Patents by Inventor Subhendu Guha

Subhendu Guha 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: 5231048
    Abstract: The glow discharge deposition of thin film materials is most advantageously carried out at a pressure which is less than the pressure of the minimum point on the deposition system's Paschen curve and at a power which is in excess of the minimum power required to sustain a deposition plasma at the particular process pressure.
    Type: Grant
    Filed: December 23, 1991
    Date of Patent: July 27, 1993
    Assignee: United Solar Systems Corporation
    Inventors: Subhendu Guha, Arindam Banerjee, Chi C. Yang, XiXiang Xu
  • Patent number: 5221854
    Abstract: A protective layer is disposed between a silver reflective electrode and a layer of transparent conductive oxide in a photovoltaic device so as to prevent oxidation of the silver. The protective layer may be continuous or discontinuous and may be fabricated from MgF.sub.2, Si.sub.x N.sub.y or T.sub.ix N.sub.y where x and y are positive numbers.
    Type: Grant
    Filed: November 18, 1991
    Date of Patent: June 22, 1993
    Assignee: United Solar Systems Corporation
    Inventors: Arindam Banerjee, Subhendu Guha, Chi C. Yang
  • Patent number: 5204272
    Abstract: Open circuit voltage of photovoltaic devices manufactured by a microwave deposition process is increased by disposing a bias wire in the microwave energized plasma and applying a positive voltage of approximately 100 volts to the wire during only a portion of the time in which the intrinsic semiconductor layer is being deposited.
    Type: Grant
    Filed: December 13, 1991
    Date of Patent: April 20, 1993
    Assignee: United Solar Systems Corporation
    Inventors: Subhendu Guha, Arindam Banerjee, Chi C. Yang
  • Patent number: 5180690
    Abstract: A method for the low temperature fabrication of doped polycrystalline semiconductor alloy material. The method includes the steps of exposing a body of semiconductor alloy material to a reaction gas containing at least a source of the dopant element, and establishing an electrical potential sufficient to sputter etch the surface of said layer, while decomposing the reaction gas. This allows for the deposition of a layer of doped amorphous semiconductor alloy material upon the body of semiconductor alloy material. Thereafter, the doped layer of amorphous semiconductor alloy material is exposed to an annealing environment sufficient to at least partially crystallize said amorphous material, and activate the dopant element.
    Type: Grant
    Filed: July 9, 1990
    Date of Patent: January 19, 1993
    Assignee: Energy Conversion Devices, Inc.
    Inventors: Wolodymyr Czubatyj, Stanford R. Ovshinsky, Guy C. Wicker, David Beglau, Ronald Himmler, David Jablonski, Subhendu Guha
  • Patent number: 5180686
    Abstract: A method of depositing a layer of doped or undoped wide band gap oxide material by chemical spray pyrolysis, upon a continuously advancing, elongated web of substrate material in a continuous, roll-to-roll process.
    Type: Grant
    Filed: October 1, 1991
    Date of Patent: January 19, 1993
    Assignee: Energy Conversion Devices, Inc.
    Inventors: Arindam Banerjee, Subhendu Guha
  • Patent number: 4891330
    Abstract: A method of fabricating doped microcrystalline semiconductor alloy material which includes a band gap widening element through a glow discharge deposition process by subjecting a precursor mixture which includes a diluent gas to an a.c. glow discharge in the absence of a magnetic field of sufficient strength to induce electron cyclotron resonance.
    Type: Grant
    Filed: March 28, 1988
    Date of Patent: January 2, 1990
    Assignee: Energy Conversion Devices, Inc.
    Inventors: Subhendu Guha, Stanford R. Ovshinsky
  • Patent number: 4816082
    Abstract: One or more thin film solar cells in which the intrinsic layer of substantially amorphous semiconductor alloy material thereof includes at least a first band gap portion and a narrower band gap portion. The band gap of the intrinsic layer is spatially graded through a portion of the bulk thickness, said graded portion including a region removed from the intrinsic layer-dopant layer interfaces. The band gap of the intrinsic layer is always less than the band gap of the doped layers. The gradation of the intrinsic layer is effected such that the open circuit voltage and/or the fill factor of the one or plural solar cell structure is enhanced.
    Type: Grant
    Filed: August 19, 1987
    Date of Patent: March 28, 1989
    Assignee: Energy Conversion Devices, Inc.
    Inventors: Subhendu Guha, Chi-Chung Yang, Stanford R. Ovshinsky
  • Patent number: 4775425
    Abstract: An n-type microcrystalline semiconductor alloy material including a band gap widening element; a method of fabricating p-type microcrystalline semiconductor alloy material including a band gap widening element; and electronic and photovoltaic devices incorporating said n-type and p-type materials.
    Type: Grant
    Filed: July 27, 1987
    Date of Patent: October 4, 1988
    Assignee: Energy Conversion Devices, Inc.
    Inventors: Subhendu Guha, Stanford R. Ovshinsky
  • Patent number: 4698234
    Abstract: Precursor gaseous mixtures from which to glow discharge deposit wide and narrow band gap semiconductor alloy material, said material characterized by improved photoconductivity and stability and improved resistance to photodegradation. There is also specifically disclosed a method of fabricating a narrow band gap semiconductor which method does not suffer from the effects of differential depletion of the components of the precursor gaseous mixture.
