Westinghouse Electric Corporation

The United States of America As Represented by the United States

Paul A Piotrowski

Charles S Duncan

Edgar L Kochka

James P McHugh

Raymond G Seidensticker

Maria E Skutch

Robert B Campbell

A lid for a susceptor in which a crystalline material is melted by induction heating to form a pool or melt of molten material from which a dendritic web of essentially a single crystal of the material is pulled through an elongated slot in the lid and the lid has a pair of generally round openings adjacent the ends of the slot and a groove extends between each opening and the end of the slot. The grooves extend from the outboard surface of the lid to adjacent the inboard surface providing a strip contiguous with the inboard surface of the lid to produce generally uniform radiational heat loss across the width of the dendritic web adjacent the inboard surface of the lid to reduce thermal stresses in the web and facilitate the growth of wider webs at a greater withdrawal rate.

Lid for improved dendritic web growth

A new lid and shield configuration for use in growing silicon dendritic web crystals is disclosed. The arrangement includes a plurality of spaced apart shields stacked above a lid having a slot therein through which dendritic web crystals are pulled. The shields also have slots in them, each successive shield having a slot slightly larger than that of the shield beneath it. The result is the ability for 100% melt replenishment plus increased productivity.

Web growth configuration for higher productivity and 100% feed rate

A method for doping a silicon melt for growing silicon dendritic web crystals is disclosed. The melt is doped with antimony prior to commencing web growth, which allows the crystals to be grown without the need for replenishing the dopant, and producing crystals having uniform resistivities. Photovoltaic cells produced from crystals grown from the antimony doped melt exhibit superior properties relative to those doped according to other methods.

Method for doping a melt

This disclosure describes an apparatus to improve the web growth attainable from prior web growth configurations. This apparatus modifies the heat loss at the growth interface in a manner that minimizes thickness variations across the web, especially regions of the web adjacent to the two bounding dendrites. In the unmodified configuration, thinned regions of web, adjacent to the dendrites, were found to be the origin of crystal degradation which ultimately led to termination of the web growth. According to the present invention, thinning adjacent to the dendrites is reduced and the incidence of crystal degradation is similarly reduced.

Apparatus for silicon web growth of higher output and improved growth

A crucible/susceptor system is described in which the walls of the crucible and the susceptor cavity are sloped outward in an angle sufficient for the force of gravity to exceed the inward pulling forces created by the high surface tension of molten silicon allowing the softened quartz crucible walls to settle into and form to the sloped walls of the susceptor thereby improving heat transfer from the susceptor to the molten silicon and improving the reproducibility of the system.

Conforming crucible/susceptor system for silicon crystal growth

A melt system including a susceptor-crucible assembly having improved gradient control when melt replenishment is used during dendritic web growth. The improvement lies in the formation of a thermal barrier in the base of the receptor which is in the form of a vertical slot in the region of the susceptor underlying the crucible at the location of a compartmental separator dividing the crucible into a growth compartment and a melt replenishment compartment. The result achieved is a step change in temperature gradient in the melt thereby providing a more uniform temperature in the growth compartment from which the dendritic web is drawn.

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Monroeville, PA, United States of America

Paul A Piotrowski