Patents by Inventor Paul A. Piotrowski

Paul A. Piotrowski has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5098287
    Abstract: 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.
    Type: Grant
    Filed: March 16, 1990
    Date of Patent: March 24, 1992
    Assignee: Westinghouse Electric Corp.
    Inventors: Charles S. Duncan, Edgar L. Kochka, Paul A. Piotrowski, Raymond G. Seidensticker
  • Patent number: 4997628
    Abstract: 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.
    Type: Grant
    Filed: August 24, 1989
    Date of Patent: March 5, 1991
    Assignee: Westinghouse Electric Corp.
    Inventor: Paul A. Piotrowski
  • Patent number: 4927489
    Abstract: 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.
    Type: Grant
    Filed: June 2, 1988
    Date of Patent: May 22, 1990
    Assignee: Westinghouse Electric Corp.
    Inventors: Robert B. Campbell, Edgar L. Kochka, Paul A. Piotrowski
  • Patent number: 4828808
    Abstract: 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.
    Type: Grant
    Filed: September 2, 1987
    Date of Patent: May 9, 1989
    Assignee: The United States of America as represented by the United States Department of Energy
    Inventors: Charles S. Duncan, Paul A. Piotrowski
  • Patent number: 4747774
    Abstract: 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.
    Type: Grant
    Filed: February 9, 1987
    Date of Patent: May 31, 1988
    Assignee: Westinghouse Electric Corp.
    Inventors: Paul A. Piotrowski, Edgar L. Kochka, Charles S. Duncan
  • Patent number: 4389377
    Abstract: 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.
    Type: Grant
    Filed: July 10, 1981
    Date of Patent: June 21, 1983
    Assignee: The United States of America as represented by the United States Department of Energy
    Inventors: Charles S. Duncan, Paul A. Piotrowski, Maria E. Skutch, James P. McHugh