Siemens Aktiengesellschaft

Richard Falckenberg

Josef Grabmaier

Gerhard Hoyler

Christa Grabmaier

Helmut Foell

Bernhard Freienstein

Lore Bernewitz

Ali Abd El Wahid

Helmut Foll

For the continuous melting of silicon granulate for a band drawing method, a melt reservoir in communication with the melt crucible based on the principle of communicating vessels, is provided in the form of a thermally insulated, annular crucible in whose center axis a rotary plate to be centrifugally accelerated is arranged, the speed thereof being continuously varied. Two pipe parts connected to one another at an angle between approximately 45.degree. to about 90.degree. are secured on the rotary plate, the one, vertical pipe part thereof serving as admission in the rotational axis and the other pipe part thereof forming the acceleration path for the granulate particles in the direction toward the annular melt crucible. On the basis of this arrangement, a uniform delivery and melting of the granulate particles in the melt surface is achieved and, thus, a continuous silicon band drawing with uniform layer thickness is enabled. The arrangement is used in the manufacture of silicon bands for solar cells.

Arrangement for the continuous melting of granulated silicon for a

A method and device for the complete emptying of flat quartz tanks or crucibles filled with silicon melt is provided. The apparatus includes an open outlet nozzle located in a floor of the tank and a tube-shaped, rod-shaped, or channel-shaped member composed of a material that is well-wettable by silicon melt that is brought into contact with the outlet nozzle after the conclusion of the drawing process. The member is in fluid communication with a collecting vessel. The outlet nozzle is so constructed and arranged that the silicon melt adjacent at the nozzle aperture is prevented from running out during the band drawing due to the curvature pressure of its downwardly, convexly arced surface. The apparatus can be used in continuous, horizontal band-drawing of silicon for solar cells.

Arrangement for the complete emptying of quartz tanks or crucibles

A method and apparatus for producing disk-shaped or wafer-shaped silicon bodies from a silicon tape produced in a horizontal tape-drawing process, utilizing a woven fabric of graphite threads as a carrier for the silicon to be crystallized. The crystallization of the molten silicon is initiated by heating sources positioned about the melt crucible. Radiation losses are reduced by providing shielding members in predetermined, prescribed intervals corresponding to the areas at which the parting lines are to be provided in the tape. The shielding members reduce the radiation losses to such an extent that a readily frangible line is produced in the area of the shielding members enabling the tape to be broken up at regular, predetermined intervals on a continuous basis.

Apparatus for parting wafer-shaped silicon bodies, useful for solar

A method for horizontal silicon tape drawing is provided which can be practiced at a high drawing speed. The carrier member uses parallel threads of a material having a higher emission factor .epsilon. than the emission factor of molten silicon and such threads serve as crystallization nucleators for silicon. A silicon melt tank is used which has a length l that is at least as long as the contacting length existing between the surface of molten silicon and the horizontally moving threads so that L=V.sub.z .multidot.t where v.sub.z is the drawing speed and t is the dwell time. The drawing direction d.sub.z is set inclined at an angle .alpha..ltoreq. 10.degree. relative to the horizontal. Radiant losses from the silicon melt surface are regulated by reflectors. The method provides the possibility of manufacturing tape-shaped silicon crystals 16 for solar cells with a constant thickness and width.

Method and apparatus for manufacturing tape-shaped silicon crystals with

A method for manufacturing crack-free, large-surface silicon crystal bodies for solar cells wherein a carrier member composed of a carbon fiber fabric is coated with silicon by bringing a molten silicon into contact with the carrier member and crystallizing it. In order to improve the wettability, the carrier member is subjected to an activating surface treatment before the coating. The method is useful for continuous manufacture of silicon sheets for solar cells.

Carbon fiber substrate pretreatment for manufacturing crack-free,

Starting plate-like silicon bodies matched to the dimensions desired in a product silicon crystal bodies are melted and then crystallized on a horizontal carrier member having a net structure using a heater arrangement. The carrier member is substantially not wettable by molten silicon and preferably consists of a quartz glass fiber fabric and is removable after the crystallization. The method is useful for the manufacture of silicon for solar cells and prevents contaminants from the carrier member from being incorporated into the product silicon crystal body and thereby deteriorating the electrical properties of the solar cells.

Method for making large-surface silicon crystal bodies

A method and an apparatus is provided for the manufacture of large-area silicon crystal bodies useful for solar cells. A carrier member consisting of a net-like graphite fabric or quartz fabric is moved horizontally through a heater arrangement carrying silicon plates on its surface which are matched to the dimensions of the carrier member. The silicon body is caused to melt and the molten silicon fills in the meshes of the net after which crystallization is induced. Meshes having dimensions up to about 10 mm.times.10 mm are thus filled with silicon. The technique involves low production costs and high product crystal quality and serves for the continuous manufacture of silicon ribbons for solar cells.

