Patents by Inventor Nelson Tansu

Nelson Tansu 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: 9525117
    Abstract: The invention is a thermoelectric device fabricated by growing a single crystal AlInN semiconductor material on a substrate, and a method of fabricating same. In a preferred embodiment, the semiconductor material is AlInN grown on and lattice-matched to a GaN template on a sapphire substrate, and the growth is performed using metalorganic vapor phase epitaxy (MOVPE).
    Type: Grant
    Filed: December 8, 2010
    Date of Patent: December 20, 2016
    Assignee: LEHIGH UNIVERSITY
    Inventors: Nelson Tansu, Hua Tong, Jing Zhang, Guangyu Liu, Gensheng Huang
  • Publication number: 20160260804
    Abstract: A material structure and system for generating a III-Nitride digital alloy.
    Type: Application
    Filed: March 4, 2016
    Publication date: September 8, 2016
    Inventors: Nelson TANSU, Wei SUN, Chee-Keong TAN
  • Patent number: 9349910
    Abstract: A light emitting device comprising a staggered composition quantum well (QW) has a step-function-like profile in the QW, which provides higher radiative efficiency and optical gain by providing improved electron-hole wavefunction overlap. The staggered QW includes adjacent layers having distinctly different compositions. The staggered QW has adjacent layers Xn, wherein X is a quantum well component and in one quantum well layer n is a material composition selected for emission at a first target light regime, and in at least one other quantum well layer n is a distinctly different composition for emission at a different target light regime. X may be an In-content layer and the multiple Xn-containing layers provide a step function In-content profile.
    Type: Grant
    Filed: January 30, 2014
    Date of Patent: May 24, 2016
    Assignee: Lehigh University
    Inventors: Nelson Tansu, Ronald A. Arif, Yik Khoon Ee, Hongping Zhao
  • Patent number: 8907321
    Abstract: A III-nitride based device provides improved current injection efficiency by reducing thermionic carrier escape at high current density. The device includes a quantum well active layer and a pair of multi-layer barrier layers arranged symmetrically about the active layer. Each multi-layer barrier layer includes an inner layer abutting the active layer; and an outer layer abutting the inner layer. The inner barrier layer has a bandgap greater than that of the outer barrier layer. Both the inner and the outer barrier layer have bandgaps greater than that of the active layer. InGaN may be employed in the active layer, AlInN, AlInGaN or AlGaN may be employed in the inner barrier layer, and GaN may be employed in the outer barrier layer. Preferably, the inner layer is thin relative to the other layers. In one embodiment the inner barrier and active layers are 15 ? and 24 ? thick, respectively.
    Type: Grant
    Filed: December 14, 2010
    Date of Patent: December 9, 2014
    Assignee: Lehigh Univeristy
    Inventors: Nelson Tansu, Hongping Zhao, Guangyu Liu, Ronald Arif
  • Publication number: 20140191189
    Abstract: A light emitting device comprising a staggered composition quantum well (QW) has a step-function-like profile in the QW, which provides higher radiative efficiency and optical gain by providing improved electron-hole wavefunction overlap. The staggered QW includes adjacent layers having distinctly different compositions. The staggered QW has adjacent layers Xn, wherein X is a quantum well component and in one quantum well layer n is a material composition selected for emission at a first target light regime, and in at least one other quantum well layer n is a distinctly different composition for emission at a different target light regime. X may be an In-content layer and the multiple Xn-containing layers provide a step function In-content profile.
    Type: Application
    Filed: January 30, 2014
    Publication date: July 10, 2014
    Applicant: LEHIGH UNIVERSITY
    Inventors: Nelson TANSU, Ronald A. ARIF, Yik Khoon EE, Hongping ZHAO
  • Patent number: 8685767
    Abstract: A double-metallic deposition process is used whereby adjacent layers of different metals are deposited on a substrate. The surface plasmon frequency of a base layer of a first metal is tuned by the surface plasmon frequency of a second layer of a second metal formed thereon. The amount of tuning is dependent upon the thickness of the metallic layers, and thus tuning can be achieved by varying the thicknesses of one or both of the metallic layers. In a preferred embodiment directed to enhanced LED technology in the green spectrum regime, a double-metallic Au/Ag layer comprising a base layer of gold (Au) followed by a second layer of silver (Ag) formed thereon is deposited on top of InGaN/GaN quantum wells (QWs) on a sapphire/GaN substrate.
