled to create a positive temperature gradient from the bottom of the mold upward, thereby causing the molten silicon to crystallize from the inner bottom of the mold upward so that the solid-liquid phase boundary, separating the crystallized silicon from the molten silicon, moves upward as the molten silicon crystallizes. As the silicon crystallizes, an inert gas is blown onto the surface of the molten silicon from a position above the surface of the molten silicon, thereby vibrating the surface of the molten silicon in such a manner that cavities are formed in the surface of the molten silicon.

Abstract: The invention relates to a device and method for depositing one or more layers onto at least one substrate placed inside a reaction chamber. The layers are deposited while using a liquid or solid starting material for one of the reaction gases utilized, which are fed via a gas admission unit to the reaction chamber where they condense or epitaxially grow on the substrate. The gas admission unit comprises a multitude of buffer volumes in which the reaction gasses enter separate of one another, and exit through closely arranged outlet openings while also being spatially separate of one another. The temperature of reaction gases is moderated while passing through the gas admission unit.

Abstract: A furnace for growing a high volume of crystals includes a plurality of individual growth stations and first and second heater matrixes. Each individual growth station has a crucible and an insulating container generally surrounding the crucible and thermally isolating the crucible from the other individual growth stations. The first and second heater matrices each include at least two legs electrically connected in parallel and each of the legs have at least two resistance heaters electrically connected in series. Each of the individual growth stations have at least one of the resistance heaters within the first heater matrix and at least one of the resistance heaters within the second heater matrix associated therewith. The resistance heaters of the first heater matrix are located above the crucibles and are preferably adapted to provide a homogeneous temperature across tops of the crucibles.

Abstract: A method and apparatus for axially growing single crystal silicon carbide is provided. Utilizing the system, silicon carbide can be grown with a dislocation density of less than 104 per square centimeter, a micropipe density of less than 10 per square centimeter, and a secondary phase inclusion density of less than 10 per cubic centimeter. As disclosed, a SiC source and a SiC seed crystal of the desired polytype are co-located within a crucible, the growth zone being defined by the substantially parallel surfaces of the source and the seed in combination with the sidewalls of the crucible. Prior to reaching the growth temperature, the crucible is evacuated and sealed, either directly or through the use of a secondary container housing the crucible. The crucible is comprised of tantalum or niobium that has been specially treated.

Abstract: A method of growing epitaxial layers on a wafer is provided and includes providing a wafer carrier having a surface for retaining the wafer; placing the wafer on the wafer-retaining surface of the wafer carrier while the wafer carrier is in a loading position separated from a spindle; transporting the wafer carrier toward the spindle; detachably mounting the wafer carrier on the upper end of the spindle for rotation therewith; and rotating the spindle and the wafer carrier while introducing one or more reactants into the reaction chamber. The invention also described several embodiments and variants of the method of the invention.

Abstract: In an application apparatus of a klinostat, an object is encapsulated in a vessel. A rotating unit rotates the vessel around n axes (n is an integer more than 1) such that gravity is equally applied to the object. A fluid supply unit supplies fluid into the vessel, while the vessel is rotated.

Abstract: A modified susceptor for use in an epitaxial deposition apparatus and process is disclosed. The modified susceptor has an inner annular ledge capable of supporting a semiconductor wafer and has a plurality of holes in the surface to allow cleaning gas utilized during an epitaxial deposition process to pass through the susceptor and contact substantially the entire back surface of the semiconductor wafer and remove a native oxide layer. Also, the plurality of holes on the susceptor allows dopant atoms out-diffused from the back surface during the epitaxial deposition process to be carried away from the front surface in an inert gas stream and into the exhaust such that autodoping of the front surface is minimized.

Abstract: A low defect (e.g., dislocation and micropipe) density silicon carbide (SiC) is provided as well as an apparatus and method for growing the same. The SiC crystal, grown using sublimation techniques, is preferably divided into two stages of growth. During the first stage of growth, the crystal grows in a normal direction while simultaneously expanding laterally. Although dislocations and other material defects may propagate within the axially grown material, defect propagation and generation in the laterally grown material are substantially reduced, if not altogether eliminated. After the crystal has expanded to the desired diameter, the second stage of growth begins in which lateral growth is suppressed and normal growth is enhanced. A substantially reduced defect density is maintained within the axially grown material that is based on the laterally grown first stage material.

