Patents by Inventor Ravindranath Droopad

Ravindranath Droopad 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).

  • Publication number: 20020195057
    Abstract: An apparatus for forming a semiconductor structure is provided. The apparatus includes a chamber and a plurality of first material sources positioned at least partially within the chamber. The plurality of first material sources are configured to provide materials for the formation of a monocrystalline accommodating buffer layer on a substrate. The plurality of first material sources includes an oxygen source. At least one second material source is also positioned at least partially within the chamber and is configured to provide material for the formation of a monocrystalline oxygen-doped material layer overlying the monocrystalline accommodating buffer layer. The apparatus also includes an oxygen-adjustment mechanism configured to adjust the partial pressure of oxygen in the chamber.
    Type: Application
    Filed: June 21, 2001
    Publication date: December 26, 2002
    Applicant: MOTOROLA, INC.
    Inventors: Ravindranath Droopad, Scott T. Massie
  • Publication number: 20020197881
    Abstract: A method of fabricating a semiconductor structure including the steps of providing a silicon substrate (10) having a surface (12), forming on the surface (12) of the silicon substrate (10), by atomic layer deposition (ALD), a monocrystalline seed layer (20;21′) comprising a silicate material and forming, by atomic layer deposition (ALD) one or more layers of a monocrystalline high dielectric constant oxide (42) on the seed layer (20;21′).
    Type: Application
    Filed: June 21, 2001
    Publication date: December 26, 2002
    Applicant: MOTOROLA, INC.
    Inventors: Jamal Ramdani, Ravindranath Droopad, Zhiyi Yu
  • Publication number: 20020195599
    Abstract: High quality epitaxial layers of monocrystalline materials can be grown overlying monocrystalline substrates such as large silicon wafers (22) by forming a compliant substrate for growing the monocrystalline layers. One way to achieve the formation of a compliant substrate includes first growing an accommodating buffer layer (24) on a silicon wafer (22). The accommodating buffer layer (24) is a layer of monocrystalline oxide spaced apart from the silicon wafer (22) by an amorphous interface layer (28) of silicon oxide. The amorphous interface layer (28) dissipates strain and permits the growth of a high quality monocrystalline oxide accommodating buffer layer.
    Type: Application
    Filed: June 20, 2001
    Publication date: December 26, 2002
    Applicant: MOTOROLA, INC.
    Inventors: Zhiyi Yu, Ravindranath Droopad
  • Publication number: 20020187600
    Abstract: A semiconductor structure exhibiting reduced leakage current is formed of a monocrystalline substrate (101) and a strained-layer heterostructure (105). The strained-layer heterostructure has a first layer (102) formed of a first monocrystalline oxide material having a first lattice constant and a second layer (104) formed of a second monocrystalline oxide material overlying the first layer and having a second lattice constant. The second lattice constant is different from the first lattice constant. The second layer creates strain within the oxide material layers, at the interface between the first and second oxide material layers of the heterostructure, and at the interface of the substrate and the first layer, which changes the energy band offset at the interface of the substrate and the first layer.
    Type: Application
    Filed: July 30, 2002
    Publication date: December 12, 2002
    Applicant: MOTOROLA, INC.
    Inventors: Zhiyi Yu, Ravindranath Droopad
  • Patent number: 6493497
    Abstract: High quality epitaxial layers of oxide can be grown overlying large silicon wafers by first growing an accommodating buffer layer on a silicon wafer. The accommodating buffer layer is a layer of monocrystalline oxide spaced apart from the silicon wafer by an amorphous interface layer of silicon oxide. The amorphous intermediate layer dissipates strain and permits the growth of a high quality monocrystalline oxide accommodating buffer layer. Any lattice mismatch between the accommodating buffer layer and the underlying silicon substrate is taken care of by the amorphous intermediate layer. Waveguides may be formed of high quality monocrystalline material atop the monocrystalline buffer layer. The waveguides can suitably be formed to modulate the wave. Monolithic integration of oxide based electro-optic devices with III-V based photonics and Si circuitry is fully realized.
