Patents by Inventor Arpan Chakraborty

Arpan Chakraborty 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: 8686466
    Abstract: A method for growth and fabrication of semipolar (Ga, Al, In, B)N thin films, heterostructures, and devices, comprising identifying desired material properties for a particular device application, selecting a semipolar growth orientation based on the desired material properties, selecting a suitable substrate for growth of the selected semipolar growth orientation, growing a planar semipolar (Ga, Al, In, B)N template or nucleation layer on the substrate, and growing the semipolar (Ga, Al, In, B)N thin films, heterostructures or devices on the planar semipolar (Ga, Al, In, B)N template or nucleation layer. The method results in a large area of the semipolar (Ga, Al, In, B)N thin films, heterostructures, and devices being parallel to the substrate surface.
    Type: Grant
    Filed: November 23, 2010
    Date of Patent: April 1, 2014
    Assignees: The Regents of the University of California, Japan Science and Technology Agency
    Inventors: Robert M. Farrell, Jr., Troy J. Baker, Arpan Chakraborty, Benjamin A. Haskell, P. Morgan Pattison, Rajat Sharma, Umesh K. Mishra, Steven P. DenBaars, James S. Speck, Shuji Nakamura
  • Patent number: 8679876
    Abstract: A laser diode and method for fabricating same, wherein the laser diode generally comprises an InGaN compliance layer on a GaN n-type contact layer and an AlGaN/GaN n-type strained super lattice (SLS) on the compliance layer. An n-type GaN separate confinement heterostructure (SCH) is on said n-type SLS and an InGaN multiple quantum well (MQW) active region is on the n-type SCH. A GaN p-type SCH on the MQW active region, an AlGaN/GaN p-type SLS is on the p-type SCH, and a p-type GaN contact layer is on the p-type SLS. The compliance layer has an In percentage that reduces strain between the n-type contact layer and the n-type SLS compared to a laser diode without the compliance layer. Accordingly, the n-type SLS can be grown with an increased Al percentage to increase the index of refraction. This along with other features allows for reduced threshold current and voltage operation.
    Type: Grant
    Filed: June 29, 2010
    Date of Patent: March 25, 2014
    Assignee: Cree, Inc.
    Inventors: Arpan Chakraborty, Monica Hansen, Steven Denbaars, Shuji Nakamura, George Brandes
  • Patent number: 8643024
    Abstract: A method for growing reduced defect density planar gallium nitride (GaN) films is disclosed. The method includes the steps of (a) growing at least one silicon nitride (SiNx) nanomask layer over a GaN template, and (b) growing a thickness of a GaN film on top of the SiNx nanomask layer.
    Type: Grant
    Filed: December 20, 2011
    Date of Patent: February 4, 2014
    Assignee: The Regents of the University of California
    Inventors: Arpan Chakraborty, Kwang-Choong Kim, James S. Speck, Steven P. DenBaars, Umesh K. Mishra
  • Patent number: 8637883
    Abstract: A light emitting diode (LED) device having a low index of refraction spacer layer separating the LED chip and a functional layer. The LED chip has a textured light emission surface to increase light extraction from the chip. The spacer layer has an index of refraction that is lower than both the LED chip and the functional layer. Most of the light generated in the LED chip passes easily into the spacer layer due to the textured surface of the chip. At the interface of the spacer layer and the functional layer the light sees a step-up in index of refraction which facilitates transmission. A portion of the light that has passed into the functional layer will be reflected or scattered back toward the spacer layer where some of it will experience total internal reflection. Total internal reflection at this interface may increase extraction efficiency by reducing the amount of light that re-enters the spacer layer and, ultimately, the LED chip where it may be absorbed.
    Type: Grant
    Filed: March 19, 2008
    Date of Patent: January 28, 2014
    Assignee: Cree, Inc.
    Inventor: Arpan Chakraborty
  • Publication number: 20130313586
    Abstract: A light emitting device comprising a three-dimensional polarization-graded (3DPG) structure that improves lateral current spreading within the device without introducing additional dopant impurities in the epitaxial structures. The 3DPG structure can include a repeatable stack unit that may be repeated several times within the 3DPG. The stack unit includes a compositionally graded layer and a silicon (Si) delta-doped layer. The graded layer is compositionally graded over a distance from a first material to a second material, introducing a polarization-induced bulk charge into the structure. The Si delta-doped layer compensates for back-depletion of the electron gas at the interface of the graded layers and adjacent layers. The 3DPG facilitates lateral current spreading so that current is injected into the entire active region, increasing the number of radiative recombination events in the active region and improving the external quantum efficiency and the wall-plug efficiency of the device.
