Patents by Inventor Krishna C. Saraswat

Krishna C. Saraswat 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: 11588066
    Abstract: Tandem solar cell configurations are provided where at least one of the cells is a metal chalcogenide cell. A four-terminal tandem solar cell configuration has two electrically independent solar cells stacked on each other. A two-terminal solar cell configuration has two electrically coupled solar cells (same current through both cells) stacked on each other. Carrier selective contacts can be used to make contact to the metal chalcogenide cell (s) to alleviate the troublesome Fermi level pinning issue. Carrier-selective contacts can also remove the need to provide doping of the metal chalcogenide. Doping of the metal chalcogenide can be provided by charge transfer. These two ideas can be practiced independently or together in any combination.
    Type: Grant
    Filed: November 5, 2019
    Date of Patent: February 21, 2023
    Assignee: The Board of Trustees of the Leland Stanford Junior Univesity
    Inventors: Koosha Nassiri Nazif, Raisul Islam, Jin-Hong Park, Krishna C. Saraswat
  • Publication number: 20210359150
    Abstract: Tandem solar cell configurations are provided where at least one of the cells is a metal chalcogenide cell. A four-terminal tandem solar cell configuration has two electrically independent solar cells stacked on each other. A two-terminal solar cell configuration has two electrically coupled solar cells (same current through both cells) stacked on each other. Carrier selective contacts can be used to make contact to the metal chalcogenide cell (s) to alleviate the troublesome Fermi level pinning issue. Carrier-selective contacts can also remove the need to provide doping of the metal chalcogenide. Doping of the metal chalcogenide can be provided by charge transfer. These two ideas can be practiced independently or together in any combination.
    Type: Application
    Filed: November 5, 2019
    Publication date: November 18, 2021
    Inventors: Koosha Nassiri Nazif, Raisul Islam, Jin-Hong Park, Krishna C. Saraswat
  • Patent number: 9595812
    Abstract: A crossed nanobeam structure for strain engineering in semiconductor devices is provided. For example, such a structure can be used for a low-threshold germanium laser. While the photonic crystal nanobeam enables light confinement in a subwavelength volume with small optical loss, another crossing nanobeam induces high tensile strain in the small region where the optical mode is tightly confined. As maintaining a small optical loss and a high tensile strain reduces the required pumping for achieving net optical gain beyond cavity losses, this technique can be used to develop an extremely low-threshold Ge laser source. Moreover, the structure can be easily integrated into electronic and photonic circuits.
    Type: Grant
    Filed: June 23, 2015
    Date of Patent: March 14, 2017
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Donguk Nam, Jan A. Petykiewicz, Devanand S. Sukhdeo, Shashank Gupta, Jelena Vuckovic, Krishna C. Saraswat
  • Patent number: 9343608
    Abstract: A depletion-mode phototransitor is disclosed. The phototransistor having a substrate, a gate, a source, a drain and a channel. The source, drain and channel are doped to be the same type of semiconductor. The substrate can be made of silicon and/or germanium. The gate can be made of either aluminum or polysilicon.
    Type: Grant
    Filed: August 15, 2014
    Date of Patent: May 17, 2016
    Assignee: Board of Regents, The University of Texas System
    Inventors: Yeul Na, Krishna C Saraswat
  • Publication number: 20150372455
    Abstract: A crossed nanobeam structure for strain engineering in semiconductor devices is provided. For example, such a structure can be used for a low-threshold germanium laser. While the photonic crystal nanobeam enables light confinement in a subwavelength volume with small optical loss, another crossing nanobeam induces high tensile strain in the small region where the optical mode is tightly confined. As maintaining a small optical loss and a high tensile strain reduces the required pumping for achieving net optical gain beyond cavity losses, this technique can be used to develop an extremely low-threshold Ge laser source. Moreover, the structure can be easily integrated into electronic and photonic circuits.