    Type: Grant
    Filed: September 26, 2000
    Date of Patent: December 10, 2002
    Assignee: Motorola, Inc.
    Inventors: Jamal Ramdani, Lyndee Hilt, Ravindranath Droopad, William Jay Ooms
  • Publication number: 20020179936
    Abstract: High quality epitaxial layers of monocrystalline materials can be grown overlying monocrystalline substrates such as large silicon wafers by forming a compliant substrate for growing the monocrystalline layers.
    Type: Application
    Filed: June 1, 2001
    Publication date: December 5, 2002
    Applicant: MOTOROLA, INC.
    Inventor: Ravindranath Droopad
  • Patent number: 6482538
    Abstract: A high quality epitaxial layer of monocrystalline Pb(Mg,Nb)O3—PbTiO3 or Pb(Mg1−xNbx)O3—PbTiO3 can be grown overlying large silicon wafers by first growing an strontium titanate layer on a silicon wafer. The strontium titanate layer is a monocrystalline layer spaced apart from the silicon wafer by an amorphous interface layer of silicon oxide.
    Type: Grant
    Filed: July 25, 2001
    Date of Patent: November 19, 2002
    Assignee: Motorola, Inc.
    Inventors: Ramamoorthy Ramesh, Yu Wang, Jeffrey M. Finder, Zhiyi Yu, Ravindranath Droopad, Kurt Eisenbeiser
  • Publication number: 20020167005
    Abstract: The present invention provides semiconductor structures and methods for forming semiconductor structures which include monocrystalline oxide films exhibiting both high dielectric constants and low leakage current densities. In accordance with various aspects of the invention, a semiconductor structure includes a monocrystalline semiconductor substrate and one or more stoichiometrically graduated monocrystalline oxide layers. The stoichiometrically graduated monocrystalline oxide layer may include a perovskite material, such as an alkaline-earth metal titanate. Semiconductor devices fabricated in accordance with aspects of the present invention exhibit a high dielectric constant as well as a reduced leakage current density.
    Type: Application
    Filed: May 11, 2001
    Publication date: November 14, 2002
    Applicant: Motorola, Inc
    Inventors: Zhiyi Yu, Ravindranath Droopad, Corey Overgaard
  • Patent number: 6479173
    Abstract: A semiconductor structure comprises a silicon substrate (10), one or more layers of single crystal oxides or nitrides (26), and an interface (14) between the silicon substrate and the one or more layers of single crystal oxides or nitrides, the interface manufactured with a crystalline material which matches the lattice constant of silicon. The interface comprises an atomic layer of silicon, nitrogen, and a metal in the form MSiN2, where M is a metal. In a second embodiment, the interface comprises an atomic layer of silicon, a metal, and a mixture of nitrogen and oxygen in the form MSi[N1−xOx]2, where M is a metal and X is 0≦X<1.
    Type: Grant
    Filed: December 17, 1999
    Date of Patent: November 12, 2002
    Assignee: Motorola, Inc.
    Inventors: Zhiyi Yu, Jun Wang, Ravindranath Droopad, Alexander Demkov, Jerald Allan Hallmark, Jamal Ramdani
  • Publication number: 20020163010
    Abstract: High quality epitaxial layers (26) of wide bandgap materials can be grown overlying monocrystalline substrates (22) such as large silicon wafers by forming a compliant substrate for growing the monocrystalline layers. One way to achieve the formation of a compliant substrate includes first growing an accommodating buffer layer (24) on a silicon wafer (22). The accommodating buffer layer (24) is a layer of monocrystalline oxide or nitride spaced apart from the silicon wafer (22) by an amorphous interface layer of silicon oxide (28). The layer of wide bandgap material (26) can be used to form electronic devices such as high frequency devices or light emitting devices such as lasers and light emitting diodes.