    Type: Grant
    Filed: December 8, 2010
    Date of Patent: April 1, 2014
    Assignee: Lehigh University
    Inventors: Nelson Tansu, Hongping Zhao, Jing Zhang, Guangyu Liu
  • Patent number: 8659005
    Abstract: A light emitting device comprising a staggered composition quantum well (QW) has a step-function-like profile in the QW, which provides higher radiative efficiency and optical gain by providing improved electron-hole wavefunction overlap. The staggered QW includes adjacent layers having distinctly different compositions. The staggered QW has adjacent layers Xn wherein X is a quantum well component and in one quantum well layer n is a material composition selected for emission at a first target light regime, and in at least one other quantum well layer n is a distinctly different composition for emission at a different target light regime. X may be an In-content layer and the multiple Xn-containing a step function In-content profile.
    Type: Grant
    Filed: December 24, 2007
    Date of Patent: February 25, 2014
    Assignee: Lehigh University
    Inventors: Nelson Tansu, Ronald A. Arif, Yik Khoon Ee, Hongping Zhao
  • Patent number: 8586963
    Abstract: A conventional semiconductor LED is modified to include a microlens layer over its light-emitting surface. The LED may have an active layer including at least one quantum well layer of InGaN and GaN. The microlens layer includes a plurality of concave microstructures that cause light rays emanating from the LED to diffuse outwardly, leading to an increase in the light extraction efficiency of the LED. The concave microstructures may be arranged in a substantially uniform array, such as a close-packed hexagonal array. The microlens layer is preferably constructed of curable material, such as polydimethylsiloxane (PDMS), and is formed by soft-lithography imprinting by contacting fluid material of the microlens layer with a template bearing a monolayer of homogeneous microsphere crystals, to cause concave impressions, and then curing the material to fix the concave microstructures in the microlens layer and provide relatively uniform surface roughness.
    Type: Grant
    Filed: December 8, 2010
    Date of Patent: November 19, 2013
    Assignee: Lehigh University
    Inventors: Nelson Tansu, James F. Gilchrist, Yik-Khoon Ee, Pisist Kumnorkaew
  • Patent number: 8569737
    Abstract: A III-Nitride semiconductor LED provides broadband light emission, across all or most of the visible light wavelength spectrum, and a method for producing same. The LED includes a polarization field management template that has a three-dimensional patterned surface. The surface may be patterned with an array of hemispherical cavities, which may be formed by growing the template around a temporary template layer of spherical or other crystals. The method involves growing a quantum well layer on the patterned surface. The topographical variations in the patterned surface of the template cause corresponding topographical variations in the quantum well layer. These variations in spatial orientation of portions of the quantum well layer cause the polarization field of the quantum well layer to vary across the surface of the LED, which leads to energy transition shifting that provides “white” light emission across a broad wavelength spectrum.
    Type: Grant
    Filed: December 8, 2011
    Date of Patent: October 29, 2013
    Assignee: Lehigh University
    Inventors: Nelson Tansu, Xiaohang Li, Hongping Zhao, Guangyu Liu, James Foster Gilchrist, Pisist Kumnorkaew
  • Patent number: 8541252
    Abstract: The use of an abbreviated GaN growth mode on nano-patterned AGOG sapphire substrates, which utilizes a process of using 15 nm low temperature GaN buffer and bypassing etch-back and recovery processes during epitaxy, enables the growth of high-quality GaN template on nano-patterned AGOG sapphire. The GaN template grown on nano-patterned AGOG sapphire by employing abbreviated growth mode has two orders of magnitude lower threading dislocation density than that of conventional GaN template grown on planar sapphire. The use of abbreviated growth mode also leads to significant reduction in cost of the epitaxy. The growths and characteristics of InGaN quantum wells (QWs) light emitting diodes (LEDs) on both templates were compared. The InGaN QWs LEDs grown on the nano-patterned AGOG sapphire demonstrated at least a 24% enhancement of output power enhancement over that of LEDs grown on conventional GaN templates.
