Patents by Inventor Davood Shahrjerdi

Davood Shahrjerdi 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: 10177266
    Abstract: A photovoltaic device and method include a substrate coupled to an emitter side structure on a first side of the substrate and a back side structure on a side opposite the first side of the substrate. The emitter side structure or the back side structure include layers alternating between wide band gap layers and narrow band gap layers to provide a multilayer contact with an effectively increased band offset with the substrate and/or an effectively higher doping level over a single material contact. An emitter contact is coupled to the emitter side structure on a light collecting end portion of the device. A back contact is coupled to the back side structure opposite the light collecting end portion.
    Type: Grant
    Filed: December 22, 2015
    Date of Patent: January 8, 2019
    Assignee: International Business Machines Corporation
    Inventors: Bahman Hekmatshoar-Tabari, Devendra K. Sadana, Ghavam G. Shahidi, Davood Shahrjerdi
  • Patent number: 10170720
    Abstract: A method for inorganic surface passivation in a photovoltaic device includes etching a native oxide over an inorganic substrate, the inorganic substrate having a surface; and forming an organic monolayer on the surface of the inorganic substrate to form a heterojunction, the organic monolayer having the following formula: ˜X—Y, wherein X is an oxygen or a sulfur; Y is an alkyl chain, an alkenyl chain, or an alkynyl chain; and X covalently bonds to the surface of the inorganic substrate by a covalent bond.
    Type: Grant
    Filed: November 21, 2017
    Date of Patent: January 1, 2019
    Assignee: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Ali Afzali-Ardakani, Bahman Hekmatshoartabari, Davood Shahrjerdi
  • Patent number: 10170719
    Abstract: A method for inorganic surface passivation in a photovoltaic device includes etching a native oxide over an inorganic substrate, the inorganic substrate having a surface; and forming an organic monolayer on the surface of the inorganic substrate to form a heterojunction, the organic monolayer having the following formula: ˜X—Y, wherein X is an oxygen or a sulfur; Y is an alkyl chain, an alkenyl chain, or an alkynyl chain; and X covalently bonds to the surface of the inorganic substrate by a covalent bond.
    Type: Grant
    Filed: December 10, 2015
    Date of Patent: January 1, 2019
    Assignee: INTERNATIONAL BUSINESS MACHINES CORPROATION
    Inventors: Ali Afzali-Ardakani, Bahman Hekmatshoartabari, Davood Shahrjerdi
  • Patent number: 10141461
    Abstract: A method for forming a multi-junction photovoltaic device includes providing a germanium layer and etching pyramidal shapes in the germanium layer such that (111) facets are exposed to form a textured surface. A first p-n junction is formed on or over the textured surface from III-V semiconductor materials. Another p-n junction is formed over the first p-n junction from III-V semiconductor materials and follows the textured surface.
    Type: Grant
    Filed: July 13, 2015
    Date of Patent: November 27, 2018
    Assignee: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Bahman Hekmatshoartabari, Ali Khakifirooz, Ghavam G. Shahidi, Davood Shahrjerdi
  • Publication number: 20180323330
    Abstract: A photovoltaic device that includes an upper cell that absorbs a first range of wavelengths of light and a bottom cell that absorbs a second range of wavelengths of light. The bottom cell includes a heterojunction comprising a crystalline germanium containing (Ge) layer. At least one surface of the crystalline germanium (Ge) containing layer is in contact with a silicon (Si) containing layer having a larger band gap than the crystalline (Ge) containing layer.
    Type: Application
    Filed: July 13, 2018
    Publication date: November 8, 2018
    Inventors: Keith E. Fogel, Bahman Hekmatshoartabari, Devendra K. Sadana, Ghavam G. Shahidi, Davood Shahrjerdi
  • Patent number: 10115773
    Abstract: Hybrid high electron mobility field-effect transistors including inorganic channels and organic gate barrier layers are used in some applications for forming high resolution active matrix displays. Arrays of such high electron mobility field-effect transistors are electrically connected to thin film switching transistors and provide high drive currents for passive devices such as organic light emitting diodes. The organic gate barrier layers are operative to suppress both electron and hole transport between the inorganic channel layer and the gate electrodes of the high electron mobility field-effect transistors.
    Type: Grant
    Filed: November 20, 2016
    Date of Patent: October 30, 2018
    Assignee: International Business Machines Corporation
    Inventors: Ali Afzali-Ardakani, Bahman Hekmatshoartabari, Devendra K. Sadana, Davood Shahrjerdi
  • Patent number: 10096711
    Abstract: Tunneling field-effect transistors including silicon, germanium or silicon germanium channels and III-N source regions are provided for low power operations. A broken-band heterojunction is formed by the source and channel regions of the transistors. Fabrication methods include selective anisotropic wet-etching of a silicon substrate followed by epitaxial deposition of III-N material and/or germanium implantation of the substrate followed by the epitaxial deposition of the III-N material.