    Type: Application
    Filed: May 4, 2001
    Publication date: November 7, 2002
    Applicant: Motorola, Inc.
    Inventors: Ravindranath Droopad, Dirk C. Jordan, Zhiyi Yu
  • Publication number: 20020164827
    Abstract: A high quality epitaxial layer of monocrystalline Pb(Zr,Ti)O3 can be grown overlying large silicon wafers by first growing an strontium titanate layer on a silicon wafer. The strontium titanate layer is a monocrystalline layer spaced apart from the silicon wafer by an amorphous interface layer of silicon oxide.
    Type: Application
    Filed: April 19, 2002
    Publication date: November 7, 2002
    Inventors: Ramoothy Ramesh, Yu Wang, Jeffrey M. Finder, Kurt Eisenbeiser, Zhiyi Yu, Ravindranath Droopad
  • Publication number: 20020163024
    Abstract: High quality epitaxial layers of monocrystalline materials can be grown overlying monocrystalline substrates such as large silicon wafers by forming a compliant substrate for growing the monocrystalline layers. One way to achieve the formation of a compliant substrate includes first growing an accommodating buffer layer (24) on a silicon wafer (22). The accommodating buffer layer is lattice matched to both the underlying silicon wafer and the overlying monocrystalline material layer (26). The monocrystalline material layer is epitaxially grown over at least a portion of the accommodating buffer layer via lateral epitaxial overgrowth.
    Type: Application
    Filed: May 4, 2001
    Publication date: November 7, 2002
    Applicant: Motorola, Inc.
    Inventors: Dirk C. Jordan, Ravindranath Droopad, Zhiyi Yu, Corey Overgaard
  • Publication number: 20020158245
    Abstract: High quality epitaxial layers of monocrystalline materials can be grown overlying monocrystalline substrates such as large silicon wafers by forming a compliant substrate for growing the monocrystalline layers. One way to achieve the formation of a complaint substrate includes first growing a monocrystalline binary metal oxide material layer (14) on a substrate (12). The binary metal oxide material layer (14) is lattice matched to both the underlying substrate (12) and the overlying monocrystalline material layer (16).
    Type: Application
    Filed: April 26, 2001
    Publication date: October 31, 2002
    Applicant: Motorola, Inc.
    Inventors: Zhiyi Yu, Ravindranath Droopad, William J. Ooms
  • Patent number: 6472276
    Abstract: A composite semiconductor including silicon and compound semiconductor, and having a silicate layer for promoting layer-by-layer monocrystalline growth. Silicon may be introduced to react with the monocrystalline oxide layer to form the silicate layer. During the fabrication process, the thickness of the amorphous oxide layer may be increased by suitable methods, such as annealing or oxygen diffusion.
    Type: Grant
    Filed: July 20, 2001
    Date of Patent: October 29, 2002
    Assignee: Motorola, Inc.
    Inventors: Lyndee L. Hilt, Ravindranath Droopad
  • Publication number: 20020153524
    Abstract: A high quality semiconductor structure includes a monocrystalline substrate and a perovskite stack overlying the substrate. The perovskite stack may be formed of a first accommodating layer formed of a first perovskite oxide material having a first lattice constant. A second accommodating layer is formed on the first accommodating layer. The second accommodating layer is formed of a second perovskite oxide material having a second lattice constant which is different from the first lattice constant of the first accommodating layer. A monocrystalline material layer is formed overlying the second accommodating layer. A strain is effected at the interface between the perovskite stack and the substrate, at the interface between the perovskite stack and the monocrystalline material layer and/or at the interface between the first accommodating layer and the second accommodating layer. The strain reduces defects in the monocrystalline material layer and results in reduced Schottky leakage current.
    Type: Application
    Filed: April 19, 2001
    Publication date: October 24, 2002
    Applicant: Motorola Inc.