    Type: Grant
    Filed: December 17, 2010
    Date of Patent: September 24, 2013
    Assignee: Lehigh University
    Inventors: Nelson Tansu, Helen M. Chan, Richard P. Vinci, Yik-Khoon Ee, Jeffrey Biser
  • Publication number: 20120217472
    Abstract: A III-Nitride semiconductor LED provides broadband light emission, across all or most of the visible light wavelength spectrum, and a method for producing same. The LED includes a polarization field management template that has a three-dimensional patterned surface. The surface may be patterned with an array of hemispherical cavities, which may be formed by growing the template around a temporary template layer of spherical or other crystals. The method involves growing a quantum well layer on the patterned surface. The topographical variations in the patterned surface of the template cause corresponding topographical variations in the quantum well layer. These variations in spatial orientation of portions of the quantum well layer cause the polarization field of the quantum well layer to vary across the surface of the LED, which leads to energy transition shifting that provides “white” light emission across a broad wavelength spectrum.
    Type: Application
    Filed: December 8, 2011
    Publication date: August 30, 2012
    Applicant: Lehigh University
    Inventors: Nelson Tansu, Xiaohang Li, Hongping Zhao, Guangyu Liu, James Foster Gilchrist, Pisist Kumnorkaew
  • Patent number: 8076667
    Abstract: A tight emitting device comprises at least one p-type layer and at least one n-type layer and a microlens array surface. A method for improving light efficiency of a light emitting device, comprises depositing polystyrene microspheres by rapid convection deposition on surface of light emitting device; depositing a monolayer of close-packed SIO2 microspheres onto the polystyrene microspheres; and heal treating to convert the polystyrene microspheres into a planar microlayer film to provide a surface comprising substantially two-dimensional (2D) hexagonal close-packed SIO2 colloidal microsphere crystals partially imposed into a polystyrene monolayer film.
    Type: Grant
    Filed: December 24, 2007
    Date of Patent: December 13, 2011
    Assignee: Lehigh University
    Inventors: Nelson Tansu, Yik Khoon Ee, James F. Gilchrist, Pisit Kumnorkaew, Ronald A. Arif
  • Publication number: 20110240082
    Abstract: The invention is a thermoelectric device fabricated by growing a single crystal AlInN semiconductor material on a substrate, and a method of fabricating same. In a preferred embodiment, the semiconductor material is AlInN grown on and lattice-matched to a GaN template on a sapphire substrate, and the growth is performed using metalorganic vapor phase epitaxy (MOVPE).
    Type: Application
    Filed: December 8, 2010
    Publication date: October 6, 2011
    Applicant: Lehigh University
    Inventors: Nelson Tansu, Hua Tong, Jing Zhang, Guangyu Liu, Gensheng Huang
  • Patent number: 8030641
    Abstract: A gallium nitride-based device has ? first GaN layer and ? type II quantum well active region over the GaN layer. The type II quantum well active region comprises at least one InGaN layer and at least one GaNAs layer, wherein the InGaN comprises ? graded molar In concentration.
    Type: Grant
    Filed: December 19, 2007
    Date of Patent: October 4, 2011
    Assignee: Lehigh University
    Inventors: Nelson Tansu, Ronald A. Arif, Yik Khoon Ee
  • Publication number: 20110204328
    Abstract: A symmetrical quantum well active layer provides enhanced internal quantum efficiency. The quantum well active layer includes an inner (central) layer and a pair of outer layers sandwiching the inner layer. The inner and outer layers have different thicknesses and bandgap characteristics. The outer layers are relatively thick and include a relatively low bandgap material, such as InGaN. The inner layer has a relatively lower bandgap material and is sufficiently thin to act as a quantum well delta layer, e.g., comprising approximately 6 ? or less of InN. Such a quantum well structure advantageously extends the emission wavelength into the yellow/red spectral regime, and enhances spontaneous emission. The multi-layer quantum well active layer is sandwiched by barrier layers of high bandgap materials, such as GaN.