    Type: Grant
    Filed: September 4, 2017
    Date of Patent: October 9, 2018
    Assignee: International Business Machines Corporation
    Inventors: Anirban Basu, Bahman Hekmatshoartabari, Davood Shahrjerdi
  • Publication number: 20180258549
    Abstract: An epitaxy method includes providing an exposed crystalline region of a substrate material. Silicon is epitaxially deposited on the substrate material in a low temperature process wherein a deposition temperature is less than 500 degrees Celsius. A source gas is diluted with a dilution gas with a gas ratio of dilution gas to source gas of less than 1000.
    Type: Application
    Filed: May 10, 2018
    Publication date: September 13, 2018
    Inventors: BAHMAN HEKMATSHOAR-TABARI, ALI KHAKIFIROOZ, ALEXANDER REZNICEK, DEVENDRA K. SADANA, GHAVAM G. SHAHIDI, DAVOOD SHAHRJERDI
  • Publication number: 20180256314
    Abstract: High resolution active matrix nanowire circuits enable a flexible platform for artificial electronic skin having pressure sensing capability. Comb-like interdigitated nanostructures extending vertically from a pair of opposing, flexible assemblies facilitate pressure sensing via changes in resistance caused by varying the extent of contact among the interdigitated nanostructures. Electrically isolated arrays of vertically extending, electrically conductive nanowires or nanofins are formed from a doped, electrically conductive layer, each of the arrays being electrically connected to a transistor in an array of transistors. The nanowires or nanofins are interdigitated with further electrically conductive nanowires or nanofins mounted to a flexible handle.
    Type: Application
    Filed: May 12, 2018
    Publication date: September 13, 2018
    Inventors: Bahman Hekmatshoartabari, Ghavam G. Shahidi, Davood Shahrjerdi
  • Publication number: 20180254361
    Abstract: A photovoltaic device and method include a crystalline substrate and an emitter contact portion formed in contact with the substrate. A back-surface-field junction includes a homogeneous junction layer formed in contact with the crystalline substrate and having a same conductivity type and a higher active doping density than that of the substrate. The homogeneous junction layer includes a thickness less than a diffusion length of minority carriers in the homogeneous junction layer. A passivation layer is formed in contact with the homogeneous junction layer opposite the substrate, which is either undoped or has the same conductivity type as that of the substrate.
    Type: Application
    Filed: April 30, 2018
    Publication date: September 6, 2018
    Inventors: TZE-CHIANG CHEN, BAHMAN HEKMATSHOARTABARI, DEVENDRA K. SADANA, DAVOOD SHAHRJERDI
  • Patent number: 10050166
    Abstract: A photovoltaic device including a single junction solar cell provided by an absorption layer of a type IV semiconductor material having a first conductivity, and an emitter layer of a type III-V semiconductor material having a second conductivity, wherein the type III-V semiconductor material has a thickness that is no greater than 50 nm.
    Type: Grant
    Filed: July 12, 2017
    Date of Patent: August 14, 2018
    Assignee: International Business Machines Corporation
    Inventors: Bahman Hekmatshoar-Tabari, Ali Khakifirooz, Devendra K. Sadana, Ghavam G. Shahidi, Davood Shahrjerdi
  • Patent number: 10043934
    Abstract: A photovoltaic device is provided in which the tunneling barrier for hole collection at either the front contact or the back contact of a silicon heterojunction cell is reduced, without compromising the surface passivation either the front contact or at the back contact. This is achieved in the present disclosure by replacing the intrinsic and/or doped hydrogenated amorphous silicon (a-Si:H) layer(s) at the back contact or at the front contact with an intrinsic and/or doped layer(s) of a semiconductor material having a lower valence band-offset than that of a:Si—H with c-Si, and/or a higher activated doping concentration compared to that of doped hydrogenated amorphous Si. The higher level of activated doping is due to the higher doping efficiency of the back contact or front contact semiconductor material compared to that of amorphous Si, and/or modulation doping of the back or front contact semiconducting material.
    Type: Grant
    Filed: June 8, 2011
    Date of Patent: August 7, 2018
    Assignee: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Bahman Hekmatshoar-Tabari, Devendra K. Sadana, Ghavam G. Shahidi, Davood Shahrjerdi
  • Patent number: 10043935
    Abstract: A photovoltaic device includes a crystalline substrate having a first dopant conductivity, an interdigitated back contact and a front surface field structure. The front surface field structure includes a crystalline layer formed on the substrate and a noncrystalline layer formed on the crystalline layer. The crystalline layer and the noncrystalline layer are doped with dopants having a same dopant conductivity as the substrate. Methods are also disclosed.
    Type: Grant
    Filed: November 19, 2015
    Date of Patent: August 7, 2018
    Assignee: International Business Machines Corporation
    Inventors: Tze-Chiang Chen, Bahman Hekmatshoartabari, Devendra K. Sadana, Davood Shahrjerdi
  • Publication number: 20180212094
    Abstract: A photovoltaic device includes a crystalline substrate having a first dopant conductivity, an interdigitated back contact and a front surface field structure. The front surface field structure includes a crystalline layer formed on the substrate and a noncrystalline layer formed on the crystalline layer. The crystalline layer and the noncrystalline layer are doped with dopants having an opposite dopant conductivity from that of the substrate. Methods are also disclosed.
