Patents by Inventor Subhash Mahajan

Subhash Mahajan 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: 9412580
    Abstract: Embodiments of the invention include methods for forming Group III-nitride semiconductor structure using a halide vapor phase epitaxy (HVPE) process. The methods include forming a continuous Group III-nitride nucleation layer on a surface of a non-native growth substrate, the continuous Group III-nitride nucleation layer concealing the upper surface of the non-native growth substrate. Forming the continuous Group III-nitride nucleation layer may include forming a Group III-nitride layer and thermally treating said Group III-nitride layer. Methods may further include forming a further Group III-nitride layer upon the continuous Group III-nitride nucleation layer.
    Type: Grant
    Filed: November 23, 2011
    Date of Patent: August 9, 2016
    Assignee: SOITEC
    Inventors: Chantal Arena, Ronald Thomas Bertram, Jr., Ed Lindow, Subhash Mahajan, Fanyu Meng
  • Patent number: 9076666
    Abstract: Methods of depositing III-nitride semiconductor materials on substrates include depositing a layer of III-nitride semi-conductor material on a surface of a substrate in a nucleation HVPE process stage to form a nucleation layer having a microstructure comprising at least some amorphous III-nitride semiconductor material. The nucleation layer may be annealed to form crystalline islands of epitaxial nucleation material on the surface of the substrate. The islands of epitaxial nucleation material may be grown and coalesced in a coalescence HVPE process stage to form a nucleation template layer of the epitaxial nucleation material. The nucleation template layer may at least substantially cover the surface of the substrate. Additional III-nitride semiconductor material may be deposited over the nucleation template layer of the epitaxial nucleation material in an additional HVPE process stage. Final and intermediate structures comprising III-nitride semiconductor material are formed by such methods.
    Type: Grant
    Filed: November 23, 2011
    Date of Patent: July 7, 2015
    Assignees: SOITEC, Arizona Board of Regents For and On Behalf Arizona State University
    Inventors: Chantal Arena, Ronald Thomas Bertram, Jr., Ed Lindow, Subhash Mahajan, Ilsu Han
  • Patent number: 9012919
    Abstract: Embodiments of the invention relate to methods of fabricating semiconductor structures, and to semiconductor structures fabricated by such methods. In some embodiments, the methods may be used to fabricate semiconductor structures of III-V materials, such as InGaN. A semiconductor layer is fabricated by growing sublayers using differing sets of growth conditions to improve the homogeneity of the resulting layer, to improve a surface roughness of the resulting layer, and/or to enable the layer to be grown to an increased thickness without the onset of strain relaxation.
    Type: Grant
    Filed: January 10, 2013
    Date of Patent: April 21, 2015
    Assignee: Soitec
    Inventors: Ed Lindow, Chantal Arena, Ronald Bertram, Ranjan Datta, Subhash Mahajan
  • Publication number: 20140217553
    Abstract: Methods of depositing III-nitride semiconductor materials on substrates include depositing a layer of III-nitride semiconductor material on a surface of a substrate in a nucleation HVPE process stage to form a nucleation layer having a microstructure comprising at least some amorphous III-nitride semiconductor material. The nucleation layer may be annealed to form crystalline islands of epitaxial nucleation material on the surface of the substrate. The islands of epitaxial nucleation material may be grown and coalesced in a coalescence HVPE process stage to form a nucleation template layer of the epitaxial nucleation material. The nucleation template layer may at least substantially cover the surface of the substrate. Additional III-nitride semiconductor material may be deposited over the nucleation template layer of the epitaxial nucleation material in an additional HVPE process stage. Final and intermediate structures comprising III-nitride semiconductor material are formed by such methods.
    Type: Application
    Filed: November 23, 2011
    Publication date: August 7, 2014
    Applicants: ARIZONA BOARD OF REGENTS FOR AND ON BEHALF OF ARIZONA STATE UNIVERSITY, Soitec
    Inventors: Chantal Arena, Ronald Thomas Bertram, JR., Ed Lindow, Subhash Mahajan, Ilsu Han
  • Patent number: 8574968
    Abstract: This invention provides methods for fabricating substantially continuous layers of a group III nitride semiconductor material having low defect densities and optionally having a selected crystal polarity. The methods include epitaxial growth nucleating and/or seeding on the upper portions of a plurality of pillars/islands of a group III nitride material that are irregularly arranged on a template structure. The upper portions of the islands have low defect densities and optionally have a selected crystal polarity. The invention also includes template structures having a substantially continuous layer of a masking material through which emerge upper portions of the pillars/islands. The invention also includes such template structures. The invention can be applied to a wide range of semiconductor materials, both elemental semiconductors, e.g., combinations of Si (silicon) with strained Si (sSi) and/or Ge (germanium), and compound semiconductors, e.g.