    Type: Application
    Filed: December 15, 2010
    Publication date: August 25, 2011
    Applicant: Lehigh University
    Inventors: Nelson Tansu, Hongping Zhao, Guangyu Liu, Gensheng Huang
  • Publication number: 20110155999
    Abstract: A conventional semiconductor LED is modified to include a microlenslayer over its light-emitting surface. The LED may have an active layer including at least one quantum well layer of InGaN and GaN. The microlens layer includes a plurality of concave microstructures that cause light rays emanating from the LED to diffuse outwardly, leading to an increase in the light extraction efficiency of the LED. The concave microstructures may be arranged in a substantially uniform array, such as a close-packed hexagonal array. The microlens layer is preferably constructed of curable material, such as polydimethylsiloxane (PDMS), and is formed by soft-lithography imprinting by contacting fluid material of the microlens layer with a template bearing a monolayer of homogeneous microsphere crystals, to cause concave impressions, and then curing the material to fix the concave microstructures in the microlens layer and provide relatively uniform surface roughness.
    Type: Application
    Filed: December 8, 2010
    Publication date: June 30, 2011
    Applicant: Lehigh University
    Inventors: Nelson Tansu, James F. Gilchrist, Yik-Khoon Ee, Pisist Kumnorkaew
  • Publication number: 20110147703
    Abstract: The use of an abbreviated GaN growth mode on nano-patterned AGOG sapphire substrates, which utilizes a process of using 15 nm low temperature GaN buffer and bypassing etch-back and recovery processes during epitaxy, enables the growth of high-quality GaN template on nano-patterned AGOG sapphire. The GaN template grown on nano-patterned AGOG sapphire by employing abbreviated growth mode has two orders of magnitude lower threading dislocation density than that of conventional GaN template grown on planar sapphire. The use of abbreviated growth mode also leads to significant reduction in cost of the epitaxy. The growths and characteristics of InGaN quantum wells (QWs) light emitting diodes (LEDs) on both templates were compared. The InGaN QWs LEDs grown on the nano-patterned AGOG sapphire demonstrated at least a 24% enhancement of output power enhancement over that of LEDs grown on conventional GaN templates.
    Type: Application
    Filed: December 17, 2010
    Publication date: June 23, 2011
    Applicant: LEHIGH UNIVERSITY
    Inventors: Nelson Tansu, Helen M. Chan, Richard P. Vinci, Yik-Khoon Ee, Jeffrey Biser
  • Publication number: 20110147702
    Abstract: A III-nitride based device provides improved current injection efficiency by reducing thermionic carrier escape at high current density. The device includes a quantum well active layer and a pair of multi-layer barrier layers arranged symmetrically about the active layer. Each multi-layer barrier layer includes an inner layer abutting the active layer; and an outer layer abutting the inner layer. The inner barrier layer has a bandgap greater than that of the outer barrier layer. Both the inner and the outer barrier layer have bandgaps greater than that of the active layer. InGaN may be employed in the active layer, AlInN, AlInGaN or AlGaN may be employed in the inner barrier layer, and GaN may be employed in the outer barrier layer. Preferably, the inner layer is thin relative to the other layers. In one embodiment the inner barrier and active layers are 15 ? and 24 ? thick, respectively.
    Type: Application
    Filed: December 14, 2010
    Publication date: June 23, 2011
    Applicant: Lehigh University
    Inventors: Nelson Tansu, Hongping Zhao, Guangyu Liu, Ronald Arif
  • Publication number: 20110133157
    Abstract: A double-metallic deposition process is used whereby adjacent layers of different metals are deposited on a substrate. The surface plasmon frequency of a base layer of a first metal is tuned by the surface plasmon frequency of a second layer of a second metal formed thereon. The amount of tuning is dependent upon the thickness of the metallic layers, and thus tuning can be achieved by varying the thicknesses of one or both of the metallic layers. In a preferred embodiment directed to enhanced LED technology in the green spectrum regime, a double-metallic Au/Ag layer comprising a base layer of gold (Au) followed by a second layer of silver (Ag) formed thereon is deposited on top of InGaN/GaN quantum wells (QWs) on a sapphire/GaN substrate.
    Type: Application
    Filed: December 8, 2010
    Publication date: June 9, 2011
    Applicant: Lehigh University
    Inventors: Nelson Tansu, Hongping Zhao, Jing Zhang, Guangyu Liu
  • Publication number: 20100327783
    Abstract: A light emitting device comprising a staggered composition quantum well.
    Type: Application
    Filed: December 24, 2007
    Publication date: December 30, 2010
    Applicant: LEHIGH UNIVERSITY
    Inventors: Nelson Tansu, Ronald A. Arif, Yik Khoon Ee, Hongping Zhao