    Type: Application
    Filed: June 23, 2015
    Publication date: December 24, 2015
    Inventors: Donguk Nam, Jan A. Petykiewicz, Devanand S. Sukhdeo, Shashank Gupta, Jelena Vuckovic, Krishna C. Saraswat
  • Publication number: 20150136214
    Abstract: Junction-less solar cells having three or more terminals are provided. Electron- and hole-selective contacts and interfaces are used in combination with two or more absorber layers having different bandgaps to provide multi-material solar cells that have no requirement for either lattice matching or current matching.
    Type: Application
    Filed: November 20, 2014
    Publication date: May 21, 2015
    Inventors: Raisul Islam, Gautam Shine, Aneesh Nainani, Krishna C. Saraswat
  • Publication number: 20140363917
    Abstract: A depletion-mode phototransitor is disclosed. The phototransistor having a substrate, a gate, a source, a drain and a channel. The source, drain and channel are doped to be the same type of semiconductor. The substrate can be made of silicon and/or germanium. The gate can be made of either aluminum or polysilicon.
    Type: Application
    Filed: August 15, 2014
    Publication date: December 11, 2014
    Applicant: The Board of Trustees of the Leland Stanford Junior University
    Inventors: YEUL NA, KRISHNA C. SARASWAT
  • Patent number: 8896083
    Abstract: A depletion-mode phototransitor is disclosed. The phototransistor having a substrate, a gate, a source, a drain and a channel. The source, drain and channel are doped to be the same type of semiconductor. The substrate can be made of silicon and/or germanium. The gate can be made of either aluminum or polysilicon.
    Type: Grant
    Filed: March 15, 2013
    Date of Patent: November 25, 2014
    Assignee: Board of Regents, The University of Texas System
    Inventors: Yeul Na, Krishna C. Saraswat
  • Publication number: 20140308801
    Abstract: Bonding of one or more semiconductor layers to a glass substrate is facilitated by depositing spin-on-glass (SOG) on the top of the semiconductor layers. The SOG is then bonded to the glass substrate, and after that, the original substrate of the semiconductor layers is removed. The resulting structure has the semiconductor layers disposed on the glass substrate with a layer of SOG sandwiched between. Bonding is always between glass and glass, and is independent of the composition of the target layers. Thus, it can provide “anything on glass”. For example, X-on-insulator (XOI), where X can be silicon, germanium, GaAs, GaN, SiC, graphene, etc. The spin-on-glass also helps with the surface roughness requirement.
    Type: Application
    Filed: April 11, 2014
    Publication date: October 16, 2014
    Applicant: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Jae Hyung Lee, Woo Shik Jung, Krishna C. Saraswat
  • Publication number: 20140264501
    Abstract: A depletion-mode phototransitor is disclosed. The phototransistor having a substrate, a gate, a source, a drain and a channel. The source, drain and channel are doped to be the same type of semiconductor. The substrate can be made of silicon and/or germanium. The gate can be made of either aluminum or polysilicon.
    Type: Application
    Filed: March 15, 2013
    Publication date: September 18, 2014
    Applicant: SEMICONDUCTOR RESEARCH CORPORATION
    Inventors: Yeul Na, KRISHNA C. SARASWAT
  • Patent number: 7919381
    Abstract: Germanium circuit-type structures are facilitated. In one example embodiment, a multi-step growth and anneal process is implemented to grow Germanium (Ge) containing material, such as heteroepitaxial-Germanium, on a substrate including Silicon (Si) or Silicon-containing material. In certain applications, defects are generally confined near a Silicon/Germanium interface, with defect threading to an upper surface of the Germanium containing material generally being inhibited. These approaches are applicable to a variety of devices including Germanium MOS capacitors, pMOSFETs and optoelectronic devices.