Abstract: An apparatus and method is provided for manufacturing a semiconductor substrate such as web crystals. The apparatus includes a chamber and a growth hardware assembly housed within the chamber. A magnetic field system produces a vertical magnetic field within the chamber.

Abstract: A crucible adapted for use in formation of a silicon crystal comprises a crucible wall including a bottom wall and a side wall. An inner layer is formed on an inner portion of the crucible wall and has distributed therein a crystallization agent containing an element selected from the group consisting of barium, aluminum, titanium and strontium.

Abstract: The invention describes a CVD reactor on solid substrates and a related method of deposition of epitaxial layers on the wafers. In the reactor of the invention, the wafer carrier is transported between a loading position and a deposition position. In the deposition position, the wafer carrier is detachably mounted on an upper end of a rotatable spindle without an intermediate susceptor. The reactor of the invention may process a single wafer at the same time. The invention also describes several embodiments and variants of the invention. One of the variants of the invention provides a decrease in a heat drain from the wafer-supporting assembly through the spindle and a novel heating arrangement therefore. The advantages of the invention include lower reactor cycle, the lower cost and longer lifetime of the component parts, and better temperature control, among others.

Abstract: A cleaned pulling room installed with a plurality of single crystal pulling apparatuses, having a plurality of operation floors and supplied with clean air as a down flow from a ceiling or an upper position neighboring the ceiling, wherein at least three operation floors are provided depending on degrees of cleanness required for operations performed on each of the floors. Thus, there is provided a pulling room that can separate dusting operations such as operations of dismantlement and cleaning of the furnace body and structural members in the furnace body and operations requiring highly clean environment such as charging of raw material into the furnace body as preparation for starting running of the pulling apparatuses, and can secure safety of the operations even when the pulling apparatuses become larger.

Abstract: Quartz member such as a quartz tube for semiconductor manufacturing equipment capable of heat treating a substrate to be treated without causing contamination, a manufacturing method of such quartz member, thermal treatment equipment furnished with such quartz member, and an analysis method of metal in quartz member are provided. A quartz specimen is immersed in hydrofluoric acid to expose a layer to be analyzed located at a prescribed depth. On an exposed surface, a decomposition liquid such as hydrofluoric acid or nitric acid is dripped to decompose only an extremely thin layer to be analyzed, followed by recovering of the decomposition liquid. The decomposition liquid is quantitatively analyzed by use of atomic absorption spectroscopy (AAS) or the like to measure an amount of metal contained in the decomposition liquid. From a difference of thicknesses before and after the decomposition and an area of dripped decomposition liquid, a volume of a decomposed layer to be analyzed is obtained.

Abstract: A process chamber used in the manufacture of a semiconductor device for etching a material layer on a semiconductor wafer includes an electrostatic chuck for holding the semiconductor wafer, and an annular edge ring which surrounds the side of the semiconductor wafer on the electrostatic chuck to prevent the semiconductor wafer from departing from its original position. The annular edge ring has a first side which faces the side of the semiconductor wafer and contacts firmly with the side of the semiconductor wafer.

Abstract: A protein crystal growth assembly including a crystal growth cell and further including a cell body having a top side and a bottom side and a first aperture defined therethrough, the cell body having opposing first and second sides and a second aperture defined therethrough. A cell barrel is disposed within the cell body, the cell barrel defining a cavity alignable with the first aperture of the cell body, the cell barrel being rotatable within the second aperture. A reservoir is coupled to the bottom side of the cell body and a cap having a top side is disposed on the top side of the cell body. The protein crystal growth assembly may be employed in methods including vapor diffusion crystallization, liquid to liquid crystallization, batch crystallization, and temperature induction batch mode crystallization.

Abstract: A method for depositing a semiconductor film on a wafer by making a source gas supplied flow almost horizontally to the surface of the wafer. When a process condition, e.g., the flow velocity or pressure of the source gas, should be changed, the source gas has its velocity and/or pressure changed so that the source gas is supplied at a substantially constant flow rate.