    Type: Grant
    Filed: July 25, 2008
    Date of Patent: November 5, 2013
    Assignees: Soitec, Arizona Board of Regents for and on Behalf of Arizona State University
    Inventors: Chantal Arena, Christiaan J. Werkhoven, Ronald Thomas Bertram, Jr., Ed Lindow, Subhash Mahajan, Ranjan Datta, Rahul Ajay Trivedi, Ilsu Han
  • Publication number: 20130234157
    Abstract: Embodiments of the invention include methods for forming Group III-nitride semiconductor structure using a halide vapor phase epitaxy (HVPE) process. The methods include forming a continuous Group III-nitride nucleation layer on a surface of a non-native growth substrate, the continuous Group III-nitride nucleation layer concealing the upper surface of the non-native growth substrate. Forming the continuous Group III-nitride nucleation layer may include forming a Group III-nitride layer and thermally treating said Group III-nitride layer. Methods may further include forming a further Group III-nitride layer upon the continuous Group III-nitride nucleation layer.
    Type: Application
    Filed: November 23, 2011
    Publication date: September 12, 2013
    Applicant: Soitec
    Inventors: Chantal Arena, Ronald Thomas Bertram, JR., Ed Lindow, Subhash Mahajan, Fanyu Meng
  • Publication number: 20130126896
    Abstract: Embodiments of the invention relate to methods of fabricating semiconductor structures, and to semiconductor structures fabricated by such methods. In some embodiments, the methods may be used to fabricate semiconductor structures of III-V materials, such as InGaN. A semiconductor layer is fabricated by growing sublayers using differing sets of growth conditions to improve the homogeneity of the resulting layer, to improve a surface roughness of the resulting layer, and/or to enable the layer to be grown to an increased thickness without the onset of strain relaxation.
    Type: Application
    Filed: January 10, 2013
    Publication date: May 23, 2013
    Applicant: Soitec
    Inventors: Ed Lindow, Chantal Arena, Ronald Bertram, Ranjan Datta, Subhash Mahajan
  • Patent number: 8377802
    Abstract: Embodiments of the invention relate to methods of fabricating semiconductor structures, and to semiconductor structures fabricated by such methods. In some embodiments, the methods may be used to fabricate semiconductor structures of III-V materials, such as InGaN. A semiconductor layer is fabricated by growing sublayers using differing sets of growth conditions to improve the homogeneity of the resulting layer, to improve a surface roughness of the resulting layer, and/or to enable the layer to be grown to an increased thickness without the onset of strain relaxation.
    Type: Grant
    Filed: March 23, 2011
    Date of Patent: February 19, 2013
    Assignee: Soitec
    Inventors: Ed Lindow, Chantal Arena, Ronald Bertram, Ranjan Datta, Subhash Mahajan
  • Patent number: 8318612
    Abstract: The invention provides methods which can be applied during the epitaxial growth of two or more layers of Group III-nitride semiconductor materials so that the qualities of successive layer are successively improved. In preferred embodiments, surface defects interact with a protective layer of a protective material to form amorphous complex regions capable of preventing the further propagation of defects and dislocations. The invention also includes semiconductor structures fabricated by these methods.
    Type: Grant
    Filed: November 14, 2008
    Date of Patent: November 27, 2012
    Assignees: Soitec, Arizona Board of Regents for and on behalf of Arizona State University
    Inventors: Chantal Arena, Subhash Mahajan
  • Patent number: 8236593
    Abstract: The invention provides methods which can be applied during the epitaxial growth of two or more layers of semiconductor materials so that the qualities of successive layer are successively improved. In preferred embodiments, surface defects present in one epitaxial layer are capped with a masking material. A following layer is then grown so it extends laterally above the caps according to the known phenomena of epitaxial lateral overgrowth. The methods of the invention can be repeated by capping surface defects in the following layer and then epitaxially growing a second following layer according to ELO. The invention also includes semiconductor structures fabricated by these methods.
    Type: Grant
    Filed: May 14, 2008
    Date of Patent: August 7, 2012
    Assignees: Soitec, Arizona Board of Regents for and on Behalf of Arizona State University
    Inventors: Chantal Arena, Subhash Mahajan, Ilsu Han
  • Publication number: 20110284863
    Abstract: Embodiments of the invention relate to methods of fabricating semiconductor structures, and to semiconductor structures fabricated by such methods. In some embodiments, the methods may be used to fabricate semiconductor structures of III-V materials, such as InGaN. A semiconductor layer is fabricated by growing sublayers using differing sets of growth conditions to improve the homogeneity of the resulting layer, to improve a surface roughness of the resulting layer, and/or to enable the layer to be grown to an increased thickness without the onset of strain relaxation.
    Type: Application
    Filed: March 23, 2011
    Publication date: November 24, 2011
    Applicants: Arizona Board of Regents for and on Behalf of Arizona State University, S.O.I.TEC SILICON ON INSULATOR TECHNOLOGIES
    Inventors: Ed Lindow, Chantal Arena, Ronald Bertram, Ranjan Datta, Subhash Mahajan
  • Publication number: 20110024747
    Abstract: The invention provides methods which can be applied during the epitaxial growth of two or more layers of Group III-nitride semiconductor materials so that the qualities of successive layer are successively improved. In preferred embodiments, surface defects interact with a protective layer of a protective material to form amorphous complex regions capable of preventing the further propagation of defects and dislocations. The invention also includes semiconductor structures fabricated by these methods.