Method large-area silicon bodies

Apparatus for the manufacture of large-surfaced, band-shaped silicon bodies for solar cells through a continuous layering process which uses a net-like structured graphite carrier unit. The net-like structure is used in conjunction with a melting pot made from graphite for receiving silicon smelt. The smelt is fed via a drain opening provided in the floor section of the melting pot to the carrier unit guided through a canal which has been arranged in horizontal direction below the melting pot. In order to ensure a continuous replacement of the smelt volume in the layering canal, the canal is shaped in downward direction as a shallow basin made from quartz, whereby the basin areas 'a' and 'b' are of different depth. In this manner, a 'reserve volume' is provided, which ensures a uniform layering. The apparatus allows a continuous production of silicon bands for solar cells.

Apparatus for manufacturing large-surface, band-shaped silicon for solar

In an exemplary embodiment, tape-shaped silicon bodies for solar cells are formed by continuous coating of a carrier body having a mesh structure. A melt bath receives the silicon melt and has a floor part with capillary openings therein for supplying the melt, the capillary openings leading perpendicularly toward the exterior of the vat and proceeding parallel to one another, and wherein a channel for the guidance of the carrier body proceeding in a horizontal direction is disposed below the melt vat in the region of the capillary openings. The guide channel for the carrier body can also be disposed above a body with capillaries proceeding parallel in a vertical direction, the body being partially immersed in the vat containing the silicon melt for the purpose of supplying the melt via the capillaries. The devices enable continuous tape drawing from a silicon melt wherein convection currents are avoided in the melt.

Device for manufacturing large-surface, tape-shaped silicon bodies for

An improved large surface, quasi-monocrystalline silicon crystal bodies of the type used in solar cells. The bodies are produced by reacting at least the surface of a carbon fiber fabric with molten silicon under conditions of temperature and viscosity sufficient to cause the molten silicon to penetrate the fabric and produce silicon carbide at at least the surface of the fibers, and immediately thereafter coating the thus reacted fabric with metallic silicon from a second molten silicon bath to produce a silicon coating.

Method for manufacturing large surface silicon crystal bodies for solar

A method for continuously manufacturing silicon tapes which are predominantly coated on one side of the carrier, for solar cells. In an exemplary embodiment, a carrier body consisting of a graphite network is conducted vertically upwards through a guide channel situated in the floor of a silicon melt bath and travels through a crystallization region where the molten silicon crystallizes on the carrier body. The surfaces of the guide channel at each side of the carrier path in the vicinity of the crystallization region are wetted by the molten silicon and have different dimensions in a direction at right angles to the carrier path. As a result of the differential in surface tension forces at the two sides of the path, a meniscus is formed which is asymmetrical relative to the channel opening thereby causing asymmetrical coating of the carrier body.

Method and device for asymmetrically coating a tape-shaped carrier body

Apparatus and method for asymmetrically coating a tape-shaped carrier body with crystallized silicon for further processing into solar cells. In an exemplary embodiment a carrier body in the form of a graphite mesh is to be drawn through a guide channel leading from the floor of a melt vat and is moistened by the melt. The silicon is caused to crystallize above the melt vat because of a temperature gradient generated at right angles relative to the path of the coated carrier body. The temperature gradient can, for example, be produced by means of single-sided heating, or by a plate-shaped body extending from the melt parallel to the carrier body, or by guide lips with upper boundaries exhibiting different heights and widths. The method and apparatus serve for the continuous manufacture of silicon tapes for solar cells.

Device for asymmetrically coating a tape-shaped carrier body with

Powder flow in an apparatus for growing crystals according to the process of Verneuil, whereby powder falls downwardly into a flame impinging on and melting a surface of a seed crystal, is made uniform by isolating the powder supply container from oscillations in the air column beneath the container induced by vertical movements of a screening grid in the apparatus. Isolation is effected by a rotating sphere in a flow tube of the apparatus between the supply container and the oscillating screen, the sphere having close tolerances to the wall of the tube and vertical grooves in its periphery. The vertical grooves and the sphere surface also can meter the falling powder.

Powder flow control device for growing Verneuil crystals

An apparatus for producing monocrystals having a relatively large cross-section by the Verneuil technique wherein a seed crystal is mounted on a movable crystal support member within a furnace means having a burner guiding flame gases and crystal growth material for impingement against the seed crystal so that the material melts and adheres to the seed crystal and forms a monocrystal which grows axially upwardly therefrom while the seed crystal member is moved axially downwardly a distance corresponding to the amount of axial crystal growth so that substantially uniform growth conditions are maintained throughout the growing process. A relatively massive flame deflector member having a central passage therein is positioned within a furnace means in spaced registry from the burner and radially about the crystal support member so as to deflect the flame gases laterally away from the growing crystal and to receive sufficient heat therefrom to form a heat reservoir for the growing crystal after flame shutdown. At least one axially movable insert member is positioned within the through passage of the deflector member and radially spaced from the crystal support member and the deflector member so as to be selectively movable in relation to the deflector member and the support member.

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Wald, Germany

Richard Falckenberg