    Type: Grant
    Filed: October 17, 1986
    Date of Patent: October 6, 1987
    Assignee: Energy Conversion Devices, Inc.
    Inventors: Stanford R. Ovshinsky, Subhendu Guha, Prem Nath, Chi C. Yang, Jeffrey Fournier, James Kulman
  • Patent number: 4696758
    Abstract: Precursor gaseous mixtures from which to glow discharge deposit wide and narrow band gap semiconductor alloy material, said material characterized by improved photoconductivity and stability and improved resistance to photodegradation. There is also specifically disclosed a method of fabricating a narrow band gap semiconductor which method does not suffer from the effects of differential depletion of the components of the precursor gaseous mixture.
    Type: Grant
    Filed: October 6, 1986
    Date of Patent: September 29, 1987
    Assignee: Energy Conversion Devices, Inc.
    Inventors: Stanford R. Ovshinsky, Subhendu Guha, Prem Nath, Chi Chung Yang, Jeffrey Fournier, James Kulman
  • Patent number: 4695859
    Abstract: A light emitting, thin film p-i-n diode characterized by aligned valence bands at the p-i interface and aligned conduction bands at the n-i interface and preferably including a layer of p-doped microcrystalline semiconductor alloy material. A photonic circuit fabricated as an integrated, solid state structure which includes a multilayered thin film light emitting element formed of semiconductor alloy material and a multilayered thin film light detecting element formed of semiconductor alloy material. The photonic circuit is particularly adapted for use as an integrated large area imager adapted to generate electrical signals corresponding to the image on an image-bearing document.
    Type: Grant
    Filed: October 20, 1986
    Date of Patent: September 22, 1987
    Assignee: Energy Conversion Devices, Inc.
    Inventors: Subhendu Guha, Satish Agarwal
  • Patent number: 4637895
    Abstract: Precursor gaseous mixtures from which to glow discharge deposit wide and narrow band gap semiconductor alloy material, said material characterized by improved photoconductivity and stability and improved resistance to photodegradation. There is also specifically disclosed a method of fabricating a narrow band gap semiconductor which method does not suffer from the effects of differential depletion of the components of the precursor gaseous mixture.
    Type: Grant
    Filed: April 1, 1985
    Date of Patent: January 20, 1987
    Assignee: Energy Conversion Devices, Inc.
    Inventors: Stanford R. Ovshinsky, Subhendu Guha, Prem Nath, Chi C. Yang, Jeffrey Fournier, James Kulman
  • Patent number: 4609771
    Abstract: A p-doped microcrystalline silicon alloy material incorporated into a tandem photovoltaic device.
    Type: Grant
    Filed: February 13, 1985
    Date of Patent: September 2, 1986
    Assignee: Sovonics Solar Systems
    Inventors: Subhendu Guha, James Kulman
  • Patent number: 4600801
    Abstract: A fluorinated, p-doped microcrystalline semiconductor alloy material; electronic devices incorporating said p-doped material; and the method for fabricating said p-doped material.
    Type: Grant
    Filed: November 2, 1984
    Date of Patent: July 15, 1986
    Assignee: Sovonics Solar Systems
    Inventors: Subhendu Guha, James Kulman
  • Patent number: 4555586
    Abstract: A photoresponsive device characterized by the capability of having photoinduced defects annealed out of the photoactive region thereof in a low temperature process. Low temperature annealability is provided by including small amounts of dopant material in the photoactive region of the semiconductor material of the device. More particularly, the incorporation of small amounts of a p-dopant, such as boron, into the intrinsic region of a p-i-n photovoltaic device lowers the annealing temperature thereof. Such low temperature annealable photovoltaic devices may be incorporated into modules designed to operate at temperatures sufficient to remove said light induced defects, thereby providing a photovoltaic module exhibiting long term stability in its energy conversion efficiency.
    Type: Grant
    Filed: August 6, 1984
    Date of Patent: November 26, 1985
    Assignee: Energy Conversion Devices, Inc.
    Inventors: Subhendu Guha, William DenBoer
  • Patent number: 4547621
    Abstract: An improved photovoltaic device characterized by long term stability in its photoconversion ability. The device is adapted to absorb incident light throughout a substantial portion of the bulk of the photoactive region thereof in a substantially uniform manner. Said uniform absorption of light is provided by grading the band gap of at least a portion of the semiconductor material of the photoactive region thereof such that the graded portions most proximate the light incident surface of the photovoltaic device have a wider band gap than do those portions more distal from the light incident surface. The band gap gradation may be smooth or stepped, and may be accomplished by compositional variation of the semiconductor materials forming the photoactive region. A method for fabricating the stable photovoltaic device of the instant invention is also provided.
    Type: Grant
    Filed: June 25, 1984
    Date of Patent: October 15, 1985
    Assignee: Sovonics Solar Systems
    Inventors: Michael Hack, Subhendu Guha