Abstract: An apparatus for growing a single crystal of semiconductor is provided, which makes it possible to grow a heavy single crystal of semiconductor of 100 kg or greater in weight even if a growing single crystal contains a neck. In the apparatus, the first and second electrodes are provided such that the first ends of the first and second electrodes are electrically connected to the power supply and the second ends of the first and second electrodes are contacted with the melt in the crucible. During the growth process, a specific voltage is applied across the first ends of the first and second electrodes, thereby forming the electrical current path interconnecting the second ends of the first and second electrodes in the melt. The magnetic field is generated with the magnetic field generator to intersect with the electrical current path in the melt. No electric current flows through the growing single crystal from the melt.

Abstract: An improved chuck for supporting elongated work pieces having conical end portions, such as single crystal ingots used to fabricate semiconductor wafers, while such. The chuck is typically used in a lathe for positioning and allowing rotation of the work piece during a grinding procedure that results in optimal work piece diameter. The chuck comprises a ring-shaped base, or socket, having a cavity defining a central axis therethrough and a series of fastener holes for securing the base to a headstock or tailstock of a lathe. The base receives within the cavity a portion of a chuck insert. The chuck insert defines a work piece support surface that is coaxial with the central axis when the chuck insert is disposed in a nominal position within the cavity of the base. The work piece support surface will typically define a continuous, arcuate, convex surface capable of supporting work pieces having conical end portions of varying diameters.

Abstract: The invention relates to a reaction vessel (1) for producing a sample, in particular a crystal, from a substance in solution or in liquid form, having several reaction chambers (6) each forming a separate gas chamber, consisting of at least one housing part, and each reaction chamber (6) has a reservoir (7) and several reaction areas (8) co-operating therewith, connected to one another and to the reservoir (7) in order to exchange gas. The reservoirs and the reaction areas co-operating with them are disposed immediately adjacent to one another in rows, distributed in a predeterminable, identical manner, these rows running parallel with one another. Each row of reservoirs (7) therefore co-operates with at least one row of reaction areas (8).

Abstract: The invention relates to an apparatus for growing thin films onto the surface of a substrate by exposing the substrate to alternately repeated surface reactions of vapor-phase reactants. The apparatus comprises at least one process chamber having a tightly sealable structure, at least one reaction chamber having a structure suitable for adapting into the interior of said process chamber and comprising a reaction space of which at least a portion is movable, infeed means connectable to said reaction space for feeding said reactants into said reaction space, and outfeed means connectable to said reaction space for discharging excess reactants and reaction gases from said reaction space, and at least one substrate adapted into said reaction space.

Abstract: A molecular beam source comprising a crucible having an opening, and a heater mounted to the crucible for evaporating by heating a molecular beam generating material accommodated in the crucible to emit a molecular beam from the opening, wherein the crucible has an accommodating section for accommodating the molecular beam generating material, a bent portion provided between the opening and the accommodating section so that the molecular beam generating material accommodated in the accommodating section does not face the opening directly, and a narrowed portion between the bent portion and the opening.

Abstract: A vapor phase growth apparatus 1 for growing a group III-V nitride semiconductor (GaN) comprises a reaction ampoule 3 having a container 11 disposed therein for containing a group III element and an inlet 7 for introducing nitrogen; excitation means 15 for plasma-exciting nitrogen introduced from the inlet 7; and heating means 13 for heating a seed crystal 10 disposed within the reaction ampoule 3 and the container 11; wherein, upon growing the group III-V nitride semiconductor on the seed crystal 10, nitrogen is introduced from the inlet 7, and no gas is let out from within the reaction ampoule 3.

Abstract: The invention relates to a multi-stage counter-current crystallization apparatus for crystallizing and subsequently separating a component in pure form from a solution, comprising a first concentration stage built up in part of: means for supplying the solution; first crystallization means, consisting of a heat exchanger of the scraped surface type for forming crystals in the solution; a first crystallization vessel for further growth of the crystals formed by the first crystallization means so as to obtain a first crystal suspension mixture containing larger crystals; first separating means for separating the larger crystals from the first crystal suspension mixture so as to obtain a first concentrated mother liquor solution; and at least one second concentration stage built up in part of: means for supplying the first concentrated mother liquor solution; second crystallization means consisting of a heat exchanger of the scraped surface type for forming crystals in the first concentrated mother liquor soluti

Abstract: A laser irradiating apparatus includes a cylindrical lens group that divides a laser beam and a cylindrical lens that re-couples a laser beam as divided. The cylindrical lens is shaped in a parallelogram whose angles are not a right angle, thereby being capable of dispersing a portion where interference is strengthened in a laser beam to restrain irradiation unevenness.