    Inventors: Zhiyi Yu, Ravindranath Droopad, William J. Ooms
  • Publication number: 20020146895
    Abstract: A method of fabricating a semiconductor structure including the steps of providing a silicon substrate (10) having a surface (12), forming on the surface (12) of the silicon substrate (10), by atomic layer deposition (ALD), a seed layer (20;21′) comprising a silicate material and forming, by atomic layer deposition (ALD) one or more layers of a high dielectric constant oxide (42) on the seed layer (20;21′).
    Type: Application
    Filed: June 11, 2002
    Publication date: October 10, 2002
    Applicant: MOTOROLA, INC.
    Inventors: Jamal Ramdani, Ravindranath Droopad, Zhiyi Yu
  • Publication number: 20020144725
    Abstract: Solar cell structures (100) including high quality epitaxial layers of monocrystalline semiconductor materials that are grown overlying monocrystalline substrates (102) such as large silicon wafers by forming a compliant substrate for growing the monocrystalline layers are disclosed. One way to achieve the formation of a compliant substrate includes first growing an accommodating buffer layer (104) on a silicon wafer. The accommodating buffer (104) layer is a layer of monocrystalline material spaced apart from the silicon wafer by an amorphous interface layer (112) of silicon oxide. The amorphous interface layer (112) dissipates strain and permits the growth of a high quality monocrystalline oxide accommodating buffer layer. The solar cell structures also include a dye (110) to increase an efficiency of the solar cell.
    Type: Application
    Filed: April 10, 2001
    Publication date: October 10, 2002
    Applicant: Motorola, Inc.
    Inventors: Dirk C. Jordan, Barbara Foley Barenburg, Ravindranath Droopad
  • Publication number: 20020140013
    Abstract: High quality ionicly-bonded semiconductor materials can be grown overlying covalently-bonded substrates (22), such as large silicon wafers, by utilizing a stable template layer (24). The template layer is formed of material consisting of alkaline earth metal, alkaline earth metal silicide, alkaline earth metal silicate and/or Zintl-type phase material. A high-quality ionicly-bonded semiconductor material (26) may then be grown over the template layer.
    Type: Application
    Filed: April 2, 2001
    Publication date: October 3, 2002
    Applicant: Motorola, Inc.
    Inventors: Zhiyi Yu, Ravindranath Droopad, Corey Overgaard
  • Publication number: 20020140012
    Abstract: High-quality epitaxial layers of narrow-bandgap monocrystalline semiconductor materials can be grown overlying monocrystalline substrates (22), such as large silicon wafers, by forming a compliant substrate for growing the monocrystalline layers. One way to achieve the formation of a compliant substrate includes first growing a monocrystalline oxide layer (24) on a silicon wafer. The oxide layer may be spaced apart from the silicon wafer by an amorphous interface layer (28) of silicon oxide. The amorphous interface layer (28) dissipates strain and permits the growth of a high-quality monocrystalline oxide layer. The oxide layer (24) is lattice-matched to both the underlying silicon wafer and the overlying monocrystalline semiconductor material layer (26). Any lattice mismatch between the oxide layer (24) and the underlying silicon substrate (22) is relieved by the amorphous interface layer (28).
    Type: Application
    Filed: March 30, 2001
    Publication date: October 3, 2002
    Applicant: Motorola, Inc.
    Inventor: Ravindranath Droopad
  • Publication number: 20020117664
    Abstract: Compound semiconductor structures and devices can be grown on patterned oxide layers deposited on silicon. The deposition of Group II-VI and Group II-V compound semiconductors on patterned wafers results in an increase in the critical thickness for lattice mismatched layers and the relief of strain energy through side walls. As a result, high crystalline quality compound semiconductor material can be grown on less expensive and more accessible substrate to more cost effectively produce semiconductor components and devices having enhanced reliability.
    Type: Application
    Filed: February 28, 2001
    Publication date: August 29, 2002
    Applicant: Motorola, Inc.
    Inventor: Ravindranath Droopad