    Type: Application
    Filed: July 30, 2013
    Publication date: November 28, 2013
    Inventor: Arpan Chakraborty
  • Publication number: 20130313516
    Abstract: LED lamps having improved light quality are disclosed. The lamps emit more than 500 lm and more than 2% of the power in the spectral power distribution is emitted within a wavelength range from about 390 nm to about 430 nm.
    Type: Application
    Filed: May 3, 2013
    Publication date: November 28, 2013
    Applicant: SORAA, INC.
    Inventors: Aurelien J. F. David, Troy A. Trottier, Michael R. Krames, Arpan Chakraborty, James W. Raring, Michael J. Grundmann
  • Publication number: 20130264540
    Abstract: A method for the fabrication of nonpolar indium gallium nitride (InGaN) films as well as nonpolar InGaN-containing device structures using metalorganic chemical vapor deposition (MOVCD). The method is used to fabricate nonpolar InGaN/GaN violet and near-ultraviolet light emitting diodes and laser diodes.
    Type: Application
    Filed: June 4, 2013
    Publication date: October 10, 2013
    Applicants: JAPAN SCIENCE AND TECHNOLOGY AGENCY, THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Arpan Chakraborty, Benjamin A. Haskell, Stacia Keller, James S. Speck, Steven P. DenBaars, Shuji Nakamura, Umesh K. Mishra
  • Publication number: 20130259080
    Abstract: An epitaxial structure for a III-Nitride based optical device, comprising an active layer with anisotropic strain on an underlying layer, where a lattice constant and strain in the underlying layer are partially or fully relaxed in at least one direction due to a presence of misfit dislocations, so that the anisotropic strain in the active layer is modulated by the underlying layer.
    Type: Application
    Filed: May 29, 2013
    Publication date: October 3, 2013
    Inventors: Hiroaki Ohta, Feng Wu, Anurag Tyagi, Arpan Chakraborty, James S. Speck, Steven P. DenBaars, Shuji Nakamura, Erin C. Young
  • Patent number: 8519437
    Abstract: A light emitting device comprising a three-dimensional polarization-graded (3DPG) structure that improves lateral current spreading within the device without introducing additional dopant impurities in the epitaxial structures. The 3DPG structure can include a repeatable stack unit that may be repeated several times within the 3DPG. The stack unit includes a compositionally graded layer and a silicon (Si) delta-doped layer. The graded layer is compositionally graded over a distance from a first material to a second material, introducing a polarization-induced bulk charge into the structure. The Si delta-doped layer compensates for back-depletion of the electron gas at the interface of the graded layers and adjacent layers. The 3DPG facilitates lateral current spreading so that current is injected into the entire active region, increasing the number of radiative recombination events in the active region and improving the external quantum efficiency and the wall-plug efficiency of the device.
    Type: Grant
    Filed: September 14, 2007
    Date of Patent: August 27, 2013
    Assignee: Cree, Inc.
    Inventor: Arpan Chakraborty
  • Patent number: 8502246
    Abstract: A method for the fabrication of nonpolar indium gallium nitride (InGaN) films as well as nonpolar InGaN-containing device structures using metalorganic chemical vapor deposition (MOVCD). The method is used to fabricate nonpolar InGaN/GaN violet and near-ultraviolet light emitting diodes and laser diodes.
    Type: Grant
    Filed: February 12, 2009
    Date of Patent: August 6, 2013
    Assignees: The Regents of the University of California, The Japan Science and Technology Agency
    Inventors: Arpan Chakraborty, Benjamin A. Haskell, Stacia Keller, James S. Speck, Steven P. DenBaars, Shuji Nakamura, Umesh K. Mishra
  • Patent number: 8492185
    Abstract: A method for fabricating large-area nonpolar or semipolar GaN wafers with high quality, low stacking fault density, and relatively low dislocation density is described. The wafers are useful as seed crystals for subsequent bulk growth or as substrates for LEDs and laser diodes.
    Type: Grant
    Filed: July 13, 2012
    Date of Patent: July 23, 2013
    Assignee: Soraa, Inc.
    Inventors: Mark P. D'Evelyn, James Speck, William Houck, Mathew Schmidt, Arpan Chakraborty
  • Patent number: 8481991
    Abstract: An epitaxial structure for a III-Nitride based optical device, comprising an active layer with anisotropic strain on an underlying layer, where a lattice constant and strain in the underlying layer are partially or fully relaxed in at least one direction due to a presence of misfit dislocations, so that the anisotropic strain in the active layer is modulated by the underlying layer.