Abstract: A crystallization apparatus and method that is adapted to crystallize a semiconductor using a non-vacuum process. In the apparatus and method, laser beams are irradiated onto a substrate to grow a crystal unilaterally from the side surface of the substrate. Grain boundaries are minimized under the air atmosphere, so that a crystallization of the substrate can be made in a non-vacuum state to improve the throughput.

Abstract: An apparatus for pulling up a strip of semiconductor crystal continuously from a crucible with a pair of endless belts has a position control device for automatically adjusting a transverse position of the strip of semiconductor crystal. The position control device is disposed in a path for pulling up the strip of semiconductor crystal from the crucible. The position control device comprises a pair of blocks disposed one on each side of the path transversely of the strip of semiconductor crystal and movable transversely of the strip of semiconductor crystal, and a pair of position sensors mounted respectively on the blocks for detecting respective edges of the strip of semiconductor crystal. The blocks have respective side faces for adjusting a direction in which the strip of semiconductor crystal is pulled up, by contacting the respective edges of the strip of semiconductor crystal.

Abstract: A process and apparatus for the regeneration of contaminated acid. The process involves cooling the contaminated acid to a lower temperature sufficient to form at least one liquid hydrate of the acid without forming a solid hydrate of the acid, maintaining the contaminated acid at the lower temperature for a time sufficient to form at least one liquid hydrate of the acid and precipitate an amount of the contaminants, separating the precipitated contaminants from the cooled acid, and warming the acid to decompose the liquid hydrate.

Abstract: A crucible for growing a single crystal therein has a seed crystal attachment portion and a peripheral portion surrounding the seed crystal attachment portion through a gap provided therebetween. The seed crystal attachment portion has a support surface for holding a seed crystal on which the single crystal is to be grown, and the support surface is recessed from a surface of the peripheral portion. The seed crystal is attached to the support surface to cover an entire area of the support surface. Accordingly, no poly crystal is formed on the seed crystal attachment portion, and the single crystal can be grown on the seed crystal with high quality.

Abstract: A process is disclosed for producing an oxide single crystal, including the steps of: melting a raw material for a single crystal of an oxide inside a crucible, contacting a seed crystal with the resulting melt, growing the oxide single crystal by pulling-down the melt through an opening of the crucible in a given pulling-down axis, and fixedly holding the seed crystal and then reducing an angle of a given crystalline orientation of the seed crystal selected for growing the single crystal to the pulling-down axis.

Abstract: A protein crystal growth assembly including a crystal growth cell and further including a cell body having a top side and a bottom side and a first aperture defined therethrough, the cell body having opposing first and second sides and a second aperture defined therethrough. A cell barrel is disposed within the cell body, the cell barrel defining a cavity alignable with the first aperture of the cell body, the cell barrel being rotatable within the second aperture. A reservoir is coupled to the bottom side of the cell body and a cap having a top side is disposed on the top side of the cell body.

Abstract: The invention relates to an apparatus for growing thin films onto the surface of a substrate by exposing the substrate to alternately repeated surface reactions of vapor-phase reactants. The apparatus comprises at least one process chamber having a tightly sealable structure, at least one reaction chamber having a structure suitable for adapting into the interior of said process chamber and comprising a reaction space of which at least a portion is movable, infeed means connectable to said reaction space for feeding said reactants into said reaction space, and outfeed means connectable to said reaction space for discharging excess reactants and reaction gases from said reaction space, and at least one substrate adapted into said reaction space.

Abstract: Crystal growth apparatus comprising a crucible for containing a supply of molten material from which the crystal may be grown and first reflection means for receiving radiation directed along an input path and reflecting radiation towards second reflection means, whereby the second reflection means reflect output radiation along an output path. The first and second reflection means are arranged at or in close proximity with the surface of the molten material such that during crystal growth they maintain a substantially constant position relative to the surface of the molten material. The apparatus may comprise support means for supporting the first and second reflection means, whereby the support means are arranged to float on the molten material. The apparatus may be a single crucible apparatus or a double crucible apparatus.