    Type: Application
    Filed: November 14, 2008
    Publication date: February 3, 2011
    Applicant: S.O.I.Tec Silicon on Insulator Technologies
    Inventors: Chantal Arena, Subhash Mahajan
  • Patent number: 7732306
    Abstract: This invention provides methods for fabricating substantially continuous layers of group III nitride semiconductor materials having low defect densities. The methods include epitaxial growth of nucleation layers on a base substrate, thermally treatment of said nucleation layer and epitaxial growth of a discontinuous masking layer. The methods outlined promote defect reduction through masking, annihilation and coalescence, therefore producing semiconductor structures with low defect densities. The invention can be applied to a wide range of semiconductor materials, both elemental semiconductors, e.g., combinations of Si (silicon) with strained Si (sSi) and/or Ge (germanium), and compound semiconductors, e.g., group II-VI and group III-V compound semiconductor materials.
    Type: Grant
    Filed: July 25, 2008
    Date of Patent: June 8, 2010
    Assignee: S.O.I.Tec Silicon on Insulator Technologies
    Inventors: Chantal Arena, Subhash Mahajan, Ranjan Datta
  • Publication number: 20100133548
    Abstract: The invention provides methods which can be applied during the epitaxial growth of two or more layers of semiconductor materials so that the qualities of successive layer are successively improved. In preferred embodiments, surface defects present in one epitaxial layer are capped with a masking material. A following layer is then grown so it extends laterally above the caps according to the known phenomena of epitaxial lateral overgrowth. The methods of the invention can be repeated by capping surface defects in the following layer and then epitaxially growing a second following layer according to ELO. The invention also includes semiconductor structures fabricated by these methods.
    Type: Application
    Filed: May 14, 2008
    Publication date: June 3, 2010
    Inventors: Chantal Arena, Subhash Mahajan, Ilsu Han
  • Publication number: 20090098343
    Abstract: This invention provides methods for fabricating substantially continuous layers of a group III nitride semiconductor material having low defect densities and optionally having a selected crystal polarity. The methods include epitaxial growth nucleating and/or seeding on the upper portions of a plurality of pillars/islands of a group III nitride material that are irregularly arranged on a template structure. The upper portions of the islands have low defect densities and optionally have a selected crystal polarity. The invention also includes template structures having a substantially continuous layer of a masking material through which emerge upper portions of the pillars/islands. The invention also includes such template structures. The invention can be applied to a wide range of semiconductor materials, both elemental semiconductors, e.g., combinations of Si (silicon) with strained Si (sSi) and/or Ge (germanium), and compound semiconductors, e.g.
    Type: Application
    Filed: July 25, 2008
    Publication date: April 16, 2009
    Inventors: Chantal ARENA, Christiaan J. Werkhoven, Ronald Thomas Bertram, JR., Ed Lidow, Subhash Mahajan, Ranjan Datta, Rahul Ajay Trivedi, Ilsu Han
  • Publication number: 20090091002
    Abstract: This invention provides methods for fabricating substantially continuous layers of group III nitride semiconductor materials having low defect densities. The methods include epitaxial growth of nucleation layers on a base substrate, thermally treatment of said nucleation layer and epitaxial growth of a discontinuous masking layer. The methods outlined promote defect reduction through masking, annihilation and coalescence, therefore producing semiconductor structures with low defect densities. The invention can be applied to a wide range of semiconductor materials, both elemental semiconductors, e.g., combinations of Si (silicon) with strained Si (sSi) and/or Ge (germanium), and compound semiconductors, e.g., group II-VI and group III-V compound semiconductor materials.
    Type: Application
    Filed: July 25, 2008
    Publication date: April 9, 2009
    Inventors: Chantal ARENA, Subhash Mahajan, Ranjan Datta
  • Patent number: 4620854
    Abstract: In the liquid phase epitaxy growth of Group III-V compound semiconductors using boat-slider apparatus, melt-carry-over is essentially eliminated by prebaking the metallic solvent (e.g., In shot) in the boat to form ingots and then etching the ingots in dilute nitric or hydrochloric acid prior to adding solutes (e.g., GaAs, InP, dopants). This process removes contaminants which coalesce on the ingots and cause poor wipe-off.
    Type: Grant
    Filed: October 21, 1985
    Date of Patent: November 4, 1986
    Assignee: AT&T Bell Laboratories
    Inventors: Daniel Brasen, Michael A. DiGiuseppe, Jose A. Lourenco, Subhash Mahajan
  • Patent number: 4566934
    Abstract: In the liquid phase epitaxy growth of Group III-V compound semiconductors using boat-slider apparatus, melt-carry-over is essentially eliminated by prebaking the metallic solvent (e.g., In shot) in the boat to form ingots and then etching the ingots in dilute nitric or hydrochloric acid prior to adding solutes (e.g., GaAs, InP, dopants). This process removes contaminants which coalesce on the ingots and cause poor wipe-off.
    Type: Grant
    Filed: October 28, 1982
    Date of Patent: January 28, 1986
    Assignee: AT&T Bell Laboratories
    Inventors: Daniel Brasen, Michael A. DiGiuseppe, Jose A. Lourenco, Subhash Mahajan