    Type: Grant
    Filed: March 8, 2010
    Date of Patent: April 5, 2011
    Assignees: Canon Kabushiki Kaisha, The Board of Trustees of the Leland Stanford Junior University
    Inventors: Ammar Munir Nayfeh, Chi On Chui, Krishna C. Saraswat, Takao Yonehara
  • Patent number: 7772078
    Abstract: Germanium circuit-type structures are facilitated. In one example embodiment, a multi-step growth and anneal process is implemented to grow Germanium (Ge) containing material, such as heteroepitaxial-Germanium, on a substrate including Silicon (Si) or Silicon-containing material. In certain applications, defects are generally confined near a Silicon/Germanium interface, with defect threading to an upper surface of the Germanium containing material generally being inhibited. These approaches are applicable to a variety of devices including Germanium MOS capacitors, pMOSFETs and optoelectronic devices.
    Type: Grant
    Filed: August 26, 2008
    Date of Patent: August 10, 2010
    Assignees: The Board of Trustees of the Leland Stanford Junior University, Canon Kabushiki Kaisha
    Inventors: Ammar Munir Nayfeh, Chi On Chui, Krishna C. Saraswat, Takao Yonehara
  • Publication number: 20100159678
    Abstract: Germanium circuit-type structures are facilitated. In one example embodiment, a multi-step growth and anneal process is implemented to grow Germanium (Ge) containing material, such as heteroepitaxial-Germanium, on a substrate including Silicon (Si) or Silicon-containing material. In certain applications, defects are generally confined near a Silicon/Germanium interface, with defect threading to an upper surface of the Germanium containing material generally being inhibited. These approaches are applicable to a variety of devices including Germanium MOS capacitors, pMOSFETs and optoelectronic devices.
    Type: Application
    Filed: March 8, 2010
    Publication date: June 24, 2010
    Applicants: CANON KABUSHIKI KAISHA, The Board of Trustees of the Leland Stanford Junior University
    Inventors: Ammar Munir Nayfeh, Chi On Chui, Krishna C. Saraswat, Takao Yonehara
  • Publication number: 20090061604
    Abstract: Germanium circuit-type structures are facilitated. In one example embodiment, a multi-step growth and anneal process is implemented to grow Germanium (Ge) containing material, such as heteroepitaxial-Germanium, on a substrate including Silicon (Si) or Silicon-containing material. In certain applications, defects are generally confined near a Silicon/Germanium interface, with defect threading to an upper surface of the Germanium containing material generally being inhibited. These approaches are applicable to a variety of devices including Germanium MOS capacitors, pMOSFETs and optoelectronic devices.
    Type: Application
    Filed: August 26, 2008
    Publication date: March 5, 2009
    Applicants: CANON KABUSHIKI KAISHA, The Board of Trustees of the Leland Stanford Junior University
    Inventors: Ammar Munir Nayfeh, Chi On Chui, Krishna C. Saraswat, Takao Yonehara
  • Patent number: 7495313
    Abstract: Germanium circuit-type structures are facilitated. In one example embodiment, a multi-step growth and anneal process is implemented to grow Germanium (Ge) containing material, such as heteroepitaxial-Germanium, on a substrate including Silicon (Si) or Silicon-containing material. In certain applications, defects are generally confined near a Silicon/Germanium interface, with defect threading to an upper surface of the Germanium containing material generally being inhibited. These approaches are applicable to a variety of devices including Germanium MOS capacitors, pMOSFETs and optoelectronic devices.
    Type: Grant
    Filed: July 22, 2005
    Date of Patent: February 24, 2009
    Assignees: Board of Trustees of the Leland Stanford Junior University, Canon Kabushiki Kaisha
    Inventors: Ammar Munir Nayfeh, Chi On Chui, Krishna C. Saraswat, Takao Yonehara
  • Patent number: 7271458
    Abstract: Excellent capacitor-voltage characteristics with near-ideal hysteresis are realized in a capacitive-like structure that uses an electrode substrate-type material with a high-k dielectric layer having a thickness of a few-to-several Angstroms capacitance-based SiO2 equivalent (“TOx, Eq”). According to one particular example embodiment, a semiconductor device structure has an electrode substrate-type material having a Germanium-rich surface material. The electrode substrate-type material is processed to provide this particular electrode surface material in a form that is thermodynamically stable with a high-k dielectric material. A dielectric layer is then formed over the electrode surface material with the high-k dielectric material at a surface that faces, lies against and is thermodynamically stable with the electrode surface material.