    Type: Application
    Filed: March 21, 2018
    Publication date: July 26, 2018
    Inventors: TZE-CHIANG CHEN, BAHMAN HEKMATSHOARTABARI, DEVENDRA K. SADANA, DAVOOD SHAHRJERDI
  • Publication number: 20180205564
    Abstract: An article of manufacture includes a substrate and a security primitive deposited on the substrate. The security primitive includes a transition metal dichalcogenide having a varying thickness. According to various embodiments, the transition metal dichalcogenide comprises a chalcogen atom (X) selected from the group consisting of S, Se, and Te and a transition metal (M) selected from the group consisting of Mo, W, Hf, and Zr. The security primitive is pixelated into a plurality of discrete regions having different luminescence. A security primitive key includes a first set of data values corresponding to a first set of coordinates of a first region and a second set of data values corresponding to a second set of coordinates of a second region. In some embodiments, the security primitive key is digitally captured through an optical reader and verified by querying a database.
    Type: Application
    Filed: December 19, 2017
    Publication date: July 19, 2018
    Inventors: Davood SHAHRJERDI, Abdullah ALHARBI
  • Patent number: 10011920
    Abstract: An epitaxy method includes providing an exposed crystalline region of a substrate material. Silicon is epitaxially deposited on the substrate material in a low temperature process wherein a deposition temperature is less than 500 degrees Celsius. A source gas is diluted with a dilution gas with a gas ratio of dilution gas to source gas of less than 1000.
    Type: Grant
    Filed: February 23, 2011
    Date of Patent: July 3, 2018
    Assignee: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Bahman Hekmatshoar-Tabari, Ali Khakifirooz, Alexander Reznicek, Devendra K. Sadana, Ghavam G. Shahidi, Davood Shahrjerdi
  • Patent number: 10008624
    Abstract: A photovoltaic device and method include a crystalline substrate and an emitter contact portion formed in contact with the substrate. A back-surface-field junction includes a homogeneous junction layer formed in contact with the crystalline substrate and having a same conductivity type and a higher active doping density than that of the substrate. The homogeneous junction layer includes a thickness less than a diffusion length of minority carriers in the homogeneous junction layer. A passivation layer is formed in contact with the homogeneous junction layer opposite the substrate, which is either undoped or has the same conductivity type as that of the substrate.
    Type: Grant
    Filed: September 28, 2015
    Date of Patent: June 26, 2018
    Assignee: International Business Machines Corporation
    Inventors: Tze-Chiang Chen, Bahman Hekmatshoartabari, Devendra K. Sadana, Davood Shahrjerdi
  • Patent number: 10008585
    Abstract: A semiconductor structure that has adjacent transistors that share a common source/drain semiconductor structure. At least one of the adjacent transistors comprising: a vertical channel and a source/drain semiconductor structure connected to the vertical channel such that the source/drain semiconductor structure has a vertical side that is substantially planar with a vertical side of the first vertical channel. The source/drain semiconductor structure extends horizontally from its vertical side farther than the first vertical channel extends from its vertical side such that a width of the source/drain is greater than a width of the first vertical channel. The first source/drain semiconductor structure is located on a layer of substrate and the vertical channel is perpendicular relative to the layer of substrate.
    Type: Grant
    Filed: June 23, 2016
    Date of Patent: June 26, 2018
    Assignee: International Business Machines Corporation
    Inventors: Kangguo Cheng, Wilfried E. Haensch, Ali Khakifirooz, Davood Shahrjerdi
  • Patent number: 9997475
    Abstract: A method for making a photovoltaic device is provided that includes the steps of providing a silicon substrate having a complementary metal-oxide semiconductor (“CMOS”); bonding a first layer of silicon oxide to a second layer of silicon oxide wherein the bonded layers are deposited on the silicon substrate; and forming a III-V photovoltaic cell on a side of the bonded silicon oxide layers opposite the silicon substrate, wherein when the III-V photovoltaic cell is exposed to radiation, the III-V photovoltaic cell generates a current that powers a memory erasure device to cause an alteration of a memory state of a memory cell in an integrated circuit.
    Type: Grant
    Filed: January 13, 2016
    Date of Patent: June 12, 2018
    Assignee: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Kenneth Rodbell, Davood Shahrjerdi
  • Patent number: 9985167
    Abstract: A photovoltaic device includes a crystalline substrate having a first dopant conductivity, an interdigitated back contact and a front surface field structure. The front surface field structure includes a crystalline layer formed on the substrate and a noncrystalline layer formed on the crystalline layer. The crystalline layer and the noncrystalline layer are doped with dopants having an opposite dopant conductivity from that of the substrate. Methods are also disclosed.
    Type: Grant
    Filed: August 14, 2013
    Date of Patent: May 29, 2018
    Assignee: International Business Machines Corporation
    Inventors: Tze-Chiang Chen, Bahman Hekmatshoartabari, Devendra K. Sadana, Davood Shahrjerdi