    Type: Grant
    Filed: August 23, 2010
    Date of Patent: July 9, 2013
    Assignee: The Regents of the University of California
    Inventors: Hiroaki Ohta, Feng Wu, Anurag Tyagi, Arpan Chakraborty, James S. Speck, Steven P. DenBaars, Shuji Nakamura, Erin C. Young
  • Publication number: 20130075770
    Abstract: A method for providing (Al,Ga,In)N thin films on Ga-face c-plane (Al,Ga,In)N substrates using c-plane surfaces with a miscut greater than at least 0.35 degrees toward the m-direction. Light emitting devices are formed on the smooth (Al,Ga,In)N thin films. Devices fabricated on the smooth surfaces exhibit improved performance.
    Type: Application
    Filed: March 27, 2012
    Publication date: March 28, 2013
    Applicant: SORAA, Inc.
    Inventors: Arpan Chakraborty, Michael Grundmann, Anurag Tyagi
  • Patent number: 8274206
    Abstract: The present invention discloses a plurality of interdigitated pixels arranged in an array, having a very low series-resistances with improved current spreading and improved heat-sinking. Each pixel is a square with sides of dimension l. The series resistance is minimized by increasing the perimeter of an active region for the pixels. The series resistance is also minimized by shrinking the space between a mesa and n-contact for each pixel.
    Type: Grant
    Filed: March 10, 2011
    Date of Patent: September 25, 2012
    Assignee: The Regents of the University of California
    Inventors: Arpan Chakraborty, Likun Shen, Umesh K. Mishra
  • Patent number: 8263500
    Abstract: A method for fabricating a semiconductor laser device, by etching facets using a photoelectrochemical (PEC) etch, so that the facets are sufficiently smooth to support optical modes within a cavity bounded by the facets.
    Type: Grant
    Filed: February 1, 2010
    Date of Patent: September 11, 2012
    Assignee: The Regents of the University of California
    Inventors: Adele C. Tamboli, Evelyn L. Hu, Steven P. DenBaars, Arpan Chakraborty
  • Patent number: 8232564
    Abstract: Methods for wafer level fabricating of light emitting diode (LED) chips are disclosed with one embodiment of a method according to the present invention comprising providing a plurality of LEDs and then coating of the LEDs with a layer of first conversion material so that at least some light from the LEDs passes through the first conversion material. The light is converted to different wavelengths of light having a first conversion material emission spectrum. The LEDs are then coated with a layer of second conversion material arranged on the first layer of conversion. The second conversion material has a wavelength excitation spectrum, and at least some light from the LEDs passes through the second conversion material and is converted. The first conversion material emission spectrum does not substantially overlap with the second conversion material excitation spectrum.
    Type: Grant
    Filed: October 13, 2008
    Date of Patent: July 31, 2012
    Assignee: Cree, Inc.
    Inventor: Arpan Chakraborty
  • Publication number: 20120187412
    Abstract: A gallium and nitrogen containing substrate structure includes a handle substrate member having a first surface and a second surface and a transferred thickness of gallium and nitrogen material. The structure has a gallium and nitrogen containing active region grown overlying the transferred thickness and a recessed region formed within a portion of the handle substrate member. The substrate structure has a conductive material formed within the recessed region configured to transfer thermal energy from at least the transferred thickness of gallium and nitrogen material.
    Type: Application
    Filed: January 24, 2011
    Publication date: July 26, 2012
    Applicant: Soraa, Inc.
    Inventors: Mark P. D'Evelyn, Arpan Chakraborty, William Houck
  • Patent number: 8178888
    Abstract: A packaged light emitting device (LED) includes a light emitting diode configured to emit primary light having a peak wavelength that is less than about 465 nm and having a shoulder emission component at a wavelength that is greater than the peak wavelength, and a wavelength conversion material configured to receive the primary light emitted by the light emitting diode and to responsively emit light having a color point with a ccx greater than about 0.4 and a ccy less than about 0.6.
    Type: Grant
    Filed: February 1, 2008
    Date of Patent: May 15, 2012
    Assignee: Cree, Inc.
    Inventor: Arpan Chakraborty
  • Publication number: 20120091467
    Abstract: A method for growing reduced defect density planar gallium nitride (GaN) films is disclosed. The method includes the steps of (a) growing at least one silicon nitride (SiNx) nanomask layer over a GaN template, and (b) growing a thickness of a GaN film on top of the SiNx nanomask layer.
    Type: Application
    Filed: December 20, 2011
    Publication date: April 19, 2012
    Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Arpan Chakraborty, Kwang-Choong Kim, James S. Speck, Steven P. DenBaars, Umesh K. Mishra
  • Publication number: 20120076165
    Abstract: A light emitting active region between a first cladding layer and a second cladding layer, wherein the first cladding layer has a lower refractive index than a refractive index of the second cladding layer, and the first cladding layer and the second cladding layer are III-nitride based.
    Type: Application
    Filed: June 7, 2010
    Publication date: March 29, 2012
    Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Arpan Chakraborty, You-Da Lin, Shuji Nakamura, Steven P. Denbaars