    Type: Grant
    Filed: March 31, 2003
    Date of Patent: September 18, 2007
    Assignee: The Board of Trustees of the LeLand Stanford Junior University
    Inventors: Chi On Chui, Krishna C. Saraswat, Baylor B. Triplett, Paul McIntyre
  • Patent number: 5469742
    Abstract: An acoustic temperature and/or film thickness monitoring system for semiconductor wafers in which the velocity of acoustic waves in the wafer is employed to measure temperature and/or thickness.
    Type: Grant
    Filed: March 9, 1993
    Date of Patent: November 28, 1995
    Inventors: Yong J. Lee, Butrus T. Khuri-Yakub, Krishna C. Saraswat
  • Patent number: 5250818
    Abstract: MOS transistors are formed in thin films of Ge/Si alloys (Ge.sub.x Si.sub.1-x). According to the process of the present invention, polycrystalline films of Ge/Si are deposited using commercially-available LPCVD equipment, which in the preferred process uses silane and germane as the sources of Ge and Si. The deposited Ge.sub.x Si.sub.1-x films are polycrystalline at temperatures for processing down to as below 400.degree. C., and the films can be doped heavily by ion implantation and annealing at temperatures as low as 600.degree. C. to give high mobility and dopant activation yielding very low resistivity. By carrying out the annealing step in the formation of the thin film transistors in the temperature range of 400.degree. to 500.degree. C., the films provide very large grain size, minimizing the impact of grain boundaries in the polycrystalline films where the thin film transistors are to be formed. As a result, thin film MOS transistors are fabricated at temperatures below 500.degree. C.
    Type: Grant
    Filed: March 1, 1991
    Date of Patent: October 5, 1993
    Assignee: Board of Trustees of Leland Stanford University
    Inventors: Krishna C. Saraswat, Tsu-Jae King
  • Patent number: 4913929
    Abstract: A novel cold wall single wafer rapid thermal/microwave remote plasma multiprocessing reactor comprising a vacuum chamber having means for mounting a wafer in the chamber, means for providing optical flux mounted adjacent one wall facing the back side of the wafer for optical heating of the wafer, and ports for plasma injection such that remote plasma can be generated and pumped into the chamber. Ports are provided for gas injection both through the plasma generating chamber and for non-plasma injection. The plasma and non-plasma ports are connected through separate manifolds to a plurality of gas sources. The comprehensive reactor design is such that several wafer processing steps can be done sequentially in situ, while providing for optimization of each processing step.
    Type: Grant
    Filed: April 21, 1987
    Date of Patent: April 3, 1990
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Mehrdad M. Moslehi, Krishna C. Saraswat
  • Patent number: RE37032
    Abstract: Layered structures (e.g., Al-Si/Ti/Al-Si . . . ) and homogeneous alloys of aluminum and aluminum/1 at. % silicon with titanium and tungsten and other refractory metals have been found to significantly reduce hillock densities in the films when small amounts of titanium or tungsten are homogeneously added. However, the resistivity of the films can become excessive. In addition, a new type of low density hillock can form. Layering of the films eliminates all hillocks and results in films of low resistivity. Such layered and homogeneous films made with Al-Si and Ti were found to be dry etchable. Electrical shorts in test structures with two levels of metal and LPCVD SiO2 as an interlayer dielectric have been characterized and layered films using Al-Si and Ti gave excellent results.
    Type: Grant
    Filed: February 19, 1999
    Date of Patent: January 30, 2001
    Assignee: The Board of Trustees of the Leland Stanford Jr. University
    Inventors: Donald S. Gardner, Krishna C. Saraswat, Troy W. Barbee, Jr.